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LED Drivers/LCD Bias
LED Drivers/LCD Bias Forum
I have 3 TLC5940's connected together and different channels on the drivers keep dieing.
I noticed that those channels who don't respond (to being told to turn off) are shorted to GND are are therefore always on!
I noticed that they tend to break when I turn on more the half the board in one request.
Due to the fact that the outputs are shorted to GND, I expect that you are driving the output somehow outside the absolute maximum rating. Please check if the output pins are seeing voltages out of the range given in the absolute maximum rating. Please check the voltage with respect to the GND pin of the IC you are measuring on.
The outputs could be damaged for example when due to GND shift the output swings negative.
Please check as well if an increased decoupling capacitor per IC helps the issue.
When you say "driving the output somehow outside the absolute maximum rating" .... you mean more than the Vled of 17 volts?
Also, when I am checking the voltage with respect to the GND pin of the IC I want to measure... I should be measuring the voltage differential between the IC GND and the Output Channel that's giving issues?
When I say outside of the absolute maximum rating, I mean either higher than the maximum or lower than the minimum value.
You do not need to measure differential, but for an accurate measurement you need to put the oscilloscope probe close to the IC pin and not somewhere else on the board.
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