TPS51222 [TI]

Fixed Frequency, 99% Duty Cycle Peak Current Mode Notebook System Power Controller; 固定频率, 99 %占空比峰值电流模式笔记本系统功率控制器
TPS51222
型号: TPS51222
厂家: TEXAS INSTRUMENTS    TEXAS INSTRUMENTS
描述:

Fixed Frequency, 99% Duty Cycle Peak Current Mode Notebook System Power Controller
固定频率, 99 %占空比峰值电流模式笔记本系统功率控制器

功率控制 控制器
文件: 总42页 (文件大小:1033K)
中文:  中文翻译
下载:  下载PDF数据表文档文件
TPS51222  
www.ti.com ............................................................................................................................................................................................... SLUS908JANUARY 2009  
Fixed Frequency, 99% Duty Cycle Peak Current Mode Notebook System Power Controller  
1
FEATURES  
2
Input Voltage Range: 4.5 V to 32 V  
APPLICATIONS  
Notebook Computer System and I/O Bus  
Output Voltage Range: 1 V to 12 V  
Point of Load in LCD TV, MFP  
Selectable Light Load Operation  
(Continuous / Auto Skip / Out-Of-Audio™ Skip)  
DESCRIPTION  
Programmable Droop Compensation  
Voltage Servo Adjustable Soft Start  
200-kHz to 1-MHz Fixed-Frequency PWM  
Current Mode Architecture  
The TPS51222 is a dual synchronous buck regulator  
controller with two LDOs. It is optimized for 5-V/3.3-V  
system controller, enabling designers to cost  
effectively complete 2-cell to 4-cell notebook system  
power supply. The TPS51222 supports high  
efficiency, fast transient response, and 99% duty  
cycle operation. It supports supply input voltage  
ranging from 4.5 V to 32 V, and output voltages from  
1 V to 12 V. Peak current mode supports stability  
operation with lower ESR capacitor and output  
accuracy. The high duty cycle (99%) operation and  
the wide input/output voltage range supports flexible  
design for small mobile PCs and a wide variety of  
other applications. The fixed frequency can be  
adjusted from 200 kHz to 1 MHz by a resistor, and  
each channel runs 180° out-of-phase. The TPS51222  
can also synchronize to the external clock, and the  
interleaving ratio can be adjusted by its duty. The  
TPS51222 is available in the 32-pin 5 × 5 QFN  
package and is specified from –40°C to 85°C.  
180° Phase Shift Between Channels  
Resistor or Inductor DCR Current Sensing  
Current Monitor Output for Each Channel  
Adaptive Zero Crossing Circuit  
Powergood Output for Each Channel  
OCL/OVP/UVP/UVLO Protections  
Thermal Shutdown (Non-Latch)  
Output Discharge Function  
Integrated Boot Strap MOSFET Switch  
QFN-32 (RTV) Package  
VBAT  
VREG5  
5 V/  
VBAT  
100 mA  
VO2  
3.3 V  
VO1  
5 V  
32 31 30 29 28 27 26 25  
1
2
3
4
5
6
7
8
DRVH1  
V5SW  
RF  
DRVH2 24  
VIN 23  
VO1  
VBAT  
EN2  
VREG3  
3.3 V/  
VREG3 22  
EN2 21  
10 mA  
EN1  
PGOOD1  
SKIPSEL1  
EN1  
TPS51222RTV  
PGOOD1  
SKIPSEL1  
CSP1  
PGOOD2 20  
SKIPSEL2 19  
CSP2 18  
PGOOD2  
SKIPSEL2  
CSN1  
CSN2 17  
9
10 11 12 13 14 15 16  
EN  
IMON1  
VO1  
IMON2  
VO2  
UDG-09009  
1
Please be aware that an important notice concerning availability, standard warranty, and use in critical applications of Texas  
Instruments semiconductor products and disclaimers thereto appears at the end of this data sheet.  
2
Out-Of-Audio, PowerPAD are trademarks of Texas Instruments.  
PRODUCTION DATA information is current as of publication date.  
Products conform to specifications per the terms of the Texas  
Instruments standard warranty. Production processing does not  
necessarily include testing of all parameters.  
Copyright © 2009, Texas Instruments Incorporated  
TPS51222  
SLUS908JANUARY 2009............................................................................................................................................................................................... www.ti.com  
These devices have limited built-in ESD protection. The leads should be shorted together or the device placed in conductive foam  
during storage or handling to prevent electrostatic damage to the MOS gates.  
FUNCTIONAL BLOCK DIAGRAM  
VIN  
EN  
V5SW  
1.25V  
4.7V/ 4.5V  
EN1 OK  
+
+
+
+
4.7V/ 4.5V  
VREG3  
V5SW OK  
VREG5  
GND  
+
V5OK  
THOK  
4.2V/ 3.8V  
Ready  
GND  
+
VREF2  
150/ 140  
Deg-C  
1.25V  
GND  
GND  
CLK2  
CLK1  
OSC  
RF  
GND  
1V +5%/ 10%  
+
+
PGOOD1  
Delay  
1V - 5%/ 10%  
1V -30%  
+
+
GND  
UVP  
CLK1  
Ready  
Fault2  
SDN2  
OVP  
1V +15%  
Clamp (+)  
Fault1  
SDN1  
COMP1  
VFB1  
Ramp  
Comp  
+
Clamp (-)  
+ PWM  
VREG5  
1V  
Enable/  
Soft-start  
+
+
VFB-AMP  
EN1  
VREF2  
VBST1  
DRVH1  
SW1  
Ramp  
Comp  
Control  
Logic  
IMON1  
+
Filter  
Amp.  
Skip  
CS-AMP  
CSN1  
CSP1  
+
OCP  
XCON  
+
VREG5  
100mV  
DRVL1  
AZC  
Discharge  
Control  
GND  
GND  
N-OCP  
+
100mV  
VREF2  
GND  
OOA  
Ctrl  
GND  
SKIPSEL1  
Channel-1 Switcher shown  
2
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TPS51222  
www.ti.com ............................................................................................................................................................................................... SLUS908JANUARY 2009  
ABSOLUTE MAXIMUM RATINGS(1)  
over operating free-air temperature range (unless otherwise noted)  
TPS51222  
–0.3 to 34  
–0.3 to 39  
–0.3 to 7  
–5 to 34  
–1 to 13.5  
–0.3 to 7  
–1 to 7  
UNIT  
VIN  
VBST1, VBST2  
VBST1, VBST2(3)  
SW1, SW2  
(2)  
Input voltage range  
V
CSN1, CSN2, CSP1, CSP2  
EN, EN1, EN2, SKIPSEL1, SKIPSEL2, VFB1, VFB2  
V5SW  
V5SW (to VREG5)(4)  
–7 to 7  
DRVH1, DRVH2  
–5 to 39  
–0.3 to 7  
V
V
(3)  
DRVH1, DRVH2  
Output voltage range(2)  
COMP1, COMP2, DRVL1, DRVL2, IMON1, IMON2, PGOOD1,  
PGOOD2, RF, VREF2, VREG5  
–0.3 to 7  
V
VREG3  
–0.3 to 3.6  
150  
V
TJ  
Junction temperature  
Storage temperature  
°C  
°C  
Tstg  
–55 to 150  
(1) Stresses beyond those listed under Absolute Maximum Ratings may cause permanent damage to the device. These are stress ratings  
only and functional operation of the device at these or any other conditions beyond those indicated under recommended operating  
conditions is not implied. Exposure to absolute-maximum-rated conditions for extended periods may affect device reliability.  
(2) All voltage values are with respect to the network ground terminal unless otherwise noted.  
(3) Voltage values are with respect to the corresponding SW terminal.  
(4) When EN is high and V5SW is grounded, or voltage is applied to V5SW when EN is low.  
DISSIPATION RATINGS (2 oz. Trace and Copper Pad with Solder)  
TA < 25°C  
POWER RATING  
DERATING FACTOR  
ABOVE TA = 25°C  
TA = 85°C  
POWER RATING  
PACKAGE  
32-pin RTV  
1.7 W  
17 mW/°C  
0.7 W  
RECOMMENDED OPERATING CONDITIONS  
MIN  
4.5  
TYP  
MAX  
32  
6
UNIT  
VIN  
Supply voltage  
V
V5SW  
–0.8  
–0.1  
–4.0  
–0.1  
–4.0  
–0.8  
VBST1, VBST2  
37  
37  
6
DRVH1, DRVH2  
DRVH1, DRVH2 (wrt SW1, 2)  
SW1, SW2  
32  
13  
I/O voltage  
V
CSP1, CSP2, CSN1, CSN2  
COMP1, COMP2, DRVL1, DRVL2, EN, EN1, EN2, IMON1, IMON2,  
PGOOD1, PGOOD2, RF, SKIPSEL1, SKIPSEL2, VFB1, VFB2,  
VREF2, VREG5  
–0.1  
6
VREG3  
–0.1  
–40  
3.5  
85  
TA  
Operating free-air temperature  
°C  
ORDERING INFORMATION  
ORDERABLE PART  
TA  
-40°C to 85°C  
PACKAGE(1)  
TRANSPORT MEDIA  
QUANTITY  
ECO PLAN  
NUMBER  
TPS51222RTVT  
TPS51222RTVR  
Tape and Reel  
Tape and Reel  
250  
Plastic Quad Flat Pack  
(32-Pin QFN)  
Green (RoHS  
and no Sb/Br)  
3000  
(1) For the most current package and ordering information, see the Package Option Addendum at the end of this document, or see the TI  
website at www.ti.com.  
Copyright © 2009, Texas Instruments Incorporated  
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3
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TPS51222  
SLUS908JANUARY 2009............................................................................................................................................................................................... www.ti.com  
ELECTRICAL CHARACTERISTICS  
over operating free-air temperature range, EN = 3.3V, VIN = 12V, V5SW = 5V (unless otherwise noted)  
PARAMETER  
SUPPLY CURRENT  
TEST CONDITIONS  
MIN  
TYP  
MAX  
UNIT  
VIN shutdown current, TA = 25°C,  
No Load, EN = 0V, V5SW = 0 V  
I(VINSDN)  
VIN shutdown current  
VIN Standby Current  
Vbat Standby Current  
V5SW Supply Current  
7
80  
15  
µA  
µA  
µA  
mA  
VIN standby current, TA = 25°C, No Load,  
EN1 = EN2 = V5SW = 0 V  
I(VINSTBY)  
I(VBATSTBY)  
120  
Vbat standby current, TA = 25°C, No Load  
500  
0.8  
SKIPSEL2 = 2V, EN2 = open, EN1 = V5SW = 0V(1)  
V5SW current, TA = 25°C, No Load,  
ENx = 5V, VFBx = 1.05 V  
I(V5SW)  
VREF2 OUTPUT  
I(VREF2) < ±10 µA, TA = 25°C  
1.98  
1.97  
2.00  
2.00  
2.02  
2.03  
V(VREF2)  
VREF2 Output Voltage  
V
I(VREF2) < ±100 µA, 4.5V < VIN < 32 V  
VREG3 OUTPUT  
V5SW = 0 V, I(VREG3) = 0 mA, TA = 25°C  
3.279  
3.135  
10  
3.313  
3.300  
15  
3.347  
3.400  
20  
V(VREG3)  
VREG3 Output Voltage  
VREG3 Output Current  
V
V5SW = 0 V, 0 mA < I(VREG3) < 10 mA,  
5.5 V < VIN < 32 V  
I(VREG3)  
VREG3 = 3 V  
mA  
VREG5 OUTPUT  
V5SW = 0 V, I(VREG5) = 0 mA, TA = 25°C  
4.99  
4.90  
5.04  
5.03  
5.09  
5.15  
V
V5SW = 0 V, 0 mA < I(VREG5) < 100 mA,  
6 V < VIN < 32 V  
V(VREG5)  
VREG5 Output Voltage  
V5SW = 0 V, 0 mA < I(VREG5) < 100 mA,  
5.5 V < VIN < 32 V  
4.50  
5.03  
5.15  
V
V5SW = 0 V, VREG5 = 4.5 V  
V5SW = 5 V, VREG5 = 4.5 V  
Turning on  
100  
200  
150  
300  
4.7  
200  
400  
4.8  
I(VREG5)  
VREG5 Output Current  
Switchover Threshold  
mA  
4.55  
0.15  
V(THV5SW)  
V
Hysteresis  
0.20  
7.7  
0.25  
td(V5SW)  
Switchover Delay  
5V SW Ron  
Turning on  
ms  
R(V5SW)  
OUTPUT  
I(VREG5) = 100 mA  
0.5  
TA = 25°C, No Load  
0.9925  
0.990  
–50  
1.000  
1.000  
1.0075  
1.010  
50  
VFB Regulation Voltage  
Tolerance  
V(VFB)  
V
TA = –40°C to 85°C , No Load  
VFBx = 1.05 V, COMPx = 1.8 V, TA = 25°C  
I(VFB)  
VFB Input Current  
nA  
R(Dischg)  
CSNx Discharge Resistance ENx = 0 V, CSNx = 0.5 V, TA = 25°C  
20  
40  
VOLTAGE TRANSCONDUCTANCE AMPLIFIER  
Gmv  
VID  
Gain  
TA = 25°C  
500  
µS  
Differential Input Voltage  
Range  
–30  
30  
mV  
TA = 0 to 85°C  
27  
22  
33  
33  
µA  
µA  
COMP Maximum Sink  
Current  
I(COMPSINK)  
COMPx = 1.8 V  
COMPx = 1.8 V  
TA = –40 to 85°C  
COMP Maximum Source  
Current  
I(COMPSRC)  
VCOMP  
–33  
2.22  
1.77  
–43  
2.26  
1.81  
µA  
V
COMP Clamp Voltage  
2.18  
1.73  
COMP Negative Clamp  
Voltage  
VCOMPN  
V
(1) Specified by design. Detail external condition follows application circuit of Figure 52.  
4
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Product Folder Link(s) :TPS51222  
TPS51222  
www.ti.com ............................................................................................................................................................................................... SLUS908JANUARY 2009  
ELECTRICAL CHARACTERISTICS (continued)  
over operating free-air temperature range, EN = 3.3V, VIN = 12V, V5SW = 5V (unless otherwise noted)  
PARAMETER  
CURRENT AMPLIFIER  
TEST CONDITIONS  
CSNx = 5V, TA = 25°C(2)  
MIN  
TYP  
MAX  
UNIT  
GC  
VIC  
Gain  
1.667  
Common mode Input  
Voltage Range  
0
13  
75  
V
Differential Input Voltage  
Range  
VID  
TA = 25°C  
–75  
mV  
POWERGOOD  
PG in from lower  
PG in from higher  
PG hysteresis  
92.5%  
95%  
105%  
5%  
5
97.5%  
V(THPG)  
PG threshold  
102.5%  
107.5%  
I(PG)  
PG sink Current  
PGOOD Delay  
PGOOD = 0.5 V  
Delay for PG in  
mA  
ms  
t(PGDLY)  
SOFTSTART  
t(SSDYL)  
t(SS)  
0.8  
1
1.2  
Soft Start Delay  
Soft Start Time  
Delay for Soft Start, ENx = Hi to SS-ramp starts  
Internal Soft Start  
200  
960  
µs  
µs  
FREQUENCY AND DUTY CONTROL  
f(SW)  
Switching Frequency  
Rf = 330 k  
Lo to Hi  
273  
0.7  
303  
1.3  
0.2  
333  
2
kHz  
V
V(THRF)  
RF Threshold  
Hysteresis  
V
Sync Input Frequency  
Range(2)  
f(SYNC)  
200  
1000  
kHz  
V(DRVH) = 90% to 10%, No Load, CCM/ OOA(2)  
V(DRVH) = 90% to 10%, No Load, Auto-skip  
V(DRVH) = 10% to 90%, No Load  
DRVH-off to DRVL-on  
120  
160  
290  
30  
40  
1
ns  
ns  
ns  
ns  
ns  
V
tONmin  
tOFFmin  
tD  
Minimum On Time  
Minimum Off Time  
Dead time  
250  
400  
50  
10  
30  
DRVL-off to DRVH-on  
70  
(2)  
V(DTH)  
V(DTL)  
DRVH-off threshold  
DRVL-off threshold  
DRVH to GND  
DRVL to GND(2)  
1
V
CURRENT SENSE  
TA = 0 to 85°C  
56  
55  
55  
54  
60  
60  
60  
60  
5
65  
68  
67  
72  
2 V< VCSNx < 12.6 V  
TA = –40 to 85°C  
TA = 0 to 85°C  
TA = –40 to 85°C  
Positive  
V(OCL)  
Current limit threshold  
mV  
0.95 V < VCSNx < 12.6 V  
Auto-Zero cross adjustable  
offset range  
VZCAJ  
0.95 V < VCSNx < 12.6 V, Auto-skip  
0.95 V < VCSNx < 12.6 V, OOA  
0.95 V < VCSNx < 12.6 V  
mV  
mV  
Negative  
–5  
Zero cross detection  
comparator Offset  
V(ZC)  
–4  
0
4
TA = 0 to 85°C  
–50  
–49  
–60  
–60  
–73  
–77  
Negative current limit  
threshold  
V(OCLN-LV)  
TA = –40 to 85°C  
(2) Specified by design.  
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TPS51222  
SLUS908JANUARY 2009............................................................................................................................................................................................... www.ti.com  
ELECTRICAL CHARACTERISTICS (continued)  
over operating free-air temperature range, EN = 3.3V, VIN = 12V, V5SW = 5V (unless otherwise noted)  
PARAMETER  
OUTPUT DRIVERS  
TEST CONDITIONS  
MIN  
TYP  
MAX  
UNIT  
Source, V(VBST-DRVH) = 0.1 V  
1.7  
1
5
3
4
2
R(DRVH)  
DRVH resistance  
DRVL resistance  
Sink, V(DRVH-SW) = 0.1 V  
Source, V(VREG5-DRVL) = 0.1 V  
Sink, V(DRVL-GND) = 0.1 V  
1.3  
0.7  
R(DRVL)  
CURRENT MONITOR  
GIMON Current monitor gain  
50  
VCSPx–VCSNx = 60 mV, 0.95 V < VCSNx < 12.6 V,  
TA = 25°C  
VIMON  
Current monitor output  
2.75  
3.00  
3.25  
200  
V
VCSPx–VCSNx = 0 mV, 0.95 V < VCSNx < 12.6 V,  
TA = 25°C  
VIMON-OFF  
Current monitor output offset  
–200  
mV  
UVP, OVP AND UVLO  
V(OVP)  
OVP Trip Threshold  
OVP detect  
UVP detect  
110%  
115%  
1.5  
120%  
t(OVPDLY)  
V(UVP)  
OVP Prop Delay  
UVP Trip Threshold  
UVP Delay  
µs  
65%  
0.8  
1.7  
75  
70%  
1
73%  
1.2  
t(UVPDLY)  
ms  
V
Wake up  
Hysteresis  
Wake up  
Hysteresis  
Wake up  
Hysteresis  
1.8  
1.9  
V(UVREF2)  
V(UVREG3)  
V(UVREG5)  
VREF2 UVLO Threshold  
VREG3 UVLO Threshold  
VREG5 UVLO Threshold  
100  
3.1  
125  
3.2  
mV  
3
V
0.10  
4.1  
0.35  
0.15  
4.2  
0.20  
4.3  
V
V
0.40  
0.44  
INTERFACE AND LOGIC THRESHOLD  
Wake up  
Hysteresis  
Wake up  
Hysteresis  
0.8  
0.1  
1
0.2  
1.2  
0.3  
V(EN)  
EN Threshold  
V
0.45  
0.1  
0.50  
0.2  
0.55  
0.3  
V(EN12)  
EN1/EN2 Threshold  
V
V
EN1/EN2 SS Start  
Threshold  
V(EN12SS)  
SS-ramp start threshold at external soft start  
1
(3)  
V(EN12SSEND)  
I(EN12)  
EN1/EN2 SS End Threshold SS-End threshold at external soft start  
2
2
V
EN1/EN2 Source Current  
VEN1/EN2 = 0V  
Continuous  
1.6  
2.4  
1.5  
2.1  
3.4  
µA  
Auto Skip  
1.9  
3.2  
SKIPSEL1/SKIPSEL2  
Setting Voltage  
V(SKIPSEL)  
V
OOA Skip (min 1/8 Fsw)  
OOA Skip (min 1/16 Fsw)  
SKIPSELx = 0 V  
SKIPSELx = 5 V  
3.8  
–0.5  
–0.5  
0.5  
0.5  
I(SKIPSEL)  
SKIPSEL Input Current  
µA  
BOOT STRAP SW  
V(FBST) Forward Voltage  
I(BSTLK) VBST Leakage Current  
THERMAL SHUTDOWN  
VVREG5-VBST, IF = 10 mA, TA = 25°C  
VVBST = 37 V, VSW = 32 V  
0.10  
0.01  
0.20  
1.5  
V
µA  
Shutdown temperature(3)  
Hysteresis(3)  
150  
10  
T(SDN)  
Thermal SDN Threshold  
°C  
(3) Specified by design.  
6
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TPS51222  
www.ti.com ............................................................................................................................................................................................... SLUS908JANUARY 2009  
DEVICE INFORMATION  
PINOUT  
RTV PACKAGE  
(TOP VIEW)  
DRVH1  
V5SW  
1
2
3
4
5
6
7
8
24  
23  
22  
21  
20  
19  
DRVH2  
VIN  
RF  
VREG3  
EN2  
TPS51122  
EN1  
PGOOD1  
SKIPSEL1  
CSP1  
PGOOD2  
SKIPSEL2  
CSP2  
18  
17  
CSN2  
CSN1  
PIN FUNCTIONS  
PIN  
I/O  
DESCRIPTION  
NAME  
COMP1  
COMP2  
CSN1  
NO.  
10  
15  
8
Loop compensation pin for current mode (error amplifier output). Connect R (and C if required) from this pin  
to VREF2 for proper loop compensation with current mode operation.  
I
I
Current sense comparator inputs (–). See the current sensing scheme section. Used as power supply for the  
current sense circuit for 5 V or higher output voltage setting. Also, used for output discharge terminal.  
CSN2  
17  
7
CSP1  
Current sense comparator inputs (+). An RC network with high quality X5R or X7R ceramic capacitor should  
be used to extract voltage drop across DCR. 0.1-µF is a good value to start the design. See the current  
sensing scheme section for more details.  
I/O  
O
CSP2  
18  
DRVH1  
DRVH2  
DRVL1  
DRVL2  
1
High-side MOSFET gate driver outputs. Source 1.7 , sink 1.0 , SW-node referenced floating driver. Drive  
voltage corresponds to VBST to SW voltage.  
24  
30  
27  
O
I
Low-side MOSFET gate driver outputs. Source 1.3 , sink 0.7 , and GND referenced driver.  
VREF2 and VREG5 linear regulators enable pin. When turning on, apply greater than 1.2 V and less than 6  
V. Connect to GND to disable.  
EN  
12  
EN1  
4
Channel 1 and channel 2 SMPS Enable Pins. When turning on, apply greater than 0.55 V and less than 6 V.  
Connect to GND to disable. Adjustable soft-start capacitance to be attached here.  
I
EN2  
21  
28  
11  
14  
5
GND  
Ground  
IMON1  
IMON2  
O
Current monitor outputs for channel 1 and channel 2. Adding an RC filter is recommended.  
PGOOD1  
PGOOD2  
Powergood window comparator outputs for channel 1 and channel 2. The recommended applied voltage  
should be less than 6 V, and the recommended pull-up resistance value is from 100 kto 1 M.  
O
20  
Frequency setting pin. Connect a frequency setting resistor to (signal) GND. Connect to an external clock for  
synchronization.  
RF  
3
I/O  
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PIN FUNCTIONS (continued)  
PIN  
I/O  
DESCRIPTION  
NAME  
NO.  
SKIPSEL1  
6
Skip mode selection pin.  
GND: Continuous conduction mode  
VREF2: Auto Skip  
I
SKIPSEL2  
19  
VREG3: OOA Auto Skip, maximum 7 skips (suitable for fsw < 400kHz)  
VREG5: OOA Auto Skip, maximum 15 skips (suitable for equal to or greater than 400kHz)  
SW2  
SW1  
25  
32  
I/O  
I
High-side MOSFET gate driver returns.  
VREG5 switchover power supply input pin. When EN1 is high, PGOOD1 indicates GOOD and V5SW  
voltage is higher than 4.8 V, switch-over function is enabled.  
Note: When switch-over is enabled, VREG5 output voltage is approximately equal to the V5SW input  
voltage.  
V5SW  
2
VBST1  
VBST2  
31  
26  
Supply inputs for high-side N-channel FET driver (boot strap terminal). Connect a capacitor (0.1-µF or  
greater is recommended) from this pin to respective SW terminal. Additional SB diode from VREG5 to this  
pin is an optional.  
I
I
VFB1  
VFB2  
VIN  
9
SMPS voltage feedback Inputs. Connect the feedback resistors divider, and should be referred to (signal)  
GND.  
16  
23  
13  
I
Supply input for 5-V and 3.3-V linear regulator. Typically connected to VBAT.  
VREF2  
O
2-V reference output. Bypass to (signal) GND with 0.22-µF of ceramic capacitance.  
Always alive 3.3 V, 10 mA low dropout linear regulator output. Bypass to (signal) GND with more than 1-µF  
ceramic capacitance. Runs from VIN supply or from VREG5 when it is switched over to V5SW input.  
VREG3  
VREG5  
22  
O
O
5-V, 100-mA low dropout linear regulator output. Bypass to (power) GND using a 10-µF ceramic capacitor.  
Runs from VIN supply. Internally connected to VBST and DRVL. Shuts off with EN. Switches over to V5SW  
when 4.8 V or above is provided.  
29  
Note: When switch-over (see above V5SW) is enabled, VREG5 output voltage is approximately equal to  
V5SW input voltage.  
8
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TYPICAL CHARACTERISTICS  
INPUT VOLTAGE SHUTDOWN CURRENT  
INPUT VOLTAGE SHUTDOWN CURRENT  
vs  
vs  
INPUT VOLTAGE  
JUNCTION TEMPERATURE  
15  
12  
15  
12  
V = 12 V  
I
T
= 25°C  
A
9
6
9
6
3
0
3
0
-50  
0
50  
100  
150  
5
10  
15  
20  
25  
30  
V – Input Voltage – V  
I
T
– Junction Temperature – °C  
J
Figure 1.  
Figure 2.  
INPUT VOLTAGE STANDBY CURRENT  
INPUT VOLTAGE STANDBY CURRENT  
vs  
vs  
JUNCTION TEMPERATURE  
INPUT VOLTAGE  
150  
120  
150  
120  
T
= 25°C  
V = 12 V  
I
A
90  
60  
90  
60  
30  
0
30  
0
-50  
0
50  
100  
150  
5
10  
15  
20  
25  
30  
T
– Junction Temperature – °C  
V – Input Voltage – V  
I
J
Figure 3.  
Figure 4.  
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TYPICAL CHARACTERISTICS (continued)  
NO LOAD BATTERY CURRENT  
NO LOAD BATTERY CURRENT  
vs  
vs  
INPUT VOLTAGE  
INPUT VOLTAGE  
1.0  
0.9  
0.8  
0.7  
0.6  
0.5  
0.4  
0.3  
0.2  
0.1  
0
1.0  
0.9  
0.8  
0.7  
0.6  
0.5  
0.4  
0.3  
0.2  
0.1  
0
EN = on  
EN1 = off  
EN2 = on  
EN = on  
EN1 = on  
EN2 = on  
5
10  
15  
20  
25  
5
10  
15  
20  
25  
V – Input Voltage – V  
I
V – Input Voltage – V  
I
Figure 5.  
Figure 6.  
BATTERY CURRENT  
vs  
INPUT VOLTAGE  
VREF2 OUTPUT VOLTAGE  
vs  
OUTPUT CURRENT  
1.0  
0.9  
0.8  
0.7  
0.6  
0.5  
0.4  
0.3  
0.2  
0.1  
0
2.02  
2.01  
2.00  
1.99  
1.98  
EN = on  
EN1 = on  
EN2 = off  
V = 12 V  
I
5
10  
15  
20  
25  
–100  
–50  
0
50  
100  
V – Input Voltage – V  
I
I
– VREF2 Output Current – mA  
VREF2  
Figure 7.  
Figure 8.  
10  
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TYPICAL CHARACTERISTICS (continued)  
VREG3 OUTPUT VOLTAGE  
vs  
VREG5 OUTPUT VOLTAGE  
vs  
OUTPUT CURRENT  
OUTPUT CURRENT  
3.40  
3.35  
3.3  
5.10  
5.05  
5.00  
4.95  
4.90  
V = 12 V  
V = 12 V  
I
I
3.25  
3.20  
0
20  
40  
60  
80  
100  
0
I
2
4
6
8
10  
I
– 5-V Linear Regulator Output Current – mA  
– 3.3-V Linear Regulator Output Current – mA  
REG5  
REG3  
Figure 9.  
Figure 10.  
SWITCHING FREQUENCY  
vs  
JUNCTION TEMPERATURE  
FORWARD VOLTAGE OF BOOST SW  
vs  
JUNCTION TEMPERATURE  
330  
320  
0.25  
0.20  
R
= 330 kW  
RF  
310  
300  
0.15  
0.10  
290  
280  
270  
0.05  
0
-50  
0
50  
100  
150  
-50  
0
50  
100  
150  
T
– Junction Temperature – °C  
T
– Junction Temperature – °C  
J
J
Figure 11.  
Figure 12.  
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TYPICAL CHARACTERISTICS (continued)  
OVP/UVP THRESHOLD VOLTAGE  
vs  
VBST LEAKAGE CURRENT  
vs  
JUNCTION TEMPERATURE  
JUNCTION TEMPERATURE  
150  
130  
1.5  
1.2  
OVP  
UVP  
110  
90  
0.9  
0.6  
70  
50  
0.3  
0
-50  
0
50  
100  
150  
-50  
0
50  
100  
150  
T
– Junction Temperature – °C  
T
– Junction Temperature – °C  
J
J
Figure 13.  
Figure 14.  
CURRENT LIMIT THRESHOLD  
vs  
JUNCTION TEMPERATURE  
5-V OUTPUT VOLTAGE  
vs  
INPUT VOLTAGE  
66  
5.2  
5.1  
5.0  
4.9  
4.8  
4.7  
4.6  
4.5  
4.4  
4.3  
4.2  
Auto-Skip Mode  
= 330 kHz  
V
(V)  
CSN  
f
SW  
1
5
64  
62  
12  
60  
58  
I
(A)  
O
0
4
8
56  
54  
-50  
0
50  
100  
150  
4.5  
5.0  
5.5  
6.0  
6.5  
7.0  
T
– Junction Temperature – °C  
V – Input Voltage – V  
I
J
Figure 15.  
Figure 16.  
12  
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TYPICAL CHARACTERISTICS (continued)  
3.3-V OUTPUT VOLTAGE  
vs  
5-V EFFICIENCY  
vs  
OUTPUT CURRENT  
INPUT VOLTAGE  
3.40  
3.35  
3.30  
3.25  
3.20  
100  
80  
Auto-Skip  
Auto-Skip Mode  
= 330 kHz  
f
SW  
60  
40  
CCM  
OOA  
I
(A)  
O
Current Mode  
20  
0
0
4
8
V = 12 V  
I
R
= 18 kW  
GV  
0.001  
0.01  
0.1  
1
10  
4.5  
5.0  
5.5  
6.0  
6.5  
7.0  
V – Input Voltage – V  
I
I
– 5-V Output Current – A  
O1  
Figure 17.  
Figure 18.  
5-V EFFICIENCY  
vs  
OUTPUT CURRENT  
3.3-V EFFICIENCY  
vs  
OUTPUT CURRENT  
100  
90  
100  
80  
V = 8 V  
I
Auto-Skip  
V = 12 V  
I
V = 20 V  
I
60  
40  
20  
CCM  
80  
70  
OOA  
V = 12 V  
I
Current Mode  
Auto-Skip  
Current Mode  
60  
50  
R
= 12 kW  
GV  
5.0-V SMPS: ON  
R
= 18 kW  
GV  
0
0.001  
0.001  
0.01  
0.1  
1
10  
0.01  
0.1  
1
10  
I
– 3.3-V Output Current – A  
I
– 5-V Output Current – A  
O2  
O1  
Figure 19.  
Figure 20.  
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TYPICAL CHARACTERISTICS (continued)  
3.3-V EFFICIENCY  
vs  
OUTPUT CURRENT  
5-V SWITCHING FREQUENCY  
vs  
OUTPUT CURRENT  
400  
350  
300  
250  
200  
150  
100  
50  
100  
90  
CCM  
V = 8 V  
I
V = 12 V  
V = 20 V  
I
I
80  
70  
60  
V = 12 V  
OOA  
I
Current Mode  
50  
40  
R
= 12 kW  
GV  
5.0-V SMPS: ON  
Auto-Skip  
0
0.001  
0.001  
0.01  
0.1  
1
10  
0.01  
0.1  
1
10  
I
– 3.3-V Output Current – A  
I
– 5-V Output Current – A  
O2  
O1  
Figure 21.  
Figure 22.  
3.3-V SWITCHING FREQUENCY  
5-V OUTPUT VOLTAGE  
vs  
OUTPUT CURRENT  
vs  
OUTPUT CURRENT  
400  
350  
300  
250  
200  
150  
100  
50  
5.10  
5.08  
5.06  
5.04  
5.02  
5.00  
4.98  
4.96  
4.94  
4.92  
4.90  
CCM  
Auto-Skip  
OOA  
CCM  
OOA  
V = 12 V  
I
Current Mode  
R
= 18 kW  
GV  
Auto-Skip  
0
0.001  
0.01  
0.1  
1
10  
0
1
2
3
4
5
6
7
8
I
– 3.3-V Output Current – A  
I
– 5-V Output Current – A  
O2  
O1  
Figure 23.  
Figure 24.  
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TYPICAL CHARACTERISTICS (continued)  
3.3-V OUTPUT VOLTAGE  
vs  
5-V OUTPUT VOLTAGE  
vs  
OUTPUT CURRENT  
OUTPUT CURRENT  
3.40  
3.38  
3.36  
3.34  
3.32  
3.30  
3.28  
3.26  
3.24  
3.22  
3.20  
5.10  
5.08  
5.06  
5.04  
5.02  
5.00  
4.98  
4.96  
4.94  
4.92  
4.90  
Auto-Skip  
and  
OOA  
Auto-Skip  
and  
OOA  
CCM  
CCM  
V = 12 V  
I
Current Mode  
(Non-droop)  
V = 12 V  
I
Current Mode  
R
= 1 kW  
GV  
C = 1.8 nF  
R
= 12 kW  
GV  
0
1
2
3
4
5
6
7
8
0
1
2
3
4
5
6
7
8
I
– 3.3-V Output Current – A  
I
– 5-V Output Current – A  
O1  
O2  
Figure 25.  
Figure 26.  
3.3-V OUTPUT VOLTAGE  
vs  
5.0-V BODE-PLOT – GAIN AND PHASE  
vs  
OUTPUT CURRENT  
FREQUENCY  
80  
60  
180  
135  
90  
3.40  
3.38  
3.36  
3.34  
3.32  
3.30  
3.28  
3.26  
3.24  
3.22  
3.20  
Phase  
Auto-Skip  
and  
OOA  
40  
20  
45  
Gain  
0
0
–20  
–40  
–60  
–80  
45  
CCM  
–90  
–135  
–180  
V = 12 V  
I
Current Mode  
V
= 5.0 V  
O
V = 12 V  
I
(Non-droop)  
I
= 8 A  
O
R
= 9.1 kW  
GV  
C = 1.8 nF  
100  
1 k  
10 k  
100 k  
1 M  
f – Frequency – Hz  
0
1
2
3
4
5
6
7
8
I
– 3.3-V Output Current – A  
O2  
Figure 27.  
Figure 28.  
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TYPICAL CHARACTERISTICS (continued)  
3.3-V BODE-PLOT – GAIN AND PHASE  
vs  
FREQUENCY  
5.0-V SWITCH-OVER WAVEFORMS  
80  
60  
180  
135  
90  
Phase  
40  
VREG5 (100 mV/div)  
20  
45  
Gain  
0
0
VO1 (100 mV/div)  
–20  
–40  
–60  
–80  
45  
–90  
–135  
–180  
V
= 3.3 V  
O
V = 12 V  
I
2 ms/div  
I
= 8 A  
O
100  
1 k  
10 k  
100 k  
1 M  
f – Frequency – Hz  
Figure 29.  
Figure 30.  
CURRENT MONITOR VOLTAGE  
vs  
OUTPUT CURRENT  
3.0  
2.5  
2.0  
V
IMON1  
1.5  
1.0  
V
IMON2  
0.5  
0
0
2
4
6
8
10  
12  
I
– Output Current – A  
OUTx  
Figure 31.  
16  
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TYPICAL CHARACTERISTICS  
5.0-V START-UP WAVEFORMS  
3.3-V START-UP WAVEFORMS  
EN2 (5V/div)  
EN1 (5V/div)  
Vout1 (2V/div)  
Vout2 (2V/div)  
PGOOD2 (5V/div)  
1msec/div  
PGOOD1 (5V/div)  
1msec/div  
Figure 32.  
5.0-V SOFT-STOP WAVEFORMS  
Figure 33.  
3.3-V SOFT-STOP WAVEFORMS  
EN2 (5V/div)  
EN1 (5V/div)  
Vout1 (2V/div)  
Vout2 (2V/div)  
PGOOD2 (5V/div)  
PGOOD1 (5V/div)  
1msec/div  
1msec/div  
Figure 34.  
Figure 35.  
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TYPICAL CHARACTERISTICS (continued)  
5.0-V LOAD TRANSIENT RESPONSE  
3.3-V LOAD TRANSIENT RESPONSE  
VI =12V, Auto-skip  
VI=12V, Auto-skip  
VO1 (100mV/div)  
VO2 (100mV/div)  
SW1 (10V/div)  
SW2 (10V/div)  
IO1 (5A/div)  
100 ms/div  
IO2 (5A/div)  
100 ms/div  
Figure 36.  
Figure 37.  
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DETAILED DESCRIPTION  
ENABLE AND SOFT START  
When EN is Low, the TPS51222 is in the shutdown state. Only the 3.3-V LDO stays alive, and consumes 7 µA  
(typically). When EN becomes High, the TPS51222 is in the standby state. The 2-V reference and the 5-V LDO  
become enabled, and consume about 80 µA with no load condition, and are ready to turn on SMPS channels.  
Each SMPS channel is turned on when ENx becomes High. After ENx is set to high, the TPS51222 begins the  
softstart sequence, and ramps up the output voltage from zero to the target voltage in 0.96 ms. However, if a  
slower soft-start is required, an external capacitor can be tied from the ENx pin to GND. In this case, the  
TPS51222 charges the external capacitor with the integrated 2-µA current source. An approximate external  
soft-start time would be tEX-SS = CEX / IEN12, which means the time from ENx = 1 V to ENx = 2 V. The recommend  
capacitance is more than 2.2 nF.  
1) Internal  
Soft-start  
EN1  
Vout1  
200ms  
960ms  
EN1<2V  
EN1>1V  
2) External  
Soft-start  
EN1  
External  
Soft-start  
time  
Vout1  
Figure 38. Enable and Soft-start Timing  
Table 1. Enable Logic States  
EN  
GND  
Hi  
EN1  
EN2  
VREG3  
ON  
VREF2  
Off  
VREG5  
Off  
CH1  
Off  
CH2  
Off  
Don’t Care  
Don’t Care  
Lo  
Hi  
Lo  
Hi  
Lo  
Lo  
Hi  
Hi  
ON  
ON  
ON  
Off  
Off  
Hi  
ON  
ON  
ON  
ON  
Off  
Off  
Hi  
ON  
ON  
ON  
ON  
ON  
Hi  
ON  
ON  
ON  
ON  
3.3-V, 10-mA LDO (VREG3)  
A 3.3-V, 10-mA, linear regulator is integrated in the TPS51222. This LDO services some of the analog circuit in  
the device and provides a handy standby supply for 3.3-V Always On voltage in the notebook system. Apply a  
2.2-µF (at least 1-µF), high quality X5R or X7R ceramic capacitor from VREG3 to (signal) GND in adjacent to the  
device.  
2-V, 100-µA Sink/Source Reference (VREF2)  
This voltage is used for the reference of the loop compensation network. Apply a 0.22-µF (at least 0.1-µF),  
high-quality X5R or X7R ceramic capacitor from VREF2 to (signal) GND in adjacent to the device.  
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5.0-V, 100-mA LDO (VREG5)  
A 5.0-V, 100-mA, linear regulator is integrated in the TPS51222. This LDO services the main analog supply rail  
and provides the current for gate drivers until switch-over function becomes enable. Apply a 10-µF (at least  
4.7-µF), high-quality X5R or X7R ceramic capacitor from VREG5 to (power) GND in adjacent to the device.  
VREG5 SWITCHOVER  
When EN1 is high, PGOOD1 indicates GOOD and a voltage of more than 4.8 V is applied to V5SW, the internal  
5V-LDO is shut off and the VREG5 is shorted to V5SW by an internal MOSFET after an 7.7-ms delay. When the  
V5SW voltage becomes lower than 4.65 V, EN1 becomes low, or PGOOD1 indicates BAD, the internal switch is  
turned off, and the internal 5V-LDO resumes immediately.  
BASIC PWM OPERATIONS  
The main control loop of the SMPS is designed as a fixed frequency, peak current mode, pulse width modulation  
(PWM) controller. It achieves stable operation with any type of output capacitors, including low ESR capacitor(s)  
such as ceramic or specialty polymer capacitors.  
The current mode scheme uses the output voltage information and the inductor current information to regulate  
the output voltage. The output voltage information is sensed by VFBx pin. The signal is compared with the  
internal 1-V reference and the voltage difference is amplified by a transconductance amplifier (VFB-AMP). The  
inductor current information is sensed by CSPx and CSNx pins. The voltage difference is amplified by another  
transconductance amplifier (CS-AMP). The output of the VFB-AMP indicates the target peak inductor current. If  
the output voltage decreases, the TPS51222 increases the target inductor current to raise the output voltage.  
Alternatively, if the output voltage rises, the TPS51222 decreases the target inductor current to reduce the output  
voltage.  
At the beginning of each clock cycle, the high-side MOSFET is turned on, or becomes ‘ON’ state. The high-side  
MOSFET is turned off, or becomes OFF state, after the inductor current becomes the target value which is  
determined by the combination value of the output of the VFB-AMP and a ramp compensation signal. The ramp  
compensation signal is used to prevent sub-harmonic oscillation of the inductor current control loop. The  
high-side MOSFET is turned on again at the next clock cycle. By repeating the operation in this manner, the  
controller regulates the output voltage. The synchronous low-side or the rectifying MOSFET is turned on each  
OFF state to keep the conduction loss minimum.  
20  
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PWM FREQUENCY CONTROL  
The TPS51222 has a fixed frequency control scheme with 180° phase shift. The switching frequency can be  
determined by an external resistor which is connected between RF pin and GND, and can be calculated using  
Equation 1.  
5
1 × 10  
f
kHz =  
ù
û
é
sw  
ë
RF kΩ  
é
ù
û
ë
(1)  
TPS51222 can also synchronize to more than 2.5 V amplitude external clock by applying the signal to the RF  
pin. The set timing of channel 1 initiates at the raising edge (1.3 V typ) of the clock and channel 2 initiates at the  
falling edge (1.1 V typ). Therefore, the 50% duty signal makes both channels 180° phase shift.  
1000  
900  
800  
700  
600  
500  
400  
300  
200  
100  
0
100  
200  
300  
400  
500  
RF - Resistance - kW  
Figure 39. Switching Frequency vs RF  
LIGHT LOAD OPERATION  
The TPS51222 automatically reduces switching frequency at light load conditions to maintain high efficiency if  
Auto Skip or Out-of-Audio™ mode is selected by SKIPSELx. This reduction of frequency is achieved by skipping  
pulses. As the output current decreases from heavy load condition, the inductor current is also reduced and  
eventually comes to the point that its peak reaches a predetermined current, ILL(PEAK), which indicates the  
boundary between heavy-load condditions and light-load conditions. Once the top MOSFET is turned on, the  
TPS51222 does not allow it to be turned off until it reaches ILL(PEAK). This eventually causes an overvoltage  
condition to the output and pulse skipping. From the next pulse after zero-crossing is detected, ILL(PEAK) is limited  
by the ramp-down signal ILL(PEAK)RAMP, which starts from 25% of the overcurrent limit setting (IOCL(PEAK): (see the  
Current Protection section) toward 5% of IOCL(PEAK) over one switching cycle to prevent causing large ripple. The  
transition load point to the light load operation ILL(DC) can be calculated in Equation 2.  
I
LL(DC) + ILL(PEAK) * 0.5   IIND(RIPPLE)  
(2)  
(V - V  
) × V  
OUT  
1
IN  
OUT  
I
=
×
IND(RIPPLE)  
L × f  
V
SW  
IN  
(3)  
where  
fSW is the PWM switching frequency which is determined by RF resistor setting or external clock  
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I
= 0.2 - 0.13´ t ´ f  
´ t ´I  
)
SW  
OCL PEAK  
(
LL(PEAK)RAMP  
ON  
(
)
(4)  
Switching frequency versus output current in the light load condition is a function of L, f, VIN and VOUT, but it  
decreases almost proportionally to the output current from the ILL(DC), as described in Equation 2; while  
maintaining the switching synchronization with the clock. Due to the synchronization, the switching waveform in  
boundary load condition (close to ILL(DC)) appears as a sub-harmonic oscillation; however, it is the intended  
operation.  
If SKIPSELx is tied to GND, the TPS51222 works on a constant frequency of fSW regardless its load current.  
Inductor  
Current  
ILL(PEAK)  
ILL(DC)  
IIND(RIPPLE)  
0
Time  
Figure 40. Boundary Between Pulse Skipping and CCM  
20% of I  
I
Ramp Signal  
LL(PEAK)  
OCL  
I
at  
LL(PEAK)  
Light Load  
7% of I  
OCL  
t
ON  
1/f  
SW  
t – Time  
Figure 41. Inductor Current Limit at Pulse Skipping  
Table 2. Skip Mode Selection  
SKIPSELx  
GND  
VREF2  
VREG3  
VREG5  
OOA Skip (maximum 7  
skips, for <400 kHz)  
OOA Skip (maximum 15 skips, for  
equal to or greater than 400kHz)  
OPERATING MODE  
Continuous Conduction  
Auto Skip  
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OUT OF AUDIO SKIP OPERATION  
Out-Of-Audio™ (OOA) light-load mode is a unique control feature that keeps the switching frequency above  
acoustic audible frequencies toward virtually no load condition while maintaining state-of-the-art high conversion  
efficiency. When OOA is selected, the switching frequency is kept higher than audible frequency range in any  
load condition. The TPS51222 automatically reduced switching frequency at light-load conditions. The OOA  
control circuit monitors the states of both MOSFETs and forces an ON state if the predetermined number of  
pulses are skipped. The high-side MOSFET is turned on before the output voltage declines down to the target  
value, so that eventually an overvoltage condition is caused. The OOA control circuit detects this overvoltage  
condition and begins modulating the skip-mode on time to keep the output voltage.  
The TPS51222 supports a wide-switching frequency range, therefore, the OOA skip mode has two selections.  
See Table 2. When the 300-kHz switching frequency is selected, a maximum of seven (7) skips (SKIPSEL=3.3  
V) makes the lowest frequency at 37.5 kHz. If a 15-skip maximum is chosen, it becomes 18.8 kHz, hence the  
maximum 7 skip is suitable for less than 400 kHz, and the maximum 15 skip is 400 kHz or greater.  
99% DUTY CYCLE OPERATION  
In a low-dropout condition such as 5-V input to 5-V output, the basic control loop attempts to maintain 100% of  
the high-side MOSFET ON. However, with the N-channel MOSFET used for the top switch, it is not possible to  
use the 100% on-cycle to charge the boot strap capacitor. TPS51222 detects the 100% ON condition and  
asserts the OFF state at the appropriate time.  
HIGH-SIDE DRIVER  
The high-side driver is designed to drive high current, low RDS(on) N-channel MOSFET(s). The drive capability is  
represented by its internal resistance, which is 1.7for VBSTx to DRVHx, and 1for DRVHx to SWx. When  
configured as a floating driver, 5 V of bias voltage is delivered from VREG5 supply. The instantaneous drive  
current is supplied by the flying capacitor between VBSTx and SWx pins. The average drive current is equal to  
the gate charge at Vgs = 5V times switching frequency. This gate drive current as well as the low-side gate drive  
current times 5 V makes the driving power which needs to be dissipated mainly from TPS51222 package. A  
dead time to prevent shoot through is internally generated between high-side MOSFET off to low-side MOSFET  
on, and low-side MOSFET off to high-side MOSFET on.  
LOW-SIDE DRIVER  
The low-side driver is designed to drive high-current low-RDS(on) N-channel MOSFET(s). The drive capability is  
represented by its internal resistance, which are 1.3for VREG5 to DRVLx and 0.7for DRVLx to GND. The  
5-V bias voltage is delivered from VREG5 supply. The instantaneous drive current is supplied by an input  
capacitor connected between VREG5 and GND. The average drive current is also calculated by the gate charge  
at Vgs = 5 V times switching frequency.  
CURRENT SENSING SCHEME  
In order to provide both good accuracy and cost effective solution, the TPS51222 supports external resistor  
sensing and inductor DCR sensing. An RC network with high quality X5R or X7R ceramic capacitor should be  
used to extract voltage drop across DCR. 0.1µF is a good value to start the design. CSPx and CSNx should be  
connected to positive and negative terminal of the sensing device respectively. The output signal of the internal  
current amplifier becomes 100 mV at the OCL setting point. This means that the current sensing amplifier  
normalize the current information signal based on the OCL setting. Attaching a RC network recommended even  
with a resistor sensing scheme to get an accurate current sensing; see the External Components Selection  
session for detailed configurations.  
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ADAPTIVE ZERO CROSSING  
TPS51222 has an adaptive zero crossing circuit which performs optimization of the zero inductor current  
detection at skip mode operation. This function pursues ideal low-side MOSFET turning off timing and  
compensates inherent offset voltage of the ZC comparator and delay time of the ZC detection circuit. It prevents  
SW-node swing-up caused by too late detection and minimizes diode conduction period caused by too early  
detection. As a result, better light load efficiency is delivered.  
CURRENT PROTECTION  
TPS51222 has cycle-by-cycle overcurrent limiting control. If the inductor current becomes larger than the  
overcurrent trip level, TPS51222 turns off high-side MOSFET, turns on low-side MOSFET and waits for the next  
clock cycle.  
IOCL(PEAK) sets peak level of the inductor current. Thus, the dc load current at overcurrent threshold, IOCL(DC), can  
be calculated as follows;  
I
OCL(DC) + IOCL(PEAK) * 0.5   IIND(RIPPLE)  
(5)  
V
OCL  
I
+
OCL(PEAK)  
R
SENSE  
(6)  
where  
RSENSE is resistance of current sensing device  
V(OCL) is the overcurrent trip threshold voltage  
In an overcurrent condition, the current to the load exceeds the current to the output capacitor thus the output  
voltage tends to fall down, and it ultimately crosses the undervoltage protection threshold and shutdown.  
POWERGOOD  
The TPS51222 has powergood output for both switcher channels. The powergood function is activated after  
softstart has finished. If the output voltage becomes within ±5% of the target value, internal comparators detect  
power good state and the powergood signal becomes high after 1ms internal delay. If the output voltage goes  
outside of ±10% of the target value, the powergood signal becomes low after 1.5µs internal delay. Apply voltage  
should be less than 6V and the recommended pull-up resistance value is from 100kto 1M.  
OUTPUT DISCHARGE CONTROL  
The TPS51222 discharges output when ENx is low. The TPS51222 discharges outputs using an internal  
MOSFET which is connected to CSNx and GND. The current capability of these MOSFETs is limited to  
discharge the output capacitor slowly. If ENx becomes high during discharge, MOSFETs are turning off, and  
some output voltage remains. SMPS changes over to soft-start. The PWM initiates after the target voltage  
overtakes the remaining output voltage.  
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OVERVOLTAGE/UNDERVOLTAGE PROTECTION  
TPS51222 monitors the output voltage to detect overvoltage and undervoltage. When the output voltage  
becomes 15% higher than the target value, the OVP comparator output goes high and the circuit latches as the  
high-side MOSFET driver OFF and the low-side MOSFET driver ON, and shuts off another channel.  
When the feedback voltage becomes lower than 70% of the target voltage, the UVP comparator output goes  
high and an internal UVP delay counter begins counting. After 1 ms, TPS51222 latches OFF both high-side and  
low-side MOSFETs, and shuts off another channel. This UVP function is enabled after soft-start has completed.  
The procedure for restarting from these protection states is:  
1. toggle EN  
2. toggle EN1 and EN2 or  
3. once hit UVLO  
UVLO PROTECTION  
The TPS51222 has undervoltage lockout protections (UVLO) for VREG5, VREG3 and VREF2. When the voltage  
is lower than UVLO threshold voltage, TPS51222 shuts off each output as shown inTable 3. This is non-latch  
protection.  
Table 3. UVLO Protection  
CH1/ CH2  
VREG5  
VREG3  
On  
VREF2  
On  
VREG5 UVLO  
VREG3 UVLO  
VREF2 UVLO  
Off  
Off  
Off  
Off  
Off  
Off  
On  
THERMAL SHUTDOWN  
The TPS51222 monitors the device temperature. If the temperature exceeds the threshold value, TPS51222  
shuts off both SMPS and 5V-LDO, and decreases the VREG3 current limitation to 5 mA (typically). This is  
non-latch protection.  
CURRENT MONITOR  
TPS51222 monitors the output current as the voltage difference between CSPx and CSNx terminal. The  
transconductance amplifier (CS-AMP) amplifies this differential voltage by 50 times and sends out from IMONx  
thermal. Adding RC filter is recommended.  
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APPLICATION INFORMATION  
EXTERNAL COMPONENTS SELECTION  
A buck converter using the TPS51222 consists of linear circuits and a switching modulator. Figure 42 shows the  
basic scheme.  
Voltage divider  
VIN  
Switching Modulator  
Ramp  
comp.  
R1  
DRVH  
Lx  
VFB  
+
Gmv  
Rs  
PWM  
+
Control  
logic  
&
+
R2  
+
DRVL  
Driver  
1.0V  
ESR  
Co  
RL  
COMP  
VREF  
Gmc  
CSP  
Rgv  
Cc  
Rgc  
+
+
CSN  
2.0V  
Error Amplifier  
Figure 42. Simplified Current Mode Functional Blocks  
The external components can be selected by following manner.  
1. Determine output voltage dividing resistors (R1 and R2: shown in Figure 42) using the next equation  
R1 + ǒV  
Ǔ
* 1.0   R2  
OUT  
(7)  
2. Determine switching frequency. Higher frequency allows smaller output capacitances, however, degrade  
efficiency due to increase of switching loss. Frequency setting resistor for RF-pin can be calculated by;  
1   105  
ƒsw [kHz]  
RF[kW] +  
(8)  
3. Choose the inductor. The inductance value should be determined to give the ripple current of  
approximately 25% to 50% of maximum output current. Recommended ripple current rate is about 30% to  
40% at the typical input voltage condition, next equation uses 33%.  
(V  
- VOUT ) × VOUT  
1
IN(TYP)  
L =  
×
0.33 x IOUT(MAX) x fSW  
V
IN(TYP)  
(9)  
The inductor also needs to have low DCR to achieve good efficiency, as well as enough room above peak  
inductor current before saturation.  
4. Determine the sensing resistor.  
Determine the sensing resistor using next equation. IOCL(PEAK) should be approximately 1.5 × IOUT(MAX) to  
1.7 × IOUT(MAX)  
.
VOCL  
IOCL(PEAK)  
RSENSE  
+
(10)  
5. Determine Rgv. Rgv should be determined from preferable droop compensation value and is given by next  
equation based on the typical number of Gmv = 500µS.  
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I
OUT(MAX)  
1
Rgv + 0.1   
  V  
 
OUT  
I
Gmv   Vdroop  
OCL(PEAK)  
(11)  
(12)  
IOUT(MAX)  
VOUT[V]  
Rgv[kW] + 200   
 
IOCL(PEAK) Vdroop[mV]  
If no-droop is preferred, attach a series RC network circuit instead of single resistor. Series resistance is  
determined using Equation 12 . Series capacitance can be arbitrarily chosen to meet the RC time constant,  
but should be kept under 1/10 of fo.  
6. Determine output capacitance Co to achieve a stable operation using the next equation. The 0 dB frequency,  
fo, should be kept under 1/3 of the switching frequency.  
Gmv   Rgv ƒsw  
5
1
ƒ0 +   IOCL(PEAK)  
 
 
t
p
3
VOUT  
Co  
(13)  
(14)  
Gmv   Rgv  
ƒsw  
15  
p
1
Co u  
  IOCL(PEAK)  
 
 
VOUT  
7. Calculate Cc. The purpose of this capacitance is to cancel zero caused by ESR of the output capacitor. If  
ceramic capacitor(s) is used, there is no need for Cc. If a combination of different capacitors is used, attach a  
RC network circuit instead of single capacitance to cancel zeros and poles caused by the output capacitors.  
With single capacitance, Cc is given in Equation 15.  
ESR  
Rgv  
Cc + Co   
(15)  
8. Choose MOSFETs Generally, the on resistance affects efficiency at high load conditions as conduction loss.  
For a low output voltage application, the duty ratio is not high enough so that the on resistance of high-side  
MOSFET does not affect efficiency; however, switching speed (tr and tf) affects efficiency as switching loss.  
As for low-side MOSFET, the switching loss is usually not a main portion of the total loss.  
RESISTOR CURRENT SENSING  
For more accurate current sensing with an external resistor, the following technique is recommended. Adding an  
RC filter to cancel the parasitic inductance of resistor, this filter value is calculated using Equation 16.  
Lx  
Rs  
Cx   Rx +  
(16)  
This equation means time-constant of Cx and Rx should match the one of Lx (ESL) and Rs.  
VIN  
Ex-resistor  
Lx(ESL)  
Rs  
DRVH  
L
Control  
logic  
&
DRVL  
Driver  
Co  
CSP  
CSN  
+
Cx  
Rx  
Figure 43. External Resistor Current Sensing  
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INDUCTOR DCR CURRENT SENSING  
To use inductor DCR as current sensing resistor (Rs), the configuration needs to change as below. However, the  
equation that must be satisfied is the same as the one for the resistor sensing.  
VIN  
Inductor  
DRVH  
Lx  
Rs(DCR)  
Control  
logic  
&
DRVL  
Driver  
Co  
Rx  
CSP  
+
Cx  
CSN  
Figure 44. Inductor DCR Current Sensing  
VIN  
Inductor  
DRVH  
Lx  
Rs(DCR)  
Control  
logic  
&
DRVL  
Driver  
Co  
Rx  
CSP  
+
Cx  
Rc  
CSN  
Figure 45. Inductor DCR Current Sensing With Voltage Divider  
TPS51222 has a fixed V(OCL) point (60 mV). In order to adjust for DCR, a voltage divider can be configured a  
described in Figure 45.  
For Rx, Rc and Cx can be calculated as shown below, and overcurrent limitation value can be calculated as  
follows:  
Lx  
Cx ´ Rx P Rc  
(
=
)
Rs  
(17)  
(18)  
Rx ) Rc  
 
1
Rs  
I
OCL(PEAK) + VOCL  
 
Rc  
Figure 46 shows the compensation technique for the temperature drifts of the inductor DCR value. This scheme  
assumes the temperature rise at the thermistor (RNTC) is directly proportional to the temperature rise at the  
inductor.  
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Inductor  
Lx  
Rs(DCR)  
RNTC  
Rx  
Rc1  
Rc2  
CO  
CSP  
+
Cx  
CSN  
Figure 46. Inductor DCR Current Sensing With Temperature Compensate  
LAYOUT CONSIDERATIONS  
Certain points must be considered before starting a PCB layout work using the TPS51222.  
Placement  
Place RC network for CSP1 and CSP2 close to the device pins.  
Place bypass capacitors for VREG5, VREG3 and VREF2 close to the device pins.  
Place frequency-setting resistor close to the device pin.  
Place the compensation circuits for COMP1 and COMP2 close to the device pins.  
Place the voltage setting resistors close to the device pins.  
Routing (sensitive analog portion)  
Use separate traces for; see Figure 47  
Output voltage sensing from current sensing (negative-side)  
Output voltage sensing from V5SW input (when VOUT = 5V)  
Current sensing (positive-side) from switch-node  
V5SW  
R1  
VFB  
R2  
H-FET  
Inductor  
Vout  
SW  
Cout  
L-FET  
R
CSP  
CSN  
C
Figure 47. Sensing Trace Routings  
Use Kelvin sensing traces from the solder pads of the current sensing device (inductor or resistor) to current  
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sensing comparator inputs (CSPx and CSNx). (See Figure 48)  
Current sensing  
Device  
RC network  
next to IC  
Figure 48. Current Sensing Traces  
Use small copper space for VFBx. These are short and narrow traces to avoid noise coupling  
Connect VFB resistor trace to the positive node of the output capacitor.  
Use signal GND for VREF2 and VREG3 capacitors, RF and VFB resistors, and the other sensitive analog  
components. Placing a signal GND plane (underneath the IC, and fully covered peripheral components) on  
the internal layer for shielding purpose is recommended. (See Figure 49)  
Use a thermal land for PowerPAD™. Five or more vias, with 0.33-mm (13-mils) diameter connected from the  
thermal land to the internal GND plane, should be used to help dissipation. Do NOT connect the GND-pin to  
this thermal land on the surface layer, underneath the package.  
Routing (power portion)  
Use wider/shorter traces of DRVL for low-side gate drivers to reduce stray inductance.  
Use the parallel traces of SW and DRVH for high-side MOSFET gate drive, and keep them away from DRVL.  
Connect SW trace to source terminal of the high-side MOSFET.  
Use power GND for VREG5, VIN and VOUT capacitors and low-side MOSFETs. Power GND and signal GND  
should be connected near the device GND terminal. (See Figure 49)  
0W resistor  
GND  
#28  
GND-pin  
To inner  
Power-GND  
layer  
To inner  
Signal-GND  
plane  
Inner Signal-GND plane  
Figure 49. GND Layout Example  
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APPLICATION CIRCUITS  
2 W S  
2 B F V  
2 T S B V  
2 L V R D  
D N G  
2 P M O C  
2 N O M I  
2 F E R V  
N E  
5 G E R V  
1 L V R D  
1 T S B V  
1 W S  
1 N O M I  
1 P M O C  
1 B F V  
Figure 50. Current Mode, DCR Sensing, 5.0-V/8-A, 3.3-V/8-A, 330-kHz  
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Table 4. Current Mode, DCR Sensing, 5.0-V/8-A, 3.3-V/8-A, 330-kHz  
SYMBOL  
C11  
SPECIFICATION  
MANUFACTURER  
Sanyo  
PART NUMBER  
6TPE330MIL  
2 × 330 µF, 6.3 V, 18 mΩ  
2 × 10 µF, 25 V  
C12  
Murata  
GRM32DR71E106K  
4TPE470MFL  
C21  
470 µF, 4.0V, 15 mΩ  
2 × 10 µF, 25 V  
Sanyo  
C22  
Murata  
GRM32DR71E106K  
FDV1040-3R3M  
FDV1040-3R3M  
FDMS8692  
L1  
3.3 µH, 10.7 A, 10.5 mΩ  
3.3 µH, 10.7 A, 10.5 mΩ  
30-V, 12 A, 10.5 mΩ  
30 V, 18 A, 5.4 mΩ  
TOKO  
L2  
TOKO  
Q11, Q21  
Q12, Q22  
Fairchild  
Fairchild  
FDMS8672AS  
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2 W S  
2 B F V  
2 T S B V  
2 L V R D  
D N G  
2 P M O C  
2 N O M I  
2 F E R V  
N E  
5 G E R V  
1 L V R D  
1 T S B V  
1 W S  
1 N O M I  
1 P M O C  
1 B F V  
Figure 51. Current Mode (Non-Droop), DCR Sensing, 5.0-V/8-A, 3.3-V/8-A, 330-kHz  
Table 5. Current Mode (Non-droop), DCR Sensing, 5.0-V/8-A, 3.3-V/8-A, 330-kHz  
SYMBOL  
SPECIFICATION  
MANUFACTURER  
PART NUMBER  
C11  
2 x 330 µF, 6.3 V 18 mΩ  
Sanyo  
6TPE330MIL  
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Table 5. Current Mode (Non-droop), DCR Sensing, 5.0-V/8-A, 3.3-V/8-A, 330-kHz (continued)  
SYMBOL  
C12  
SPECIFICATION  
MANUFACTURER  
Murata  
PART NUMBER  
GRM32DR71E106K  
4TPE470MFL  
2 x 10 µF, 25 V  
C21  
470 µF, 4.0V, 15 mΩ  
2 x 10 µF, 25 V  
Sanyo  
C22  
Murata  
GRM32DR71E106K  
FDV1040-3R3M  
FDV1040-3R3M  
FDMS8692  
L1  
3.3 µH, 10.7 A, 10.5 mΩ  
3.3 µH, 10.7 A, 10.5 mΩ  
30-V, 12-A, 10.5 mΩ  
30-V, 18-A, 5.4 mΩ  
TOKO  
L2  
TOKO  
Q11, Q21  
Q12, Q22  
Fairchild  
Fairchild  
FDMS8672AS  
34  
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Product Folder Link(s) :TPS51222  
TPS51222  
www.ti.com ............................................................................................................................................................................................... SLUS908JANUARY 2009  
2 W S  
2 B F V  
2 T S B V  
2 L V R D  
D N G  
2 P M O C  
2 N O M I  
2 F E R V  
N E  
5 G E R V  
1 L V R D  
1 T S B V  
1 W S  
1 N O M I  
1 P M O C  
1 B F V  
Figure 52. Current Mode, DCR Sensing, 5.0-V/5-A, 3.3-V/5-A, 300-kHz  
Table 6. Current Mode, DCR Sensing, 5.0-V/5-A, 3.3-V/5-A, 300-kHz  
SYMBOL  
SPECIFICATION  
MANUFACTURER  
PART NUMBER  
C11  
2 × 120 µF, 6.3V, 15 mΩ  
Panasonic  
EEFCX0J121R  
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Product Folder Link(s) :TPS51222  
TPS51222  
SLUS908JANUARY 2009............................................................................................................................................................................................... www.ti.com  
Table 6. Current Mode, DCR Sensing, 5.0-V/5-A, 3.3-V/5-A, 300-kHz (continued)  
SYMBOL  
C12  
SPECIFICATION  
MANUFACTURER  
Murata  
PART NUMBER  
GRM32DR71E106K  
EEFCX0G221R  
GRM32DR71E106K  
CEP125-4R0MC-H  
CEP125-4R0MC-H  
IRF7821  
2 × 10 µF, 25 V  
C21  
2 × 220 µF, 4.0 V, 15 mΩ  
2 × 10 µF, 25 V  
Panasonic  
Murata  
C22  
L1  
4.0 µH, 10.3 A, 6.6 mΩ  
4.0 µH, 10.3 A, 6.6 mΩ  
30 V, 13.6 A, 9.5 mΩ  
30 V, 13.8 A, 5.8 mΩ  
Sumida  
Sumida  
IR  
L2  
Q11, Q21  
Q12, Q22  
IR  
IRF8113  
36  
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Product Folder Link(s) :TPS51222  
PACKAGE MATERIALS INFORMATION  
www.ti.com  
28-Aug-2012  
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)  
TPS51222RTVR  
TPS51222RTVR  
TPS51222RTVT  
TPS51222RTVT  
WQFN  
WQFN  
WQFN  
WQFN  
RTV  
RTV  
RTV  
RTV  
32  
32  
32  
32  
3000  
3000  
250  
330.0  
330.0  
180.0  
180.0  
12.4  
12.4  
12.4  
12.4  
5.3  
5.3  
5.3  
5.3  
5.3  
5.3  
5.3  
5.3  
1.5  
1.5  
1.5  
1.5  
8.0  
8.0  
8.0  
8.0  
12.0  
12.0  
12.0  
12.0  
Q2  
Q2  
Q2  
Q2  
250  
Pack Materials-Page 1  
PACKAGE MATERIALS INFORMATION  
www.ti.com  
28-Aug-2012  
*All dimensions are nominal  
Device  
Package Type Package Drawing Pins  
SPQ  
Length (mm) Width (mm) Height (mm)  
TPS51222RTVR  
TPS51222RTVR  
TPS51222RTVT  
TPS51222RTVT  
WQFN  
WQFN  
WQFN  
WQFN  
RTV  
RTV  
RTV  
RTV  
32  
32  
32  
32  
3000  
3000  
250  
367.0  
367.0  
210.0  
210.0  
367.0  
367.0  
185.0  
185.0  
35.0  
35.0  
35.0  
35.0  
250  
Pack Materials-Page 2  
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