I developed an HW based on TLC5940 which is connected to a µC. It was for 3 days on a permanent test and it worked without any problem.
The signal level was also ok at the start of the test.
3 Day later, out of 27 boards, 3 are not working anymore. By troubleshooting through measurement, I measure the signal on each pin and the level from µC was not more 3,4V but 3,7V. Also, the SCLK pin from µC is not toggling anymore as you can see in the picture (Yellow is the input voltage 24V which is step down to 5V and 3,4V, blue is the Blank signal at around 3,7V and SCLK signal toggling between 0V and 700mV)
The SCLK signal is trying to toggle but not up to 3,4V or 3,7V.
What could be the cause of this issue?
Furthermore, some LED on the board is not any more controllable, meaning the out0-out15 of the TLC9540 is always on and the LED are getting extremely hell. This LED is always on when some others are off
=> of course my LED driver (TLC5940) defects, since changing the driver, everything works as usual.
The signal level was also ok at the start of the test.
3 Day later, out of 27 boards, 3 are not working anymore. By troubleshooting through measurement, I measure the signal on each pin and the level from µC was not more 3,4V but 3,7V. Also, the SCLK pin from µC is not toggling anymore as you can see in the picture (Yellow is the input voltage 24V which is step down to 5V and 3,4V, blue is the Blank signal at around 3,7V and SCLK signal toggling between 0V and 700mV)
The SCLK signal is trying to toggle but not up to 3,4V or 3,7V.
What could be the cause of this issue?
Furthermore, some LED on the board is not any more controllable, meaning the out0-out15 of the TLC9540 is always on and the LED are getting extremely hell. This LED is always on when some others are off
=> of course my LED driver (TLC5940) defects, since changing the driver, everything works as usual.
What could be the cause?
I have also measured the temperature on the board with pottant. It is between 95°C and 108°C since the pottant does not have good thermal conductivity. Could this be the cause, since, in the datasheet, the recommended free air temperature is from -40°C to 85°C, awaiting a temperature below the pottant to be more than 108°C?
will be delighted for any advice to find the cause.
I have also measured the temperature on the board with pottant. It is between 95°C and 108°C since the pottant does not have good thermal conductivity. Could this be the cause, since, in the datasheet, the recommended free air temperature is from -40°C to 85°C, awaiting a temperature below the pottant to be more than 108°C?
will be delighted for any advice to find the cause.
