LM5141QRGEVM: Output problem when test EVM

Frank QIN

Part Number: LM5141QRGEVM
Other Parts Discussed in Thread: LM5141, LM5145

Hello team,

I'm testing a LM5141 EVM. It is in FPWM mode and output voltage is 5V. DC input is 8V.

When I increase the CC load to over 1.6A, the output voltage goes down to between 1.6V and 3.5V and jumping between this range, also the current can't be steady. While they never goes to 0.

This condition seems only happened when input voltage is below 16V, the output data looks well when I increase the Vinput.

Why is that happened?

Many thanks

over 3 years ago

0 Daniel Li14 over 3 years ago

TI__Mastermind 27030 points

can you check your CC load output current as well as your input current limit, most like you limit the input current, make the Vin drop down.

Thanks

0 Frank QIN over 3 years ago in reply to Daniel Li14

TI__Expert 5170 points

Hello Daniel,

The input current limit is 5A, and the situation happens at 1A. So maybe it's not related to input current limit. The load output current jumps like the same as voltage.

Is there any other possible reason?

Many thanks

Frank

0 Timothy Hegarty over 3 years ago in reply to Frank QIN

TI__Mastermind 49207 points

Hi Frank,

Please check the Vin, Vout and Iout waveforms and see if the hiccup mode time matches what's set by the RES capacitance. Maybe this specific EVM has an issue with manufacturing.We can order you a new EVM if needed. Also, we have the LM5145 voltage-mode controller as another option to consider.

Regards,

Tim

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LM5141QRGEVM: Output problem when test EVM