Variable Low current DC voltage from high input voltage up to 100 V.

This below circuit based in Intersil's ISL6719 can produce 1.5V to 20V DC at a current of 100 milli Amps from a unregulated DC source of 17 V to 100 V DC. The linear regulator used in this circuit is ISL6719 from Intersil Corp.

It uses very few external components and does not require any inductor.
 

C1 = 0.1 micro farads ceramic capacitor
C2 = 1 micro farad electrolytic or tantalum capacitor
C3 = 220 pico farad ceramic capacitor
R1 and R2 = Depends on the required output voltage (see the formula in the above picture)

For datasheet and further details visit

http://www.intersil.com/cda/deviceinfo/0,1477,ISL6719,0.html