AD8240

www.DataSheet4U.com LED Driver/Monitor AD8240 FEATURES PWM input for LED brightness control Open LED detection Latch-off overcurrent protection Constant voltage regulated output Supply range: 9 V to 27 V Regulated voltage range: 12.5 V to 27 V Operating current: 300 µA Shutdown current: 10 µA Temperature range −40°C to +125°C 8-lead MSOP package FUNCTIONAL BLOCK DIAGRAM VPLUS SHUNT 5 6 BASE 7 VO 8 RSENSE VSENSE 1 10kΩ 5V 2 REFERENCE LATCH-OFF DRIVER R1 350kΩ PWM 3 R2 250kΩ 04824-0-001 GENERAL DESCRIPTION The AD8240 LED driver/monitor, in combination with an external transistor, supplies a constant 12 V to drive LED lamps. This allows cost-effective LED lamp monitoring and short-circuit protection. The output is regulated at 12 V when the supply voltage is between 12.5 V and 27 V. A CMOS compatible, level-dependent, digital input can be used for PWM control of the LED brightness. VO is turned on when the PWM input is high and turned off when the input is low. The AD8240 is designed to work with a PWM frequency up to 500 Hz, and a typical PWM range from 5% to 95%. Open LED detection is accomplished by measuring the change in LED lamp current caused by an open LED(s) through the use of an internal high-side current-sense amplifier that amplifies the voltage across an external current shunt. The voltage across the shunt resistor is amplified to a level that can be measured by a microcontroller A/D converter or a comparator. The ability to measure the change in LED lam...