Other Parts Discussed in Thread: LM5146
Tool/software:
I tested the evaluation board with a 48V input and resistive loads up to 6.5A and it performed well.
I tried fitting an external variable resistor between the TRIM and AGND connectors to adjust the voltage. As I was adjusting the variable resistror, capacitor C1 failed (case distorted by internal pressure, electrolyte leaked). At the same time, the LM5146 chip failed. It no longer gives any output.
The part used for C1 is a Panasonic part EEE-FK2A330P (from bill of materials for EVM). This has an ESR of 700 mOhm and is rated for a ripple current of 200mA.
I looked at the quickstart spreadsheet for the LM5146 and entered the 12V / 8A specification of the EVM. The spreadsheet recommends an input capacitor with maximum ESR of 30 mOhms and ripple current of 3.5A.
Why is there such a difference between the recomended part and the part used in the EVM? I am begining a design with this part and I need to understand.
8863.LM5146-Q1 Quickstart Tool r2 - 48Vin 12Vout 8A 400kHz.xlsm
