TPS62130: The constant source current of SS pin is lager than one in TPS62130 datasheet.

Kazuya Nakai59

Part Number: TPS62130

Hello guys,

One of my customers is evaluating TPS62130 for their next products. Then they found the rising time of SS pin voltage at the device starting is shorter than the time calculated by equation 10 on page 16.

In order to find the cause, they measured the connected capacitor value by LCR meter and the constant source current by current tester. As a result, the capacitance was 0.1uF as shown value. But the constant source current was 3.0uA. The devcie datasheet says the maximum souce current is 2.7uA and typical value is 2.5uA.

Do you know why the source current is higher than the datasheet value?

Also does TI tests the current value at the final test?

Your reply would be much appreciated.

Best regards,

Kazuya.

over 6 years ago

0 JohnTucker over 6 years ago

TI__Guru**** 191445 points

Kazuya,

Let me check into it.

0 JohnTucker over 6 years ago in reply to JohnTucker

TI__Guru**** 191445 points

Kazuya,

I verified that the SS charge current is in fact tested in production. Can you provide a waveform of the start up? Can you provide the capacitor part number?

0 Kazuya Nakai59 over 5 years ago in reply to JohnTucker

Guru 21505 points

Hello John,

I'm sorry for my late response.

The capacitor part number is UMK105BJ104KV-F.

https://ds.yuden.co.jp/TYCOMPAS/ut/detail?pn=UMK105BJ104KV-F%20%20&u=M

The customer measured the source current again at SS terminal of TPS62130 with SS=0V using more accurate LCR meter.

As the result was 2.7uA. Also the capacitor was 101nF.

But the soft start time which SS votage increases from 0V to 1.25V was shorter than the calculated value by equation, t =CV/I=101nF * 1.25V/2.7uF.

I think some current flows into SS terminal. Now I am asking them if there is the curret flowing path.

If you have any advice, could you please give me it?

Thank you again and best regards,

Kazuya.

0 JohnTucker over 5 years ago in reply to Kazuya Nakai59

TI__Guru**** 191445 points

Kazuya,

If you have waveforms, I can examine them.

0 Kazuya Nakai59 over 5 years ago in reply to JohnTucker

Guru 21505 points

Hello John,

I see.

I will confirm to the customer whether the waveform can be upload to E2E site or not.

Thank you and best regards,

Kazuya Nakai.

0 JohnTucker over 5 years ago in reply to Kazuya Nakai59

TI__Guru**** 191445 points

Kayuza,

You can always contact me directly. j(dash)tucker(at)ti(dot)com.

0 Kazuya Nakai59 over 5 years ago in reply to JohnTucker

Guru 21505 points

Hello John,

Thank you for your kindness.

I sent a e-mail to you now.

Thank you again and best regards,

Kazuya.

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TPS62130: The constant source current of SS pin is lager than one in TPS62130 datasheet.