PMP2493.3, Buck Converter with Minimum Component Count to Drive LEDs (21.5V @ 450mA)

PMP2493.3, Buck Converter with Minimum Component Count to Drive LEDs (21.5V @ 450mA). TPS40200 controller can be used as a low-cost LED driver. With an input voltage rating of 4.5 to 52 V, it can power LED strings with regulated current and up to a 45 V drop across the string. Current is sensed across a resistor between the cathode of the string and ground and is compared against a 696 mV reference to provide regulated current. Because the driver is a buck and not a boost or flyback, an open string will not produce voltages above the input voltage and over-voltage protection is not needed. The driver can operate in either the continuous or discontinuous mode. for output voltages above 35 V the discontinuous mode is needed due to duty cycle limitation above 35 V. The circuit shown has a Pulse Width Modulator (PWM) input for dimming purposes. Targeted current can be set with jumpers