60V/120V Dual LED Controller with Exponential PWM and Scalable Dimming

The LT8355-1 a dual-channel DC/DC controller designed to drive two strings of high current LEDs. The fixed frequency, current mode architecture results in stable operation over a wide range of supply and output voltages. Voltage feedback pins serve as the inputs for several LED protection features and makes it possible for the converters to operate as a constant-voltage sources.

The LT8355-1 senses output current at the high or low side of the load. The product of CTRL2 and IADJ2 inputs provides analog programming of the output current for channel 2. Channel 1 output current is programmed through CTRL1 input. The PWM input and PWMTG high side PMOS driver provides precision time-based LED dimming capability. When driven by an external digital signal, the PWM input provides LED dimming ratios of up to 20,000:1 at 100Hz. When driven by a constant voltage, the PWM input selects from one of 128 internally generated, precision, exponentially spaced dimming ratios ranging from 0.78% up to 100%.

APPLICATIONS

* High Voltage LED Applications

* Automotive Head Lamps/Running Lamps

* Accurate Current Limited Voltage Regulator

All registered trademarks and trademarks are the property of their respective owners. Protected by U.S. patents, including 7199560, 7321203, 7746300, 8116045.

* Two independent High Voltage LED Driver Controllers Channels

* 128:1 Internal Exponential PWM Dimming

* Two-Pin Multiplying Analog Dimming (CH2)

* Spread Spectrum Frequency Modulation

* 20,000:1 External PWM Dimming at 100Hz

* Rail-to-Rail LED Current Sensing: 0V to 120V

* ±2% LED Current Regulation

* ±2% Output Voltage Regulation

* LED Short/Open Protection and Indication

* Wide Input Voltage Range (5V to 60V)