MAX8822

The MAX8822 drives up to four white light-emitting diodes (LEDs) with regulated constant current for display backlighting in cell phones, digital cameras, PDAs, and other handheld devices. By utilizing a proprietary negative 0.5x inverting charge pump and innovative independent low-dropout (LDO) adaptive current regulators,very high efficiency of MAX8822 is achieved over the full 1-cell Li+ battery voltage range, even with large LED VF mismatch.

Features of the MAX8822 are:(1)independent adaptive voltage supply for each LED; (2)24mA to 0.1mA dimming range; (3)1% (typ) current accuracy and 0.3% current matching; (4)flexible single-wire control for dimming and LDO output voltage; (5)soft-start limits inrush current; (6)thermal shutdown and open- and short-circuit protection; (7)tiny 16-pin, 3mm x 3mm thin QFN package(0.8mm max height) with exposed paddle.The 1MHz fixed-frequency switching allows for tiny external components. The regulation scheme is optimized to ensure low EMI and low input ripple. Two 200mA, low-noise, high power-supply-rejection-ratio (PSRR) LDOs with programmable output voltages are included on-chip to provide power to camera modules or other devices.

The absolute maximum ratings of the MAX8822 can be summarized as:(1)NEG to GND:-6.0V to +0.3V;(2)storage temperature range:-65 to +150;(3)C1P, C2P to GND:-0.3V to (VIN + 0.3V);(4)junction temperature:+150;(5)IN, REF, ENLED, ENLDO, LDO1, LDO2 to NEG:-0.3V to +6.0V;(6)continuous power dissipation:1177mW.Stresses above those listed under Absolute Maximum Ratings may cause permanent damage to the device. This is a stress rating only; functional operation of the device at these or any other conditions above those indicated in the operational section of this specification is not implied.Exposure to absolute maximum rating conditions for extended periods may affect device reliability.The MAX8822 contains special circuitry to detect an LED_ short-circuit condition at startup only, and disables that current regulator to avoid wasting battery power. If an LED fails short-circuit detection after startup, that current regulator continues current-regulated operation until IC power is cycled and the short circuit is detected during the subsequent startup.