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BQ76PL455A-Q1: Power Down in stack position, EVM1402

Norbert Klaes
Prodigy 80 points
Part Number: BQ76PL455A-Q1
Other Parts Discussed in Thread: BQ76PL455A

Hi all,

i´m working on a system with two bq76pl455a-q1.

Device #0 is in bottom position, set to single communication mode and communicates with microcontroller via UART.

Device #2 is in top position and comm. mode ist set to differential, and communicates via daisy chain communication.

So far we can can wake up the devices, configure AFE, baudrate and so on.

Right now every 20 ms all the results are transmitted and evaluated by the micro.

The only thing we are struggling with is the power down procedure.

If we broadcast the power down command, only the bottom device, that is directly connected to the micro is going into shutdwon mode.

The green LED on EVM1402 is still glowing. It does not glow until it is wake up during power up procedure, but once it is glowing we found no other way to power down than
disconnecting the battery connector.

Help is appreciated how to power down

bq76PL455A-Q1

  • 0
    TI__Intellectual 2520 points

    Hello Norbert,

    Writing a '1' to PWRDN  of DEV_CTRL will cause the device to shut down. This is usually broadcast to the entire stack of ICs to shut
    down all of the bq76PL455A devices at the same time. It should works.

    Please connect wakeup pin of device 2# to ground.

    You may also issue Single Device Write to put device 2# into shutdown.

    Andy

  • 0 in reply to Andy Li55
    Prodigy 80 points

    Hello Andy,

    thanks for your reply. The WAKEUP pin was the problem. On EVM1402 #2 we had to put J7 Pin6 (nWAKE) to J7 Pin4( RX, with 10k pull up internally).
    On EVM1402 there is an inverting gate, so that wakeup is now always low.

    Now it works fine.

    Norbert