LM5170-Q1: the output can't load

Xianrong Shang

Part Number: LM5170-Q1
Other Parts Discussed in Thread: LM5170EVM-BIDIR, , LM5170

Hello!

I meet some issue when debug my LM5170-Q1 board. the schmatic is refer to LM5170EVM-BIDIR, and the Design Calculator . the condition is 50Vin, 12Vout1/50A, 12Vout2/50A.

the DC source is the battery model.

1. I set the OVP point is 17V on the 12Vout, But it can't protect when reach the point.

2. It only can load 1A each channel.

over 7 years ago

0 Youhao Xi over 7 years ago

TI__Guru* 78260 points

What do you mean Vout1 and Vout2? Do you refer to the two channels? Note that the max current in each channel is limited to about 30A by the ISET clamp with the resistor divider R81-R86, and the onboard inductor cannot support higher current. It can deliver 60A with both channels are turned on, but it cannot deliver 50A in one channel. In order to pass 25A per channel, the ISETA voltage should be established at 1.25V.

The EVM is fully tested, and we have many EVMs shipped in the past year and none have been reported having issues like this. If the board is not damaged somehow, I am afraid some jumpers are not set up correctly, or some parts are changed wrongly. Please following the EVM user guide to use the EVM in your evaluation.

0 Xianrong Shang over 7 years ago in reply to Youhao Xi

Intellectual 855 points

Dear Youhao,

I will check the Iset.

By the way, I have no EVM on hand, Could you please lend the EVM to me ? Just for compare some waveforms with the EVM.

0 Youhao Xi over 7 years ago in reply to Xianrong Shang

TI__Guru* 78260 points

The EVM is available on TI store.

0 Xianrong Shang over 7 years ago in reply to Xianrong Shang

Intellectual 855 points

Dear Youhao,
The board can load 13A with the efficiency 95%. but I can't set 25A or 30A Now, I haven't find why.

According to your suggestion, if I want 100A, then I use 2pcs LM5170-Q1, and 25A per channel. isn't it ??

0 Youhao Xi over 7 years ago in reply to Xianrong Shang

TI__Guru* 78260 points

If you cannot set 25A or 30A, can you measure if the ISETA signal has enough voltage to command the IC to regulate the current at that level? If ISETA is high but the current does not match, then you may hit the peak current limit and you should increase IPK resistor. If ISETA is low, check you voltage loop circuit where something clamps ISETA from being established higher.

It's not necessary to use 2pcs to support 100A. We have customers using 1 LM5170 to support 100A. The channel current is mainly limited by the inductor and MOSFETs that you use, and also by the thermal issues that you may end up with.

0 Xianrong Shang over 7 years ago in reply to Youhao Xi

Intellectual 855 points

I will check and debug as your suggest.

Thank you, Youhao.

0 Youhao Xi over 7 years ago in reply to Xianrong Shang

TI__Guru* 78260 points

Let's close this thread for the time being. If you have follow-on questions, you can create a new post, or reopen this one. Good luck in your debugging.

0 Xianrong Shang over 7 years ago in reply to Youhao Xi

Intellectual 855 points

Thank you! Youhao.

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LM5170-Q1: the output can't load