LMZ14201_15 [TI]

SIMPLE SWITCHER 6V to 42V, 1A Power Module in Leaded SMT-TO Package;
LMZ14201_15
型号: LMZ14201_15
厂家: TEXAS INSTRUMENTS    TEXAS INSTRUMENTS
描述:

SIMPLE SWITCHER 6V to 42V, 1A Power Module in Leaded SMT-TO Package

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LMZ14201  
SNVS649I JANUARY 2010REVISED OCTOBER 2015  
®
LMZ14201 SIMPLE SWITCHER 6V to 42V, 1A Power Module in Leaded SMT-TO Package  
1 Features  
2 Applications  
1
Integrated Shielded Inductor  
Simple PCB Layout  
Point of Load Conversions From 12-V and 24-V  
Input Rail  
Time-Critical Projects  
Flexible Start-Up Sequencing Using External Soft-  
Start and Precision Enable  
Space Constrained and High Thermal  
Requirement Applications  
Protection Against Inrush Currents and Faults  
Such as Input UVLO and Output Short Circuit  
Negative Output Voltage Applications  
(See AN-2027) SNVA425  
–40°C to 125°C Junction Temperature Range  
Single Exposed Pad and Standard Pinout for Easy  
Mounting and Manufacturing  
3 Description  
The LMZ14201 SIMPLE SWITCHER® power module  
is an easy-to-use step-down DC-DC solution that can  
drive up to 1-A load with exceptional power  
conversion efficiency, line and load regulation, and  
output accuracy. The LMZ14201 is available in an  
Fast Transient Response for Powering FPGAs  
and ASICs  
Low Output Voltage Ripple  
Pin-to-Pin Compatible Family:  
innovative  
package  
that  
enhances  
thermal  
LMZ1420x (42 V Maximum 3 A, 2 A, 1 A)  
performance and allows for hand or machine  
soldering.  
LMZ1200x (20 V Maximum 3 A, 2 A, 1 A)  
Fully Enabled for WEBENCH® Power Designer  
Electrical Specifications  
The LMZ14201 can accept an input voltage rail  
between 6 V and 42 V and deliver an adjustable and  
highly accurate output voltage as low as 0.8 V. The  
LMZ14201 only requires three external resistors and  
four external capacitors to complete the power  
solution. The LMZ14201 is a reliable and robust  
design with the following protection features: thermal  
shutdown, input UVLO, output overvoltage protection,  
short-circuit protection, output current limit, and  
allows start-up into a prebiased output. A single  
resistor adjusts the switching frequency up to 1 MHz.  
6-W Maximum Total Output Power  
Up to 1-A Output Current  
Input Voltage Range 6 V to 42 V  
Output Voltage Range 0.8 V to 6 V  
Efficiency up to 90%  
Performance Benefits  
Operates at High Ambient Temperature With  
No Thermal Derating  
Device Information(1)(2)  
High Efficiency Reduces System Heat  
Generation  
PART NUMBER  
PACKAGE  
BODY SIZE (NOM)  
LMZ14201  
TO-PMOD (7)  
10.16 mm × 9.85 mm  
Low Radiated Emissions (EMI) Tested With  
EN55022 Class B Standard  
(1) For all available packages, see the orderable addendum at  
the end of the data sheet.  
Low External Component Count  
(2) Peak reflow temperature equals 245°C. See SNAA214 for  
more details.  
Simplified Application Schematic  
Efficiency 12-V Input at 25°C  
100  
LMZ14201  
95  
90  
85  
80  
75  
70  
65  
60  
55  
50  
6.0  
5.0  
3.3  
2.5  
1.8  
1.5  
1.2  
V
IN  
V
OUT  
C
R
ON  
FF  
0.8  
R
FBT  
Enable  
R
COUT  
FBB  
C
C
SS  
IN  
25°C  
0
0.2  
0.4  
0.6  
0.8  
1
OUTPUT CURRENT (A)  
1
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.  
 
 
 
 
 
 
 
 
LMZ14201  
SNVS649I JANUARY 2010REVISED OCTOBER 2015  
www.ti.com  
Table of Contents  
1
2
3
4
5
6
Features.................................................................. 1  
Applications ........................................................... 1  
Description ............................................................. 1  
Revision History..................................................... 2  
Pin Configuration and Functions......................... 3  
Specifications......................................................... 3  
6.1 Absolute Maximum Ratings ...................................... 3  
6.2 ESD Ratings.............................................................. 3  
6.3 Recommended Operating Conditions....................... 4  
6.4 Thermal Information.................................................. 4  
6.5 Electrical Characteristics........................................... 4  
6.6 Typical Characteristics ............................................. 6  
Detailed Description ............................................ 11  
7.1 Overview ................................................................. 11  
7.2 Functional Block Diagram ....................................... 11  
7.3 Feature Description................................................. 11  
7.4 Device Functional Modes........................................ 12  
8
Application and Implementation ........................ 13  
8.1 Application Information............................................ 13  
8.2 Typical Application .................................................. 13  
Power Supply Recommendations...................... 19  
9
10 Layout................................................................... 19  
10.1 Layout Guidelines ................................................. 19  
10.2 Layout Example .................................................... 21  
10.3 Power Dissipation and Board Thermal  
Requirements........................................................... 22  
11 Device and Documentation Support ................. 23  
11.1 Device Support...................................................... 23  
11.2 Documentation Support ........................................ 23  
11.3 Community Resources.......................................... 23  
11.4 Trademarks........................................................... 23  
11.5 Electrostatic Discharge Caution............................ 23  
11.6 Glossary................................................................ 23  
7
12 Mechanical, Packaging, and Orderable  
Information ........................................................... 23  
4 Revision History  
NOTE: Page numbers for previous revisions may differ from page numbers in the current version.  
Changes from Revision H (August 2015) to Revision I  
Page  
Added this new bullet in the Power Module SMT Guidelines section .................................................................................. 19  
Changes from Revision G (May 2015) to Revision H  
Page  
Changed the title of the document ......................................................................................................................................... 1  
Changes from Revision F (October 2013) to Revision G  
Page  
Added Pin Configuration and Functions section, ESD Rating table, Feature Description section, Device Functional  
Modes, Application and Implementation section, Power Supply Recommendations section, Layout section, Device  
and Documentation Support section, and Mechanical, Packaging, and Orderable Information section .............................. 1  
Removed Easy-to-Use Pin Package image .......................................................................................................................... 1  
Removed Evaluation Board Schematic Diagram and BOM section..................................................................................... 22  
Changes from Revision E (March 2013) to Revision F  
Page  
Added Peak Reflow Case Temp = 245°C ............................................................................................................................. 1  
Deleted 10 mils ...................................................................................................................................................................... 5  
Changed 10 mils................................................................................................................................................................... 19  
Added Power Module SMT Guidelines section.................................................................................................................... 19  
Changed 10 mils................................................................................................................................................................... 22  
2
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SNVS649I JANUARY 2010REVISED OCTOBER 2015  
5 Pin Configuration and Functions  
NDW Package  
7-Pin TO-PMOD  
Top View  
VOUT  
FB  
SS  
GND  
EN  
RON  
VIN  
7
6
5
4
3
2
1
Exposed Pad  
Connect to GND  
Pin Functions  
PIN  
TYPE  
DESCRIPTION  
NO.  
NAME  
1
VIN  
Power  
Supply input — Nominal operating range is 6 V to 42 V . A small amount of internal  
capacitance is contained within the package assembly. Additional external input  
capacitance is required between this pin and exposed pad.  
2
3
RON  
EN  
Analog  
Analog  
On Time Resistor — An external resistor from VIN to this pin sets the ON-time of the  
application. Typical values range from 25 kΩ to 124 kΩ.  
Enable — Input to the precision enable comparator. Rising threshold is 1.18 V nominal;  
90 mV hysteresis nominal. Maximum recommended input level is 6.5 V.  
4
5
GND  
SS  
Ground  
Analog  
Ground — Reference point for all stated voltages. Must be externally connected to EP.  
Soft-Start — An internal 8-µA current source charges an external capacitor to produce  
the soft-start function. This node is discharged at 200 µA during disable, overcurrent,  
thermal shutdown and internal UVLO conditions.  
6
FB  
Analog  
Feedback — Internally connected to the regulation, overvoltage, and short-circuit  
comparators. The regulation reference point is 0.8 V at this input pin. Connected the  
feedback resistor divider between the output and ground to set the output voltage.  
7
VOUT  
EP  
Power  
Output Voltage — Output from the internal inductor. Connect the output capacitor  
between this pin and exposed pad.  
Ground  
Exposed Pad — Internally connected to pin 4. Used to dissipate heat from the package  
during operation. Must be electrically connected to pin 4 external to the package.  
6 Specifications  
6.1 Absolute Maximum Ratings  
over operating free-air temperature range (unless otherwise noted)(1)(2)(3)  
MIN  
–0.3  
–0.3  
MAX  
43.5  
7
UNIT  
V
VIN, RON to GND  
EN, FB, SS to GND  
Junction Temperature  
Storage Temperature  
V
150  
150  
°C  
°C  
–65  
(1) Stresses beyond those listed under Absolute Maximum Ratings may cause permanent damage to the device. These are stress ratings  
only, which do not imply functional operation of the device at these or any other conditions beyond those indicated under Recommended  
Operating Conditions. Exposure to absolute-maximum-rated conditions for extended periods may affect device reliability.  
(2) If Military/Aerospace specified devices are required, please contact the Texas Instruments Sales Office/ Distributors for availability and  
specifications.  
(3) For soldering specifications, see product folder at www.ti.com and SNOA549.  
6.2 ESD Ratings  
VALUE  
UNIT  
V(ESD)  
Electrostatic discharge  
Human body model (HBM), per ANSI/ESDA/JEDEC JS-001(1)  
±2000  
V
(1) JEDEC document JEP155 states that 500-V HBM allows safe manufacturing with a standard ESD control process.  
Copyright © 2010–2015, Texas Instruments Incorporated  
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SNVS649I JANUARY 2010REVISED OCTOBER 2015  
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6.3 Recommended Operating Conditions  
over operating free-air temperature range (unless otherwise noted)(1)  
MIN  
6
MAX  
42  
UNIT  
V
VIN  
EN  
0
6.5  
V
Operation Junction Temperature  
40  
125  
°C  
(1) Absolute Maximum Ratings are limits beyond which damage to the device may occur. Recommended Operating Ratings are conditions  
under which operation of the device is intended to be functional. For ensured specifications and test conditions, see the Electrical  
Characteristics.  
6.4 Thermal Information  
LMZ14201  
THERMAL METRIC(1)  
NDW (TO-PMOD)  
UNIT  
7 PINS  
19.3  
21.5  
1.9  
4 layer JEDEC Printed Circuit Board, 100 vias, No air flow  
2 layer JEDEC Printed Circuit Board, No air flow  
Junction-to-ambient  
thermal resistance  
RθJA  
°C/W  
°C/W  
RθJC(top)  
Junction-to-case (top) thermal resistance  
(1) For more information about traditional and new thermal metrics, see the Semiconductor and IC Package Thermal Metrics application  
report, SPRA953.  
6.5 Electrical Characteristics  
Limits are for TJ = 25°C only unless otherwise noted. Minimum and Maximum limits are ensured through test, design or  
statistical correlation. Typical values represent the most likely parametric norm at TJ = 25°C, and are provided for reference  
purposes only. Unless otherwise stated the following conditions apply: VIN = 24 V, Vout = 3.3 V  
PARAMETER  
SYSTEM PARAMETERS  
ENABLE CONTROL(3)  
TEST CONDITIONS  
MIN(1)  
TYP(2)  
MAX(1) UNIT  
VEN  
EN threshold trip point  
VEN rising  
1.18  
V
over the junction temperature  
(TJ) range of –40°C to +125°C  
1.10  
1.25  
VEN-HYS  
SOFT-START  
ISS  
EN threshold hysteresis  
VEN falling  
VSS = 0 V  
90  
8
mV  
SS source current  
µA  
over the junction temperature  
(TJ) range of –40°C to +125°C  
5
11  
ISS-DIS  
SS discharge current  
-200  
1.95  
µA  
CURRENT LIMIT  
ICL  
Current limit threshold  
DC average  
A
3
over the junction temperature  
(TJ) range of –40°C to +125°C  
1.4  
ON/OFF TIMER  
tON-MIN  
ON timer minimum pulse  
width  
150  
260  
ns  
ns  
tOFF  
OFF timer pulse width  
(1) Min and Max limits are 100% production tested at 25°C. Limits over the operating temperature range are ensured through correlation  
using Statistical Quality Control (SQC) methods. Limits are used to calculate Average Outgoing Quality Level (AOQL).  
(2) Typical numbers are at 25°C and represent the most likely parametric norm.  
(3) EN 55022:2006, +A1:2007, FCC Part 15 Subpart B: 2007. See AN-2024 and layout for information on device under test.  
4
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LMZ14201  
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SNVS649I JANUARY 2010REVISED OCTOBER 2015  
Electrical Characteristics (continued)  
Limits are for TJ = 25°C only unless otherwise noted. Minimum and Maximum limits are ensured through test, design or  
statistical correlation. Typical values represent the most likely parametric norm at TJ = 25°C, and are provided for reference  
purposes only. Unless otherwise stated the following conditions apply: VIN = 24 V, Vout = 3.3 V  
PARAMETER  
TEST CONDITIONS  
MIN(1)  
TYP(2)  
MAX(1) UNIT  
REGULATION AND OVERVOLTAGE COMPARATOR  
VFB  
In-regulation feedback  
voltage  
VSS >+ 0.8 V  
TJ = -40°C to  
125°C  
0.798  
over the junction temperature  
(TJ) range of –40°C to +125°C  
V
.777  
0.818  
IO = 1 A  
VSS > +0.8 V  
TJ = 25°C  
0.786  
0.802  
0.818  
V
IO = 10 mA  
VFB-OV  
IFB  
Feedback overvoltage  
protection threshold  
0.92  
5
V
Feedback input bias  
current  
nA  
mA  
μA  
IQ  
Non Switching Input  
Current  
VFB= 0.86 V  
VEN= 0 V  
1
ISD  
Shut Down Quiescent  
Current  
25  
THERMAL CHARACTERISTICS  
TSD  
Thermal Shutdown  
Rising  
Falling  
165  
15  
°C  
°C  
TSD-HYST  
Thermal shutdown  
hysteresis  
PERFORMANCE PARAMETERS  
ΔVO  
Output Voltage Ripple  
Line Regulation  
Load Regulation  
Efficiency  
8
.01%  
1.5  
mV  
PP  
ΔVO/ΔVIN  
ΔVO/IOUT  
η
VIN = 12 V to 42 V, IO= 1 A  
VIN = 24 V  
mV/A  
VIN = 24 V VO = 3.3 V IO = 1 A  
92%  
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6.6 Typical Characteristics  
Unless otherwise specified, the following conditions apply: VIN = 24 V; CIN = 10 uF X7R Ceramic; CO = 100 uF X7R Ceramic;  
TA = 25 C for efficiency curves and waveforms.  
100  
95  
90  
85  
80  
75  
70  
65  
60  
55  
50  
0.3  
0.25  
0.2  
3.3  
2.5  
3.3  
2.5  
1.8  
1.5  
1.2  
1.8  
1.5  
0.8  
1.2  
0.8  
0.15  
0.1  
25°C  
0.05  
0
25°C  
0
0.2  
0.4  
0.6  
0.8  
1
0.6  
OUTPUT CURRENT (A)  
0
1
0.2  
0.4  
0.8  
OUTPUT CURRENT (A)  
Figure 1. Efficiency 6-V Input at 25°C  
Figure 2. Dissipation 6-V Input at 25°C  
100  
0.45  
6.0  
5.0  
95  
90  
85  
80  
75  
70  
65  
60  
55  
50  
6.0  
5.0  
3.3  
2.5  
1.8  
1.5  
1.2  
0.375  
3.3  
2.5  
0.3  
1.8  
1.5  
0.8  
0.225  
1.2  
0.8  
0.15  
25°C  
0.075  
25°C  
0
0
0.6  
1
0.2  
0.4  
0.8  
0
0.2  
0.4  
0.6  
0.8  
1
OUTPUT CURRENT (A)  
OUTPUT CURRENT (A)  
Figure 4. Dissipation 12-V Input at 25°C  
Figure 3. Efficiency 12-V Input at 25°C  
0.7  
100  
95  
0.6  
0.5  
0.4  
0.3  
6.0  
6.0  
90  
5.0  
5.0  
3.3  
3.3  
2.5  
85  
2.5  
1.8  
80  
1.8  
75  
70  
65  
60  
0.2  
0.1  
55  
25°C  
0
25°C  
50  
0
0.6  
OUTPUT CURRENT (A)  
1
0.2  
0.4  
0.8  
0
0.2  
0.4  
0.6  
0.8  
1
OUTPUT CURRENT (A)  
Figure 6. Dissipation 24-V Input at 25°C  
Figure 5. Efficiency 24-V Input at 25°C  
6
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Typical Characteristics (continued)  
Unless otherwise specified, the following conditions apply: VIN = 24 V; CIN = 10 uF X7R Ceramic; CO = 100 uF X7R Ceramic;  
TA = 25 C for efficiency curves and waveforms.  
100  
95  
90  
85  
80  
75  
70  
65  
60  
55  
50  
1.2  
1.0  
0.8  
0.6  
0.4  
0.2  
0
6.0  
5.0  
6.0  
5.0  
3.3  
3.3  
25°C  
0.2  
25°C  
0.6  
OUTPUT CURRENT (A)  
0
0.4  
0.6  
0.8  
1
0.2  
0.4  
0.8  
1
0
OUTPUT CURRENT (A)  
Figure 7. Efficiency 36-V Input at 25°C  
Figure 8. Dissipation 36-V Input at 25°C  
100  
95  
1.2  
1.0  
0.8  
0.6  
0.4  
0.2  
0
6.0  
5.0  
90  
85  
80  
75  
70  
65  
60  
55  
50  
6.0  
5.0  
3.3  
3.3  
25°C  
0.2  
25°C  
0
0.6  
OUTPUT CURRENT (A)  
1
0
0.4  
0.6  
0.8  
1
0.2  
0.4  
0.8  
OUTPUT CURRENT (A)  
Figure 9. Efficiency 42-V Input at 25°C  
Figure 10. Dissipation 42-V Input at 25°C  
0.45  
100  
95  
0.375  
0.3  
3.3  
2.5  
1.8  
1.5  
3.3  
90  
2.5  
1.8  
85  
1.5  
1.2  
80  
0.225  
0.15  
0.075  
0
75  
70  
65  
60  
1.2  
85°C  
55  
85°C  
50  
0
0.2  
0.4  
0.6  
0.8  
1
0
0.6  
OUTPUT CURRENT (A)  
1
0.2  
0.4  
0.8  
OUTPUT CURRENT (A)  
Figure 11. Efficiency 6-V Input at 85°C  
Figure 12. Dissipation 6-V Input at 85°C  
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Typical Characteristics (continued)  
Unless otherwise specified, the following conditions apply: VIN = 24 V; CIN = 10 uF X7R Ceramic; CO = 100 uF X7R Ceramic;  
TA = 25 C for efficiency curves and waveforms.  
100  
95  
90  
85  
80  
75  
70  
65  
60  
55  
50  
0.45  
0.375  
0.3  
5.0  
3.3  
2.5  
1.8  
1.5  
5.0  
3.3  
2.5  
1.8  
1.5  
1.2  
0.225  
0.15  
0.075  
0
1.2  
85°C  
85°C  
0
0.2  
0.4  
0.6  
0.8  
1
0.6  
0
1
0.2  
0.4  
0.8  
OUTPUT CURRENT (A)  
OUTPUT CURRENT (A)  
Figure 13. Efficiency 8-V Input at 85°C  
Figure 14. Dissipation 8-V Input at 85°C  
100  
0.6  
95  
6.0  
0.5  
0.4  
0.3  
0.2  
0.1  
0
6.0  
5.0  
5.0  
90  
85  
3.3  
2.5  
3.3  
2.5  
1.8  
1.5  
1.2  
80  
75  
70  
65  
60  
55  
50  
1.8  
1.5  
1.2  
85°C  
85°C  
0.2  
0.6  
OUTPUT CURRENT (A)  
0
0.4  
0.8  
0
0.2  
0.4  
0.6  
0.8  
1
1
OUTPUT CURRENT (A)  
Figure 15. Efficiency 12-V Input at 85°C  
Figure 16. Dissipation 12-V Input at 85°C  
100  
95  
1.2  
1.0  
90  
85  
80  
75  
70  
65  
60  
55  
50  
6.0  
5.0  
3.3  
2.5  
0.8  
6.0  
5.0  
1.8  
0.6  
0.4  
3.3  
2.5  
0.2  
0
1.8  
85°C  
0.2  
OUTPUT CURRENT (A)  
85°C  
0
0.4  
0.6  
0.8  
1
0.6  
0
0.2  
0.4  
0.8  
1
OUTPUT CURRENT (A)  
Figure 17. Efficiency 24-V Input at 85°C  
Figure 18. Dissipation 24-V Input at 85°C  
8
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Typical Characteristics (continued)  
Unless otherwise specified, the following conditions apply: VIN = 24 V; CIN = 10 uF X7R Ceramic; CO = 100 uF X7R Ceramic;  
TA = 25 C for efficiency curves and waveforms.  
100  
95  
90  
85  
80  
75  
70  
65  
60  
55  
50  
1.2  
1.0  
0.8  
0.6  
0.4  
0.2  
0
6.0  
5.0  
6.0  
5.0  
3.3  
3.3  
85°C  
85°C  
0.2  
OUTPUT CURRENT (A)  
0.6  
OUTPUT CURRENT (A)  
0
0.2  
0.4  
0.8  
1
0
0.4  
0.6  
0.8  
1
Figure 20. Dissipation 36-V Input at 85°C  
Figure 19. Efficiency 36-V Input at 85°C  
1.2  
100  
6.0  
5.0  
95  
1.0  
90  
85  
0.8  
6.0  
5.0  
80  
3.3  
0.6  
75  
3.3  
70  
0.4  
0.2  
65  
60  
55  
85°C  
85°C  
0
0
50  
0.6  
OUTPUT CURRENT (A)  
1
0.2  
0.4  
0.8  
0
0.2  
0.4  
0.6  
0.8  
1
OUTPUT CURRENT (A)  
Figure 22. Dissipation 42-V Input at 85°C  
Figure 21. Efficiency 42-V Input at 85°C  
3.34  
3.36  
24  
3.34  
42  
3.32  
42  
3.32  
3.30  
36  
24  
8
8
12 20  
6
6
3.30  
3.28  
3.26  
3.28  
20  
12  
36  
3.26  
3.24  
85°C  
25°C  
0
0.2  
0.4  
0.6  
0.8  
1.0  
0.8  
OUTPUT CURRENT (A)  
1.0  
0.4  
0.6  
0
0.2  
OUTPUT CURRENT (A)  
Figure 24. Line and Load Regulation at 85°C  
Figure 23. Line and Load Regulation at 25°C  
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Typical Characteristics (continued)  
Unless otherwise specified, the following conditions apply: VIN = 24 V; CIN = 10 uF X7R Ceramic; CO = 100 uF X7R Ceramic;  
TA = 25 C for efficiency curves and waveforms.  
0.5 A/Div  
20 mV/Div  
200 Ps/Div  
Figure 25. Output Ripple  
24VIN 3.3 VO 1 A, BW = 200 MHz  
Figure 26. Transient Response  
24VIN 3.3 VO 0.5-A to 1-A Step  
1.2  
1
2.4  
2.3  
2.2  
2.1  
2.0  
1.9  
1.8  
0.8  
0.6  
0.4  
0.2  
0
SHORT CIRCUIT  
6V  
IN  
12V  
IN  
ONSET  
ÆJA = 19°C/W  
24V  
IN  
25°C  
VOUT = 3.3V  
36V  
IN  
0
5
10  
15  
20  
25  
50  
70 80  
90  
60  
100 110 120  
AMBIENT TEMPERATURE (C)  
INPUT VOLTAGE (V)  
Figure 27. Thermal Derating VOUT = 3.3 V  
Figure 28. Current Limit 1.8 VOUT at 25°C  
2.4  
2.5  
2.3  
2.4  
SHORT CIRCUIT  
SHORT CIRCUIT  
2.3  
2.2  
2.1  
2.2  
ONSET  
2.0  
2.1  
ONSET  
1.9  
2.0  
25°C  
1.8  
0
85°C  
1.9  
30  
INPUT VOLTAGE (V)  
50  
10  
20  
40  
0
10  
20  
30  
40  
50  
INPUT VOLTAGE (V)  
Figure 29. Current Limit 3.3 VOUT at 25°C  
Figure 30. Current Limit 3.3 VOUT at 85°C  
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7 Detailed Description  
7.1 Overview  
7.1.1 COT Control Circuit Overview  
Constant On Time control is based on a comparator and an ON-time one-shot, with the output voltage feedback  
compared with an internal 0.8-V reference. If the feedback voltage is below the reference, the main MOSFET is  
turned on for a fixed ON-time determined by a programming resistor RON. RON is connected to VIN such that ON-  
time is reduced with increasing input supply voltage. Following this ON-time, the main MOSFET remains off for a  
minimum of 260 ns. If the voltage on the feedback pin falls below the reference level again the ON-time cycle is  
repeated. Regulation is achieved in this manner.  
7.2 Functional Block Diagram  
Vin  
1
VIN  
Linear reg  
C
IN  
Cvcc  
5
SS  
Css  
ON  
3
EN  
0.47 PF  
VOUT  
R
7
2
6
RON  
V
O
Timer  
C
10 PH  
FF  
Co  
FB  
R
FBT  
Internal  
Passives  
Regulator IC  
R
FBB  
GND  
4
7.3 Feature Description  
7.3.1 Output Overvoltage Comparator  
The voltage at FB is compared to a 0.92-V internal reference. If FB rises above 0.92-V the ON-time is  
immediately terminated. This condition is known as overvoltage protection (OVP). It can occur if the input voltage  
is increased very suddenly or if the output load is decreased very suddenly. Once OVP is activated, the top  
MOSFET ON-times will be inhibited until the condition clears. Additionally, the synchronous MOSFET will remain  
on until inductor current falls to zero.  
7.3.2 Current Limit  
Current limit detection is carried out during the OFF-time by monitoring the current in the synchronous MOSFET.  
Referring to the Functional Block Diagram, when the top MOSFET is turned off, the inductor current flows  
through the load, the PGND pin and the internal synchronous MOSFET. If this current exceeds 2.0 A (typical) the  
current limit comparator disables the start of the next ON-time period. The next switching cycle will occur only if  
the FB input is less than 0.8V and the inductor current has decreased below 2.0 A. Inductor current is monitored  
during the period of time the synchronous MOSFET is conducting. So long as inductor current exceeds 2.0 A,  
further ON-time intervals for the top MOSFET will not occur. Switching frequency is lower during current limit due  
to the longer OFF-time.  
NOTE  
Current limit is dependent on both duty cycle and temperature as illustrated in the graphs  
in the Typical Characteristics section.  
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Feature Description (continued)  
7.3.3 Thermal Protection  
The junction temperature of the LMZ14201 should not be allowed to exceed its maximum ratings. Thermal  
protection is implemented by an internal Thermal Shutdown circuit which activates at 165 °C (typical) causing the  
device to enter a low power standby state. In this state the main MOSFET remains off causing VO to fall, and  
additionally the CSS capacitor is discharged to ground. Thermal protection helps prevent catastrophic failures for  
accidental device overheating. When the junction temperature falls back below 145 °C (typical Hyst = 20 °C) the  
SS pin is released, VO rises smoothly, and normal operation resumes.  
Applications requiring maximum output current especially those at high input voltage may require application  
derating at elevated temperatures.  
7.3.4 Zero Coil Current Detection  
The current of the lower (synchronous) MOSFET is monitored by a zero coil current detection circuit which  
inhibits the synchronous MOSFET when its current reaches zero until the next ON-time. This circuit enables the  
DCM operating mode, which improves efficiency at light loads.  
7.3.5 Prebiased Start-Up  
The LMZ14201 will properly start up into a prebiased output. This startup situation is common in multiple rail  
logic applications where current paths may exist between different power rails during the startup sequence. The  
following scope capture shows proper behavior during this event.  
OUTPUT  
VOLTAGE  
3.3V OUTPUT  
1.0 V/Div  
2V PRE-BIAS  
0.5 A/Div  
OUTPUT  
CURRENT  
2.0 V/Div  
1 ms/Div  
ENABLE  
Figure 31. Prebiased Start-Up  
7.4 Device Functional Modes  
7.4.1 Discontinuous Conduction and Continuous Conduction Modes  
At light-load, the regulator operates in discontinuous conduction mode (DCM). With load currents above the  
critical conduction point, it operates in continuous conduction mode (CCM). When operating in DCM the  
switching cycle begins at zero amps inductor current; increases up to a peak value, and then recedes back to  
zero before the end of the OFF-time. During the period of time that inductor current is zero, all load current is  
supplied by the output capacitor. The next ON-time period starts when the voltage on the FB pin falls below the  
internal reference. The switching frequency is lower in DCM and varies more with load current as compared to  
CCM. Conversion efficiency in DCM is maintained because conduction and switching losses are reduced with  
the smaller load and lower switching frequency.  
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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. Customers should  
validate and test their design implementation to confirm system functionality.  
8.1 Application Information  
The LMZ14201 is a step-down DC-to-DC power module. It is typically used to convert a higher DC voltage to a  
lower DC voltage with a maximum output current of 1 A. The following design procedure can be used to select  
components for the LMZ14201. Alternately, the WEBENCH software may be used to generate complete designs.  
When generating a design, the WEBENCH software uses iterative design procedure and accesses  
comprehensive databases of components. For more details, go to www.ti.com.  
8.2 Typical Application  
U1  
EP  
V
IN  
Enable  
LMZ14201TZ-ADJ  
3.3V @ 1A  
O
6.0V to 42V  
R
ENT  
C
FF  
0.022 PF  
FBT  
3.32k  
68.1k  
R
ON  
R
61.9k  
C
1
O
C 2  
O
C
R
SS  
C
2
C
1
FBB  
IN  
IN  
R
ENB  
1 PF  
100 PF  
0.022 PF  
1.07k  
D1  
10 PF  
1 PF  
11.8k  
OPT  
Figure 32. Evaluation Board Schematic Diagram  
Table 1. Schematic Bill of Materials  
VOUT  
5 V  
RFBT  
5.62 K  
3.32 K  
2.26 K  
1.87 K  
1 K  
RFBB  
1.07 K  
1.07 K  
1.07 K  
1.50 K  
1.13 K  
8.45 K  
39.2  
RON  
VIN RANGE  
7.7...42 V  
6...42 V  
6...30 V  
6...25 V  
6...21 V  
6...19 V  
6...18 V  
100 K  
61.9 K  
47.5 K  
32.4 K  
28 K  
3.3 V  
2.5 V  
1.8 V  
1.5 V  
1.2 V  
0.8 V  
4.22 K  
0
22.6 K  
24.9 K  
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Table 2. Bill of Materials  
REF DES  
U1  
DESCRIPTION  
SIMPLE SWITCHER ®  
1 µF, 50V, X7R  
10 µF, 50V, X7R  
1 µF, 50V, X7R  
100 µF, 6.3V, X7R  
3.32 kΩ  
CASE SIZE  
PFM-7  
1206  
MANUFACTURER  
Texas Instruments  
Taiyo Yuden  
Taiyo Yuden  
Taiyo Yuden  
Taiyo Yuden  
Vishay Dale  
Vishay Dale  
Vishay Dale  
Vishay Dale  
Vishay Dale  
TDK  
MANUFACTURER P/N  
LMZ14201TZ-ADJ  
Cin1  
UMK316B7105KL-T  
UMK325BJ106MM-T  
UMK316B7105KL-T  
JMK325BJ107MM-T  
CRCW06033K32FKEA  
CRCW06031K07FKEA  
CRCW060361k9FKEA  
CRCW060368k1FKEA  
CRCW060311k8FKEA  
C1608X7R1H223K  
C1608X7R1H223K  
Optional  
Cin2  
1210  
CO1  
1206  
CO2  
1210  
RFBT  
RFBB  
RON  
RENT  
RENB  
CFF  
0603  
1.07 kΩ  
0603  
61.9 kΩ  
0603  
68.1 kΩ  
0603  
11.8 kΩ  
0603  
22 nF, ±10%, X7R, 16V  
22 nF, ±10%, X7R, 16V  
5.1V  
0603  
CSS  
0603  
TDK  
D1  
SOD-23  
8.2.1 Design Requirements  
For this example the following application parameters exist.  
VIN Range = Up to 42 V  
VOUT = 0.8 V to 5 V  
IOUT = 1 A  
Please refer to the table in Table 1 for more information.  
8.2.2 Detailed Design Procedure  
8.2.2.1 Design Steps for the LMZ14201 Application  
The LMZ14201 is fully supported by WEBENCH and offers the following: Component selection, electrical and  
thermal simulations as well as the build-it board for a reduction in design time. The following list of steps can be  
used to manually design the LMZ14201 application.  
1. Select minimum operating VIN with enable divider resistors  
2. Program VO with divider resistor selection  
3. Program turnon time with soft-start capacitor selection  
4. Select CO  
5. Select CIN  
6. Set operating frequency with RON  
7. Determine module dissipation  
8. Lay out PCB for required thermal performance  
8.2.2.1.1 Enable Divider, RENT and RENB Selection  
The enable input provides a precise 1.18-V band-gap rising threshold to allow direct logic drive or connection to  
a voltage divider from a higher enable voltage such as VIN. The enable input also incorporates 90 mV (typical) of  
hysteresis resulting in a falling threshold of 1.09 V. The maximum recommended voltage into the EN pin is 6.5 V.  
For applications where the midpoint of the enable divider exceeds 6.5 V, a small Zener diode can be added to  
limit this voltage.  
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The function of this resistive divider is to allow the designer to choose an input voltage below which the circuit  
will be disabled. This implements the feature of programmable under voltage lockout. This is often used in  
battery powered systems to prevent deep discharge of the system battery. It is also useful in system designs for  
sequencing of output rails or to prevent early turnon of the supply as the main input voltage rail rises at power-  
up. Applying the enable divider to the main input rail is often done in the case of higher input voltage systems  
such as 24V AC/DC systems where a lower boundary of operation should be established. In the case of  
sequencing supplies, the divider is connected to a rail that becomes active earlier in the power-up cycle than the  
LMZ14201 output rail. The two resistors should be chosen based on the following ratio:  
RENT / RENB = (VIN UVLO/ 1.18 V) – 1  
(1)  
The LMZ14201 demonstration and evaluation boards use 11.8 kfor RENB and 68.1 kfor RENT resulting in a  
rising UVLO of 8 V. This divider presents 6.25 V to the EN input when the divider input is raised to 42 V.  
The EN pin is internally pulled up to VIN and can be left floating for always-on operation.  
8.2.2.1.2 Output Voltage Selection  
Output voltage is determined by a divider of two resistors connected between VO and ground. The midpoint of  
the divider is connected to the FB input. The voltage at FB is compared to a 0.8-V internal reference. In normal  
operation an ON-time cycle is initiated when the voltage on the FB pin falls below 0.8 V. The main MOSFET ON-  
time cycle causes the output voltage to rise and the voltage at the FB to exceed 0.8 V. As long as the voltage at  
FB is above 0.8 V, ON-time cycles will not occur.  
The regulated output voltage determined by the external divider resistors RFBT and RFBB is:  
VO = 0.8V × (1 + RFBT / RFBB  
)
(2)  
(3)  
Rearranging terms; the ratio of the feedback resistors for a desired output voltage is:  
RFBT / RFBB = (VO / 0.8V) - 1  
These resistors should be chosen from values in the range of 1.0 kΩ to 10.0 kΩ.  
For VO = 0.8 V the FB pin can be connected to the output directly so long as an output preload resistor remains  
that draws more than 20 µA. Converter operation requires this minimum load to create a small inductor ripple  
current and maintain proper regulation when no load is present.  
A feed-forward capacitor is placed in parallel with RFBT to improve load step transient response. Its value is  
usually determined experimentally by load stepping between DCM and CCM conduction modes and adjusting for  
best transient response and minimum output ripple.  
A table of values for RFBT , RFBB , CFF, and RON is included in the applications schematic.  
8.2.2.1.3 Soft-Start Capacitor Selection  
Programmable soft-start permits the regulator to slowly ramp to its steady state operating point after being  
enabled, thereby reducing current inrush from the input supply and slowing the output voltage rise-time to  
prevent overshoot.  
Upon turnon, after all UVLO conditions have been passed, an internal 8-µA current source begins charging the  
external soft-start capacitor. The soft-start time duration to reach steady-state operation is given by the formula:  
tSS = VREF × CSS / Iss = 0.8V × CSS / 8 µA  
(4)  
This equation can be rearranged as follows:  
CSS = tSS × 8 μA / 0.8 V  
(5)  
Use of a 0.022-μF results in 2.2 ms soft-start interval which is recommended as a minimum value.  
As the soft-start input exceeds 0.8 V the output of the power stage will be in regulation. The soft-start capacitor  
continues charging until it reaches approximately 3.8V on the SS pin. Voltage levels between 0.8 V and 3.8 V  
have no effect on other circuit operation. Note the following conditions will reset the soft-start capacitor by  
discharging the SS input to ground with an internal 200-μA current sink.  
The enable input being “pulled low”  
Thermal shutdown condition  
Overcurrent fault  
Internal VCC UVLO (Approximately 4 V input to VIN)  
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8.2.2.1.4 CO Selection  
None of the required CO output capacitance is contained within the module. At a minimum, the output capacitor  
must meet the worst-case minimum ripple current rating of 0.5 × ILR P-P, as calculated in Equation 20 below.  
Beyond that, additional capacitance will reduce output ripple so long as the ESR is low enough to permit it. A  
minimum value of 10 μF is generally required. Experimentation will be required if attempting to operate with a  
minimum value. Ceramic capacitors or other low ESR types are recommended. See AN-2024 for more detail.  
Equation 6 provides a good first pass approximation of CO for load transient requirements:  
COISTEP*VFB × L × VIN/ (4 × VO × (VIN – VO) × VOUT-TRAN  
)
(6)  
Solving:  
CO1 A × 0.8 V × 10 μH × 24 V / (4 × 3.3 V × ( 24 V – 3.3 V) × 33 mV) 21.3 μF  
(7)  
The LMZ14201 demonstration and evaluation boards are populated with a 100-uF 6.3-V X5R output capacitor.  
Locations for other output capacitors are provided.  
8.2.2.1.5 CIN Selection  
The LMZ14201 module contains an internal 0.47 µF input ceramic capacitor. Additional input capacitance is  
required external to the module to handle the input ripple current of the application. This input capacitance should  
be very close to the module. Input capacitor selection is generally directed to satisfy the input ripple current  
requirements rather than by capacitance value. Worst-case input ripple current rating is dictated by Equation 8:  
I(CIN(RMS)) 1 / 2 × IO × (D / 1-D)  
where  
D VO / VIN  
(8)  
(As a point of reference, the worst-case ripple current will occur when the module is presented with full load  
current and when VIN = 2 × VO).  
Recommended minimum input capacitance is 10-uF X7R ceramic with a voltage rating at least 25% higher than  
the maximum applied input voltage for the application. It is also recommended that attention be paid to the  
voltage and temperature deratings of the capacitor selected. It should be noted that ripple current rating of  
ceramic capacitors may be missing from the capacitor data sheet and you may need to contact the capacitor  
manufacturer for this rating.  
If the system design requires a certain minimum value of input ripple voltage ΔVIN be maintained then Equation 9  
may be used.  
CIN IO × D × (1–D) / fSW-CCM × ΔVIN  
(9)  
If ΔVIN is 1% of VIN for a 24-V input to 3.3-V output application this equals 240 mV and fSW = 400 kHz.  
CIN1 A × 3.3 V / 24 V × (1– 3.3 V/24 V) / (400000 × 0.240 V)  
0.9 μF  
Additional bulk capacitance with higher ESR may be required to damp any resonant effects of the input  
capacitance and parasitic inductance of the incoming supply lines.  
8.2.2.1.6 RON Resistor Selection  
Many designs will begin with a desired switching frequency in mind. For that purpose Equation 10 can be used.  
f
SW(CCM) VO / (1.3 × 10-10 × RON  
)
(10)  
This can be rearranged as  
R
ON VO / (1.3 × 10 -10 × fSW(CCM)  
)
(11)  
The selection of RON and fSW(CCM) must be confined by limitations in the ON-time and OFF-time for the COT  
Control Circuit Overview section.  
The ON-time of the LMZ14201 timer is determined by the resistor RON and the input voltage VIN. It is calculated  
as follows:  
tON = (1.3 × 10-10 × RON) / VIN  
(12)  
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The inverse relationship of tON and VIN gives a nearly constant switching frequency as VIN is varied. RON should  
be selected such that the ON-time at maximum VIN is greater than 150 ns. The ON-timer has a limiter to ensure  
a minimum of 150 ns for tON. This limits the maximum operating frequency, which is governed by Equation 13:  
fSW(MAX) = VO / (VIN(MAX) × 150 ns)  
(13)  
This equation can be used to select RON if a certain operating frequency is desired so long as the minimum ON-  
time of 150 ns is observed. The limit for RON can be calculated as follows:  
R
ON VIN(MAX) × 150 nsec / (1.3 × 10 -10  
)
(14)  
If RON calculated in Equation 11 is less than the minimum value determined in Equation 14 a lower frequency  
should be selected. Alternatively, VIN(MAX) can also be limited to keep the frequency unchanged.  
NOTE  
The minimum OFF-time of 260 ns limits the maximum duty ratio. Larger RON (lower FSW  
)
should be selected in any application requiring large duty ratio.  
8.2.2.1.6.1 Discontinuous Conduction and Continuous Conduction Mode Selection  
Operating frequency in DCM can be calculated as follows:  
2
f
SW(DCM) VO × (VIN-1) × 10 μH × 1.18 × 1020 × IO/(VIN–VO) × RON  
(15)  
In CCM, current flows through the inductor through the entire switching cycle and never falls to zero during the  
OFF-time. The switching frequency remains relatively constant with load current and line voltage variations. The  
CCM operating frequency can be calculated using Equation 7 above.  
Figure 33 shows a comparison pair of waveforms of the showing both CCM (upper) and DCM operating modes.  
The approximate formula for determining the DCM/CCM boundary is as follows:  
IDCB VO × (VIN–VO) / (2 × 10 μH × fSW(CCM) × VIN)  
(16)  
Figure 34 shows a typical waveform showing the boundary condition.  
500 mA/Div  
2.00 Ps/Div  
500 mA/Div  
2.00 Ps/Div  
Figure 34. Transition Mode Operation  
VIN = 24 V, VO = 3.3 V, IO = 0.29 A  
Figure 33. CCM and DCM Operating Modes  
VIN = 12 V, VO = 3.3 V, IO = 1 A / 0.25 A  
The inductor internal to the module is 10 μH. This value was chosen as a good balance between low and high  
input voltage applications. The main parameter affected by the inductor is the amplitude of the inductor ripple  
current (ILR). ILR can be calculated with:  
ILR P-P = VO × (VIN– VO) / (10 µH × fSW × VIN)  
where  
VIN is the maximum input voltage and fSW is determined from Equation 10.  
(17)  
If the output current IO is determined by assuming that IO = IL, the higher and lower peak of ILR can be  
determined. Be aware that the lower peak of ILR must be positive if CCM operation is required.  
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8.2.3 Application Curves  
100  
95  
90  
85  
80  
75  
70  
65  
60  
55  
50  
1.2  
1
0.8  
0.6  
0.4  
0.2  
0
0.4  
0.6  
0.8  
1
0
0.2  
50 60  
70 80  
90 100 110 120  
OUTPUT CURRENT (A)  
AMBIENT TEMPERATURE (°C)  
Figure 35. Efficiency VIN = 24 V VOUT = 5.0 V  
Figure 36. Thermal Derating Curve  
VIN = 24 V, VOUT = 5.0 V  
80.0  
70.0  
60.0  
50.0  
40.0  
EN 55022 CLASS B LIMIT  
30.0  
20.0  
10.0  
0.0  
0
1000  
200  
400  
600  
FREQUENCY (MHz)  
800  
Figure 37. Radiated Emissions (EN 55022 Class B)  
from Evaluation Board  
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9 Power Supply Recommendations  
The LMZ14201 device is designed to operate from an input voltage supply range between 4.5 V and 42 V. This  
input supply should be well regulated and able to withstand maximum input current and maintain a stable  
voltage. The resistance of the input supply rail should be low enough that an input current transient does not  
cause a high enough drop at the LMZ14201 supply voltage that can cause a false UVLO fault triggering and  
system reset. If the input supply is more than a few inches from the LMZ14201, additional bulk capacitance may  
be required in addition to the ceramic bypass capacitors. The amount of bulk capacitance is not critical, but a 47-  
μF or 100-μF electrolytic capacitor is a typical choice.  
10 Layout  
10.1 Layout Guidelines  
PCB layout is an important part of DC-DC converter design. Poor board layout can disrupt the performance of a  
DC-DC converter and surrounding circuitry by contributing to EMI, ground bounce and resistive voltage drop in  
the traces. These can send erroneous signals to the DC-DC converter resulting in poor regulation or instability.  
Good layout can be implemented by following a few simple design rules.  
1. Minimize area of switched current loops.From an EMI reduction standpoint, it is imperative to minimize  
the high di/dt paths during PCB layout. The high current loops that do not overlap have high di/dt content that  
will cause observable high-frequency noise on the output pin if the input capacitor (Cin1) is placed at a  
distance away from the LMZ14201. Therefore place CIN1 as close as possible to the LMZ14201 VIN and  
GND exposed pad. This will minimize the high di/dt area and reduce radiated EMI. Additionally, grounding for  
both the input and output capacitor should consist of a localized top side plane that connects to the GND  
exposed pad (EP).  
2. Have a single point ground.The ground connections for the feedback, soft-start, and enable components  
should be routed to the GND pin of the device. This prevents any switched or load currents from flowing in  
the analog ground traces. If not properly handled, poor grounding can result in degraded load regulation or  
erratic output voltage ripple behavior. Provide the single point ground connection from pin 4 to EP.  
3. Minimize trace length to the FB pin.Both feedback resistors, RFBT and RFBB, and the feed forward  
capacitor CFF, should be close to the FB pin. Because the FB node is high impedance, maintain the copper  
area as small as possible. The trace are from RFBT, RFBB, and CFF should be routed away from the body of  
the LMZ14201 to minimize noise.  
4. Make input and output bus connections as wide as possible.This reduces any voltage drops on the input  
or output of the converter and maximizes efficiency. To optimize voltage accuracy at the load, ensure that a  
separate feedback voltage sense trace is made to the load. Doing so will correct for voltage drops and  
provide optimum output accuracy.  
5. Provide adequate device heat-sinking.Use an array of heat-sinking vias to connect the exposed pad to the  
ground plane on the bottom PCB layer. If the PCB has a plurality of copper layers, these thermal vias can  
also be employed to make connection to inner layer heat-spreading ground planes. For best results use a 6  
× 6 via array with minimum via diameter of 8 mils thermal vias spaced 59 mils (1.5 mm). Ensure enough  
copper area is used for heat-sinking to keep the junction temperature below 125°C.  
10.1.1 Power Module SMT Guidelines  
The recommendations below are for a standard module surface mount assembly  
Land Pattern – Follow the PCB land pattern with either soldermask defined or non-soldermask defined pads  
Stencil Aperture  
For the exposed die attach pad (DAP), adjust the stencil for approximately 80% coverage of the PCB land  
pattern  
For all other I/O pads use a 1:1 ratio between the aperture and the land pattern recommendation  
Solder Paste – Use a standard SAC Alloy such as SAC 305, type 3 or higher  
Stencil Thickness – 0.125 to 0.15 mm  
Reflow - Refer to solder paste supplier recommendation and optimized per board size and density  
Refer to AN SNAA214 for Reflow information  
Maximum number of reflows allowed is one  
Copyright © 2010–2015, Texas Instruments Incorporated  
Submit Documentation Feedback  
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SNVS649I JANUARY 2010REVISED OCTOBER 2015  
www.ti.com  
Layout Guidelines (continued)  
Figure 38. Sample Reflow Profile  
Table 3. Sample Reflow Profile Table  
MAX TEMP  
(°C)  
REACHED TIME ABOVE REACHED TIME ABOVE REACHED TIME ABOVE REACHED  
PROBE  
MAX TEMP  
235°C  
235°C  
245°C  
245°C  
260°C  
260°C  
1
2
3
242.5  
242.5  
241.0  
6.58  
0.49  
6.39  
0.00  
7.10  
0.00  
7.10  
0.55  
6.31  
0.00  
0.00  
7.09  
0.42  
6.44  
0.00  
0.00  
20  
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Copyright © 2010–2015, Texas Instruments Incorporated  
Product Folder Links: LMZ14201  
LMZ14201  
www.ti.com  
SNVS649I JANUARY 2010REVISED OCTOBER 2015  
10.2 Layout Example  
V
IN  
V
O
LMZ14201  
VOUT  
VIN  
High  
di/dt  
C
in1  
C
O1  
GND  
Loop 2  
Loop 1  
Figure 39. Minimize Area of Current Loops in Buck Module  
Top View  
Thermal Vias  
GND  
GND  
EPAD  
CIN  
COUT  
1
2
3
4
5
6
7
VOUT  
VIN  
RON  
RFBT  
RENT  
RENB  
CFF  
CSS  
RFBB  
GND Plane  
Figure 40. PCB Layout Guide  
Figure 41. EVM Board Layout - Top View  
Copyright © 2010–2015, Texas Instruments Incorporated  
Submit Documentation Feedback  
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LMZ14201  
SNVS649I JANUARY 2010REVISED OCTOBER 2015  
www.ti.com  
Layout Example (continued)  
Figure 42. EVM Board Layout - Bottom View  
10.3 Power Dissipation and Board Thermal Requirements  
For the design case of VIN = 24 V, VO = 3.3 V, IO = 1A, TAMB(MAX) = 85°C , and TJUNCTION = 125°C, the device  
must see a thermal resistance from case to ambient of less than:  
RθCA< (TJ-MAX – TAMB(MAX)) / PIC-LOSS – RθJC  
(18)  
Given the typical thermal resistance from junction to case to be 1.9 °C/W. Use the 85°C power dissipation curves  
in the Typical Performance Characteristics section to estimate the PIC-LOSS for the application being designed. In  
this application it is 0.52W.  
RθCA = (125 — 85) / 0.52 W — 1.9 = 75  
(19)  
To reach RθCA = 75, the PCB is required to dissipate heat effectively. With no airflow and no external heat, a  
good estimate of the required board area covered by 1 oz. copper on both the top and bottom metal layers is:  
Board Area_cm2 = 500°C x cm2/W / RθJC  
(20)  
As a result, approximately 6 square cm of 1 oz copper on top and bottom layers is required for the PCB design.  
Additional area will decrease die temperature proportionately. The PCB copper heat sink must be connected to  
the exposed pad. Approximately thirty six, 8 mils thermal vias spaced 59 mils (1.5 mm) apart must connect the  
top copper to the bottom copper. For an example of a high thermal performance PCB layout of approximately 31  
square cm area. Refer to the Evaluation Board application note AN-2024 SNVA422. For more information on  
thermal design see AN-2020 SNVA419 and AN-2026 SNVA424.  
22  
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Copyright © 2010–2015, Texas Instruments Incorporated  
Product Folder Links: LMZ14201  
LMZ14201  
www.ti.com  
SNVS649I JANUARY 2010REVISED OCTOBER 2015  
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  
Design Summary LMZ1 and LMZ2 Power Modules, SNAA214  
AN-2027 Inverting Application for the LMZ14203 SIMPLE SWITCHER Power Module, SNVA425  
Evaluation Board Application Note AN-2024, SNVA422  
AN-2020 Thermal Design By Insight, Not Hindsight, SNVA419  
AN-2026 Effect of PCB Design on Thermal Performance of SIMPLE SWITCHER Power Modules, SNVA424  
11.3 Community Resources  
The following links connect to TI community resources. Linked contents are 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.  
TI E2E™ Online Community TI's Engineer-to-Engineer (E2E) Community. Created to foster collaboration  
among engineers. At e2e.ti.com, you can ask questions, share knowledge, explore ideas and help  
solve problems with fellow engineers.  
Design Support TI's Design Support Quickly find helpful E2E forums along with design support tools and  
contact information for technical support.  
11.4 Trademarks  
E2E is a trademark of Texas Instruments.  
WEBENCH, SIMPLE SWITCHER are registered trademarks of Texas Instruments.  
All other trademarks are the property of their respective owners.  
11.5 Electrostatic Discharge Caution  
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.  
11.6 Glossary  
SLYZ022 TI Glossary.  
This glossary lists and explains terms, acronyms, and definitions.  
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 © 2010–2015, Texas Instruments Incorporated  
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PACKAGE OPTION ADDENDUM  
www.ti.com  
3-Sep-2015  
PACKAGING INFORMATION  
Orderable Device  
Status Package Type Package Pins Package  
Eco Plan  
Lead/Ball Finish  
MSL Peak Temp  
Op Temp (°C)  
-40 to 125  
Device Marking  
Samples  
Drawing  
Qty  
(1)  
(2)  
(6)  
(3)  
(4/5)  
LMZ14201TZ-ADJ/NOPB  
LMZ14201TZE-ADJ/NOPB  
LMZ14201TZX-ADJ/NOPB  
ACTIVE  
TO-PMOD  
TO-PMOD  
TO-PMOD  
NDW  
7
7
7
250  
Green (RoHS  
& no Sb/Br)  
CU SN  
CU SN  
CU SN  
Level-3-245C-168 HR  
Level-3-245C-168 HR  
Level-3-245C-168 HR  
LMZ14201  
TZ-ADJ  
ACTIVE  
ACTIVE  
NDW  
NDW  
45  
Green (RoHS  
& no Sb/Br)  
-40 to 125  
LMZ14201  
TZ-ADJ  
500  
Green (RoHS  
& no Sb/Br)  
-40 to 125  
LMZ14201  
TZ-ADJ  
(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) Eco Plan - The planned eco-friendly classification: Pb-Free (RoHS), Pb-Free (RoHS Exempt), or Green (RoHS & no Sb/Br) - please check http://www.ti.com/productcontent for the latest availability  
information and additional product content details.  
TBD: The Pb-Free/Green conversion plan has not been defined.  
Pb-Free (RoHS): TI's terms "Lead-Free" or "Pb-Free" mean semiconductor products that are compatible with the current RoHS requirements for all 6 substances, including the requirement that  
lead not exceed 0.1% by weight in homogeneous materials. Where designed to be soldered at high temperatures, TI Pb-Free products are suitable for use in specified lead-free processes.  
Pb-Free (RoHS Exempt): This component has a RoHS exemption for either 1) lead-based flip-chip solder bumps used between the die and package, or 2) lead-based die adhesive used between  
the die and leadframe. The component is otherwise considered Pb-Free (RoHS compatible) as defined above.  
Green (RoHS & no Sb/Br): TI defines "Green" to mean Pb-Free (RoHS compatible), and free of Bromine (Br) and Antimony (Sb) based flame retardants (Br or Sb do not exceed 0.1% by weight  
in homogeneous material)  
(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/Ball Finish - Orderable Devices may have multiple material finish options. Finish options are separated by a vertical ruled line. Lead/Ball Finish 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  
3-Sep-2015  
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  
3-Sep-2015  
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)  
LMZ14201TZ-ADJ/NOPB  
TO-  
PMOD  
NDW  
NDW  
7
7
250  
500  
330.0  
24.4  
10.6 14.22  
5.0  
16.0  
24.0  
Q2  
LMZ14201TZX-ADJ/NOP  
B
TO-  
PMOD  
330.0  
24.4  
10.6 14.22  
5.0  
16.0  
24.0  
Q2  
Pack Materials-Page 1  
PACKAGE MATERIALS INFORMATION  
www.ti.com  
3-Sep-2015  
*All dimensions are nominal  
Device  
Package Type Package Drawing Pins  
SPQ  
Length (mm) Width (mm) Height (mm)  
LMZ14201TZ-ADJ/NOPB  
LMZ14201TZX-ADJ/NOPB  
TO-PMOD  
TO-PMOD  
NDW  
NDW  
7
7
250  
500  
367.0  
367.0  
367.0  
367.0  
45.0  
45.0  
Pack Materials-Page 2  
MECHANICAL DATA  
NDW0007A  
BOTTOM SIDE OF PACKAGE  
TOP SIDE OF PACKAGE  
TZA07A (Rev D)  
www.ti.com  
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