Negative Voltage

Thread Starter

sciengart

Joined Mar 25, 2020
36
I just want some quick clarity.

If a circuit calls for a Vcc of +12v and a Vee of -12v, AND GND, can I just use a 24v supply with a stiff 12v rail and gnd as -12v?
 

Alec_t

Joined Sep 17, 2013
11,277
What you can do with a 24V supply is make a voltage divider with two equal value resistors to give a 12V point which then becomes your new virtual Gnd. The original Gnd terminal becomes your new '-12V' rail. However, if your circuit requires more than a few mA then the virtual ground would need buffering with a unity-gain amplifier (e.g. op-amp).
 

MisterBill2

Joined Jan 23, 2018
6,039
A resistive voltage divider would sort of work if the currents drawn from the positive half and the negative half stayed equal. Of course the resistive divider approach is inefficient in addition to being unstable. So it is a poor choice for most applications. In some applications there are other options, so can we have an explanation of the specific application, since there may be other options possible?
 

MrChips

Joined Oct 2, 2009
21,091
There are ways of doing this depending on the application and current requirements.

1) resistor voltage divider
2) resistor voltage divider and buffer opamp
3) switching negative supply LMC7660
4) rail spltter IC, TLE2426
 
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