Linear Li+ Battery Charger with Integrated Pass FET, Thermal Regulation, and ACOK Flag in 3mm x 3mm TDFN

The MAX1508 is an intelligent, stand-alone constant-current, constant-voltage (CCCV), thermally regulated linear charger for a single-cell lithium-ion (Li+) battery. The MAX1508 integrates the current-sense circuit, MOS pass element, and thermal-regulation circuitry, and also eliminates the reverse-blocking Schottky diode, to create the simplest and smallest charging solution for hand-held equipment.

The MAX1508 functions as a stand-alone charger to control the charging sequence from the prequalification state through fast-charge, top-off charge, and full-charge indication. The MAX1508Y and MAX1508Z eliminate the prequalification state to allow startup into a load without a battery.

Proprietary thermal-regulation circuitry limits the die temperature to +100°C when fast charging or while exposed to high ambient temperatures, allowing maximum charging current without damaging the IC.

The MAX1508 achieves high flexibility by providing an adjustable fast-charge current by an external resistor. Other features include the charging status (active-low CHG) of the battery, an active-low control input (active-low EN) for the MAX1508 and MAX1508Z (active-high control input for the MAX1508Y), and an active-low input power-source detection output (active-low ACOK).

The MAX1508 accepts a +4.25V to +13V supply, but disables charging when the input voltage exceeds +7V to protect against unqualified or faulty AC adapters. The MAX1508 operates over the extended temperature range (-40°C to +85°C) and is available in a compact 8-pin thermally enhanced 3mm x 3mm thin DFN package with 0.8mm height.

Applications

* Bluetooth® Equipment * Cell Phones/Cordless Phones * Charging Cradles and Docks * Digital Cameras and MP3 Players * PDAs * USB Appliances

* Stand-Alone Linear 1-Cell Li+ Battery Charger

* No External FET, Reverse-Blocking Diode, or Current-Sense Resistor Required

* Programmable Fast-Charge Current (0.8A max)

* Proprietary Die-Temperature Regulation Control (+100°C)

* +4.25V to +13V Input Voltage Range with Input Overvoltage Protection (OVP) Above +7V

* Charge-Current Monitor for Fuel Gauging

* Low Dropout Voltage—130mV at 0.425A

* Input Power-Source Detection Output (Active-Low ACOK)

* Soft-Start Limits Inrush Current

* No Prequalification State for the MAX1508Y and MAX1508Z

* Charge Status Output (Active-Low CHG) for LED or Microprocessor Interface

* Small 3mm x 3mm 8-Pin Thin DFN Package, 0.8mm High

* Active-Low Charge Enable (Active-Low EN) (MAX1508 and MAX1508Z)

* Active-High Charge Enable (EN) (MAX1508Y)