Guru
Joined: 11/12/2012
Location: United KingdomPosts: 11980
| Posted: 11:55pm 24 Jan 2016 |
The regulator on the ILI9341 is a 3V LDO device, so it just regulates 3.3V to 3V. The spec on the ILI9341 controller gives an absolute maximum of 4.6V for the logic input and the supply voltage with normal maximum for operation of 3.3V.
The chip also uses a 2.0V supply for its core logic. This is nothing to do with the voltage regulator on the PCB and is generated by the chip itself in the same way that the PIC32 generates its internal 1.8V supply (stabilising this is what the VCAP capacitor is for on the PIC32).
So if you are using a 3.3V supply shorting out J1 is fine as you are staying within all normal operating conditions.
The backlight LED supply is completely separate, doesn't go through the regulator, and is sourced on the LED pin. There is an onboard current limiting resistor of 3.9ohm from the LED pin. I measure 40mA with a 3.3V supply connected to LED. For a brighter display you can connect 5V to LED direct to give 150mA which will probably shorten display life or for optimum brightness PWM a 5V supply onto the LED pin using a npn transistor to drive a p-channel mosfet.