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TPS650861: Powering DRV5V_x_x inputs

Jacek Renkas
Prodigy 130 points
Part Number: TPS650861

Hello,

I have a question about DRV5V_2_A1 and DRV5V_1_6 inputs.

Do they have to be powered up simultaneously?

Here is what I want to do:

1. After VSYS turns on, I want DRV5V_1_6 (for BUCK 1 and 6) to be powered by LDO5P0. DRV5V_2_A1 will not be powered up at this time.

2. After BUCK1 is enabled and starts up it generates 5V used for my system and to power DRV5V_2_A1.

3. Now LDOA1 is powered and BUCK2 can be enabled.

I came to this solution because I want to use LDOA1 output in my system without loading LDO5P0.

So the ultimate question is if I can power DRV5V_1_6 first and then after some time power DRV5V_2_A1?

  • 0
    TI__Genius 12735 points

    Hi Jacek,

    To achieve this you need to use V5ANA. If you connect DRV5V_1_6 and DRV5V_2_A1 to LDO5P0 they will be supplied by the internal 5V LDO. Then you can take the output of BUCK1 and connect it to V5ANA, which has a comparator circuit with a load switch. This load switch will enable whenever the input at V5ANA is >5V and this will also disable the 5V LDO. At this point, you will be able to supply both DRV5Vxx pins with the output of BUCK1 and you will only be loading the 5V LDO on startup to get BUCK1 up to the proper output voltage. A diagram of this circuit is shown on page 2 of the datasheet and I have also included a screenshot below.

    Best regards,

    Layne J