Hi, I'm currently designing a portable hand-held terminal around a PIC16F628 (the cheapest variant of 18-pin PIC in my Box O' PICs). The problem is, this thing has to run off a Lithium battery - that's 3V, 1AH (if I can get one that big). I've got the power consumption of the chip itself down to 30uA (37kHz internal oscillator), but I still haven't found a way to generate the -3V contrast voltage for the LCD display. I've built up a charge-pump using two 1N4148s and some capacitors (a 0.1uF and a 0.22uF) but I can only get -1.8V out of it. Does anyone know how I might be able to get -3V out of a chargepump? I don't want to add a chargepump controller IC due to the increase in current consumption. It would be handy if the chargepump connected to RB3 (PWM Out) as this would enable me to vary the PWM rate to adjust the contrast. The other advantage to using the PWM controller would be that I could turn off the PWM output at the same time as the LCD power, thereby reducing the power consumption. Any ideas? Thanks. -- Phil. philpem@dsl.pipex.com http://www.philpem.dsl.pipex.com/ -- http://www.piclist.com hint: To leave the PICList mailto:piclist-unsubscribe-request@mitvma.mit.edu