Detect LED died in LED Mesaage Display?

[khongai]

Help me, How to do it?

 

[namqn]

Re: Detect LED died in LED Message Display?

Just display a whole block on your display (all LED on), or move a full vertical bar through the display at a low enough speed to catch the dead LEDs.

Cheers,

 

[khongai]

but LED display very far from me ( about 1km)

 

[Taner]

you can use a current sense of the LED display, with current sensor

 

[kender]

you can use a current sense of the LED display, with current sensor

You can also sense the voltage drop across the LED. If the LED has failed open, the voltage will go to the power supply voltage. If the LED failed short, the voltage will go to zero.

 

[namqn]

but LED display very far from me ( about 1km)

You did not say that in the first post.

As some people have suggested, you can sense the current goes through the driver outputs, by using a current sensor, or by measuring just the voltage at the driver outputs.

Cheers,

 

[Taner]

sorry friends, i mean a current sensor of the output of the driver

 

[mondunno]

scan leds one by one. just check the drop across the "current limit resistance"(the one in series, with all leds) which ever led shows VCC as drop, its disconnected

 

[kender]

scan leds one by one. just check the drop across the "current limit resistance"(the one in series, with all leds) which ever led shows VCC as drop, its disconnected

Would an LED display have a single currelt-limiting resistor? I doubt it.

 

[kosta]

The TLC5940 is a 16-channel constant-current sink LED driver.

The TLC5940 features two error information circuits. The LED open detection (LOD) indicates a broken or disconnected LED at an output terminal. The thermal error flag (TEF) indicates an overtemperature condition.