The PT16751 is a Headlight LED controller for automotive with high accuracy peak current mode. The device implements a fixed-frequency peak current mode control technique with programmable switching frequency, slope compensation, and soft-start timing. The controller is designed to support a range of step-up or step-down driver topologies. It incorporates a high voltage (65V) rail-to-rail current sense amplifier that can directly measure LED current using a high-side series sense resistor. The amplifier is designed to achieve low input offset voltage and attain better than ±4% LED current accuracy over junction temperature range of 25°C to 140°C and output common-mode voltage range of 3V to 60V.

This LED controller can independently modulate LED current using either analog or PWM dimming techniques. Linear analog dimming response with 15:1 range is obtained by varying the voltage from 140 mV to 2.25 V across the high impedance analog adjust (IADJ) input. PWM dimming of LED current is achieved by modulating the PWM/DIM input pin with the desired duty cycle or by enabling the internal PWM generator circuit. The DC input voltage at PWM/DIM pin is translated by the PWM generator, to corresponding duty cycle by comparing it to the internal triangle wave generator. PDRV gate driver output can be used to enable series FET dimming functionality to get over 1000:1 contrast ratio.

The PT16751 provides perfect protection to prevent LED lights overheating and damage. Connect IADJ2 pin to a voltage divider circuit which includes NTC thermistor to obtain the temperature of LED board. TEMPA set the derating curve of LED current when LED lights is overheat, and TEMPB set the thermal shutdown temperature.

The PT16751 supports continuous LED status check through the current monitor (IMON/FLT) output. IMON/FLT pin outputs 5.07V (typical) to indicate device overheat (typical at 175°C), LED over-current, over-voltage and under-voltage conditions.