LT8355-1 Datasheet

• 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 V_IN UVLO with Hysteresis
• Side Solderable 28-Lead 4mm × 5mm QFN Package
• AEC-Q100 Qualified for Automotive Applications

• High Voltage LED Applications
• Automotive Head Lamps/Running Lamps
• Accurate Current Limited Voltage Regulator

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%.