Low Noise, High Efficiency Charge Pump for White LEDs

The LTC3202 is a low noise, constant frequency charge pump DC/DC converter that uses fractional conversion to increase efficiency in white LED applications. The part can be used to produce a regulated voltage or current of up to 125mA from a 2.7V to 4.5V input. Low external parts count (two flying capacitors and two small bypass capacitors at VIN and VOUT) make the LTC3202 ideally suited for small, battery-powered applications.

An internal 2-bit DAC allows LED current to be adjusted for LED brightness control. The LTC3202 also has thermal shutdown protection and can survive a continuous short-circuit from VOUT to GND. Built-in soft-start circuitry prevents excessive inrush current during start-up. High switching frequency enables the use of small external capacitors. A low current shutdown feature disconnects the load from VIN and reduces quiescent current to less than 1µA.

The LTC3202 is available in the 10-pin MSOP and 3mm x 3mm DFN packages.

Applications

* White LED Backlighting

* Programmable Boost Current Source

* Low Noise Constant Frequency Operation

* 25% Less Input Current Than Doubler Charge Pump

* High Output Current: Up To 125mA

* Small Application Circuit

* Regulated Output Voltage or Current

* Automatic Soft-Start

* VIN Range: 2.7V to 4.5V

* No Inductors

* 1.5MHz Switching Frequency

* ICC < 1µA in Shutdown

* Available in 10-Pin MSOP and 3mm x 3mm DFN Packages