AD8240

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As a result, the constant voltage driving/monitoring method is

the lowest cost and least-prone-to-failure method for driving

and monitoring LEDs from a system perspective. This is

primarily because the number of wires and connections can be

minimized. By using a constant voltage driver and measuring

the current, an LED lamp can be driven and monitored using

only two wires (power and ground). In many cases, this can be

reduced to one wire when the chassis or shared ground return

is used. This is a similar architecture used with incandescent

bulbs, which means no changes to the wiring harness are

necessary with this LED implementation.

Most automotive platforms no longer use a switch on the

dashboard to directly control the incandescent lamps. These

lamps are now controlled and driven by the body control ECU.

By using this constant voltage architecture, the control and drive

function for the LEDs can remain in the ECU with minimal

design modification.

Constant voltage driving/monitoring is a proven method

already in use in a number of automotive platforms to drive

LED tail, running, and turn-indicator lamps.

The AD8240 LED lamp driver/monitor is designed for use in

the body control or related module. When used this way, it is

very similar to the method that has been used to control

external incandescent lamps. By utilizing the existing lamp

driving architecture, additional modules are not required to

drive the external lamps, which further minimizes the cost.

It is possible to retrofit existing lamp driving modules with

the AD8240 with minimal engineering time required.