LM5171EVM-BIDIR: LM5171 EVM-BIDIR not working in boost mode.

To fix the issue: Jumper J1 must be moved when changing from bulk to boost mode. The Lm5171 evaluation module documentation doesn't indicate this requirement.  The figure 2.5 and the comment are wrong.

Hi Bruno,

I don't see a reason why J1 need to be changed.

Can you share your test conditions: HV voltage, LV voltage and current?

Best Regards,

Feng

Hi fend,

My setup is very simple: I use a programmable power supply Rhode Schward HMP4040 connected to 12 v terminal inputs and and connect a electronic load on the 48V terminal outputs. Max current of laboratory supply is setup at 10A. The electrinc laod is programmed to sink 0.1A. See photos for details.

I don't understand why the board enters in overcurrent when terminal 48 V is selected for UVLO input pin.

Regards

Bruno

Hi Bruno,

I believe the power supply has a sensitive current limit and it enters current limit at EVM startup. 

Please set a higher current limit for the power supply or reduce the peak current limit of the EVM.

Best Regards,

Feng

Hi Feng,

For my tests I set the current limit of the power supply to 10A. This is the highest value I can use and that I used for my tests.

How can I reduce the current limit on the EVM board? Is my configuration incorrect? Note that when I do tests without any load on the HV side, the board goes into an overcurrent state.

The board has cleary a problem:  A oscillogram of the output 48V shows that the board enters in oscillation mode at startup.

 Can you test from your side my setup to confirm or infirm the problem?

Kind regards,

Bruno

Hi Bruno,

I suppose you can parallel two channels of your supply.

The startup current can go up to 30A/channel;

Reduce R14 for lower peak current.

Best Regards,

Feng