TPS7A8300: Voltage Leak At Output Before LDO is ON

NAIM OTHMAN

Part Number: TPS7A8300
Other Parts Discussed in Thread: TPS7A85, TPS7A84

Hi TI Team,

I have a question on TPS7A8300

We have power supply rail as above.

First of all the 1.5V is output from buck converter, and then ANALOG_0.9V is enabled before ANALOG_1.2V, and the FPGA leaked the voltage before ANALOG_1.2V is enabled.

So we have the ON and OFF waveform as below. There is some leakage at ANALOG_1.2V but it does not exceed 0.9V.

My question is;

Will this leakage give any effect to the ANALOG_1.2V LDO in terms of operability and reliabilty?

We dont want to add additional load switch or change the LDO due to design constraint.

Best Regards

Naim

over 2 years ago

0 Nick Butts over 2 years ago

TI__Mastermind 38075 points

Hi Naim,

As long as the leakage-induced voltage seen at the output of the LDO does not exceed the 1.5V input to the LDO, it is not an issue. The potential concerns with this would be EOS at the output (i.e. exceeding abs max rating) or the output rising above the input and causing reverse current, but it does not appear that either of these are happening. Reliability is not affected by having a small voltage at the output like this.

Regards,

Nick

0 NAIM OTHMAN over 2 years ago in reply to Nick Butts

Intellectual 270 points

Thank you Nick.

0 NAIM OTHMAN over 2 years ago in reply to Nick Butts

Intellectual 270 points

Hello Nick,

I have additional question.

Our current selection is TPS7A8300RGRR.

But due to some extra requirement, we are considering other package compatible devices which are as below.

TPS7A8300ARGRR

TPS7A8500RGRR

TPS7A8400ARGRR

I assume that these devices are also compatible with the same leakage conditions. Am I correct?

Best Regards

Naim

+1 Srikanth Lolla Venkata over 2 years ago in reply to NAIM OTHMAN

TI__Genius 12040 points

Hello Naim,

Yes, since the Abs Max ratings are not being violated, TPS7A84 & TPS7A85 should not see any reliability issues for the leakage conditions you have described above. These devices have active output discharge circuit designed into them, so you may see GND current increase by a few mA. Thanks!

Regards,

Srikanth

0 NAIM OTHMAN over 2 years ago in reply to Srikanth Lolla Venkata

Intellectual 270 points

TQ Srikanth!

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TPS7A8300: Voltage Leak At Output Before LDO is ON