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[FAQ] BQ25700A: How soon could the host write to the buck-boost charger after power on?

Part Number: BQ25700A

When an input source plugs in, the charger checks the input source voltage to turn on LDO and all the bias circuits. It sets the input current limit before the converter starts.

The power-up sequence from DC source is as follows:

  1. 50 ms after VBUS above VVBUS_CONVEN, enable 6 V LDO and CHRG_OK goes HIGH
  2. Input voltage and current limit setup
  3. Battery CELL configuration
  4. 150 ms after VBUS above VVBUS_CONVEN, converter powers up.

Suggest waiting for 200ms, before sending a new register value to the charger.