High Efficiency Switching Mode Battery Charger

RT9531

The RT9531 is a PWM switch mode battery charger controller to fast charge single or multiple Li-Ion, NiMH and NiCd batteries, using constant current or constant voltage control. Maximum current can be easily adjusted by external resistor. The constant voltage output can support up to 4 Li-Ion cells with 0.5% accuracy. A third control loop limits the input current drawing from the adapter during charging. This allows simultaneous operation of the equipment and fast battery charging without over loading to the adapter.

The RT9531 can charge batteries from 2.5V to 4.2V with dropout voltage as low as 0.4V. A diode is not required in series with the battery because the charger automatically enters a 10μA sleep mode when the adapter is unplugged. A logic output indicates Li-Ion full charge when current drops to 20% of the full-scale adjusted charge current.

Applications

Notebook Computers
Portable Instruments
Chargers for Li-Ion, NiMH, NiCd and Lead Acid Rechargeable Batteries

Key Spec.

	RT9531A
Status	EOL
Vin (min) (V)	4.5
Vin (max) (V)	28
Battery Charge Voltage (max) (V)	4.2
Status Indicator	Yes
Charger Type	Switching
Input Source	AC Adapter
Features	Current Mode Control;Enable Input;OCP;OVP;SCP;UVP
Package Type	WQFN4x4-16
Built-in Power MOSFETs	No

Features

Fast Charging for Li-Ion, NiMH and NiCd Batteries
Preset Battery Voltages : 4.2V
High Efficiency : Up to 95%
Precision 0.5% Charging Voltage Accuracy
5% Charging Current Accuracy
Charging Current Adjusted by Resistor
0.4V Dropout Voltage
Input Current Limit Maximizes Charging Rate
475kHz Switching Frequency
Flag Indicates Li-Ion Charge Completion
Auto Shutdown with Adapter Removal
Only 10μA Battery Drain When Idle
Available in an WQFN-16L 4x4 Package
RoHS Compliant and Halogen Free