TPSM8A29 [TI]

TPSM8A28, TPSM8A29 2.7-V to 16-V Input, 12-A, 15-A Buck Power Modules with Differential Remote Sense;
TPSM8A29
型号: TPSM8A29
厂家: TEXAS INSTRUMENTS    TEXAS INSTRUMENTS
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TPSM8A28, TPSM8A29 2.7-V to 16-V Input, 12-A, 15-A Buck Power Modules with Differential Remote Sense

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TPSM8A28, TPSM8A29  
SLVSFQ9A – AUGUST 2021 – REVISED NOVEMBER 2021  
TPSM8A28, TPSM8A29 2.7-V to 16-V Input, 12-A, 15-A Buck Power Modules with  
Differential Remote Sense  
1 Features  
3 Description  
TPSM8A28: 3-V to 16-V input range up to 12 A  
TPSM8A29: 4-V to 16-V input range up to 15 A  
2.7-V to 16-V input range with external bias  
ranging from 4.75 V to 5.3 V  
Output voltage range: 0.6 V to 5.5 V  
Integrated MOSFET, inductor, and basic passives  
D-CAP3control mode with fast load-step  
response  
Supports all ceramic output capacitors  
0.6-V reference voltage has ±1% tolerance from  
–40°C to +125°C junction temperature  
Selectable FCCM or auto-skip Eco-modefor high  
light-load efficiency  
Programmable current limit with RTRIP  
Pin-selectable switching frequency: 600 kHz, 800  
kHz, 1 MHz  
The TPSM8A28 and TPSM8A29 buck power modules  
are small and highly efficient. This module family  
contains integrates inductor and basic passives, and  
does not require external compensation, minimizing  
solution size.  
Features include differential remote sense, high-  
performance integrated MOSFETs, and an accurate  
0.6-V reference, D-CAP3control mode,selectable  
Skip-mode and programmable soft-start.  
TPSM8A28 and TPSM8A29 are lead-free, and fully  
RoHS compliant without exemption.  
Device Information  
PART NUMBER  
TPSM8A28  
PACKAGE(1)  
B3QFN-RDG  
B3QFN-RDG  
BODY SIZE (NOM)  
6.5 mm × 7.5 mm  
6.5 mm × 7.5 mm  
TPSM8A29  
Differential remote sense for high output accuracy  
Programmable soft-start time  
External reference input for tracking  
Prebiased start-up capability  
(1) For all available packages, see the orderable addendum at  
the end of the data sheet.  
Open-drain power-good output  
Hiccup for OC and UV faults, latch-off for OV faults  
6.5-mm × 7.5-mm × 4.0-mm, RDG package  
Fully RoHS compliant without exemption  
2 Applications  
Data center switch  
Core router  
Single board computer  
Optical module  
VOUT  
VIN  
VOUT  
DNC  
SW  
VIN  
EN  
VCC  
Vosns+  
Vosns-  
TPSM8A28  
TPSM8A29  
FB  
PGOOD  
MODE  
TRIP  
VSNS-  
SS/  
REFIN  
AGND  
PGND  
Net-tie  
Efficiency Graph  
Simplified Schematic  
An IMPORTANT NOTICE at the end of this data sheet addresses availability, warranty, changes, use in safety-critical applications,  
intellectual property matters and other important disclaimers. PRODUCTION DATA.  
 
 
 
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SLVSFQ9A – AUGUST 2021 – REVISED NOVEMBER 2021  
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Table of Contents  
1 Features............................................................................1  
2 Applications.....................................................................1  
3 Description.......................................................................1  
4 Revision History.............................................................. 2  
5 Pin Configuration and Functions...................................3  
6 Specifications.................................................................. 5  
6.1 Absolute Maximum Ratings........................................ 5  
6.2 ESD Ratings............................................................... 5  
6.3 Recommended Operating Conditions.........................5  
6.4 Thermal Information....................................................6  
6.5 Electrical Characteristics.............................................6  
6.6 Typical Characteristics................................................9  
7 Detailed Description......................................................10  
7.1 Overview...................................................................10  
7.2 Functional Block Diagram.........................................10  
7.3 Feature Description...................................................11  
7.4 Device Functional Modes..........................................19  
8 Application and Implementation..................................23  
8.1 Application Information............................................. 23  
8.2 Typical Application.................................................... 23  
9 Power Supply Recommendations................................34  
10 Layout...........................................................................35  
10.1 Layout Guidelines................................................... 35  
10.2 Layout Example...................................................... 35  
10.3 EMI..........................................................................36  
11 Device and Documentation Support..........................38  
11.1 Device Support........................................................38  
11.2 Documentation Support.......................................... 38  
11.3 Receiving Notification of Documentation Updates..38  
11.4 Support Resources................................................. 38  
11.5 Trademarks............................................................. 38  
11.6 Electrostatic Discharge Caution..............................38  
11.7 Glossary..................................................................38  
12 Mechanical, Packaging, and Orderable  
Information.................................................................... 39  
4 Revision History  
NOTE: Page numbers for previous revisions may differ from page numbers in the current version.  
Changes from Revision * (August 2021) to Revision A (November 2021)  
Page  
Changed TPSM8A29 from Advance Information to Production Data and added TPSM8A28........................... 1  
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5 Pin Configuration and Functions  
PGND  
VOUT  
VOUT 10  
25  
11  
20  
19  
PGND  
PGND  
1
21 PGND  
FB  
TRIP  
9
8
12  
13  
PGOOD  
SW  
VCC  
2
3
4
5
6
7
VSNS-  
AGND  
18 EN  
24 PGND  
22  
PGND  
MODE  
BOOT  
VIN  
7
6
5
4
3
2
14 AGND  
17  
16  
15  
VIN  
VIN  
SS/REF IN  
15  
16  
17  
VIN  
VIN  
23 VIN  
23 VIN  
VIN  
VIN  
SS/REF IN  
BOOT  
MODE  
VIN  
14 AGND  
PGND  
22  
24 PGND  
VCC  
SW  
18 EN  
AGND  
TRIP  
8
9
13  
12  
VSNS-  
FB  
PGOOD  
19  
20  
21 PGND  
PGND  
1
PGND  
VOUT 10  
25  
11  
PGND  
VOUT  
Figure 5-1. 25-Pin B3QFN RDG Package (Top View) Figure 5-2. 25-Pin B3QFN RDG Package (Bottom  
View)  
Table 5-1. Pin Functions  
PIN  
TYPE(1)  
DESCRIPTION  
NAME  
NO.  
1, 20, 21,  
22, 24, 25  
PGND  
G
O
Power ground of internal low-side MOSFET  
Output switching terminal of the power converter. No external connection needed. Do not  
connect.  
SW  
2
Internal 4.5-V LDO output. Float or connect to an external power supply between 4.75 V  
and 5.3 V to save the power losses on the internal LDO. The voltage source on this pin  
powers both the internal circuitry and gate driver. A 1-μF bypass capacitor is built in. No  
external bypass capacitors are required.  
VCC  
3
I/O  
Power-supply input pins for the integrated power MOSFET pair and the internal LDO.  
Place the decoupling input capacitors from the VIN pins to PGND pins as close as  
possible.  
4, 5, 16, 17,  
23  
VIN  
P
Supply rail for the high-side gate driver. A boot capacitor is integrated inside module. No  
external connection is needed. Do not connect.  
BOOT  
6
I/O  
The MODE pin sets Forced continuous-conduction mode (FCCM) or Skip-mode  
operation. It also selects the operating frequency by connecting a resistor from the MODE  
pin to AGND pin. ±1% tolerance resistor is recommended. See Table 7-1 for details.  
MODE  
AGND  
TRIP  
7
8, 14  
9
I
G
Ground pin. Reference point for the internal control circuits  
Current limit setting pin. Connect a resistor to AGND to set the current limit trip point.  
±1% tolerance resistor is highly recommended. See Section 7.3.9 for details on the OCL  
setting.  
I/O  
These pins are connected to the output terminal of inductor. Connect these pins to output  
bypass capacitors.  
VOUT  
FB  
10, 11  
12  
O
I
Output voltage feedback input. A resistor divider from the VOUT to VSNS– (tapped to FB  
pin) sets the output voltage.  
The return connection for a remote voltage sensing configuration. It is also used as  
ground for the internal reference. Short to AGND for a single-end sense configuration.  
VSNS–  
13  
I
Dual-function pin. Soft-start function: Connecting a capacitor to the VSNS– pin programs  
the soft-start time. Minimum soft-start time (1.5 ms) is fixed internally. REFIN function: The  
device always looks at the voltage on this SS/REFIN pin as the reference for the control  
loop. The internal reference voltage can be overridden by an external DC voltage source  
on this pin for tracking application.  
SS/REFIN  
EN  
15  
18  
I/O  
I
Enable pin. The enable pin turns the DC/DC switching converter on or off. Floating the EN  
pin before start-up disables the converter. The recommended operating condition for EN  
pin is maximum 5.5 V. Do not connect the EN pin to the VIN pin directly.  
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Table 5-1. Pin Functions (continued)  
PIN  
TYPE(1)  
DESCRIPTION  
NAME  
NO.  
Open-drain power-good status signal. When the FB voltage moves outside the specified  
limits, PGOOD goes low after a 2-µs delay.  
PGOOD  
19  
O
(1) I = Input, O = Output, P = Supply, G = Ground  
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6 Specifications  
6.1 Absolute Maximum Ratings  
over operating free-air temperature range (unless otherwise noted)(1)  
MIN  
–0.3  
–0.3  
–3.0  
–3.0  
–0.3  
–0.3  
–0.3  
–0.3  
–0.3  
MAX  
18  
UNIT  
VIN  
DC  
18  
SW  
Transient < 10 ns  
Transient < 2 ns  
22  
Input voltage(2)  
22  
BOOT  
24  
V
VSNS–  
+0.3  
6
TRIP, MODE, SS/REFIN, FB, EN  
PGOOD  
6
Output voltage  
VCC  
6
Mechanical shock  
Mil-STD-883H, Method 2002.5, 1 msec, 1/2 sine, mounted  
500  
20  
G
G
Mechanical vibration Mil-STD-883H, Method 2007.3, 20 to 2000 Hz  
Operating junction temperature, TJ  
–40  
–55  
125  
150  
°C  
°C  
Storage temperature, Tstg  
(1) Operation outside the Absolute Maximum Ratings may cause permanent device damage. Absolute Maximum Ratings do not imply  
functional operation of the device at these or any other conditions beyond those listed under Recommended Operating Conditions.  
If used outside the Recommended Operating Conditions but within the Absolute Maximum Ratings, the device may not be fully  
functional, and this may affect device reliability, functionality, performance, and shorten the device lifetime.  
(2) All voltages are with respect to network ground terminal.  
6.2 ESD Ratings  
VALUE  
±2000  
±500  
UNIT  
Human-body model (HBM), per ANSI/ESDA/JEDEC JS-001(1)  
Charged-device model (CDM), per ANSI/ESDA/JEDEC JS-002(2)  
Electrostatic  
discharge  
V(ESD)  
V
(1) JEDEC document JEP155 states that 500-V HBM allows safe manufacturing with a standard ESD control process. Manufacturing with  
less than 500-V HBM is possible with the necessary precautions.  
(2) JEDEC document JEP157 states that 250-V CDM allows safe manufacturing with a standard ESD control process.  
6.3 Recommended Operating Conditions  
over operating free-air temperature range (unless otherwise noted)  
MIN  
2.7  
MAX  
16  
UNIT  
VIN with valid external bias on VCC  
VIN with internal LDO, TPSM8A28  
VIN with internal LDO, TPSM8A29  
External reference to SS/REFIN  
External bias range for VCC  
VIN to enable the converter with internal LDO  
TRIP, MODE, FB, EN  
3.0  
16  
4.0  
16  
0.5  
1.2  
5.3  
V
Input voltage  
4.75  
3.3  
–0.1  
–50  
–0.1  
4.5  
5.5  
50  
VSNS– (refer to AGND)  
PGOOD  
mV  
V
5.5  
5.3  
10  
Output voltage  
VCC  
Input current  
PGOOD  
0
mA  
°C  
Junction temperature, TJ  
Operating junction temperature  
–40  
125  
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6.4 Thermal Information  
TPSM8A28 TPSM8A29  
THERMAL METRIC(1)  
RDG (B3QFN)  
25 PINS  
21.6  
UNIT  
RθJA  
Junction-to-ambient thermal resistance  
Junction-to-case (top) thermal resistance  
Junction-to-board thermal resistance  
°C/W  
°C/W  
°C/W  
RθJC(top)  
RθJB  
7.5  
13.0  
(1) For more information about traditional and new thermal metrics, see the Semiconductor and IC Package Thermal Metrics Application  
Report.  
6.5 Electrical Characteristics  
TJ = –40°C to +125°C, VCC = Internal 4.5V LDO, both TPSM8A29 and TPSM8A28 (unless otherwise noted)  
PARAMETER  
TEST CONDITIONS  
MIN  
TYP  
MAX  
UNIT  
SUPPLY CURRENT  
VIN operating nonswitching supply  
current  
VEN = 2 V, VFB = 0.65 V, VIN = 12 V, no  
external bias on the VCC pin  
IQ_VIN  
680  
9.5  
680  
75  
850  
20  
µA  
µA  
µA  
µA  
VEN = 0 V, VIN =12 V, no external bias on the  
VCC pin  
ISD_VIN  
IQ_VCC  
ISD_VCC  
VIN shutdown supply current  
VCC quiescent current  
VCC shutdown current  
TJ = 25°C, VEN = 2 V, VFB = 0.65 V, VIN = 5  
V, 5.0 V external bias on the VCC pin  
820  
85  
TJ = 25°C, VEN = 0 V, VIN = 0 V, 5.0 V  
external bias on the VCC pin  
REFERENCE VOLTAGE  
VINTREF Internal REF voltage  
TJ = 25°C  
600  
mV  
mV  
mV  
nA  
Internal REF voltage tolerance  
Internal REF voltage tolerance  
FB input current  
TJ = 0°C to 70°C  
TJ = –40°C to 125°C  
VFB = VINTREF  
597  
594  
603  
606  
100  
IFB  
50  
70  
OUTPUT DISCHARGE  
VIN = 12 V, VCC = internal LDO, Vsw = 0.5  
V, power conversion disabled  
RDischg  
Output discharge resistance  
Ω
SWITCHING FREQUENCY  
VIN = 12 V, VOUT = 1.2 V, RMODE = 0 Ω to  
AGND  
490  
720  
840  
620  
800  
750  
880  
VO switching frequency, FCCM  
operation  
VIN = 12 V, VOUT = 1.2 V, RMODE = 30.1 kΩ  
to AGND  
fSW  
kHz  
VIN = 12 V, VOUT = 1.2 V, RMODE = 60.4 kΩ  
to AGND  
1000  
70  
1250  
tON(min)  
tOFF(min)  
ENABLE  
VENH  
Minimum on time  
Minimum off time  
TJ = 25°C(1)  
85  
ns  
ns  
TJ = 25°C, HS FET gate falling to rising(1)  
220  
EN enable threshold voltage (rising)  
EN disable threshold voltage (falling)  
EN hysteresis voltage  
1.17  
0.97  
1.22  
1.02  
0.2  
1.27  
1.07  
V
V
VENL  
VENHYST  
VENLEAK  
V
EN input leakage current  
VEN = V  
0.5  
5
µA  
EN pin to AGND. EN floating disables the  
converter.  
EN internal pulldown resistance  
6500  
kΩ  
INTERNAL VCC LDO  
VCC  
Internal LDO output voltage  
VIN = 12 V, ILOAD = 2 mA  
VCC rising  
4.32  
2.80  
2.62  
4.5  
2.87  
2.7  
4.68  
2.94  
2.77  
V
V
V
VCC undervoltage-lockout (UVLO)  
threshold voltage  
VCCUVLO  
VCC falling  
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6.5 Electrical Characteristics (continued)  
TJ = –40°C to +125°C, VCC = Internal 4.5V LDO, both TPSM8A29 and TPSM8A28 (unless otherwise noted)  
PARAMETER  
TEST CONDITIONS  
MIN  
TYP  
MAX  
UNIT  
VCC undervoltage-lockout (UVLO)  
threshold voltage  
VCCUVLO  
VCCDO  
VCC hysteresis  
0.17  
V
LDO low-droop dropout voltage  
LDO overcurrent limit  
VIN = 3.0 V, IVCC_LOAD = 2 mA, TJ = 25°C  
All VINs, all temperature  
62  
75  
mV  
mA  
105  
158  
STARTUP  
VO rising from 0 V to 95% of final setpoint,  
CSS/REFIN = open  
tSS  
Soft-start time  
1
1.5  
ms  
SS/REFIN sourcing current  
SS/REFIN sinking current  
VSS/REFIN = 0 V  
VSS/REFIN = 1 V  
36  
12  
µA  
µA  
The delay from EN goes high to the first SW  
rising edge with internal LDO configuration.  
CVCC = 2.2 µF. CSS/REFIN = 220 nF  
EN to first switching delay, internal  
LDO  
0.93  
2
ms  
The delay from EN goes high to the  
first SW rising edge with external VCC  
bias configuration. VCC bias must reach  
regulation before EN ramp up. CSS/REFIN  
= 220 nF.  
EN to first switching delay, external  
VCC bias  
550  
900  
µs  
PGOOD COMPARATOR  
FB rising, PGOOD low to high  
FB rising, PGOOD high to low  
FB falling, PGOOD high to low  
FB rising, PGOOD stays high  
89%  
113%  
77%  
92.5%  
116%  
95%  
119%  
83%  
VPGTH  
PGOOD threshold  
80%  
VPGTH  
IPG  
OOB (out-of-bounds) threshold  
PGOOD sink current  
103%  
105.5%  
108%  
VPGOOD = 0.4 V, VIN = 12 V, VCC = Internal  
LDO  
25  
mA  
mV  
IPGOOD = 5.5 mA, VIN = 12 V, VCC = internal  
LDO  
IPG  
PGOOD low-level output voltage  
PGOOD delay time  
400  
Delay for PGOOD from low to high  
Delay for PGOOD from high to low  
1.0  
0.5  
1.4  
5
ms  
µs  
tPG_delay  
PGOOD leakage current when  
pulled high  
IPG_lkg  
TJ = 25°C, VPGOOD = 3.3 V, VFB = VINTREF  
5
850  
µA  
mV  
mV  
V
VIN = 0 V, VCC = 0 V, VEN = 0 V, PGOOD  
pulled up to 3.3 V through a 100-kΩ resistor  
710  
850  
PGOOD clamp low-level output  
voltage  
VIN = 0 V, VCC = 0 V, VEN = 0 V, PGOOD  
pulled up to 3.3 V through a 10-kΩ resistor  
1000  
1.5  
Minimum VCC for valid PGOOD  
output  
OVERCURRENT PROTECTION  
RTRIP  
RTRIP  
TRIP pin resistance range  
TRIP pin resistance range  
TPSM8A28  
TPSM8A29  
4.02  
0
14.7  
14.7  
kΩ  
kΩ  
Current limit threshold, TPSM8A29 Valley current on LS FET, 0 kΩ ≤ RTRIP ≤ 3.3  
IOCL  
14.8  
18.4  
21.7  
A
only  
kΩ TPSM8A29 only  
IOCL  
Current limit threshold  
Current limit threshold  
Current limit threshold  
KOCL for RTRIP equation  
Negative current limit threshold  
Valley current on LS FET, RTRIP = 4.02 kΩ  
Valley current on LS FET, RTRIP = 4.99 kΩ  
Valley current on LS FET, RTRIP = 10 kΩ  
12.0  
9.9  
14.2  
12.0  
16.3  
14.1  
8.1  
A
A
IOCL  
IOCL  
3.9  
6.0  
A
KOCL  
INOCL  
60000  
–10  
A Ω  
A
All VINs  
–12  
–8  
Zero-cross detection current  
threshold, open loop  
IZC  
VIN = 12 V, VCC = Internal LDO  
400  
mA  
UVLO  
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6.5 Electrical Characteristics (continued)  
TJ = –40°C to +125°C, VCC = Internal 4.5V LDO, both TPSM8A29 and TPSM8A28 (unless otherwise noted)  
PARAMETER  
TEST CONDITIONS  
MIN  
TYP  
MAX  
2.7  
UNIT  
V
Rising  
Falling  
2.1  
2.4  
VINUVLO  
VIN UVLO threshold voltage  
1.55  
1.85  
2.15  
V
Overvoltage-protection (OVP)  
threshold voltage  
VOVP  
113%  
116%  
119%  
THERMAL SHUTDOWN  
Thermal shutdown threshold(1)  
Thermal shutdown hysteresis(1)  
Temperature rising  
165  
30  
°C  
°C  
TSDN  
(1) Specified by design. Not production tested.  
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6.6 Typical Characteristics  
100  
95  
90  
85  
80  
75  
70  
65  
60  
55  
100  
95  
90  
85  
80  
75  
70  
65  
60  
55  
50  
Output Voltage  
Output Voltage  
0.6 V  
0.8 V  
1.0 V  
1.2 V  
1.8 V  
2.5 V  
3.3 V  
5.0 V  
0.6 V  
0.8 V  
1.0 V  
1.2 V  
1.8 V  
2.5 V  
3.3 V  
5 V  
0
1
2
3
4
5
6
7
8
9 10 11 12 13 14 15  
IOUT (A)  
0
1
2
3
4
5
6
7
8
9 10 11 12 13 14 15  
Figure 6-2. Efficiency vs Output Current, 12 VIN, 600 KHz,  
FCCM, Internal VCC LDO  
IOUT (A)  
Figure 6-1. Efficiency vs Output Current, 12 VIN, 600 KHz, Skip  
Mode, Internal VCC LDO  
115  
110  
105  
100  
95  
115  
110  
105  
100  
95  
90  
90  
85  
85  
80  
80  
400 LFM  
200 LFM  
100 LFM  
400 LFM  
200 LFM  
100 LFM  
75  
75  
70  
70  
Nat Conv  
65  
Nat Conv  
65  
0
3
6
Output Current (A)  
9
12  
15  
0
3
6
Output Current (A)  
9
12  
15  
PTPS  
PTPS  
Figure 6-3. SOA, 12 V 1VoutIN, 600 KHz, FCCM, Internal VCC  
LDO  
Figure 6-4. SOA, 12 V 3.3VoutIN, 600 KHz, FCCM, Internal VCC  
LDO  
115  
110  
105  
100  
95  
115  
110  
105  
100  
95  
90  
90  
85  
85  
80  
80  
400 LFM  
100 LFM  
200 LFM  
400 LFM  
200 LFM  
100 LFM  
75  
75  
70  
70  
Nat Conv  
65  
Nat Conv  
65  
0
2.5  
5 7.5  
Output Current (A)  
10  
12.5  
0
3
6
Output Current (A)  
9
12  
15  
PTPS  
PTPS  
Figure 6-5. SOA, 12 V 5.0VoutIN, 600 KHz, FCCM, Internal VCC  
LDO  
Figure 6-6. SOA, 5Vin 1.0VoutIN, 600 KHz, FCCM, Internal VCC  
LDO  
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7 Detailed Description  
7.1 Overview  
The TPSM8A28 and TPSM8A29 power modules feature high effcieincy and small footprint. These devices are  
suitable for low voltage point-of-load applications up to 15 A. The conversion input voltage ranges from 2.7 V  
to 16 V, and the external VCC input voltage ranges from 4.75 V to 5.3 V, and output voltage ranges from 0.6  
V to 5.5 V. These power modules uses D-CAP3mode control combined with adaptive on-time architecture.  
The D-CAP3mode uses emulated current information to control the modulation and tracks the preset switching  
frequency over a wide range of input and output voltages. Advantages of this control scheme is that it does  
not require a phase-compensation network outside, which makes the device easy-to-use and also allows low  
external component count. Further advantage of this control scheme is that it supports stable operation with all  
low-ESR output capacitors (such as ceramic capacitor and low-ESR polymer capacitor). It also adjusts switching  
frequency as needed during load-step transient.  
7.2 Functional Block Diagram  
PGOOD  
Soft-start  
PG Falling  
SS/REFIN  
generator  
Threshold  
+
UV  
Internal  
Soft-start  
VIN  
EN  
PGOOD Driver  
LDO  
+
OV  
VCC  
Reference  
generator  
VCC  
PG Rising  
Threshold  
FB  
BOOT  
REG  
PGOOD  
+
+
+
VCCOK  
Control Logic  
VINOK  
BOOT  
VIN  
VCC UVLO  
VSNS-  
VIN  
PWM  
+
VIN UVLO  
ñ
ñ
ñ
ñ
ñ
ñ
ñ
ñ
tON generator  
Minimum On/Off  
Light Load  
FCCM/Skip  
Internal  
Ramp  
VCC UVLO  
VIN UVLO  
VOUT  
XCON  
EN  
Enable  
Output OVP/UVP  
Thermal Shutdown  
EN  
+
1.22 V / 1.02 V  
SW  
Valley Current  
Limit & ZCD  
OC  
Limit  
TRIP  
MODE  
AGND  
PGND  
MODE  
Selection  
Fsw &  
Mode  
+
ThermalOK  
165°C /  
135°C  
Output Soft  
Discharge  
GND  
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7.3 Feature Description  
7.3.1 Internal VCC LDO and Using External Bias on VCC Pin  
The TPSM8A28 and TPSM8A29 power modules have internal 4.5-V LDO that takes input from VIN rail and  
output to VCC. When the VIN voltage rises above the VINUVLO rising threshold, and the EN voltage rises above  
the enable threshold (typically 1.22 V), the internal LDO is enabled and starts regulating output voltage on the  
VCC pin. The VCC voltage provides the bias voltage for the internal analog circuitry and also provides the supply  
voltage for the gate drives.  
The VCC pin has an internal bypass capacitor integrated inside the module and does not require external  
bypassing. An external bias that is above the output voltage of the internal LDO can override the internal LDO.  
This enhances the efficiency of the converter because the VCC current now runs off this external bias instead of  
the internal linear regulator.  
The VCC UVLO circuit monitors the VCC pin voltage and disables the whole converter when VCC falls below the  
VCC UVLO falling threshold. Maintaining a stable and clean VCC voltage is required for a smooth operation of  
the device.  
The following are considerations when using an external bias on the VCC pin:  
When the external bias is applied on the VCC pin early enough (for example, before EN signal comes in), the  
internal LDO is always forced off and the internal analog circuits has a stable power supply rail at their power  
enable.  
(Not recommended) If the external bias is applied on the VCC pin late (for example, after EN signal comes  
in), any power-up and power-down sequencing can be applied as long as there is no excess current pulled  
out of the VCC pin. It is important to understand that an external discharge path on the VCC pin, which can  
pull a current higher than the current limit of the internal LDO from the VCC pin, can potentially turn off VCC  
LDO thereby shutting down the converter output.  
A good power-up sequence is when at least the VIN UVLO rising threshold or EN rising threshold is satisfied  
later than the VCC UVLO rising threshold. For example, VIN applied first, then the external bias applied, and  
then EN signal goes high.  
7.3.2 Enable  
When the EN pin voltage rises above the enable threshold voltage (typically 1.22 V) and VIN rises above the  
VIN UVLO rising threshold, the device enters its internal power-up sequence. The EN to first switching delay is  
specified in the Start-Up section in the Electrical Characteristics table.  
When using the internal VCC LDO, the internal power-up sequence includes three sequential steps. During the  
first period, the VCC voltage is charged up on the VCC bypass capacitor by a 11-mA current source. The length  
of this VCC LDO start-up time varies with the capacitance on the VCC pin. However, if VIN voltage ramps up  
very slowly, the VCC LDO output voltage is limited by theVIN voltage level, so the VCC LDO start-up time can  
be extended longer. Since the VCC LDO start-up time is relatively long, the internal VINTREF build-up happens  
and finishes during this period. Once the VCC voltage crosses above the VCC UVLO rising threshold (typically  
2.87 V), the device moves to the second step, power-on delay. The MODE pin setting detection, SS/REFIN pin  
detection, and control loop initialization are finished within this 285-μs delay. The soft-start ramp starts when the  
285-μs power-on delay finishes. During the soft-start ramp power stage, switching does not happen until the  
SS/REFIN pin voltage reaches 50 mV. This introduces a SS delay, which varies with the external capacitance on  
the SS/REFIN pin.  
Figure 7-1 shows an example where the VIN UVLO rising threshold is satisfied earlier than the EN rising  
threshold. In this scenario, the VCC UVLO rising threshold becomes the gating signal to start the internal  
power-up sequence, and the sequence between VIN and EN does not matter.  
When using an external bias on the VCC pin, the internal power-up sequence still includes three sequential  
steps. The first period is much shorter since the VCC voltage is built up already. A 100-µs period allows the  
internal references start up and stabilize. This 100-µs period includes not only the 0.6-V VINTREF, but also all of  
the other reference voltages for various functions. The device then moves to the second step, power-on delay.  
The MODE pin setting detection, SS/REFIN pin detection, and control loop initialization are finished within this  
285-μs delay. The soft-start ramp starts when the 285-μs power-on delay finishes. During the soft-start ramp  
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power stage, switching does not happen until the SS/REFIN pin voltage reaches 50 mV. This introduced a SS  
delay, which varies with the external capacitance on the SS/REFIN pin.  
Figure 7-2 shows an example where both the VIN UVLO rising threshold and EN rising threshold are satisfied  
later than the VCC UVLO rising threshold. In this scenario, the VIN UVLO rising threshold or EN rising threshold,  
whichever is satisfied later, becomes the gating signal to start the internal power-up sequence.  
2.4V  
VIN  
1.22V  
EN  
2.87V  
VCC LDO  
Power-on  
delay  
VCC LDO  
Startup  
50mV  
SS/REFIN  
SS delay  
FB  
SW pulses are omitted to  
simplify the illustration  
……  
SW  
Figure 7-1. Internal Power-up Sequence Using Internal LDO  
2.87V  
VCC  
External  
3.3V Bias  
2.4V  
VIN  
EN  
1.22V  
Power-on  
delay  
VREF  
Build-up  
SS/REFIN  
50mV  
SS delay  
FB  
SW pulses are omitted to  
simplify the illustration  
……  
SW  
Figure 7-2. Internal Power-up Sequence Using External Bias  
The EN pin has an internal filter to avoid unexpected ON or OFF due to small glitches. The time constant of this  
RC filter is 5 µs. For example, when applying a 3.3-V voltage source on the EN pin, which jumps from 0 V to  
3.3 V with ideal rising edge, the internal EN signal reaches 2.086 V after 5 µs, which is 63.2% of applied 3.3-V  
voltage level.  
A internal pulldown resistor is implemented between the EN pin and AGND pin. To avoid impact to the EN  
rising/falling threshold, this internal pulldown resistor is set to 6.5 MΩ. With this pulldown resistor, floating the  
EN pin before start-up keeps the device under disabled state. During nominal operation when the power stage  
switches, this large internal pulldown resistor may not have enough noise immunity to hold the EN pin low.  
The recommended operating condition for EN pin is maximum 5.5 V. Do not connect the EN pin to the VIN pin  
directly.  
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7.3.3 Output Voltage Setting  
The output voltage is programmed by the voltage divider resistors, RFB_HS and RFB_LS. Connect RFB_HS between  
the FB pin and the positive node of the load, and connect RFB_LS between the FB pin and the VSNS– pin. The  
recommended RFB_LS value is 10 kΩ, ranging from 1 kΩ to 20 kΩ. Determine RFB_HS by using Equation 1.  
VO - V  
INTREF  
RFB _HS  
=
ìRFB _LS  
V
INTREF  
(1)  
The FB accuracy is determined by two elements. The first element is the accuracy of the internal 600-mV  
reference, which is applied to the SS/REFIN pin unless an external VREF is applied. Both TPSM8A28 and  
TPSM8A29 offer ±0.5% VINTREF accuracy from a 0°C to 85°C temperature range, and ±1.0% VINTREF accuracy  
from a -40°C to 125°C temperature range. The second element is the SS/REFIN-to-FB accuracy, which tells the  
user how accurately the control loop regulates the FB node to the SS/REFIN pin. The TPSM8A29 offers ±0.6%  
SS/REFIN-to-FB accuracy from a -40°C to 125°C temperature range. For example, when operating from a 0°C  
to 85°C temperature range, the total FB accuracy is ±1.1%, which includes the impact from the chip junction  
temperature and also the variation from part to part.  
To improve the overall VOUT accuracy, using ±1% accuracy or better resistor for FB voltage divider is highly  
recommended.  
Regardless of remote sensing or single-end sensing connection, the FB voltage divider, RFB_HS and RFB_LS  
must be always placed as close as possible to the device.  
,
7.3.3.1 Remote Sense  
The TPSM8A28 and TPSM8A29 modules feature remote sense function through the FB and VSNS– pins.  
Remote sense function compensates a potential voltage drop on the PCB traces, helping maintain VOUT  
tolerance under steady state operation and load transient event. Connecting the FB voltage divider resistors  
to the remote location allows sensing of the output voltage at a remote location. The connections from the FB  
voltage divider resistors to the remote location must be a pair of PCB traces with at least 12-mil trace width, and  
must implement Kelvin sensing across a high bypass capacitor of 0.1 μF or higher. The ground connection of the  
remote sensing signal must be connected to the VSNS– pin. The VOUT connection of the remote sensing signal  
must be connected to the feedback resistor divider with the lower feedback resistor, RFB_LS, terminated at the  
VSNS– pin. To maintain stable output voltage and minimize the ripple, the pair of remote sensing lines must stay  
away from any noise sources such as inductor and SW nodes, or high frequency clock lines. It is recommended  
to shield the pair of remote sensing lines with ground planes above and below.  
Single-ended VO sensing is often used for local sensing. For this configuration, connect the higher FB resistor,  
RFB_HS, to a high-frequency local bypass capacitor of 0.1 μF or higher, and short VSNS– to AGND.  
The recommended VSNS– operating range (refer to AGND pin) is –50 mV to +50 mV.  
7.3.4 Internal Fixed Soft Start and External Adjustable Soft Start  
The TPSM8A28 and TPSM8A29 power modules allow both internal fixed soft start and external adjustable soft  
start. The internal soft-start time is 1.5 ms. The soft-start time can be increased by adding a soft-start (SS)  
capacitor between the SS/REFIN and VSNS– pins. The total SS capacitor value can be determined by Equation  
2. The device follows the longer SS ramp among the internal SS time and the SS time determined by the  
external SS capacitors.  
The device does not require a capacitor from the SS/REFIN pin to AGND, so it is not recommended to place a  
capacitor from the SS/REFIN pin to AGND. If both CSS/REFIN-to-VSNS– and CSS/REFIN-to-AGND capacitors exist,  
place CSS/REFIN-to-VSNS– more closely to the shortest trace back to the VSNS– pin.  
The SS/REFIN pin is discharged internally during the internal power-on delay to make sure the soft-start ramp  
always starts from zero.  
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t
SS(ms)ì36(mA )  
CSS(nF)=  
VINTREF( V)  
(2)  
7.3.5 External REFIN for Output Voltage Tracking  
The TPSM8A28 and TPSM8A29 provide analog input pin (SS/REFIN) to accept an external reference (that is,  
a DC voltage source). The device always looks at the voltage on this SS/REFIN pin as the reference for the  
control loop. When an external voltage reference is applied between the SS/REFIN pin and VSNS– pin, it acts  
as the reference voltage, so the FB voltage follows this external voltage reference exactly. The same ±0.6%  
SS/REFIN-to-FB accuracy from a -40°C to 125°C temperature range applies here too.  
In the middle of internal power-on delay, a detection circuit senses the voltage on the SS/REFIN pin to tell  
whether an active DC voltage source is applied. Before the detection happens, the SS/REFIN pin tries to  
discharge any energy on the SS/REFIN capacitors through an internal 120-Ω resistor to AGND, lasting 125  
µs. Then, within a 32-µs window, the detection circuit compares the SS/REFIN pin voltage with an internal  
reference equal to 89% of VINTREF. This discharge operation makes sure a SS capacitor with left-over energy is  
not wrongly detected as a voltage reference. If the external voltage reference failed to supply sufficient current  
and hold a voltage level higher than 89% of VINTREF, the SS/REFIN detection circuit provides a wrong detection  
result.  
If the detection result is that the SS/REFIN pin voltage holds higher than 89% of VINTREF, which tells an active  
DC voltage source is used as external reference, the device always uses the SS/REFIN pin voltage instead  
of the internal VINTREF as the reference for PGOOD threshold, VOUT OVP, and VOUT UVP threshold. On this  
configuration, since the SS/REFIN pin senses a DC voltage and no soft-start ramp on this pin, the internal fixed  
soft start is used for start-up. Once the internal soft-start ramp finishes, the power-good signal becomes high  
after a 1.06-ms internal delay. The whole internal soft-start ramp takes 2 ms to finish because the soft-start ramp  
goes beyond VINTREF  
.
If the detection result is that SS/REFIN pin voltage falls below 89% of VINTREF, which tells no external reference  
is connected, the device first uses the internal fixed VINTREF as the reference for PGOOD threshold, VOUT OVP,  
and VOUT UVP threshold. On this configuration, given the SS/REFIN pin sees a soft-start ramp on this pin, the  
slower ramp amongst the internal fixed soft start and the external soft start determines the start-up of FB. Once  
both the internal and external soft-start ramp finishes, the power-good signal becomes high after a 1.06-ms  
internal delay. The whole internal soft-start ramp takes 2 ms to finish. The external soft-start done signal goes  
high when FB reaches a threshold equal to VINTREF – 50 mV. The device waits for the PGOOD status transition  
from low to high, then starts using the SS/REFIN pin voltage instead of the internal VINTREF as the reference for  
PGOOD threshold, VOUT OVP, and VOUT UVP threshold.  
On this external REFIN configuration, applying a stabilized DC external reference to SS/REFIN pin before the  
EN high signal is recommended. During the internal power-on delay, the external reference must be capable  
of holding the SS/REFIN pin equal to or higher than 89% of VINTREF, so that the device can correctly detect  
the external reference and choose the right thresholds for power good, VOUT OVP, and VOUT UVP. After the  
power-good status transits from low to high, the external reference can be set in a range of 0.5 V to 1.2 V. To  
overdrive the SS/REFIN pin during nominal operation, the external reference has to be able to sink more than  
36-µA current if the external reference is lower than the internal VINTREF, or source more than 12-µA current  
if the external reference is higher than the internal VINTREF. When driving the SS/REFIN pin by an external  
reference through a resistor divider, the resistance of the divider must be low enough to provide the sinking or  
sourcing current capability.  
If the external voltage source must transition up and down between any two voltage levels, the slew rate must be  
no more than 1 mV/μs.  
7.3.6 Frequency and Operation Mode Selection  
The TPSM8A29 provides forced CCM operation for tight output ripple applications and auto-skip Eco-mode for  
high light-load efficiency. The TPSM8A29 allows users to select the switching frequency and operation mode by  
connecting a resistor from the MODE pin to the AGND pin. Table 7-1 lists the resistor values for the switching  
frequency and operation mode selection. TI recommends ±1% tolerance resistors with a typical temperature  
coefficient of ±100 ppm/°C.  
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The MODE state is set and latched during the internal power-on delay period. Changing the MODE pin  
resistance after the power-on delay does not change the status of the device. The internal circuit sets the  
MODE pin status to 600 kHz / Skip mode if the MODE pin is left open during the power-on delay period.  
To make sure the internal circuit detects the desired option correctly, do not place any capacitor on the MODE  
pin.  
Table 7-1. MODE Pin Selection  
MODE PIN  
CONNECTIONS  
OPERATION MODE UNDER LIGHT  
LOAD  
SWITCHING FREQUENCY  
(fSW) (kHz)  
Short to VCC  
Skip-mode  
Skip-mode  
600  
800  
243-kΩ ± 10% to AGND  
121-kΩ ± 10% to AGND  
60.4-kΩ ±10% to AGND  
30.1-kΩ ±10% to AGND  
Short to AGND  
Skip-mode  
1000  
1000  
800  
Forced CCM  
Forced CCM  
Forced CCM  
600  
7.3.7 D-CAP3™ Control  
The TPSM8A28 and TPSM8A29 use D-CAP3mode control to achieve fast load transient while maintaining the  
ease-of-use feature. The D-CAP3control architecture includes an internal ripple generation network, enabling  
the use of very low ESR output capacitors such as multi-layered ceramic capacitors (MLCC) and low-ESR  
polymer capacitors. No external current sensing network or voltage compensators are required with D-CAP3™  
control architecture. The role of the internal ripple generation network is to emulate the ripple component of the  
inductor current information and then combine it with the voltage feedback signal to regulate the loop operation.  
The amplitude of the ramp is determined by VIN, VOUT, operating frequency, and the R-C time-constant of the  
internal ramp circuit. At different switching frequency settings (see Table 7-1), the R-C time-constant varies  
to maintain a relatively constant ramp amplitude. Also, the device uses internal circuitry to cancel the DC  
offset caused by the injected ramp, and significantly reduce the DC offset caused by the output ripple voltage,  
especially under light-load condition.  
For any control topologies supporting no external compensation design, there is a minimum range, maximum  
range, or both, of the output filter it can support. The output filter used is a low-pass L-C circuit. This L-C filter  
has double pole that is described in Equation 3.  
1
f
=
P
2´ p´ L  
´ C  
OUT  
OUT  
(3)  
At low frequencies, the overall loop gain is set by the output set-point resistor divider network and the internal  
gain. The low frequency L-C double pole has a 180-degree drop in phase. At the output filter frequency, the  
gain rolls off at a –40 dB per decade rate and the phase drops rapidly. The internal ripple generation network  
introduces a high-frequency zero that reduces the gain roll off from –40 dB to –20 dB per decade and increases  
the phase by 90 degrees per decade above the zero frequency.  
The inductor and capacitor selected for the output filter must be such that the double pole of Equation 3 is  
located no higher than 1/30th of operating frequency. Choose very small output capacitance leads to relatively  
high frequency L-C double pole, which allows the overall loop gain to stay high until the L-C double frequency.  
Make sure the zero from the internal ripple generation network has relatively high frequency as well. The loop  
with very small output capacitance can have too high of crossover frequency, which is not desired. Use Table 7-2  
to help locate the internal zero based on the selected switching frequency.  
Table 7-2. Locating the Zero  
SWITCHING  
FREQUENCIES  
(fSW) (kHz)  
ZERO (fZ) LOCATION (kHz)  
600  
800  
84.5  
84.5  
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Table 7-2. Locating the Zero (continued)  
SWITCHING  
FREQUENCIES  
(fSW) (kHz)  
ZERO (fZ) LOCATION (kHz)  
1000  
106  
In general, where reasonable (or smaller) output capacitance is desired, the output ripple requirement and load  
transient requirement can be used to determine the necessary output capacitance for stable operation.  
1
f
=
= f  
Z
P
2´ p´ L  
´ C  
OUT  
OUT  
(4)  
For the maximum output capacitance recommendation, select the inductor and capacitor values so that the L-C  
double pole frequency is no less than 1/100th of the operating frequency. With this starting point, verify the small  
signal response on the board using the following one criteria:  
Phase margin at the loop crossover is greater than 50 degrees  
The actual maximum output capacitance can go higher as long as the phase margin is greater than 50 degrees.  
However, small signal measurement (bode plot) must be done to confirm the design.  
If MLCC is used, consider the derating characteristics to determine the final output capacitance for the design.  
For example, when using an MLCC with specifications of 10 µF, X5R, and 6.3 V, the derating by DC bias and AC  
bias are 80% and 50%, respectively. The effective derating is the product of these two factors, which in this case  
is 40% and 4 µF. Consult with capacitor manufacturers for specific characteristics of the capacitors to be used in  
the system/applications.  
For higher output voltage at or above 2 V, additional phase boost can be required in order to secure sufficient  
phase margin due to phase delay/loss for higher output voltage (large on time (tON)) setting in a fixed on-time  
topology based operation. A feedforward capacitor placed in parallel with RFB_HS wasfound to be very effective  
to boost the phase margin at loop crossover. Refer to Optimizing Transient Response of Internally Compensated  
dc-dc Converters With Feedforward Capacitor Application Report for details.  
Besides boosting the phase, a feedforward capacitor feeds more VOUT node information into the FB node by the  
AC coupling. This feedforward during load transient event enables the control loop a faster response to VOUT  
deviation. However, this feedforward during steady state operation also feeds more VOUT ripple and noise into  
FB. High ripple and noise on FB usually leads to more jitter, or even double pulse behavior. To determine the  
final feedforward capacitor value, impacts to phase margin, load transient performance, and ripple and nosie on  
FB must be all considered. Using Frequency Analysis equipment to measure the crossover frequency and the  
phase margin is recommended.  
7.3.8 Low-Side FET Zero-Crossing  
A zero-crossing circuit is used to perform the zero inductor-current detection during Skip-mode operation. The  
function compensates the inherent offset voltage of the Z-C comparator and delay time of the Z-C detection  
circuit. The zero-crossing threshold is set to a positive value to avoid negative inductor current. As a result, the  
TPSM8A28 and TPSM8A29 power modules deliver better light-load efficiency.  
7.3.9 Current Sense and Positive Overcurrent Protection  
For a buck converter, during the on time of the high-side FET, the switch current increases at a linear rate  
determined by the following:  
input voltage  
output voltage  
the on time  
the output inductor value  
During the on time of the low-side FET, this current decreases linearly. The average value of the switch current  
equals to the load current.  
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The output overcurrent limit (OCL) is implemented using a cycle-by-cycle valley current detect control circuit.  
The inductor current is monitored during the on time of the low-side FET by measuring the low-side FET  
drain-to-source current. If the measured drain-to-source current of the low-side FET is above the current limit  
threshold, the low-side FET stays ON until the current level becomes lower than the current limit threshold.  
This type of behavior reduces the average output current sourced by the device. During an overcurrent  
condition, the current to the load exceeds the current to the output capacitors. Thus, the output voltage tends to  
decrease. Eventually, when the output voltage falls below the undervoltage-protection threshold (80%), the UVP  
comparator detects it and shuts down the device after a wait time of 68 µs. The device then enters a hiccup  
sleep period for approximately 14 ms. After this waiting period, the device attempts to start up again/remains  
latched off state (both high-side and low-side FETs are latched off) until a reset of VIN or a re-toggling on the EN  
pin. Figure 7-3 shows the cycle-by-cycle valley current limit behavior as well as the wait time before the device  
shuts down.  
If an OCL condition happens during start-up, the device still has cycle-by-cycle current limit based on low-side  
valley current. After soft start is finished, the UV event, which is caused by the OC event, shuts down the device  
and enters Hiccup mode with a wait time of 68 µs.  
The resistor, RTRIP, connected from the TRIP pin to AGND sets current limit threshold. ±1% tolerance resistor is  
highly recommended because a worse tolerance resistor provides less accurate OCL threshold.  
To protect the device from unexpected connection on the TRIP pin, an internal fixed OCL clamp is implemented.  
This internal OCL clamp limits the maximum valley current on LS FET when TRIP pin has too small resistance to  
AGND, or is accidently shorted to ground.  
6ì104  
KOCL  
RTRIP  
=
=
V -V ì V  
V -V ì V  
(
)
(
)
1
2
1
1
2
1
IN  
O
O
IN  
O
O
IOCLIM  
-
ì
ì
IOCLIM  
-
ì
ì
V
Lì fSW  
V
L ì fSW  
IN  
IN  
(5)  
where  
IOCLIM is overcurrent limit threshold for load current in A  
RTRIP is TRIP resistor value in Ω  
VIN is input voltage value in V  
VO is output voltage value in V  
L is output inductor value in µH  
fSW is switching frequency in MHz  
Figure 7-3. Overcurrent Protection  
7.3.10 Low-Side FET Negative Current Limit  
The device has a fixed, cycle-by-cycle negative current limit. Similar with the positive overcurrent limit, the  
inductor current is monitored during the on time of the low-side FET. To prevent too large negative current  
flowing through low-side FET, when the low-side FET detects –10-A current (typical threshold), the device  
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turns off low-side FET and then turns on high-side FET for a proper on time (determined by VIN/VO/fSW). After  
high-side FET on time expires, the low-side FET turns on again.  
The device must not trigger the –10-A negative current limit threshold during nominal operation, unless a  
too small inductor value is chosen or the inductor becomes saturated. This negative current limit is used to  
discharge output capacitors during an output OVP or an OOB event. See Section 7.3.12 and Section 7.3.13 for  
details.  
7.3.11 Power Good  
TPSM8A28 and TPSM8A29 have gower-good output that output high when the converter output voltage is within  
specification. The power-good output is an open-drain output and must be pulled up to VCC pin or an external  
voltage source (< 5.5 V) through a pullup resistor (typically 30.1 kΩ). The recommended power-good pullup  
resistor value is 1 kΩ to 100 kΩ.  
Once both the internal and external soft-start ramp finishes, the power-good signal becomes high after a  
1.06-ms internal delay. The whole internal soft-start ramp takes 2 ms to finish. The external soft-start done signal  
goes high when FB reaches a threshold equal to VINTREF – 50 mV. If the FB voltage drops to 80% of the VINTREF  
voltage or exceeds 116% of the VINTREF voltage, the power-good signal latches low after a 2-µs internal delay.  
The power-good signal can only be pulled high again after re-toggling EN or a reset of VIN.  
If the input supply fails to power up the device, for example VIN and VCC both stays at zero volts, the  
power-good pin clamps low by itself when this pin is pulled up through an external resistor.  
Once the VCC voltage level rises above the minimum VCC threshold for valid PGOOD output (maximum 1.5 V),  
internal power-good circuit is enabled to hold the PGOOD pin to the default status. By default, PGOOD is pulled  
low and this low-level output voltage is no more than 400 mV with 5.5-mA sinking current. The power-good  
function is fully activated after the soft-start operation is completed.  
7.3.12 Overvoltage and Undervoltage Protection  
The TPSM8A28 and TPSM8A29 devices monitor a resistor-divided feedback voltage to detect overvoltage  
and undervoltage events. When the FB voltage becomes lower than 80% of the VINTREF voltage, the UVP  
comparator detects and an internal UVP delay counter begins counting. After the 68-µs UVP delay time, the  
device enters Hiccup mode and re-starts with a sleep time of 14 ms. The UVP function enables after the  
soft-start period is complete.  
When the FB voltage becomes higher than 116% of the VINTREF voltage, the OVP comparator detects and the  
circuit latches OFF the high-side MOSFET driver and turns on the low-side MOSFET until reaching a negative  
current limit INOCL. Upon reaching the negative current limit, the low-side FET is turned off, and the high-side  
FET is turned on again for a proper on time (determined by VIN/VO/fSW). The device operates in this cycle until  
the output voltage is pulled lower than the UVP threshold voltage for 68 µs. After the 68-µs UVP delay time, both  
the high-side FET and the low-side FET are latched OFF. The fault is cleared with a reset of VIN or by retoggling  
the EN pin.  
During the 68-μs UVP delay time, if output voltage becomes higher than the UV threshold, thus it is not qualified  
for the UV event, the timer is reset to zero. When the output voltage triggers the UV threshold again, the timer of  
the 68 μs re-starts.  
7.3.13 Out-Of-Bounds (OOB) Operation  
TPSM8A28 and TPSM8A29 devices have out-of-bounds (OOB) overvoltage protection that protects the output  
load at a much lower overvoltage threshold of 5% above the VINTREF voltage. OOB protection does not trigger an  
overvoltage fault, so the device is on non-latch mode after an OOB event. OOB protection operates as an early  
no-fault overvoltage-protection mechanism. During the OOB operation, the controller operates in forced CCM  
mode. Turning on the low-side FET beyond the zero inductor current quickly discharges the output capacitor  
thus helps the output voltage to fall quickly towards the setpoint. During the operation, the cycle-by-cycle  
negative current limit is also activated for the safe operation of the internal FETs.  
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7.3.14 Output Voltage Discharge  
When the device is disabled through EN, it enables the output voltage discharge mode. This mode forces both  
high-side and low-side FETs to latch off, but turns on the discharge FET, which is connected from SW to PGND,  
to discharge the output voltage. Once the FB voltage drops below 100 mV, the discharge FET is turned off.  
The output voltage discharge mode is activated by any of below fault events:  
EN pin goes low to disable the converter.  
Thermal shutdown (OTP) is triggered.  
VCC UVLO (falling) is triggered.  
VIN UVLO (falling) is triggered.  
7.3.15 UVLO Protection  
The device monitors the voltage on both the VIN and the VCC pins. If the VCC pin voltage is lower than the  
VCCUVLO falling threshold voltage, the device shuts off. If the VCC voltage increases beyond the VCCUVLO rising  
threshold voltage, the device turns back on. VCC UVLO is a non-latch protection.  
When the VIN pin voltage is lower than the VINUVLO falling threshold voltage but the VCC pin voltage is still  
higher than the VCCUVLO rising threshold voltage, the device stops switching and discharges SS/REFIN pin.  
Once the VIN voltage increases beyond the VINUVLO rising threshold voltage, the device re-initiates the soft start  
and switches again. VIN UVLO is a non-latch protection.  
7.3.16 Thermal Shutdown  
The device monitors internal junction temperature. If the temperature exceeds the threshold value (typically  
165°C), the device stops switching and discharges the SS/REFIN pin. When the temperature falls approximately  
30°C below the threshold value, the device turns back on with a re-initiated soft start. Thermal shutdown is a  
non-latch protection.  
7.4 Device Functional Modes  
7.4.1 Auto-Skip Eco-Mode Light Load Operation  
While the MODE pin is pulled to VCC directly or connected to AGND pin through a resistor larger than 121 kΩ,  
the device automatically reduces the switching frequency at light-load conditions to maintain high efficiency. This  
section describes the operation in detail.  
As the output current decreases from heavy load condition, the inductor current also decreases until the rippled  
valley of the inductor current touches zero level. Zero level is the boundary between the continuous-conduction  
and discontinuous-conduction modes. The synchronous MOSFET turns off when this zero inductor current is  
detected. As the load current decreases further, the converter runs into discontinuous-conduction mode (DCM).  
The on time is maintained to a level approximately the same as during continuous-conduction mode operation  
so that discharging the output capacitor with a smaller load current to the level of the reference voltage requires  
more time. The transition point to the light-load operation IO(LL) (for example: the threshold between continuous-  
and discontinuous-conduction mode) is calculated as shown in Equation 6.  
V
- V  
´ V  
(
)
OUT OUT  
V
IN  
1
IN  
I
=
´
OUT LL  
( )  
2´L ´ f  
SW  
(6)  
where  
fSW is the switching frequency  
Using only ceramic capacitors is recommended for Skip mode.  
7.4.2 Forced Continuous-Conduction Mode  
When the MODE pin is tied to the AGND pin through a resistor less than 60.4 kΩ, the controller operates  
in continuous conduction mode (CCM) during light-load conditions. During CCM, the switching frequency  
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maintained to an almost constant level over the entire load range, which is suitable for applications requiring  
tight control of the switching frequency.  
7.4.3 Powering the Device From a 12-V Bus  
Both TPSM8A28 and TPSM8A29 can be powered by a single 12-V bus. In this configuration, the internal LDO is  
powered by a 12-V bus and generates a 4.5-V output to bias the internal analog circuitry and also powers up the  
gate drives. The VIN range under this configuration for TPSM8A29 is 4 V to 16 V for up to 15-A load current. VIN  
range for TPSM8A28 is 3 V to 16 V for up to 12 A. Figure 7-4 shows an example for this single VIN configuration.  
VIN and EN are the two signals to enable the part. For a start-up sequence, any sequence between the VIN and  
EN signals can power the device up correctly.  
VIN: 4V – 16V  
10  
11  
VOUT  
VOUT  
4
VIN  
VIN  
VIN  
VIN  
VOUT  
5
CIN  
16  
17  
23  
EN  
18  
19  
EN  
CFF, Optional  
PGOOD  
PGOOD  
Vosns+  
COUT  
RPG_pullup  
12  
FB  
3
7
9
8
VCC  
RFB_HS  
RFB_LS  
RMODE  
MODE  
TRIP  
Vosns-  
RTRIP  
13  
15  
VSNS-  
CSS  
SS/  
REFIN  
AGND  
PGND  
Figure 7-4. Single VIN Configuration With 12-V Bus  
7.4.4 Powering the Device From a 5.0-V Bus  
The TPSM8A29 can deliver up to a 15-A load current when powering from a 5-V bus, 12 A for TPSM8A28.  
To make sure the internal analog circuitry and the gate drives are powered up properly, the VCC pin must be  
shorted to the VIN pins with a low impedance trace. A trace with at least 24-mil width is recommended. Due  
to the maximum rating limit on the VCC pin, the VIN input range under this configuration is 4.75 V to 5.3 V.  
The input voltage must stay higher than both VIN UVLO and VCC UVLO, otherwise the device shuts down  
immediately. Figure 7-5 shows an example for this single VIN configuration.  
VIN and EN are the two signals to enable the part. For start-up sequence, any sequence between the VIN and  
EN signals can power the device up correctly.  
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VIN: 4.75V-5.3V  
10  
11  
VOUT  
VOUT  
4
VIN  
VIN  
VIN  
VIN  
VOUT  
5
CIN  
16  
17  
23  
EN  
18  
19  
EN  
CFF, Optional  
PGOOD  
PGOOD  
Vosns+  
COUT  
RPG_pullup  
12  
FB  
3
7
9
8
VCC  
RFB_HS  
RFB_LS  
RMODE  
MODE  
TRIP  
Vosns-  
RTRIP  
13  
15  
VSNS-  
CSS  
SS/  
REFIN  
AGND  
PGND  
Figure 7-5. Single VIN Configuration With 5.0-V Bus  
7.4.5 Powering the Device From a Split-Rail Configuration  
The TPSM8A28 and TPSM8A29 devices can be configured to split-rail by using an independent power supply  
that applies a valid bias on to VCC pin. Connecting a valid VCC bias to the VCC pin overrides the internal LDO,  
thus saves power loss on that linear regulator and helps to improve overall system level efficiency. 5.0-V rail is  
the common choice as VCC bias. With a stable VCC bias, the VIN input range under this configuration can be as  
low as 2.7 V and up to 16 V for both TPSM8A28 and TPSM8A29.  
Figure 7-6 shows an example for this split rail configuration.  
The VCC external bias current during nominal operation varies with the bias voltage level and also the operating  
frequency. For example, by setting the device to Skip mode, the VCC pins decreases current draw from the  
external bias when the frequency decreases under light-load condition. The typical VCC external bias current  
under FCCM operation is listed in the Electrical Characteristics table to help the user prepare the capacity of the  
external bias.  
Under split rail configuration, VIN, VCC bias, and EN are the signals to enable the part. For start-up sequence,  
it is recommended that at least one of VIN UVLO rising threshold and EN rising threshold is satisfied later than  
VCC UVLO rising threshold. A practical start-up sequence example is: VIN applied first, then the external bias  
applied, and then EN signal goes high.  
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VIN: 2.75-16V  
10  
11  
VOUT  
VOUT  
4
VIN  
VIN  
VIN  
VIN  
VOUT  
5
CIN  
16  
17  
23  
EN  
18  
19  
EN  
CFF, Optional  
PGOOD  
PGOOD  
Vosns+  
COUT  
RPG_pullup  
VCC: 4.75V to 5.3V  
12  
FB  
3
7
9
8
VCC  
RFB_HS  
RFB_LS  
RMODE  
MODE  
TRIP  
Vosns-  
RTRIP  
13  
15  
VSNS-  
CSS  
SS/  
REFIN  
AGND  
PGND  
Figure 7-6. Split Rail Configuration With External VCC Bias  
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8 Application and Implementation  
Note  
Information in the following applications sections is not part of the TI component specification,  
and TI does not warrant its accuracy or completeness. TI’s customers are responsible for  
determining suitability of components for their purposes, as well as validating and testing their design  
implementation to confirm system functionality.  
8.1 Application Information  
The TPSM8A28 and TPSM8A29 power modules feature an integrated power inductor and some basic passives.  
The devices are small and highly efficient, suitable for low output voltage point-of-load applications up to 15  
A. These devices features proprietary D-CAP3mode control combined with adaptive on-time architecture.  
This combination builds modern low-duty-ratio and ultra-fast load-step-response DC/DC converters in an ideal  
fashion. The output voltage ranges from 0.6 V to 5.5 V. The conversion input voltage ranges from 2.7 V to 16  
V, and the VCC input voltage ranges from 4.75 V to 5.3 V. The D-CAP3control mode uses emulated current  
information to control the modulation. An advantage of this control scheme is that it does not require an external  
phase-compensation network, which makes the device easy to use and also allows for a low external component  
count. Another advantage of this control scheme is that it supports stable operation with all low-ESR output  
capacitors (such as ceramic capacitor and low-ESR polymer capacitor). Adaptive on-time control tracks the  
preset switching frequency over a wide range of input and output voltages while increasing switching frequency  
as needed during a load-step transient.  
8.2 Typical Application  
The schematic shows a typical application for the TPSM8A29. This example describes the design procedure of  
converting an input voltage range of 9.6 V to 14.4 V to a 1-V output, up to 15-A load current.  
VOUT: 1 V, 15  
A
VIN: 4 to 16V  
VIN  
2
1
1
2
4
5
16  
17  
23  
10  
11  
VOUT  
VIN  
VIN  
VIN  
VIN  
VIN  
VOUT  
VOUT  
COUT  
8x47uF  
CIN  
2x22uF  
REN_T  
20k  
6
3
BOOT  
VCC  
BOOT  
VCC  
PGND  
RPGOOD  
30.1k  
13 VSNS-  
VSNS  
PGND  
R1  
REN_B  
10k  
19 PGOOD  
15 SS/REF  
12 FB  
C  
6.65k  
PGOOD  
SS/REF_IN  
FB  
PGND  
EN 18  
EN  
PGND  
R2  
10.0k  
Mode  
7
9
2
8
14  
AGND  
MODE  
TRIP  
SW  
AGND  
AGND  
TRIP  
SW  
1
20  
21-22  
24-25  
PGND  
PGND  
PGND  
PGND  
0
RTRIP  
4.02k  
AGND  
PGND  
PGND  
NT1  
TPSM8A29RDGR  
AGND  
AGND  
PGND  
Figure 8-1. Application Circuit Diagram  
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8.2.1 Design Requirements  
This design uses the parameters listed in Table 8-1. A switching frequency of 600 kHz was chosen to maximize  
efficiency. See Table 7-1 for all switching frequency and operating mode configurations.  
Table 8-1. Design Example Specifications  
DESIGN PARAMETER  
Voltage range  
CONDITION  
MIN  
TYP  
12  
MAX  
UNIT  
V
VIN  
9.6  
14.4  
VOUT  
ILOAD  
Output voltage  
1.0  
V
Output load current  
15  
A
VRIPPLE Output voltage ripple  
VIN = 12 V, IOUT = 15 A  
10  
mVPP  
V TRANS Output voltage undershoot and IOUT = 50% to 100% step, 5 A/µs slew rate  
overshoot after load step  
±50  
mV  
IOVER  
tSS  
Output overcurrent  
Soft-start time  
15  
1.5  
A
ms  
kHz  
fSW  
Switching frequency  
600  
Operating mode  
FCCM  
25  
TA  
Operating temperature  
°C  
8.2.2 Detailed Design Procedure  
The external component selection is a simple process using D-CAP3mode. Select the external components  
using the following steps.  
8.2.2.1 Output Voltage Setting Point  
The output voltage is programmed by the voltage-divider resistors, R1 and R2, shown in Equation 7. Connect  
R1 between the FB pin and the output, and connect R2 between the FB pin and VSNS–. The recommended R2  
value is 10 kΩ, but it can also be set to another value between the range of 1 kΩ to 20 kΩ. Determine R1 by  
using Equation 7. For 1.0 VOUT, a value of 6.65 kΩ is chosen.  
V
V  
INTREF  
OUT  
1 V 0.6 V  
R1 =  
× R2 =  
× 10 kΩ = 6.65 kΩ  
(7)  
V
0.6 V  
INTREF  
8.2.2.2 Choose the Inductor  
An optimized 0.6-μH inductor is integrated inside the module.  
8.2.2.3 Set the Current Limit (TRIP)  
The RTRIP resistor sets the valley current limit. Equation 8 calculates the recommended current limit target.  
Equation 9 calculates the RTRIP resistor to set the current limit. The typical valley current limit target is 15.0 A,  
and the closest standard value for RTRIP is 4.02 kΩ.  
V
V  
× V  
OUT OUT  
IN MIN  
0.6 μH × V  
9.6 V 1 V × 1 V  
1
2
1
2
I
= I  
OUT  
×
= 15 A −  
×
= 13.756 A  
0.6 μH × 9.6 V × 600 kHz  
(8)  
(9)  
LIMVALLEY  
× fsw  
IN MIN  
60000  
LIMVALLEY  
60000  
= 4.0 kΩ  
15 A  
R
=
=
TRIP  
I
With the current limit set, Equation 10 calculates the typical maximum output current at current limit. Equation 11  
calculates the typical peak current at current limit. For worst case calculations, the tolerance of the inductance  
(20%) and the current limit must be included.  
V
V  
× V  
OUT OUT  
IN MIN  
0.6 μH × V  
9.6 V 1 V × 1 V  
1
2
1
2
I
= I  
×
= 15 A −  
×
= 16.24 A  
0.6 μH × 9.6 V × 600 kHz  
(10)  
OUTLIM  
LIMVALLEY  
× fsw  
IN MIN  
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V
V  
× V  
OUT OUT  
IN MAX  
0.6 μH × V  
14.4 V 1 V × 1 V  
1
2
1
2
I
= I  
×
= 15 A −  
×
= 16.29 A  
0.6 μH × 14.4 V × 600 kHz  
(11)  
L PEAK  
LIMVALLEY  
× fsw  
IN MAX  
8.2.2.4 Choose the Output Capacitor  
There are three considerations for selecting the value of the output capacitor.  
1. Stability  
2. Steady state output voltage ripple  
3. Regulator transient response to a change load current  
First, the minimum output capacitance must be calculated based on these three requirements. Equation 12  
calculates the minimum capacitance to keep the LC double pole below 1/30th the fSW to meet stability  
requirements. This requirement helps to keep the LC double pole close to the internal zero.  
2
2
30  
2π × fsw  
1
30  
1
C
>
×
=
×
= 105.5 μF  
(12)  
OUT_STABILITY  
0.6 μH  
0.6 μH  
2π × 600 kHz  
V
Vout  
IN MAX  
V
Vout  
0.6 μH × fsw  
14.4 V 1V  
1V  
0.6 μH × 600kHz  
×
×
IN MAX  
14.4 V  
C
>
=
= 53.8 μF  
(13)  
OUT_RIPPLE  
8 × V  
× fsw  
8 × 10 mV × 600kHz  
ripple  
Equation 13 calculates the minimum capacitance to meet the steady state output voltage ripple requirement  
of 10 mV. This calculation is for FCCM operation and does not include the portion of the output voltage ripple  
caused by the ESR or ESL of the output capacitors. Equation 14 and Equation 15 calculate the minimum  
capacitance to meet the transient response requirement of ±50 mV for a 7.5-A step. These equations calculate  
the necessary output capacitance to hold the output voltage steady while the inductor current ramps up or ramps  
down after a load step.  
Vout  
2
2
1V  
0.6 μH × I  
STEP  
×
+ toff  
0.6 μH × 7.5  
×
+ 220ns  
V
× fsw  
IN MIN  
9.6 V × 600kHz  
9.6 V 1 V  
9.6 V × 600kHz  
C
>
=
(14)  
OUT_UNDERSHOOT  
V
V  
IN MIN  
OUT  
2 × 50mV × 1V ×  
220ns  
2 × V  
× V  
×
OUT  
toff  
TRANS  
V
× fsw  
IN MIN  
= 104.4 μF  
2
2
0.6 μH × I  
0.6 μH × 7.5  
STEP  
× V  
C
>
=
= 337.5 μF  
2 × 50mV × 1V  
(15)  
OUT_OVERSHOOT  
2 × V  
TRANS  
OUT  
The output capacitance needed to meet the overshoot requirement is the highest value, so this sets the  
required minimum output capacitance for this example. Stability requirements can also limit the maximum output  
capacitance. Equation 16 calculates the recommended maximum output capacitance. This calculation keeps  
the LC double pole above 1/100th the fSW. It can be possible to use more output capacitance but the stability  
must be checked through a bode plot or transient response measurement. The selected output capacitance  
is 8 × 47-μF ceramic capacitors. When using ceramic capacitors, the capacitance must be derated due to  
DC and AC bias effects. The selected capacitors derate to approximately 95% of their nominal value giving  
an effective total capacitance of approximately 357 μF. This effective capacitance meets the minimum and  
maximum requirements.  
2
2
50  
π × fsw  
1
50  
1
C
<
×
=
×
= 1172.7 μF  
(16)  
OUT_STABILITY  
0.6 μH  
0.6 μH  
π × 600 kHz  
This application uses all ceramic capacitors so the effects of ESR on the ripple and transient were ignored. If  
using non-ceramic capacitors, as a starting point, the ESR must be below the values calculated in Equation 17 to  
meet the ripple requirement and Equation 18 to meet the transient requirement. For more accurate calculations  
or if using mixed output capacitors, the impedance of the output capacitors must be used to determine if the  
ripple and transient requirements can be met.  
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V
RIPPLE  
10 mV  
×
R
<
<
=
= 3.86 mΩ  
(17)  
ESR_RIPPLE  
ESR_TRANS  
V
Vout  
14.4 V 1 V  
1 V  
IN MAX  
V
Vout  
0.6 μH × fsw  
×
14.4 V  
0.6 μH × 600 kHz  
IN MAX  
V
TRANS  
50 mV  
7.5 A  
R
=
= 6.67 mΩ  
(18)  
I
STEP  
8.2.2.5 Choose the Input Capacitors (CIN)  
The device requires input bypass capacitors between the VIN and PGND pins to bypass the power stage.  
The bypass capacitors must be placed as close as possible to the pins of the IC as the layout will allow. At  
least 10-µF of ceramic capacitance is required. Two 0.1-μF and one 1-nF capacitors are integrated inside to  
the module package, eliminating the need for typical high frequency bypass capacitors. However, they can be  
used if desired. The high frequency bypass capacitors minimizes high frequency voltage overshoot across the  
power-stage. The ceramic capacitors must be high-quality dielectric of X6S or better for their high capacitance-  
to-volume ratio and stable characteristics across temperature. In addition to this, more bulk capacitance can be  
needed on the input depending on the application to minimize variations on the input voltage during transient  
conditions.  
The input capacitance required to meet a specific input ripple target can be calculated with Equation 19.  
A recommended target input voltage ripple is 5% the minimum input voltage, 480 mV in this example. The  
calculated input capacitance is 4.86 μF, and the minimum input capacitance of 10 µF exceeds this. This example  
meets these two requirements with 2 × 22-µF ceramic capacitors. An input capacitor must be used on both sides  
of the module during layout, close to pins 5 and 16.  
Vout  
1 V  
9.6 V  
Vout × Iout × 1 −  
1 V × 15 A × 1 −  
V
IN MIN  
C
>
=
= 4.86 μF  
600 kHz × 9.6 V × 480 mV  
(19)  
IN  
fsw × V  
× V  
IN MIN  
IN_RIPPLE  
The capacitor must also have an RMS current rating greater than the maximum input RMS current in the  
application. The input RMS current the input capacitors must support is calculated by Equation 20 and is 4.588 A  
in this example. The ceramic input capacitors have a current rating greater than this.  
2
V
Vout  
IN MIN  
V
Vout  
0.6 μH × fsw  
×
V
Vout  
IN MIN  
V
IN MIN  
Vout  
2
I
=
=
×
× I  
+
=
(20)  
(21)  
CIN RMS  
OUT  
V
12  
IN MIN  
IN MIN  
2
9.6 V 1 V  
1 V  
×
9.6 V  
0.6 μH × 600 kHz  
1 V  
9.6 V  
9.6 V 1 V  
2
I
×
× 15 A +  
= 4.588 A  
CIN RMS  
9.6 V  
12  
For applications requiring bulk capacitance on the input, such as ones with low input voltage and high current,  
the selection process in this article is recommended.  
8.2.2.6 Soft-Start Capacitor (SS/REFIN Pin)  
The capacitor placed on the SS/REFIN pin can be used to extend the soft-start time past the internal 1.5-ms  
soft start. The required external capacitance can be calculated with Equation 2. The module incorporates a 1-nF  
capacitor between the SS/REFIN pin and VSNS-. This example uses a minimum default soft-start time of 1.5  
ms.  
8.2.2.7 EN Pin Resistor Divider  
A resistor divider on the EN pin can be used to increase the input voltage the converter begins its startup  
sequence. To set the start voltage, first select the bottom resistor (REN_B). The recommended value is between  
1 kΩ and 100 kΩ. There is an internal pulldown resistance with a nominal value of 6 MΩ. This must be included  
for the most accurate calculations. This is especially important when the bottom resistor is a higher value, near  
100 kΩ. This example uses a 10-kΩ resistor and this combined with the internal resistance in parallel results in  
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an equivalent bottom resistance of 9.98 kΩ. The top resistor value for the target start voltage is calculated with  
Equation 22. In this example, the nearest standard value of 20 kΩ is selected for REN_T. When selecting a start  
voltage in a wide input range application, be cautious that the EN pin absolute maximum voltage of 6 V is not  
exceeded.  
R
× V  
start  
EN_B  
V
10 kΩ × 3.7 V  
10 kΩ = 20 kΩ  
1.22 V  
R
=
R  
=
(22)  
EN_T  
EN_B  
ENH  
The start and stop voltages with the selected EN resistor divider can be calculated with Equation 23 and  
Equation 24, respectively.  
R
+ R  
EN_B  
EN_T  
R
20 kΩ + 10 kΩ  
10 kΩ  
V
= V  
×
ENH  
= 1.22 V ×  
= 3.66 V  
(23)  
start  
EN_B  
R
+ R  
EN_T  
EN_B  
20 kΩ + 10 kΩ  
10 kΩ  
V
= V  
×
= 1 . 02 V ×  
= 3.06 V  
(24)  
stop  
ENL  
R
EN_B  
8.2.2.8 VCC Bypass Capacitor  
A 1.0-μF bypass capacitor is integrated inside the module. No external bypass is required.  
8.2.2.9 BOOT Capacitor  
A 0.1-μF boot capacitor is integrated inside the module, no additional boot capacitor is necessary.  
8.2.2.10 PGOOD Pullup Resistor  
The PGOOD pin is open-drain so a pullup resistor is required when using this pin. The recommended value is  
between 1 kΩ and 100 kΩ.  
8.2.3 Application Curves  
100  
95  
90  
85  
80  
75  
70  
65  
60  
55  
50  
100  
95  
90  
85  
80  
75  
70  
65  
60  
55  
50  
5 Vin  
12 Vin  
16 Vin  
5 VIN  
12 VIN  
16 VIN  
0
1
2
3
4
5
6
7
8
9
10 11 12 13 14 15  
0
1
2
3
4
5
6
7
8
9
10 11 12 13 14 15  
IOUT (A)  
IOUT (A)  
VOUT = 0.6 V fsw = 600 kHz Internal bias  
FCCM  
VOUT = 0.8 V fsw = 600 kHz Internal bias  
FCCM  
Figure 8-2. Efficiency  
Figure 8-3. Efficiency  
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100  
95  
90  
85  
80  
75  
70  
65  
60  
55  
50  
100  
95  
90  
85  
80  
75  
70  
65  
60  
55  
50  
5 Vin  
12 Vin  
16 Vin  
5 Vin  
12 Vin  
16 Vin  
0
1
2
3
4
5
6
7
8
9
10 11 12 13 14 15  
0
1
2
3
4
5
6
7
8
9 10 11 12 13 14 15  
IOUT (A)  
IOUT (A)  
VOUT = 1.0 V fsw = 600 kHz Internal bias  
FCCM  
VOUT = 1.2 V fsw = 600 kHz Internal bias  
FCCM  
Figure 8-4. Efficiency  
Figure 8-5. Efficiency  
100  
95  
90  
85  
80  
75  
70  
65  
60  
55  
50  
100  
95  
90  
85  
80  
75  
70  
65  
60  
55  
50  
5 Vin  
12 Vin  
16 Vin  
5 Vin  
12 Vin  
16 Vin  
0
1
2
3
4
5
6
7
8
9
10 11 12 13 14 15  
0
1
2
3
4
5
6
7
8
9 10 11 12 13 14 15  
IOUT (A)  
IOUT (A)  
VOUT = 1.8 V fsw = 600 kHz Internal bias  
FCCM  
VOUT = 2.5 V fsw = 600 kHz Internal bias  
FCCM  
Figure 8-6. Efficiency  
Figure 8-7. Efficiency  
100  
95  
90  
85  
80  
75  
70  
65  
60  
55  
50  
100  
95  
90  
85  
80  
75  
70  
65  
60  
55  
50  
8 Vin  
12 Vin  
16 Vin  
8 Vin  
12 Vin  
16 Vin  
0
1
2
3
4
5
6
7
8
9
10 11 12 13 14 15  
0
1
2
3
4
5
6
7
8
9 10 11 12 13 14 15  
IOUT (A)  
IOUT (A)  
VOUT = 3.3 V fsw = 600 kHz Internal bias  
FCCM  
VOUT = 5 V  
fsw = 600 kHz Internal bias  
FCCM  
Figure 8-8. Efficiency  
Figure 8-9. Efficiency  
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95  
92.5  
90  
0.601  
0.6008  
0.6006  
0.6004  
0.6002  
0.6  
0.5998  
0.5996  
0.5994  
0.5992  
0.599  
87.5  
85  
82.5  
80  
77.5  
75  
0.5988  
0.5986  
0.5984  
0.5982  
0.598  
Input Voltage  
5 V  
Switching Frequency  
600 kHz  
12 V  
16 V  
800 kHz  
1000 kHz  
72.5  
70  
0
1
2
3
4
5
6
7
8
9 10 11 12 13 14 15  
0
1
2
3
4
5
6
7
8
9
10 11 12 13 14 15  
IOUT (A)  
IOUT (A)  
VOUT = 0.6 V fSW = 600 kHz Internal bias  
FCCM  
VIN = 12 V  
VOUT = 1 V  
Internal bias  
FCCM  
Figure 8-11. Load Regulation  
Figure 8-10. Efficiency  
0.801  
0.80075  
0.8005  
0.80025  
0.8  
1.003  
1.0025  
1.002  
0.79975  
0.7995  
0.79925  
0.799  
1.0015  
1.001  
0.79875  
0.7985  
0.79825  
0.798  
0.79775  
0.7975  
0.79725  
0.797  
1.0005  
Input Voltage  
5 V  
1
0.9995  
0.999  
Input Voltage  
5 V  
12 V  
16 V  
12 V  
16 V  
0
1
2
3
4
5
6
7
8
9 10 11 12 13 14 15  
0
1
2
3
4
5
6
7
8
9
10 11 12 13 14 15  
IOUT (A)  
IOUT (A)  
VOUT = 0.8 V fSW = 600 kHz Internal bias  
FCCM  
VOUT = 1.0 V fSW = 600 kHz Internal bias  
Figure 8-13. Load Regulation  
1.805  
FCCM  
Figure 8-12. Load Regulation  
1.202  
1.2015  
1.201  
1.2005  
1.2  
1.804  
1.803  
1.802  
1.801  
1.8  
Input Voltage  
5 V  
Input Voltage  
5 V  
1.1995  
1.199  
1.799  
1.798  
12 V  
16 V  
12 V  
16 V  
0
1
2
3
4
5
6
7
8
9
10 11 12 13 14 15  
0
1
2
3
4
5
6
7
8
9
10 11 12 13 14 15  
IOUT (A)  
IOUT (A)  
VOUT = 1.2 V fSW = 600 kHz Internal bias  
FCCM  
VOUT = 1.8 V fSW = 600 kHz Internal bias  
FCCM  
Figure 8-14. Load Regulation  
Figure 8-15. Load Regulation  
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2.505  
2.504  
2.503  
2.502  
2.501  
2.5  
3.34  
3.335  
3.33  
3.325  
3.32  
2.499  
2.498  
2.497  
2.496  
2.495  
3.315  
3.31  
Input Voltage  
5 V  
Input Voltage  
8 V  
12 V  
16 V  
12 V  
16 V  
3.305  
3.3  
0
1
2
3
4
5
6
7
8
9
10 11 12 13 14 15  
0
1
2
3
4
5
6
7
8
9
10 11 12 13 14 15  
IOUT (A)  
IOUT (A)  
VOUT = 2.5 V fSW = 600 kHz Internal bias  
FCCM  
VOUT = 3.3 V fSW = 600 kHz Internal bias  
FCCM  
Figure 8-16. Load Regulation  
Figure 8-17. Load Regulation  
5.02  
5.015  
5.01  
5.005  
5
1.005  
1.004  
1.003  
1.002  
1.001  
1
0.999  
0.998  
0.997  
0.996  
0.995  
4.995  
4.99  
4.985  
4.98  
Input Voltage  
5 V  
12 V  
16 V  
0
1
2
3
4
5
6
7
8
9
10 11 12 13 14 15  
4
5
6
7
8
9
10 11 12 13 14 15 16  
VIN (V)  
IOUT (A)  
VOUT = 5 V fSW = 600 kHz Internal bias  
FCCM  
VOUT = 1.0  
V
Internal  
bias  
fSW = 600  
kHz  
IOUT = 5 A  
FCCM  
Figure 8-18. Load Regulation  
Figure 8-19. Line Regulation  
1,000  
650  
625  
600  
575  
550  
525  
500  
475  
450  
950  
900  
850  
800  
750  
700  
650  
600  
550  
500  
450  
400  
350  
Switching Frequency  
600 kHz  
Output Voltage  
800 kHz  
1000 kHz  
0.6 V  
1.0 V  
0
1
2
3
4
5
6
7
8
9
10 11 12 13 14 15  
4
5
6
7
8
9
10 11 12 13 14 15 16  
VIN (V)  
IOUT (A)  
VIN = 12 V  
VOUT = 1.0 V Internal bias  
FCCM  
IOUT = 5 A  
fSW = 600 kHz Internal bias  
FCCM  
Figure 8-20. Switching Frequency  
Figure 8-21. Switching Frequency  
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700  
1,200  
1,100  
1,000  
900  
650  
600  
550  
500  
450  
800  
700  
Output Voltage  
Output Voltage  
600  
0.6 V  
0.8 V  
1.0 V  
1.2 V  
1.8 V  
2.5 V  
3.3 V  
5.0 V  
0.6 V  
0.8 V  
1.0 V  
1.2 V  
1.8 V  
2.5 V  
3.3 V  
5.0 V  
500  
400  
400  
0
0
1
2
3
4
5
6
7
8
9 10 11 12 13 14 15  
1
2
3
4
5
6
7
8
9 10 11 12 13 14 15  
IOUT (A)  
IOUT (A)  
fSW = 1000  
kHz  
VIN = 12 A  
fSW = 600 kHz Internal bias  
FCCM  
VIN = 12 V  
Internal bias  
FCCM  
Figure 8-22. Switching Frequency  
Figure 8-23. Switching Frequency  
700  
675  
650  
625  
600  
575  
550  
525  
500  
1,200  
1,150  
1,100  
1,050  
1,000  
950  
900  
850  
800  
750  
Load Current  
Load Current  
1 mA  
1 A  
10 A  
15 A  
1 mA  
1 A  
10 A  
15 A  
700  
650  
5 A  
5 A  
600  
0.5  
1
1.5  
2
2.5  
3
3.5  
4
4.5  
5
0.5  
1
1.5  
2
2.5  
3
3.5  
4
4.5  
5
VOUT (V)  
VOUT (V)  
VIN = 12 V  
fSW = 600 kHz Internal bias  
FCCM  
fSW = 1000  
kHz  
VIN = 12 V  
Internal bias  
FCCM  
Figure 8-24. Switching Frequency  
Figure 8-25. Switching Frequency  
In the following images, all measurements taken with VIN = 12 V, VOUT = 1 V, fSW = 600 kHz, internal bias, TAMB  
= 25°C  
IOUT = 15 A  
FCCM  
IOUT = 0 A  
FCCM  
Figure 8-27. Output Voltage Ripple, VRIPPLE = 7.6  
mV  
Figure 8-26. Output Voltage Ripple, VRIPPLE = 6.4  
mV  
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IOUT = 0 A  
DCM  
IOUT = 0.5 A  
DCM  
Figure 8-28. Output Voltage Ripple, VRIPPLE = 20.3  
mV  
Figure 8-29. Output Voltage Ripple, VRIPPLE = 10.4  
mV  
IOUT = 0 A  
DCM  
IOUT = 1 A  
DCM  
Figure 8-31. Startup Through VIN (Enable Floating)  
Figure 8-30. Output Voltage Ripple, VRIPPLE = 8.8  
mV  
IOUT = 0 A  
DCM  
IOUT = 15 A  
FCCM  
Figure 8-33. Startup Through Enable  
Figure 8-32. Startup Through VIN (Enable Floating)  
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IOUT = 15 A  
FCCM  
IOUT = 0 A  
FCCM  
Figure 8-34. Startup Through Enable  
Figure 8-35. Startup Through Enable into  
Prebiased Load  
ISTEP = 7.5 A - 15 A - 7.5 A  
5 A/μs  
IOUT = 15 A  
FCCM  
Figure 8-37. Transient Response, VPP = 74 mV  
Figure 8-36. Shutdown Through Enable  
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9 Power Supply Recommendations  
The devices are designed to operate from a wide input voltage supply range between 2.7 V and 16 V when  
the VCC pin is powered by an external bias ranging from 4.75 V to 5.3 V. Both input supplies (VIN and VCC  
bias) must be well regulated. Proper bypassing of input supplies (VIN and VCC bias) is also critical for noise  
performance, as are PCB layout and grounding scheme. See the recommendations in Section 10.  
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10 Layout  
10.1 Layout Guidelines  
Before beginning a design using one of the devices, consider the following:  
Place the input and output capacitors on the top side of the PCB. In order to shield and isolate the small  
signal traces from noisy power lines, insert at least one solid ground inner plane.  
At least thirteen PGND vias are required to be placed as close as possible to the PGND pins (pins 1, 20, 21,  
22, 24, and 25). This minimizes parasitic impedance and also lowers thermal resistance.  
Always place the feedback resistors near the device to minimize the FB trace distance, no matter single-end  
sensing or remote sensing.  
– For remote sensing, the connections from the FB voltage divider resistors to the remote location should  
be a pair of PCB traces with at least 12-mil trace width, and should implement Kelvin sensing across a  
high bypass capacitor of 0.1 μF or higher. The ground connection of the remote sensing signal must be  
connected to the VSNS– pin. The VOUT connection of the remote sensing signal must be connected to the  
feedback resistor divider with the lower feedback resistor terminated at the VSNS– pin. To maintain stable  
output voltage and minimize the ripple, the pair of remote sensing lines should stay away from any noise  
sources such as inductor and SW nodes, or high frequency clock lines. And it is recommended to shield  
the pair of remote sensing lines with ground planes above and below.  
– For single-end sensing, connect the higher FB resistor to a high-frequency local bypass capacitor of  
0.1-μF or higher, and short VSNS– to AGND with shortest trace.  
Pin 8 (AGND pin) must be connected to a solid PGND plane at a single point. Use the common AGND via to  
connect the TRIP and MODE resistors to the inner ground plane if applicable. Pin 14 is also an AGND pin,  
and is connected internally to pin 8. No external connection between pins 8 and 14 is required, however, pin  
8 must be used as the AGND connection.  
See Figure 10-1 for the layout recommendation.  
10.2 Layout Example  
Figure 10-2. Recommended Layout Bottom Side  
Figure 10-1. Recommended Layout Top Side  
10.2.1 Thermal Performance on the TI EVM  
Test conditions: fSW = 600 kHz, VIN = 12 V, VOUT = 1 V, IOUT = 15 A, COUT = 8 × 47 µF (1206/6.3V/X7R), IC:  
82.5°C  
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Figure 10-3. Thermal Image at 25°C Ambient, 12 Vin, 1 Vout, 15 A, 600 kHz  
Test conditions:  
fSW = 600 kHz, VIN = 12 V, VOUT = 5 V, IOUT = 12 A, COUT = 8 × 47 µF (1206/6.3V/X7R)  
IC: 88.7°C  
Figure 10-4. Thermal Image at 25°C Ambient, 12 Vin,5 Vout, 12 A, 600 kHz  
10.3 EMI  
The TPSM8A28 and TPSM8A29 are compliant with EN55011 Class-A radiated emissions. Figure 11-1 and  
Figure 11-2 show examples of radiated emissions plots. The graphs include the plots of the antenna in the  
horizontal and vertical positions.  
Copyright © 2021 Texas Instruments Incorporated  
36  
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Product Folder Links: TPSM8A28 TPSM8A29  
 
TPSM8A28, TPSM8A29  
SLVSFQ9A – AUGUST 2021 – REVISED NOVEMBER 2021  
www.ti.com  
The EMI plots were measured using the standard TPSM8A29EVM with Ferrite 61 type beads on the input wire.  
Figure 10-5. Radiated Emissions 12-V Input, 1.0-V Outputs, 15-A/Output Load  
Figure 10-6. Radiated Emissions 5-V Input, 1-V Output, 15-A/Output Load  
Copyright © 2021 Texas Instruments Incorporated  
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Product Folder Links: TPSM8A28 TPSM8A29  
 
 
TPSM8A28, TPSM8A29  
SLVSFQ9A – AUGUST 2021 – REVISED NOVEMBER 2021  
www.ti.com  
11 Device and Documentation Support  
11.1 Device Support  
11.1.1 Third-Party Products Disclaimer  
TI'S PUBLICATION OF INFORMATION REGARDING THIRD-PARTY PRODUCTS OR SERVICES DOES NOT  
CONSTITUTE AN ENDORSEMENT REGARDING THE SUITABILITY OF SUCH PRODUCTS OR SERVICES  
OR A WARRANTY, REPRESENTATION OR ENDORSEMENT OF SUCH PRODUCTS OR SERVICES, EITHER  
ALONE OR IN COMBINATION WITH ANY TI PRODUCT OR SERVICE.  
11.2 Documentation Support  
11.2.1 Related Documentation  
Optimizing Transient Response of Internally Compensated dc-dc Converters With Feedforward Capacitor  
Application Report  
11.3 Receiving Notification of Documentation Updates  
To receive notification of documentation updates, navigate to the device product folder on ti.com. Click on  
Subscribe to updates to register and receive a weekly digest of any product information that has changed. For  
change details, review the revision history included in any revised document.  
11.4 Support Resources  
TI E2Esupport forums are an engineer's go-to source for fast, verified answers and design help — straight  
from the experts. Search existing answers or ask your own question to get the quick design help you need.  
Linked content is provided "AS IS" by the respective contributors. They do not constitute TI specifications and do  
not necessarily reflect TI's views; see TI's Terms of Use.  
11.5 Trademarks  
D-CAP3and Eco-mode, are trademarks of TI.  
TI E2Eis a trademark of Texas Instruments.  
All trademarks are the property of their respective owners.  
11.6 Electrostatic Discharge Caution  
This integrated circuit can be damaged by ESD. Texas Instruments recommends that all integrated circuits be handled  
with appropriate precautions. Failure to observe proper handling and installation procedures can cause damage.  
ESD damage can range from subtle performance degradation to complete device failure. Precision integrated circuits may  
be more susceptible to damage because very small parametric changes could cause the device not to meet its published  
specifications.  
11.7 Glossary  
TI Glossary  
This glossary lists and explains terms, acronyms, and definitions.  
Copyright © 2021 Texas Instruments Incorporated  
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SLVSFQ9A – AUGUST 2021 – REVISED NOVEMBER 2021  
www.ti.com  
12 Mechanical, Packaging, and Orderable Information  
The following pages include mechanical, packaging, and orderable information. This information is the most  
current data available for the designated devices. This data is subject to change without notice and revision of  
this document. For browser-based versions of this data sheet, refer to the left-hand navigation.  
Copyright © 2021 Texas Instruments Incorporated  
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Product Folder Links: TPSM8A28 TPSM8A29  
 
PACKAGE OPTION ADDENDUM  
www.ti.com  
15-Dec-2021  
PACKAGING INFORMATION  
Orderable Device  
Status Package Type Package Pins Package  
Eco Plan  
Lead finish/  
Ball material  
MSL Peak Temp  
Op Temp (°C)  
Device Marking  
Samples  
Drawing  
Qty  
(1)  
(2)  
(3)  
(4/5)  
(6)  
PTPSM8A29RDGR  
TPSM8A28RDGR  
ACTIVE  
ACTIVE  
B3QFN  
B3QFN  
RDG  
RDG  
25  
25  
1000  
1000  
TBD  
Call TI  
Call TI  
-40 to 125  
-40 to 125  
RoHS (In  
Work) & Green  
(In Work)  
NIPDAU  
Level-3-250C-168 HR  
TPSM8A28  
TPSM8A29RDGR  
ACTIVE  
B3QFN  
RDG  
25  
1000  
RoHS (In  
Work) & Green  
(In Work)  
NIPDAU  
Level-3-250C-168 HR  
-40 to 125  
TPSM8A29  
(1) The marketing status values are defined as follows:  
ACTIVE: Product device recommended for new designs.  
LIFEBUY: TI has announced that the device will be discontinued, and a lifetime-buy period is in effect.  
NRND: Not recommended for new designs. Device is in production to support existing customers, but TI does not recommend using this part in a new design.  
PREVIEW: Device has been announced but is not in production. Samples may or may not be available.  
OBSOLETE: TI has discontinued the production of the device.  
(2) RoHS: TI defines "RoHS" to mean semiconductor products that are compliant with the current EU RoHS requirements for all 10 RoHS substances, including the requirement that RoHS substance  
do not exceed 0.1% by weight in homogeneous materials. Where designed to be soldered at high temperatures, "RoHS" products are suitable for use in specified lead-free processes. TI may  
reference these types of products as "Pb-Free".  
RoHS Exempt: TI defines "RoHS Exempt" to mean products that contain lead but are compliant with EU RoHS pursuant to a specific EU RoHS exemption.  
Green: TI defines "Green" to mean the content of Chlorine (Cl) and Bromine (Br) based flame retardants meet JS709B low halogen requirements of <=1000ppm threshold. Antimony trioxide based  
flame retardants must also meet the <=1000ppm threshold requirement.  
(3) MSL, Peak Temp. - The Moisture Sensitivity Level rating according to the JEDEC industry standard classifications, and peak solder temperature.  
(4) There may be additional marking, which relates to the logo, the lot trace code information, or the environmental category on the device.  
(5) Multiple Device Markings will be inside parentheses. Only one Device Marking contained in parentheses and separated by a "~" will appear on a device. If a line is indented then it is a continuation  
of the previous line and the two combined represent the entire Device Marking for that device.  
(6)  
Lead finish/Ball material - Orderable Devices may have multiple material finish options. Finish options are separated by a vertical ruled line. Lead finish/Ball material values may wrap to two  
lines if the finish value exceeds the maximum column width.  
Important Information and Disclaimer:The information provided on this page represents TI's knowledge and belief as of the date that it is provided. TI bases its knowledge and belief on information  
provided by third parties, and makes no representation or warranty as to the accuracy of such information. Efforts are underway to better integrate information from third parties. TI has taken and  
Addendum-Page 1  
PACKAGE OPTION ADDENDUM  
www.ti.com  
15-Dec-2021  
continues to take reasonable steps to provide representative and accurate information but may not have conducted destructive testing or chemical analysis on incoming materials and chemicals.  
TI and TI suppliers consider certain information to be proprietary, and thus CAS numbers and other limited information may not be available for release.  
In no event shall TI's liability arising out of such information exceed the total purchase price of the TI part(s) at issue in this document sold by TI to Customer on an annual basis.  
Addendum-Page 2  
PACKAGE MATERIALS INFORMATION  
www.ti.com  
16-Dec-2021  
TAPE AND REEL INFORMATION  
*All dimensions are nominal  
Device  
Package Package Pins  
Type Drawing  
SPQ  
Reel  
Reel  
A0  
B0  
K0  
P1  
W
Pin1  
Diameter Width (mm) (mm) (mm) (mm) (mm) Quadrant  
(mm) W1 (mm)  
TPSM8A28RDGR  
TPSM8A29RDGR  
B3QFN  
B3QFN  
RDG  
RDG  
25  
25  
1000  
1000  
330.0  
330.0  
16.4  
16.4  
6.9  
6.9  
7.9  
7.9  
4.3  
4.3  
12.0  
12.0  
16.0  
16.0  
Q1  
Q1  
Pack Materials-Page 1  
PACKAGE MATERIALS INFORMATION  
www.ti.com  
16-Dec-2021  
*All dimensions are nominal  
Device  
Package Type Package Drawing Pins  
SPQ  
Length (mm) Width (mm) Height (mm)  
TPSM8A28RDGR  
TPSM8A29RDGR  
B3QFN  
B3QFN  
RDG  
RDG  
25  
25  
1000  
1000  
336.0  
336.0  
336.0  
336.0  
48.0  
48.0  
Pack Materials-Page 2  
PACKAGE OUTLINE  
B3QFN - 4.1 mm max height  
PLASTIC QUAD FLAT PACK- NO LEAD  
RDG0025A  
6.6  
6.4  
B
A
7.6  
7.4  
PIN 1 INDEX AREA  
4.1  
3.9  
C
SEATING PLANE  
0.08  
0.01  
0.00  
C
2.45  
2.35  
4X  
1.85  
1.75  
(0.2) TYP  
0.55  
0.45  
4X  
4X 0.8  
11  
10  
25  
1.21  
1.11  
4X  
24  
0.56  
0.46  
2X 6.15  
2X 4.55  
23  
2X 1.23  
22  
21  
2X 2.59  
1
20  
0.4  
0.3  
16X  
14X 0.65  
0.7  
0.6  
0.1  
16X  
1.25  
1.15  
PIN 1 ID  
4X  
C A B  
0.1  
C
A B  
0.05  
C
0.05  
C
4226094/A 08/2020  
NOTES:  
1. All linear dimensions are in millimeters. Any dimensions in parenthesis are for reference only. Dimensioning and tolerancing  
per ASME Y14.5M.  
2. This drawing is subject to change without notice.  
3. The package thermal pad must be soldered to the printed circuit board for optimal thermal and mechanical performance.  
www.ti.com  
EXAMPLE BOARD LAYOUT  
B3QFN - 4.1 mm max height  
PLASTIC QUAD FLAT PACK- NO LEAD  
RDG0025A  
(6.05)  
(5.5)  
2X (2.4)  
(1.8)  
(0.05) MIN  
ALL AROUND  
TYP  
(R 0.05) TYP  
20  
1
16X 0.35  
2X 2.52  
23  
2X (6.15)  
2X (4.55)  
0.000 PKG  
(0.51)  
(0.91)  
3X (1.92)  
(2.92)  
14X (0.65)  
10  
11  
4X (0.5)  
16X (0.85)  
4X (1.4)  
(Ø0.2) TYP  
LAND PATTERN EXAMPLE  
EXPOSED METAL SHOWN  
SCALE: 12X  
SOLDER MASK  
OPENING  
0.05 MIN  
ALL AROUND  
0.05 MAX  
ALL AROUND  
METAL  
EXPOSED METAL  
SOLDER MASK  
OPENING  
METAL UNDER  
SOLDER MASK  
EXPOSED METAL  
SOLDER MASK  
DEFINED  
NON- SOLDER MASK  
DEFINED  
(PREFERRED)  
SOLDER MASK DETAILS  
4226094/A 08/2020  
NOTES: (continued)  
4. This package is designed to be soldered to a thermal pad on the board. For more information, see Texas Instruments literature  
number SLUA271 (www.ti.com/lit/slua271).  
5. Vias are optional depending on application, refer to device data sheet. If any vias are implemented, refer to their locations shown  
on this view. It is recommended that vias under paste be filled, plugged or tented.  
www.ti.com  
EXAMPLE STENCIL DESIGN  
B3QFN - 4.1 mm max height  
PLASTIC QUAD FLAT PACK- NO LEAD  
RDG0025A  
(6.05)  
(5.5)  
(R 0.05) TYP  
8X (0.9)  
20  
1
16X 0.35  
22  
8X 0.96  
2X (0.6)  
23  
2X (6.15)  
2X (4.55)  
0.000 PKG ℄  
2X 0.51  
2X (1.28)  
24  
2X (2.55)  
(2.92)  
14X (0.65)  
10  
11  
4X (0.5)  
16X (0.85)  
4X (1.4)  
(Ø0.2) TYP  
SOLDER PASTE EXAMPLE  
BASED ON 0.1 mm THICK STENCIL  
SOLDER COVERAGE:  
PIN 21 & 22 : 57%  
PIN 23 : 67%  
PIN 24 & 25 : 57%  
SCALE: 15X  
4226094/A 08/2020  
NOTES: (continued)  
6. Laser cutting apertures with trapezoidal walls and rounded corners may offer better paste release. IPC-7525 may have alternate  
design recommendations.  
www.ti.com  
IMPORTANT NOTICE AND DISCLAIMER  
TI PROVIDES TECHNICAL AND RELIABILITY DATA (INCLUDING DATA SHEETS), DESIGN RESOURCES (INCLUDING REFERENCE  
DESIGNS), APPLICATION OR OTHER DESIGN ADVICE, WEB TOOLS, SAFETY INFORMATION, AND OTHER RESOURCES “AS IS”  
AND WITH ALL FAULTS, AND DISCLAIMS ALL WARRANTIES, EXPRESS AND IMPLIED, INCLUDING WITHOUT LIMITATION ANY  
IMPLIED WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE OR NON-INFRINGEMENT OF THIRD  
PARTY INTELLECTUAL PROPERTY RIGHTS.  
These resources are intended for skilled developers designing with TI products. You are solely responsible for (1) selecting the appropriate  
TI products for your application, (2) designing, validating and testing your application, and (3) ensuring your application meets applicable  
standards, and any other safety, security, regulatory or other requirements.  
These resources are subject to change without notice. TI grants you permission to use these resources only for development of an  
application that uses the TI products described in the resource. Other reproduction and display of these resources is prohibited. No license  
is granted to any other TI intellectual property right or to any third party intellectual property right. TI disclaims responsibility for, and you  
will fully indemnify TI and its representatives against, any claims, damages, costs, losses, and liabilities arising out of your use of these  
resources.  
TI’s products are provided subject to TI’s Terms of Sale or other applicable terms available either on ti.com or provided in conjunction with  
such TI products. TI’s provision of these resources does not expand or otherwise alter TI’s applicable warranties or warranty disclaimers for  
TI products.  
TI objects to and rejects any additional or different terms you may have proposed. IMPORTANT NOTICE  
Mailing Address: Texas Instruments, Post Office Box 655303, Dallas, Texas 75265  
Copyright © 2021, Texas Instruments Incorporated  

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