USB/AC Adapter, Li+ Linear Battery Charger with Integrated 50mΩ Battery Switch in TDFN

The MAX8856 complete 1-cell Li+ battery charge-management IC operates from either a USB port or AC adapter. It integrates a battery disconnect switch, current-sense circuit, PMOS pass element, and thermal-regulation circuitry, while eliminating the external reverse-blocking Schottky diode, to create a simple and small charging solution. The charging sequence initiates from power-OK indication, through prequalification, fast-charge, top-off charge, and finally charging-complete indication for single-cell Li+ batteries. Charging is controlled using constant current, constant voltage, or constant die-temperature (CCCVCTJ) regulation for safe operation in handhelds.

Two logic inputs (active-low EN1, active-low EN2) select suspend mode, 100mA, 500mA, or ≤ 1A input current limits to comply with USB requirements. Proprietary thermal-regulation circuitry limits the die temperature to +100°C to prevent excessive heat on the system PC board. Additional safety features include an NTC thermistor input (THM) to protect the battery. A 3.5V to 4.2V SYS output, in conjunction with the low-RDSON battery switch, powers the system even when the battery is deeply discharged or not installed. The IC also offers a +3.3V/500µA output (VL), a charging status flag (active-low CHG), and an input-supply detection flag (active-low POK). The MAX8856 operates from a +4.25V to +5.5V supply and includes undervoltage lockout below +3.4V and overvoltage protection up to +14V.

Applications

* Cellular Phones, Smartphones, PDAs * Digital Cameras, MP3 Players * USB Appliances, Charging Cradles and Docks

* Small, 3mm x 3mm Thermally Enhanced TDFN Package (0.8mm max height)

* USB-Compliant Suspend Mode (20µA)

* Selectable 100mA, 500mA, and Up to 1A Input Current Limits

* USB or AC Adapter Input

* +6V to +14V Input Overvoltage Protection

* Input UVLO Below +4V Rising (3.5V Falling)

* Automatic Current Sharing Between Battery Charging and System

* Die Temperature Regulation (+100°C)

* Low Dropout Voltage, 250mV at 0.5A

* NTC Thermistor Input

* Charge Status and Input-Supply Detection Flags