LM5145-Q1: LM5145QRGYRQ1

Vasanth Mangi

Part Number: LM5145-Q1
Other Parts Discussed in Thread: LM5146

Tool/software:

I have design buck converter (LM5145-Q1), input voltage is 54V and output voltage is vary from 1V to 10V by adjusting feedback resistor at max.8A load. I am getting expected output voltage as per feedback resistor adjustment without load. The moment connect load at min.0.5A load, then output voltage is dropping too much square ware is coming at output. Please find the circuit diagram below

over 1 year ago

0 Timothy Hegarty over 1 year ago

TI__Guru* 75882 points

Vasanth,

Go ahead and enter the design parameters and component values in the quickstart calculator. It may be instability.

Regards,

Tim

0 Timothy Hegarty over 1 year ago in reply to Timothy Hegarty

TI__Guru* 75882 points

The 2nd stage LC filter complicates the stability. I recommend removing the 2nd inductor.

0 Timothy Hegarty over 1 year ago in reply to Timothy Hegarty

TI__Guru* 75882 points

Also, IRF740 are super old, super lossy 400V FETs and not really suitable here. I recommend using 5 x 6mm footprint FETs, max 100V. Take a look at the LM5146 EVM for reference (12V/8A/400kHz).

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LM5145-Q1: LM5145QRGYRQ1