Hello.
We are currently evaluating BQ24230 for a product using single-cell Li-Polymer battery and USB power, and have encountered an issue with charging. We are using a custom board, and I've attached relevant part of the schematic. Note: CHG and PGOOD are pulled up by the MCU, BAT_SENSE_BIAS and BAT_SENSE are both high impedance, but should not affect anything anyway.
When idle (i.e., when no charger is connected), MCU keeps CE high (inactive), EN1 and EN2 both low (100 mA internal current limit).
As soon as a charger is connected, following sequence of events occurs:
- After a small delay, BQ24230 asserts PGOOD, and starts regulating voltage at OUT at 4.4 volts.
- MCU negotiates current limit through USB.
- After negotiation, MCU sets CE low, EN1 high, EN2 low (500 mA internal current lmiit).
- Almost immediately, BQ24230 sets CHG low.
- Exactly 50 ms later, BQ24230 sets CHG high and performs no further charging attempts, until CE is toggled, but keeps PGOOD active.
MCU keeps CE, EN1 and EN2 in that state until PGOOD goes high, then it returns to the idle state.
Cell voltage is in normal range (around 3.5 - 3.6 volts), voltage on TS is also normal (around 0.66 volts). Current limit and battery supplement mode both operate correctly, and OUT is powered from the battery when no input voltage is present.
I have noticed that during charge attempt, voltage on ISET never rises above zero.
What could be possible causes of this issue?
