TPS82740A: Input of linear regulator output

Dice-K

Mastermind 6500 points

Part Number: TPS82740A
Other Parts Discussed in Thread: TPS650861

Hi support team,

Is there a problem if I input the output of the linear regulator to the VIN of the TPS82740A?

Example below,
TPS650861.LDOA1 -> TPS82740A.VIN

Regards,
Dice-K

over 3 years ago

0 Davor Pavlovski over 3 years ago

TI__Expert 3611 points

Hi Dice-K,

I don't see why there would be a problem, as long as the input voltage to the TPS82740A is within recommended operating conditions between 2.2V and 5.5V.

Regards,
Davor

0 Dice-K over 3 years ago in reply to Davor Pavlovski

Mastermind 6500 points

Hi Davor,
Thank you for your reply.

I am worried that the LDO's current limit will be activated at startup and the DCDC input voltage will drop below 2.2V.
I give up this configuration.

Best regards,
Dice-K

0 Davor Pavlovski over 3 years ago in reply to Dice-K

TI__Expert 3611 points

Hi Dice-K,

The TPS82740A has a soft-start capability, which lowers the inrush current during startup. And during this soft-start period, the current limit of both switches will be typically 150mA. For more details about the softstart parameters of the TPS82740A, please check the part of the electrical characteristics table on page 6 of the datasheet and Section 9.4.2. Also I can see that the LDOA1 of the TPS650861 has a maximum recommended current of 200mA.

Regards,
Davor

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TPS82740A: Input of linear regulator output