Description

The MAX1574 charge pump drives up to three whiteLEDs with regulated constant current for uniform intensity.By utilizing adaptive 1x/2x charge-pump modes andvery-low-dropout current regulators, it achieves 180mAoutput drive capability and high efficiency over the 1-celllithium-battery input voltage range. Fixed-frequency(1MHz) switching allows for tiny external components,and the regulation scheme is optimized to ensure low EMIand low input ripple.The MAX1574 uses an external resistor to set the fullscale100% LED current. An enable input (EN) is used forsimple on/off control or can be pulsed repeatedly to setlower LED current in multiple steps down to 5%. Once thedesired brightness is set, the MAX1574 maintains constantLED current as long as EN is kept high. If EN is keptlow for more than 2ms, the MAX1574 enters shutdown.The MAX1574 is available in a 10-pin 3mm x 3mm TDFNpackage (0.8mm max height).ApplicationsCamera Strobes/Flashes and Movie LightsCell Phones/SmartphonesLCD BacklightsPDAs, Digital Cameras, and Camcorders