TPS7A90: External Diode for output discharge

Takashi Onawa

Part Number: TPS7A90

Hi Team,

I have one quick question.

Does TPS7A90 need external diode between Input and output for discharging, if Vout > Vin condition exists in customer use case?

Regards,

Takashi Onawa

over 3 years ago

0 Kyle Van Renterghem over 3 years ago

TI__Genius 13085 points

Hi Onawa-san,

That is correct, TPS7A90 doesn't have reverse current protection so if Vout>Vin then the protection diode will be needed.

0 Takashi Onawa over 3 years ago in reply to Kyle Van Renterghem

TI__Genius 13200 points

Hi Kyle-san,

Thanks for you prompt response on this.

OK, I understood that SBD is needed to protect reverse current on Vout>Vin.

Could you tell me which point the SBD should be connected to Vout line on, 1 or 2 below?

The customer thinks "1" is better for output protection but they are concerned that the stability of the loop may be affected by the parasitic capacity of SBD.

Also, Could you review the layout below and point out anything that isn't good if there are?

Regards,

Takashi Onawa

0 Kyle Van Renterghem over 3 years ago in reply to Takashi Onawa

TI__Genius 13085 points

Hi Onawa-san,

The diode can be connected to either #1 or #2 and shouldn't cause a big difference in the protection since the Vin/Vout planes will have very low resistance (assuming it is kept close to the LDO like the layout you have shown above).

As for the layout you provided it looks good.

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TPS7A90: External Diode for output discharge