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TPS548D26: Tie VCC and AVIN together for external bias configuration

Tony Liu
Prodigy 31 points
Part Number: TPS548D26

Tool/software:

In the Figure 6-2 of the datasheet for using external VCC bias, it suggests to tie VCC and AVIN pins together and then connects to VDRV via a 1ohm resistor. But in Figure 7-1, it shows AVIN ties to VDRV pin together and VCC goes to VDRV with a 1ohm resistor for external bias configuration. Please advise which one we should follow.

And about the power up sequence for external bias configuration, is it ok to power up PVIN, VDRV and EN pins at the same time? (The paragraph above Figure 6-2 mentions the preferred sequence: VDRV => PVIN => EN)

  • 0
    TI__Mastermind 49430 points

    Hi Tony,

    Both Fig 6-2 and Fig 7-1 are correct.

    For Fig 6-1, you can connect since AVIN is the supply voltage for VCC LDO. if tied AVIN to VCC together, it will disable internal LDO.

    For Fig 7-1,  you need to zoom in the schematic carefully since there is no dot to connect AVIN and VDRV there. AVIN connects to PVIN_IC together through J6 jumper 4 and jumper 6.

    Regarding power up sequence, please follow the datasheet, VRDV external---PVIN---EN.

    Thanks,

    Nancy

  • 0 in reply to Nancy Zhang
    Prodigy 31 points

    Hi Nancy,

    Yes, I noticed no dot from VCC to R12 in Figure 7-1. In Figure 7-1, could you kindly advise where I can connect AVIN and VCC together as suggested in Figure 6-1? The VCC doesn't go to J6 at all. It only goes to TP22 and R12.

    Thank you,

    Tony

  • 0 in reply to Tony Liu
    TI__Mastermind 49430 points

    Hi Tony,

    Yes, please connect AVIN and VCC together as suggested in Fig 6-1. VCC doesn't go to J6, I mean AVIN pin goes to J6 with same net name which connects AVIN to PVIN. Please follow Fig 6-1.

    Thanks,

    Nancy