MAX8647

The MAX8647 drives up to six white LEDs or two sets of RGB LEDs with regulated constant current for display backlight and fun light applications. By utilizing an inverting charge pump and extremely lowdropout adaptive current regulators, these ICs MAX8647 achieve very high efficiency over the full 1-cell Li+ battery voltage range and even with large LED forward voltage mismatch. The 1MHz fixed-frequency switching allows for tiny external components.The regulation scheme is optimized to ensure low EMI and low input ripple. The MAX8647 includes thermal shutdown, openand short-circuit protection.

Features of the MAX8647 are:(1)six adaptive current regulators; (2)independent voltage supply for each LED; (3)individual LED brightness control (MAX8647); (4)low 70A quiescent current; (5)low 1A shutdown current; (6)inrush current limit; (7)ta derating function protects LEDs; (8)16-Pin, 3mm x 3mm Thin QFN package.When VIN is higher than the forward voltage of the white LED plus the 0.15V headroom of the current regulator,the LED current returns through GND. If this condition is satisfied for all six white LEDs, the charge pump of MAX8647 remains inactive. When the input voltage drops so that the current-regulator headroom cannot be maintained for any of the individual white LEDs, the inverting charge pump of MAX8647 activates and generates a voltage on the NEG pin that is no greater than 5V below VIN.

The absolute maximum ratings of the MAX8647 can be summarized as:(1)VDD, IN, SCL, SDA, ENA, ENB, ENC to GND:-0.3V to +6.0V;(2)storage temperature range:-65 to +150;(3)NEG to GND:-6V to +0.3V;(4)junction temperature:+150;(5)C2N to GND:-6V to +0.3V;(6)continuous power dissipation:1667mW.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.Ceramic capacitors are recommended due to their small size, low cost, and low ESR. Select ceramic capacitors that maintain their capacitance over temperature and DC bias. Capacitors with X5R or X7R temperature characteristics generally perform well. Recommended values are shown in the Typical Operating Circuit. Using a larger value input capacitor helps to reduce input ripple.