DESCRIPTION

The LT?8355-1 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.

FEATURES

- 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)

- PMOS Switch Driver for PWM and Output Disconnect

- Independent Channel Dimming

- Constant-Voltage and Constant-Current Regulation

- Adjustable Switching Frequency 100kHz to 2MHz

- Independent OPEN/SHORT LED FAULT per channel

- Programmable VIN UVLO with Hysteresis

- Side Solderable 28-Lead 4mm × 5mm QFN Package

- AEC-Q100 Qualified for Automotive Applications

APPLICATIONS

- High Voltage LED Applications

- Automotive Head Lamps/Running Lamps

- Accurate Current Limited Voltage Regulator