TPS40170: TPS40170 OCP/SCP issues

Heng Chuan Shu said:

Part Number: TPS40170

Hi,

We are seeing OCP/SCP issue in our latest batch of production.  The OCP/SCP was triggered at lower load current.

Previous batch - Load upto 15A without OCP/SCP issue.

Latest batch - OCP/SCP triggered at 7A.

We have checked and swapped the Rilim, Rscp(the scp multiplier resistor), Rbootstrap, Cbootstrap, RC snubbers, HFET and LFET but could not find the root cause.  What other area shall we look at.  Could it be TPS40170 batch issue?  We haven't swapped it yet.

Best regards,

HC

 

Forgot to mention.  It seems like SCP issue as the problem go away when we set the SCP multiplier to 7 by removing the Rscp (10kohm).  We try to increase the Rilim resistor the problme still persists

HI

have you change the TPS40170 with old batch and new batch?  does OCP issue follow device or board?

Thanks

Hi Daniel,

We did the swap IC (TPS40170) between old and new batch, the SCP/OCP issue still there.  Any other area that we can study?

Other observations we found are - changing Rscp multiplier resistor to 20kohm will distort the Bode plot.  Similar thing was observed when Rilim was chnaged to higher value.

Best regards,

HC  

Hi

when you mean the SCP/OCP issue still there, you mean the old batch of TPS40170 still have issue or no issue?

can you share the schematic?  and test the SW waveform see whether it is stable when current goes higher?

Thanks

Hi,

Old batch no issue.  Only new batch has issue.  Means swapping IC make no difference.

Can you give me your your email, i cant share schematic on public forum.

Best regards,

HC

HI 

pls send to daniel-li@ti.com , any design changed compare to old and new batch ?

Thanks