Texas Instruments LM5157EVM-SEPIC User Manual

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User's Guide
LM5157 SEPIC Evaluation Module
The LM5157EVM-SEPIC Evaluation Module (EVM) is designed to showcase the LM5157 wide input voltage
converter, implementing a SEPIC converter with a coupled inductor. The EVM operates at 2.1 MHz, and it
produces a regulated output of 12 V, 12 W from an input of 4 V to 32 V. When the input voltage is between
4 V to 6 V, the output power is derated down to 6 W. The factory-installed converter is the LM5157-Q1.
However, by replacing the IC, the EVM can also be used to demonstrate the performance of the LM51571-Q1,
LM5157, LM51571, LM51581-Q1, LM5158-Q1, LM51581, and LM5158. The difference between the LM5157-Q1
and LM51571-Q1, or between the LM5157 and LM51571, is that the latter has a lower switch current limit for
applications with less output current need.
1 Features and Electrical Performance...................................................................................................................................
1.1 Electrical Parameters.........................................................................................................................................................
1.2 EVM Power Derating Curve...............................................................................................................................................
1.3 Terminals and Signal Test Points.......................................................................................................................................
2 Application Schematic...........................................................................................................................................................
3 EVM Picture.............................................................................................................................................................................5
4 Test Setup and Procedure......................................................................................................................................................6
4.1 Bench Setup.......................................................................................................................................................................6
4.2 Test Equipment..................................................................................................................................................................
4.3 Precautions........................................................................................................................................................................
5 Test Data..................................................................................................................................................................................7
5.1 Efficiency............................................................................................................................................................................7
5.2 Output Regulation..............................................................................................................................................................
5.3 Thermal Performance........................................................................................................................................................
5.4 Typical Power Up...............................................................................................................................................................
5.5 Output Ripple Voltage........................................................................................................................................................
5.6 Step Load Response........................................................................................................................................................11
5.7 Bode Plots........................................................................................................................................................................14
6 Schematics............................................................................................................................................................................15
7 Bill of Materials.....................................................................................................................................................................
8 Board Layout.........................................................................................................................................................................18
Figure 1-1. Power Derating vs. Input Voltage..............................................................................................................................
Figure 2-1. Typical SEPIC Schematic Employing the LM5157/LM51571 and Coupled Inductor................................................
Figure 3-1. LM5157EVM-SEPIC 3D-Rendered
Figure 4-1. Test Setup.................................................................................................................................................................
Figure 5-1. Efficiency vs. Load under Normal V
Figure 5-2. Efficiency vs. Load under Low V
Figure 5-3. Output Regulation vs Input Voltage, I
Figure 5-4. Output Regulation vs Load, v
Figure 5-5. Thermal Image: V
Figure 5-6. EVM Power Up under I
Figure 5-7. Output Ripple Voltage under V
Figure 5-8. Output Ripple Voltage under V
Figure 5-9. Step Load Response under V
Figure 5-10. Step Load Response under V
Figure 5-11. Step Load Response under V
Figure 5-12. EVM Bode Plots, Vin = 12 V, Vout = 12V, Iout = 1 A.............................................................................................
SNVU738 - MARCH 2022
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ABSTRACT

Table of Contents

List of Figures
Picture...............................................................................................................5
, F = 2.1
IN SW
, F = 2.1 MHz...................................................................................................7
IN SW
= 1 A.........................................................................................................7
OUT
= 12 V......................................................................................................................7
IN
= 6 V, I = 1 A, V = 6 V, No Forced Air
IN OUT BIAS
= 1 A..............................................................................................................................
OUT
= 6 V and I
IN OUT
= 18 V and I
IN OUT
= 6 V, I = 0.5 to 1 A Step.................................................................................
IN OUT
= 12 V, I = 0.5 to 1 A
IN OUT
= 30 V, I = 0.5 to 1 A Step.............................................................................
IN OUT
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MHz..............................................................................................7
Cooling...............................................................8
= 1 A.............................................................................................
= 1 A.........................................................................................
Step.............................................................................12
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LM5157 SEPIC Evaluation Module
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