Diodes Incorporated ZXLD1320

Description

The ZXLD1320 is an inductive DC-DC converter, with an internal switch, designed for driving single or multiple LEDs in series up to a total of 1.5A output current.

Applications cover both commercial and automotive environments with input voltages ranging from 4V to 18V. Depending upon supply voltage and external components, this can provide up to 24W of output power.

The device employs a variable 'on' and 'off' time control scheme with adjustable peak switch current limiting and operates in the step-down (Buck) operating mode, offering higher power efficiency and lower systemcost than conventional PFM circuitry.

The device includes the DC-DC converter, a high-side current monitor and an NPN switching transistor to provide an integrated solution offering small PCB size, competitive cost/performance, high power efficiency of DC-DC conversion and maximum LED brightness/reliability. More importantly, itretains design flexibility to add customer specific features.

The feedback control circuitry inside the ZXLD1320 provides excellent load and current regulation, resulting in very stable LED current over the full operating voltage and temperature range.

The LED current can be adjusted from 100% down to 10% of the set value by applying a dc voltage to the ADJ pin and down to 1% by applying a PWM signal. An on-chip LED protection circuit also allows output current tobe reduced linearly above a predetermined threshold temperature using an external thermistor at the TADJ pin.

External resistors set nominal average LED current and coil peak current independently.

The 'Power-OK' (POK) output flag remains high during normal operation, but switches low if the switch transistor remains on for more than 500μs. This provides indication of a low battery, or fault condition. The POK output may be used to drive an LED or the input of an MCU.

The device can be shut down by applying a continuous low level dc voltage to the ADJ pin.

Features

• Step-down LED driver
• 4V to 18V input voltage range
• Up to 1.5A output current
• Typical efficiency# > 85%
• User-defined thermal control of LED output current using external thermistor
• High output current stability over input voltage and temperature
• 12μA 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

Remarks:Bill of materialsRefer page no.15

Typical applications

• General LED lighting
• High power LED flashlights
• Automotive lighting
• LED back-up lighting
• Low voltage halogen lamp replacement

More information

• Datasheet
• IC product information