Supertex, Inc. has announced the HV9921/22 family of 3-pin, switch-mode LED driver ICs. With the MOSFET integrated to the IC, the HV9921/22 family allows for high efficiency driving of low current LEDs in signage or general lighting applications. The regulated LED current is internally fixed at 20 mA for HV9921 and 50 mA for the HV9922. The device has an operating range of 20V DC to 450V DC, which allows for universal AC input operation of 85V AC to 256V AC. It is a pulse width modulation (PWM) controller and driver IC used in a buck (step down) converter topology. The HV9921/22 utilizes peak current-mode control in the buck converter topology to allow ease of use, requiring no compensation. It also uses fixed off-time operation of the MOSFET, which allows the HV9921/22 to drive LED string voltages to approximately 80 percent of the input voltage. Because the product is a switch mode driver that offers high efficiency, it can be placed in applications where space, size and thermal considerations are at a premium. HV9921 and HV9922 are available in a TO-92 or SOT-89 package. Supertex Inc.