Joe,
Maxim has the MAX1620 LCD bias supply IC, which appears to be able to convert any voltage from 1.8V to 20V (typically 3.3V or 5V) into an adjustable positive or negative voltage from -27V to +27V, good for ca.
20-30 mA.Datasheet:
greetings, Tom
Hi
I am after a switching IC that can produce -20 to -25V (1~10mA) DC from
Any pointers would be appreciated.
Regards JG
hello all, i have a similiar problem. i need to get from 5 volts to
12 volts but i need to have an average of 500ma and max i 900ma at 12 volts. i know i cant do this w/ any dc-dc converter that i know of but can someone help me in building this circuit. i hate to think that i would have to use an oscillator-transformer-rectifier-regulator circuit just to go from 5 volts to 12-15 volts but not really sure.just a quick overview of what im doing is i have a wireless ydi etherant antenna that the built in amplifier runs on 12 volts and i wanted to use the pc usb 5 volt supply to power the amplifier by converting it to 12 volts. i know from the specs. on the wi-fi amplifier that it pulls average of 500ma and max of 900ma. is this too much power for the usb on a pc or can this be done?? thanks for any help!!
Forget it. To get 900mA at 12v, you need about 2.5A at 5v (allowing for some losses). A USB device can draw 100mA, as a 'low power' device, and a _maximum_ of
0.5A, as a 'high power' device (this has to be negotated with the USB host). Add the other circuitry to drive the unit, and you need to think in terms of something like a 1A/12v 'wall-wart', rather than making any attempt to draw this from USB. The conversion from 5v to 12v, an be simply done with a boost inverter (just an inductor needed, no transformer), with something like the LM2577, but you need to rethink where you are getting the power.Best Wishes
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