Hello Everyone,
I have a bit of a design issue that is preventing me from using a basic switching white LED driver the way it was intended to be used. I am using the MIC2297 as well it's development board to design a back light circuit which should be pretty simple. The problem is that we first intended to use a constant current source PWM'd to control dimming ( I should mention that this project is for an LCD Touch Screen ) which we designed in but caused the screen to flicker because of voltage droop and had to resort using a huge cap as a band-aid solution. We are now at the point were the band-aid needs to come off and now we are in a pickle.
The development board works great at regulating using it's own LEDs while being powered using our product but the instant the we disable the on-board LEDs and apply it to our application all regulation stops and nothing works. We traced the problem back and found out that due to a design restriction we were bypassing the feedback pin so no regulation was occurring.
This project consists of a mother and daughter board, one is the CPU board and the other is the Interface board. The CPU board controls the PWM and can not be respun to fix the issue, but the IO board can. The only access I have to the CPU from the Interface board is back light power (after the schottky ) and ground, please see the provided pdf for clarity.
This is also my first post, so if i did anything wrong let me know and I will not repeat it. I did take a look to see if there was a solution already available but no one had one.
Thank you for taking the time to very my post
Jason
I have a bit of a design issue that is preventing me from using a basic switching white LED driver the way it was intended to be used. I am using the MIC2297 as well it's development board to design a back light circuit which should be pretty simple. The problem is that we first intended to use a constant current source PWM'd to control dimming ( I should mention that this project is for an LCD Touch Screen ) which we designed in but caused the screen to flicker because of voltage droop and had to resort using a huge cap as a band-aid solution. We are now at the point were the band-aid needs to come off and now we are in a pickle.
The development board works great at regulating using it's own LEDs while being powered using our product but the instant the we disable the on-board LEDs and apply it to our application all regulation stops and nothing works. We traced the problem back and found out that due to a design restriction we were bypassing the feedback pin so no regulation was occurring.
This project consists of a mother and daughter board, one is the CPU board and the other is the Interface board. The CPU board controls the PWM and can not be respun to fix the issue, but the IO board can. The only access I have to the CPU from the Interface board is back light power (after the schottky ) and ground, please see the provided pdf for clarity.
This is also my first post, so if i did anything wrong let me know and I will not repeat it. I did take a look to see if there was a solution already available but no one had one.
Thank you for taking the time to very my post
Jason
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