LED lighting control reference design for machine vision

3rd September 2018

Lanna Deamer

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This LED lighting control reference design demonstrates an approach to drive and control a string of multiple high power light emitting diodes (LEDs). This reference design is targeted for industrial machine vision systems and is also suitable for other industrial or automotive lighting applications.

The design allows users to programme LED current and timing to enable the safe overdriving of LEDs for increased brightness.

The design can operate autonomously but can also be triggered or generate a trigger through an isolated interface.

Internal circuit blocks support a wide input voltage range, a programmable input current, and input power control as well as protect against reverse polarity, overvoltage and overtemperature.

Features

LED string voltage up to 24V
Programmability of multiple parameters:
- LED current: 200mA to 2.4A
- LED mode: Continuous or pulsed 200ns to 4.9s
- LED pulse repetition: 0.2Hz to 10kHz
- Trigger delay time: 10μs for trigger input
- Multi-pulse time, and current bracketing to support AEB and HDR imaging
Cascaded dual power stages:
- Pre-Boost: Wide 8 to 36V, 15W system input with adaptive inductor current limit
- Buck: Fast inductor current ramping
Isolated trigger and UART interface:
- Isolated 5V, 50mA output
- Sinking NPN– and TTL trigger IN and OUT
Comprehensive system supervision and protection:
- Onboard temperature sensors and voltage supervision
- Ultra-fast output overvoltage protection
eFuse: Reverse protection, adaptive overcurrent limit, and input power limit
EEPROM for up to 256 bits of user data