TPS65235-1: TPS65235, TPS652353 ISET limit does not match Rset value

Michael Heitner

Part Number: TPS65235-1
Other Parts Discussed in Thread: TPS65235, TPS652353

Tool/software:

We are using a TPS65235-1 with Rset of 330k. This means that our current limit should be at 440mA.

However, we are finding that the current limits at about 370-380mA at 18V output. What are the possible causes of this?

I found the following thread: https://e2e.ti.com/support/power-management-group/power-management/f/power-management-forum/804213/tps65235-1-over-current-protection-resister?tisearch=e2e-sitesearch&keymatch=TPS65235%2520iset#.

However, it does not provide much detail. How does the EXTM input affect the ISET current limit? Why is it dependent on the output voltage when EXTM is high?

Is this issue the same on the TPS65235 and TPS652353, or is it limited to the TPS65235-1?

Regards,

Michael

11 months ago

0 Colin Chen 11 months ago

TI__Mastermind 21041 points

Hi Michael,

Let me check and reply you later.

Thanks,

Colin

0 Colin Chen 10 months ago

TI__Mastermind 21041 points

HI Michael,

It is normal to have some variation when set ISET by RSET.

We suggest you can relatively increase RSET to have a lower ISET.

Hope it can help you.

Thanks,

Colin

0 Michael Heitner 10 months ago in reply to Colin Chen

Prodigy 20 points

This is well beyond normal variation and is occurring across multiple parts at a similar offset.

Did you look at the related posting I referenced in my original question? Can you provide more details on that issue?

0 Colin Chen 10 months ago in reply to Michael Heitner

TI__Mastermind 21041 points

Hi Michael,

There is another overcurrent protection for boost inside.

Maybe it triggers this limits. I suggest you set e ISW bit as 1b.

Thanks,

Colin

0 Michael Heitner 10 months ago in reply to Colin Chen

Prodigy 20 points

We are still evaluating this.

0 Colin Chen 10 months ago in reply to Michael Heitner

TI__Mastermind 21041 points

Hi Michael,

Got you, any further question please let me know.

Thanks,

Colin

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TPS65235-1: TPS65235, TPS652353 ISET limit does not match Rset value