RT8489

® RT8489 High Voltage 4-CH LED Driver Controller General Description The RT8489 is a 4-CH LED driver controller that delivers well matched LED current to each channel of LED string. With external current sources, the number of LEDs per string is only limited by the current source and the VIN/ VOUT conditions. The current mode PWM Boost type controller operates at an adjustable switching frequency of up to 1MHz, with a wide VIN range covering from 7V to 28V. The switch driver is designed to drive industrial grade high power MOSFETs. The PWM loop selects and regulates the LED string with the highest voltage string to 0.7V, thus allowing voltage mismatches between the LED strings. The RT8489 automatically detects and excludes any open and/or broken strings during operation from the PWM loop to prevent VOUT from over voltage. The LED currents on all channels are simply adjustable with a resistor on each channel. Three convenient dimming methods are provided : 1. Analog dimming is linearly controlled by an external voltage. 2. True digitally controlled PWM dimming can regulate the duty cycle of the LED current. 3. For noise free PWM dimming, use an on board output clamping amplifier as a low pass filter to convert PWM dimming signals into analog dimming signals. Other protection features include adjustable output over voltage protection, PWM switch current limit and thermal shutdown. Features z Wide Operation Voltage Range : 7V to 28V z Programmable Channel Current z 3% Current...