White LED supply from MAX232 charge pump.

[hugo_nz]

max232 charge pump

Hi,

Does anyone know how well this would work:
Using a MAXIM RS232 driver IC (specifically the MAX3222) to generate a ~7.5V, 15mA supply to drive a white LED frontlight on a colour TFT LCD. How would this work when the serial port is in use? Not in use?

Are there any other ways people have used to get a white LED bias supply, "for free" i.e. without a dedicated IC.

We were also considering a diode/capacitor voltage doubler off of one of the switchmode supply rails.

Thanks

 

[rauol]

voltage doubler for led using 555 timer

:lol: You can use a standard 555 timer Ic to to be used as a Voltage doubler or as a viltage inverter or as a pulse width modulator.
you can specify the input source voltage and the required voltage,current and the required no. of LEDs you want to use, for a comment. :roll:

 

[PaulHolland]

555 timer charge pump

Hi,

On the MAX3222 you can get the voltage you are looking for from pin 3 (+) and 7 (-)... don't use the status lines like RTS/DTR...

Paul.