Trouble on LED driver


#1

Hi

I have a trouble on my propboard. This one have the LED drivers number 3 KO I don’t know why.
I just change the power supply from 7V to 3,7 by short the two circuit and remove the resistor. I was working in this configuration and few day after the LED 3 did not work. Do have an Idee of what i could be try or tests to isolate the trouble.

Best Regards


#2

Dear Dadoo

To isolate the problem please follow the next tests:


The first thing to do, change the LED. If the new LED light, the previous LED is burned.

If the new LED does not light, please test if the PWM is arrived to the point 1 using an oscilloscope . If you do not own one, use a tester to measure some voltage in this point. If the oscilloscope shown a PWM signal or the tester indicates some voltage, means the PWM is arrived.

If the PWM does not arrived, indicates that the MCU pin 16 (PA2) is burned or you have any software problem.

If you are sure that PWM is arrived at the point 1, please check the point 2 using a tester or oscilloscope to test if here is any voltage. If not, please use a tester in “beep” mode to check if the coil is open (point 3). If the coil is open, please replace it (Mouser P/N 652-SRN6028-3R9M).

If the coil is OK, please use a tester in “beep” mode to test if the shunt resistor R14 (point 4) is open, measuring between point 4 and GND. If R14 is open, replace it with a 0805 0.1 Ohm resistor.

If all is OK, the led driver LED2001 could be burned.


#3

Thank you,

my board works now again thank you


#4

Hi @Dadoo,

Can you explain what was the problem, please?

Thanks.


#5

Hi

it was the R14 resistor.