Analog Devices LT8355-1 | Demoboard EVAL-LT8355-1-AZ

Description

Evaluation board EVAL-LT8355-1-AZ is a high voltage dual LED controller featuring the LT8355-1. Channel 1 is assembled as a boost LED driver and channel 2 as a buck-boost mode LED driver. Either channel can be altered to a boost LED driver or buck-boost mode LED driver by adjusting the FB network and LED connection. EVAL-LT8355-1-AZ drives a single string of LEDs per channel when the input is between 8V and 18V. Channel 1 drives up to 72V of LEDs at 450mA and channel 2 drives up to 30V of LEDs at 1A. EVAL-LT8355-1-AZ has an undervoltage lockout (UVLO) set at 6.2V falling and 7.5V rising. EVAL-LT8355-1-AZ features PWM dimming, analog dimming, shutdown, open LED and short LED fault protection and reporting.EVAL-LT8355-1-AZ runs at 250kHz switching frequency and features spread spectrum frequency modulation (SSFM) modulating its switching frequency from 250kHz to 310kHz to reduce EMI emissions. Small ceramic input and output capacitors are used to save space and cost. A high voltage 100V external power switch and 100V catch diode are used on each channel for up to 32W boost output for channel 1 and up to 30W buck-boost mode output for channel 2 as assembled. The open LED overvoltage protection (OVP) uses the IC’s constant voltage regulation loop to limit the LED+ to LED– voltage if the LED string is opened to approximately 81V for channel 1 and 36V for channel 2.

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

Typical applications

• High Voltage LED Applications, Automotive Head Lamps/Running Lamps

More information

• Datasheet
• IC product information