40V LED Driver with Temperature Compensation

The ZLED7010, one of our ZLED Family of LED control ICs, is an inductive step-down converter that is optimal for driving a single LED or multiple LEDs (connected in series) from a voltage source greater than the voltage rating of the LED. The ZLED7010 operates in continuous mode. Capable of operating efficiently with voltage supplies ranging from 6 VDC to 40 VDC, it is ideal for low-voltage lighting applications. The ZLED7010 minimizes current consumption by remaining in a low-current standby mode (output is off) until a voltage of ≥0.3V is applied to the ADJI pin. In operating mode, the ZLED7010 can source LEDs with an output current of ≤750mA (≤30 watts of output power) that is externally adjustable. The ZLED7010's integrated output switch and high-side current sensing circuit use an external resistor to adjust the average out-put current. LED control is achieved via an external control signal at the ZLED7010's ADJI pin, implemented as a pulse-width modulation (PWM) waveform for a gated output current or a DC voltage for continuous current. The ZLED7010 provides a temperature compensation function for maintaining stable and reliable LED operation. LED over-temperature conditions are detected via a negative temperature coefficient (NTC) thermistor mounted close to the LEDs. If an over-temperature condition occurs, the NTC value reaches the value of a threshold resistor and the IC reduces LED current automatically. After the circuit recovers to a safe temperature, current returns to the set value. ADJO outputs and ADJI inputs of consecutive ICs can be interconnected as a driver chain deploying the temperature compensation information of the predecessor. This reduces the part count because only the first stage of the series requires an NTC.