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AD8240:  LED Driver/Monitor

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 ...More

AD8240:  LED Driver/Monitor

Product 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 lamp current is the key benefit of constant-voltage LED lamp driving.

The output is current-limited by latching off the output voltage when the current reaches a preset level. The current limit is set by selecting the value of the external current shunt that causes the output of the sense amplifier to slightly exceed the 5 V reference level when the current exceeds a maximum level. When the sense amplifier output exceeds 5 V, it trips an internal comparator that causes the driver to latch off the output voltage. The latch is reset during the next PWM cycle. The overcurrent condition can also be detected by a microcontroller or external comparator by measuring the sense amplifier output.

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  • PWM input for LED Brightness Control
  • Open LED Detection
  • Latch-off Overcurrent Protection
  • Constant Voltage Regulated Output
  • Regulated Voltage Range: 12.5V to 27V
  • Supply range: 9V to 27 V
  • Operating current: 300 µA
  • Shutdown current: 10 µA
  • Temperature range -40°C to +125°C
  • 8-lead MSOP package
  • Base Drive (mA): 250mA
  • Dimming Control: PWM
  • Efficency (%): n/a
  • Frequency Range : DC to 500 Hz
  • Input Voltage Range (Vcc): 9 to 27V
  • LED #: 1
  • Package: 8-MSOP
  • Shutdown: X
  • Supply Current : 0.36mA

Functional Block Diagram for AD8240

AD8240 Diagram
Functional Block Diagram for AD8240

Similar Products

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Part# Input Voltage Range (Vcc) Supply Current Efficency (%) Base Drive (mA) Frequency Range LED # Shutdown Dimming Control Package Price* (1000-4999)
AD8240 9 to 27V 0.36mA n/a 250 DC to 500 Hz 1 X PWM 8-MSOP $1.29
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* The pricing listed here is provided only for budgetary purposes as recommended list price in U.S. Dollars in the United States ex factor per unit for the stated volume. Pricing displayed for Evaluation Boards and Kits is based on 1-piece pricing.
** Pricing is currently unavailable. Click on the product number to see the Product Page for additional information.

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*The USA list pricing shown is for BUDGETARY USE ONLY, shown in United States dollars (FOB USA per unit for the stated volume), and is subject to change. International prices may differ due to local duties, taxes, fees and exchange rates. For volume-specific price or delivery quotes, please contact your local Analog Devices, Inc. sales office or authorized distributor. Pricing displayed for Evaluation Boards and Kits is based on 1-piece pricing.
**Sample availability may be better than production availability. Please enter samples into your cart to check sample availability.