ZXLD1320DCATC Diodes Incorporated

ZXLD1320 Buck mode DC-DC converter for LED driving with 1.5A output and current control Description The ZXLD1320 is an inductive DC-DC The feedback control circuitry inside the converter, with an internal switch, designed ZXLD1320 provides excellent load and current for driving single or multiple LEDs in series up regulation, resulting in very stable LED current to a total of 1.5A output current. over the full operating voltage and temperature range. Applications cover both commercial and automotive environments with input voltages The LED current can be adjusted from 100% ranging from 4V to 18V. Depending upon down to 10% of the set value by applying a dc supply voltage and external components, this voltage to the ADJ pin and down to 1% by can provide up to 24W of output power. applying a PWM signal. An on-chip LED protection circuit also allows output current to The device employs a variable on and off be reduced linearly above a predetermined time control scheme with adjustable peak threshold temperature using an external switch current limiting and operates in the thermistor at the TADJ pin. step-down (Buck) operating mode, offering higher power efficiency and lower system External resistors set nominal average LED cost than conventional PFM circuitry. current and coil peak current independently. The device includes the DC-DC converter, a The Power-OK (POK) output flag remains high high-side current monitor and an NPN during normal operation, but switches low if the switching transistor to provide an integrated switch transistor remains on for more than solution offering small PCB size, competitive 500 s. This provides indication of a low battery, cost/performance, high power efficiency of or fault condition. The POK output may be used DC-DC conversion and maximum LED to drive an LED or the input of an MCU. brightness/reliability. More importantly, it The device can be shut down by applying a retains design flexibility to add customer continuous low level dc voltage to the ADJ pin. specific features. Features Applications Step-down LED driver Low voltage halogen lamp replacement 4V to 18V input voltage range with LEDs Up to 1.5A output current High power LED flashlights Typical efficiency > 85% LED back-up lighting User-defined thermal control of LED General LED lighting output current using external thermistor High output current stability over input Automotive lighting voltage and temperature 12A typical standby current LED current adjustable from 100% down to 2% Adjustable soft-start Power OK flag output Capable of driving 4 LEDs in series Note* : Using standard external components as specified under electrical characteristics. Efficiency is dependent upon external component types and values. Higher efficiency is possible with alternative coils. Issue 1 - January 2008 1 www.zetex.com Zetex Semiconductors plc 2008ZXLD1320 Pin connections (top-view) Package view Package DFN14 Package (bottom view). 14-Pin DFN with exposed pad 45 chamfer denotes Pin 1 4mm x 3mm 0.50mm pitch 1.5W T =70C A Block diagram Issue 1 - January 2008 2 www.zetex.com Zetex Semiconductors plc 2008