TPS51200: Output Rising / Falling time

Eric Fang1

Part Number: TPS51200

Dears,

I follow the reference design on SPEC page.23 "8.3.3 3.3-VIN, LP DDR3 or DDR4 Configuration", but when I check the reference output voltage I found it seems like not smooth.

And VO pin have the same phenomenon, is any way to explain this?

Please see the waveform on channel 1.

Eric

over 5 years ago

0 Weidong Zhu over 5 years ago

TI__Expert 5965 points

Hi Eric,

REFOUT starts when internal reference voltage reaches 0.39V, so it's not a soft start and slew rate is higher at the beginning of the startup.

Regards,

Weidong

0 Eric Fang1 over 5 years ago in reply to Weidong Zhu

Intellectual 620 points

Hi Weidong,

We check the VO pin have the same waveform, so it be applicable the same reason?

Eric

0 Weidong Zhu over 5 years ago in reply to Eric Fang1

TI__Expert 5965 points

Hi Eric,

Yes, VTT output will follow REFOUT, so it's the same reason.

Regards,

Weidong

0 Eric Fang1 over 5 years ago in reply to Weidong Zhu

Intellectual 620 points

Hi Weidong,

So this not smooth phenomenon when power on can be waive?

Eric

0 Weidong Zhu over 5 years ago in reply to Eric Fang1

TI__Expert 5965 points

Hi Eric,

As long as VTT voltage is less than VDDQ/VPP it is ok.

Regards,

Weidong

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TPS51200: Output Rising / Falling time