TPSM84A21: Loop Response Measurement

Hirotsugu Kobayashi

Part Number: TPSM84A21

Hi team,

I would like to measure the loop response of TPSM84A21EVM.

There is R7(0 ohm) on the EVM, can I measure changing R7?

Is it possible to measure even if there is 10-ohm between VOUT and VS+ inside?

Best Regards,

0 Yitzhak Bolurian over 1 year ago

Hi Hirotsugu,

No need to change R7.

The 10 Ohms and the capacitors in parallel with it actually support Bode plot measurement.

Attached in how our vendor of Bode plot measurement equipment describes the measurement across the 10 Ohms.

Regards,

Yitzhak Bolurian

0 Hirotsugu Kobayashi over 1 year ago in reply to Yitzhak Bolurian

Hi Yitzhak,

I understand, I will try using internal 10 Ohms.

Best Regards,

0 Hirotsugu Kobayashi over 1 year ago in reply to Hirotsugu Kobayashi

Hi Ytzhak,

I measured the loop response using internal 10 Ohms. R7 was removed.

Vin:12V, Vout=1.2V, Iout=5A

Gain increases at high frequencies, is this correct?

Best Regards,

0 Yitzhak Bolurian over 1 year ago in reply to Hirotsugu Kobayashi

Hi Hirotsugu,

As you know, you should not care about frequencies above the switching frequency.

Here are two plots that I have found from similar device for your reference:

Both gain and phase go high and then come back at certain frequency.

Hope this helps.

Regards,

Yitzhak

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