TPS65120: TPS65120 issue

Part Number: TPS65120

Hi everybody,

I'm developping an electronic card with a 7 inches TFT touch screen (Winstar - WF70GTIAGDNT0#). This screen is controlled by a STM32F429IG microcontroller.

My screen needs several voltage to work :

- VCC voltage : 3V3 which is made by a buck converter

- VCOM voltage : 3V7 which is made by a TL431

- VGH voltage : 16V which is made by a TPS65120

- VGL voltage : -7V which is made by a TPS65120

- VMAIN voltage : 3V3 which made by a TPS65120

My issue comes from the TPS65120. If I didn't connect my screen on the board, all voltages work perfectly. If I connect the screen but without microcontroller, all voltages work perfectly. But with screen and microcontroller, all voltages are collapsing (VGH = 300mV; VGL = -250mV) as if the screen needs to much current, but without the microcontroller, it's not the case.

If you have any ideas, I'll be very happy.

Thank you in advance,


Fabrice Péden