Hi Tanya,

Adding RC delay from VIN to EN should  have worked and you can increase values of R and C significantly to observe a larger delay. Can you please provide a scope capture of the VIN and EN pins on the same plot?

Kind Regards,

Liaqat

Hi Liaqat,

OK. I will check that.

I have one more query. In my design VO1=5.5V, VO2=-5.5V. But when I connect my LCD VO2 is changing to -5.1V. What may be the reason?  am attaching the schematics for reference. Please have a look at it, and let me know if any feedbacks.

Regards,

Tanya

Hello,

I have another query related to the negative voltage. For eg. if I tune the resistor divider to 6V, the voltage observed is 5.1V. What may be the reason for this?

Regards,
Tanya

Hello,

The reason for only getting -5.1 for negative supply is that your VO1 is 5.5V and this 5.5V is used as a input supply for inverting change pump to generate negative supply. There is some voltage drop across the schottky diodes for inverting charge pump and that is the reason for only getting -5.1V. If you only need +/-5.5V supply (no VGH supply), a better device will be TPS65130/131.

Kind Regards,

Liaqat

Hi Liaqat,

Thanks for the update.

How can I use TPS65105 to provide +/-5.5V in the most efficient way? I have also attached schematics of the same. Could you please review.

Regards,
Tanya