MAX8645X

The MAX8645X charge pumps drive up to eight white LEDs with regulated constant current for uniform intensity. The main group of LEDs (M1M6) can be driven up to 30mA per LED for backlighting. The flash group of LEDs (F1 and F2) of MAX8645X is independently controlled and can be driven up to 200mA per LED (or 400mA total).Two 200mA LDOs are on-board to provide power for camera functions. The LDOs' output voltages of MAX8645X are pin programmable to meet different camera-module requirements.

Features of the MAX8645X are:(1)two internal low-noise 200mA LDOs; (2)94% Max/85% avg efficiency (PLED/PBATT) over Li+ battery discharge; (3)0.2% typical LED current matching; (4)adaptive 1x/1.5x/2x mode switchover; (5)single-wire, serial-pulse interface for brightness control (32 steps); (6)thermal TA derating function; (7)low input ripple and EMI; (8)2.7V to 5.5V supply voltage range; (9)soft-start, overvoltage, and thermal-shutdown protection; (10)28-pin TQFN, 4mm x 4mm package.

The absolute maximum ratings of the MAX8645X can be summarized as:(1)PIN, IN, OUT, REFBP to GND:-0.3V to +6.0V;(2)storage temperature range:-65 to +150;(3)C1N, C2N to GND :-0.3V to (VIN + 1V);(4)junction temperature:+150;(5)IPGND to GND:-0.3V to +0.3V.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 MAX8645X includes soft-start circuitry to limit inrush current at turn-on. Once the input voltage of MAX8645X is applied, the output capacitor is charged directly from the input with a ramped current source (with no chargepump action) until the output voltage approaches the input voltage. Once the output capacitor is charged, the charge pump determines if 1x, 1.5x, or 2x mode is required. In the case of 1x mode, the soft-start is terminated and normal operation begins. In the case of 1.5x or 2x mode, soft-start operates until the lowest voltage of M1M6 and F1, F2 reaches regulation. If the output of MAX8645X is shorted to ground or is pulled to less than 1.25V, the output current is limited by soft-start.