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BQ76PL455A-Q1: sch problems

Qianqian
Genius 5010 points
Part Number: BQ76PL455A-Q1

Hello TI Experts,

I am evaluating BQ76PL455 now and have below doults need your help:

1.The isolation must be two sides like ADUM5402?  Can I use one side ADUM2402?

   But if I use isolation like ADUM2402,when BQ76PL455 is in shutdown mode,their will be no input voltage to ADUM2402,the BQ76PL455 cannot be woke up~

So must I use isolations like ADUM5402? So what's the function of NPN? Is it necessary to use NPN?

2.Is it necessary to put an inverter between BQ76PL455's Wake up  pin and Isolation?Can I know why? I see their's somebody do like this but I have no idea why to do it~

  • 0
    TI__Genius 11480 points

    Hi Fawn,

    It looks like the ADUM2402 device has integrated isolated power. You can power the main side from the MCU 5V supply, and transfer it over to power VIO of the PL455. That should be ok.

    The NPN is the external BJT for a linear regulator that powers all of the pl455 VDIG circuitry. It is necessary to have.

    The inverter for Wakeup helps with compatability for the USB-TTL cable that we use to communicate to our EVM with our GUI. It is not completely necessary. Wakeup needs only a high pulse (0 - 1 - 0)  for ~200us to wake up, if i remember the time correctly.