TPS62130: TPS62130RGTR: SW-GND Jitter issue

Hi Yanwei,

It is normal to have large or small jitter with different devices due to DCS control. The poor jitter may be caused by test condition or application as well.

Thanks,

Colin

Hi Colin Chen,

The following two test waveforms are from two batches of chips. Under steady-state conditions, they were tested with an electronic load carrying 3A.

As shown in the left figure below, two chips from this batch were tested, and the jitter test results were consistent and good.

As shown in the right figure below, two chips from this batch were tested, and the jitter test results were consistent but poor.

When the load is constant, there is significant jitter and frequency variation observed.Is this an indication of instability in the control circuit?

Please help analyze and confirm this.

Thank you!

Hi,
Colin will reply after weedkend. Thanks.

Hi Yanwei,

Were the two batches chips tested on same board?

Were the test condition for both result same?

Could you make a ABA test to check whether it caused by board difference.

Anyway, the jitter is normal for DCS control and it is not the indication of instability.,

Thanks,

Colin 

Hi Colin Chen,

Were the two batches chips tested on same board?--------Yes.

Were the test condition for both result same?--------Yes.

Could you make a ABA test to check whether it caused by board difference？------Yes.

The test found that for one batch, the Jitter test results for the 2 samples were consistent and relatively good; for another batch, the Jitter test results for the 2 samples were also consistent but relatively poor. When the chips from the two batches were swapped for testing, it was found that the results followed the chips, indicating it is unrelated to the board.

The output uses an electronic load, and the load is constant; therefore, the PWM control should be relatively stable, and there should not be significant control adjustments.However, the current test performance is as if there is a large load transient. Is this normal?

Thank you!

Hi Yanwei,

I would like to know if the set up of electronic load is constant current or constant resistor?

If it is constant current, it shouldn't have the load transient. Please check the current meter.

Actually, I see vout is stable, the relatively larger jitter is normal to DCS control.

Thanks,

Colin

Hi Colin Chen,

The set up of electronic load is constant current.

For the batches that perform relatively poorly in the Jitter test, significant jitter is observed when the constant current of 3A and 2A.

If it is constant current,the Jitter test should be relatively stable.

I reviewed the introduction to TI DCS control, and my understanding is that some jitter in the Jitter test during load transients is normal, but is it also normal

to observe significant jitter when the input voltage and output current are constant?

Could this indicate that there might be some instability in the internal drive control circuitry?

Thank you!

Hi Colin Chen,

Thank you very much for your patient response！