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