TPS53515: Pre-bias or parallel operation

Here is partial schematic.

Hi Tiger,

    Looks like 3VSB is also 3.3V. As long as the voltage does not exceed the OVP threshold of 116% (approx 3.84V), it would not register an OVP fault.

If it registers an OVP fault, then the system would react to the fault and try to latch off the part using the sequence provided in the datasheet.

Also, does the VCC3 supply have enough capacitance - so that it can absorb any energy dumped by the converter when Q24 is ON?

What is the intent of paralleling these power supplies?

Regards,

Gerold

Hi Gerold,

The VCC3 is from ATX power supply, suppose there is enough capacitance.

The purpose is to switchover between these 2 sources.

When system is in S0, 3VSB supply is from VCC3 and it will switchover to TPS53515 output in S5.

However, there is a droop when to switchover from VCC3 to TPS53515 output because TPS53515 will have 400uS propagation delay and 1mS soft start.

Do you see any other risk?

Is it possible to lead TPS53515 become to boost?

Thanks and Best regards,

Tiger

Thanks David!

The MODE is tied to ground via 0Ohm. So TPS53515 is in Auto Skip mode.

Hi Tiger,

   Have you looked at TI ORing controllers which help with this paralleling operation?

http://www.ti.com/power-management/power-switches/ideal-diodes-oring-controllers/overview.html

regards,

Gerold