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Dual Regulated Supply from Single Voltage 2014-05-28

Here's a variation on the previous Dual Supply circuit that uses an LM317 to generate 10V and then a LT1118 to provide a split virtual ground and supply ±5V.

The circuit depends upon the unique sink/source characteristic of the LT1118 to carry any imbalanced ground current between the plus and minus loads.
The advantage of this circuit is that the total plus and minus current can go to the 1.5A rating of the LM317, although the maximum imbalance between the plus and minus currents is limited to 400mA as determined by the maximum sink capability of the LT1118.
Also most of the power will be dissipated by the LM317.

Below is an LTspice simulation of the circuit configured to generate ±5V from a 13V supply.
It's shown with the virtual ground point as the circuit ground. This is arbitrary and the ground can be referenced where desired.

Of course the usual requirements for heat sinking apply to the LM317 and the LT1118.
The LM317 will dissipate (Vin-10V)* Iout.
The LT1118 maximum dissipation will be about 1W.

Split Supply.gif


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