The step-down switching controller is designed to charge a series stack of batteries. The battery charging cycle has two phases - constant current (CC) and constant voltage (CV). During the constant current phase, the charger regulates the charging current to the limit in REG0x14(). Once the voltage on SRN reaches the limit in REG0x15, the charger enters CV mode to regulate the battery voltage. The following conditions must be valid to start charge:
- Charge is enabled through SMBus (REG0x12[0], default is 0, charge enabled)
- ILIM pin voltage is higher than VILIM(RISE) (120 mV nominal)
- All ChargeCurrent(), ChargeVoltage() and InputCurrent() registers have valid value programmed
- ACOK is valid (see Device Power Up for details)
- ACFET and RBFET turn on without latchoff failure (see System Power Selection for details)
- VSRN does not exceed BATOVP threshold
- IC temperature does not exceed TSHUT threshold
- Not in ACOC condition (see Device Protections Features for details)
One of the following conditions stops on-going charging:
- Charge is inhibited through SMBus(REG0x12[0] = 1)
- ILIM pin voltage is lower than VILIM(FALL) (75 mV nominal)
- ChargeCurrent(), ChargeVoltage() or InputCurrent() is set to 0 or out of range
- ACOK is pulled low (see Device Power Up for details)
- ACFET turns off
- VSRN exceeds BATOVP threshold
- TSHUT IC temperature threshold is reached
- ACOC is detected (see Device Protections Features for details)
- Short circuit is detected (see Inductor Short, MOSFET Short Protection for details)
- Watchdog timer expires if watchdog timer is enabled (see Charger Timeout for details)