TFT Backlight

[tiwari.sachin]

I am using the below schematic to drive the backlights of the display. Also given are backlight LED specs

While using this, I see a lot of flickering and the IC and inductor also gets heated up.

Have a chosen a wrong part or am I missing something in the design.

 

[RCinFLA]

You are pulling close to 0.5 amps at 5v, which if powered from a USB source could be near limit. With switcher startup surge, make sure your 5v source can handle the peak current.

 

[tiwari.sachin]

I am not using power from USB and the source is capable of supplying 5V 3A

 

[KlausST]

Hi,

Have a chosen a wrong part

One of the most critical part is the inductor of the step up circuit. It needs to be carefully selected according IC datasheet.

Simple debugging tests are: measure 5V, 24V and the voltage across 33R whether they have the expected values and whether they are stable.
A DVM can give only raw (timing) informations, better use a scope.

You did use a 24V power supply circuit. It can't compensate for VF drifts (21.7V ... 24.5V). Why didn't you use a dedicated step up LED driver circuit?

Not related to the LED problem:
Don't use an inductor in the GND line of the LCD (L34). GND should be clean (low GND bounce), low impedance and should refer to a common GND level.
All signals (power, logic...) should refer to the same GND node.
An inductor in the GND line makes things worse.

Klaus