TLC5923: output current drop

Hi Ben,

Do you mean the CH#1 is separated, and CH#2,#3,#4 are connected together?

If so, It should be the reason that the supply voltage has been changed when the CH#2,#3,#4 shutdown. Could you help to test the transient voltage of the supply power?

If not this reason, please let me know, thanks!

Hi Shawn,

All LEDs on each channels are separated, but connect to the same power source.

We will test voltage transient and see if it is the root or not, thanks!

Ben

Hi Shawn,


There are no transient voltage after we turn on/off LED.
May I know which item I should check first about this issue?
Thanks!

-Ben

Hi Ben,

If it is not the supply power, it should be the ground problem. Since the ground is not the ideal, there are resistance between the device ground to earth ground, and also each channels ground also different and have the different resistance to the device ground. These resistance cause the channel current deviation when channel current changes.

Can you help to check the PCB layout to see if it is the ground problem? Also, please help to test if turn off CH1,2,3/1,2,4/1,3,4 and see the current of CH4/CH3/CH2.

thanks!
Best regard!