User’s Guide
LM5123EVM-BST Evaluation Module
ABSTRACT
The LM5123EVM-BST evaluation module showcases the features and performance of the LM5123-Q1 wide
input voltage synchronous boost controller. The standard configuration is designed to provide a regulated output
of 24-V at 200-W, from an input voltage of 8-V to 18-V and switching at 440 kHz. The output voltage can be
dynamically up to 33-V using the TRK pin of the LM5123-Q1.
This EVM is designed for ease of configuration, enabling an user to evaluate many different applications on
the same module. Functionality includes: low I
Q
operation, internal feedback resistors, bypass mode operation
when V
IN
is greater than V
OUT
, dynamic output voltage tracking, power good (PGOOD) indicator, programmable
frequency dithering, programmable undervoltage lock out (UVLO), and overvoltage protection.
Table of Contents
1 Introduction
.............................................................................................................................................................................
3
1.1 Applications........................................................................................................................................................................
3
1.2 Features.............................................................................................................................................................................
3
2 EVM Setup
...............................................................................................................................................................................
4
2.1 EVM Characteristics...........................................................................................................................................................
5
2.2 EVM Connectors and Test Points......................................................................................................................................
5
2.3 EVM Configurations...........................................................................................................................................................
7
3 Test Setup and Procedures
....................................................................................................................................................
8
3.1 Equipment..........................................................................................................................................................................
8
4 Test Results
.............................................................................................................................................................................
9
4.1 Efficiency ...........................................................................................................................................................................
9
4.2 Load Regulation ..............................................................................................................................................................
10
4.3 Thermal Performance......................................................................................................................................................
10
4.4 Start-up Waveforms..........................................................................................................................................................
11
4.5 Steady State Operation....................................................................................................................................................
11
4.6 Load Transient Response................................................................................................................................................
12
4.7 Output Voltage Tracking...................................................................................................................................................
13
5 PCB Layers
............................................................................................................................................................................
14
6 Schematic
..............................................................................................................................................................................
16
7 Bill of Materials
.....................................................................................................................................................................
17
8 Revision History
...................................................................................................................................................................
21
List of Figures
Figure 1-1. Typical Application Circuit.........................................................................................................................................
3
Figure 2-1. EVM Photo................................................................................................................................................................
4
Figure 2-2. Fixed Output Voltage Configuration..........................................................................................................................
7
Figure 2-3. Variable Output Voltage Configuration .....................................................................................................................
7
Figure 3-1. EVM Test Setup.........................................................................................................................................................
8
Figure 4-1. Efficiency: V
OUT
= 24-V.............................................................................................................................................
9
Figure 4-2. Efficiency: V
OUT
= 24-V Light Load............................................................................................................................
9
Figure 4-3. 24-V Load Regulation..............................................................................................................................................
10
Figure 4-4. Thermal Performance: V
IN
= 8-V, V
OUT
= 24-V P
OUT
= 200-W, No Forced Airflow.................................................
10
Figure 4-5. V
IN
= 8-V, V
OUT
= 24-V, P
OUT
= 200-W....................................................................................................................
11
Figure 4-6. V
IN
= 10-V, V
OUT
= 24-V, P
OUT
= 200-W..................................................................................................................
11
Figure 4-7. V
IN
= 14-V, V
OUT
= 24-V, P
OUT
= 200-W..................................................................................................................
11
Figure 4-8. V
IN
= 18-V, V
OUT
= 24-V, P
OUT
= 200-W..................................................................................................................
11
Figure 4-9. V
IN
= 8-V, V
OUT
= 24-V, P
OUT
= 200-W....................................................................................................................
11
Figure 4-10. V
IN
= 10-V, V
OUT
= 24-V, P
OUT
= 200-W................................................................................................................
11
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Table of Contents
SNVU737A – DECEMBER 2020 – REVISED DECEMBER 2021
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LM5123EVM-BST Evaluation Module
1
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