BQ24004EVM: 2 Cell Li-Ion/Li-Pol Charger, 1A

The bq24004/5/6 series ICs are advanced Li-Ion linear charge management devices for highly integrated and space-limited applications. They combine high-accuracy current and voltage regulation; FET pass-transistor and reverse-blocking Schottky; battery conditioning, temperature, or input-power monitoring; charge termination; charge-status indication; and charge timer in a small, 20-lead TSSOP PowerPAD package.

The bq24004/5/6 continuously measures battery temperature using an external thermistor. For safety reasons, the bq24004/5/6 inhibits charge until the battery temperature is within the user-defined thresholds. Alternatively, the user can monitor the input voltage to qualify charge. The bq24004/5/6 series then charge the battery in three phases: preconditioning, constant current and constant voltage.

If the battery voltage is below the internal low-voltage threshold, the bq24004/5/6 uses trickle-charge to condition the battery. A preconditioning timer is provided for additional safety. Following pre-conditioning, the bq24004/5/6 applies a constant-charge current to the battery. An external sense-resistor sets the magnitude of the current. The constant-current phase is maintained until the battery reaches the charge-regulation voltage. The bq24004/5/6 then transitions to the constant voltage phase. The user can configure the device for cells with either coke or graphite anodes.