The MC34673 is a cost-effective fully-integrated battery charger for Li-Ion or Li-Polymer batteries. It tolerates an input voltage up to 28 V, which eliminates the input over-voltage-protection circuit required in handheld devices. A charge cycle includes trickle, constant-current (CC) and constant-voltage (CV) charge modes.
The CC-mode current is programmable up to 1.2 A with an external resistor. The constant voltage is fixed at 4.2 V. The trickle-mode current is pre-set to 20% of the CC-mode current when the battery voltage is lower than the trickle-mode threshold. The end-of-charge (EOC) current threshold is pre-set to 10% of the CC-mode current to save the board space and cost. A charge-current thermal-foldback feature limits the charge current when the IC internal temperature rises to a pre-set threshold.
The MC34673 has a 2.6 V falling power-on-reset (POR) threshold, making it ideal to work with current-limited power supplies. Three indication pins (PPR, CHG and FAST) can be simply interfaced to a microprocessor or LEDs. When no power supply is connected, or when disabled, the charger draws less than 1.0 µA leakage current from the battery.