Other Parts Discussed in Thread: ISO7742
Hello,
we are facing the problem that, the wake up ping is not working properly because of the state of RX before we power the BMS. In more detail:
We are using an ISO7742F to have low levels as default state. When we are in shutdown, the isolator is not powered. Consequently, the RX pin is low. When we switch on the BMS we power the isolator and the RX pin is set to high. Afterwards, the 1-0-1 transition is performed to wake up the BQ. This is not working. When we use a ISO7742 with default value high and a manipulated circuit, so that RX is high from the beginning on, wake up is working. The question is now, how long must the RX pin high so that a subsequent wake up ping is detected properly? In the datasheet I have found a tUART(RXMIN) variable, but there is no value for it. Can it work if the RX pin is low a the beginning? Or is the BQ falling in some strange state? What do we have to consider with this setup?
I hope you can answer this question. Thank you.
BR
Christian
