02-12-2016, 03:03 PM
(02-12-2016, 02:42 PM)Terry Wrote: It will work quite happily with a 1.5V input and the value of R2 sets the output voltage - 111kΩ for 15V, using the formula shown and 1.5V input.
Also, this is incorrect.
1.23V is the reference voltage. That's fixed inside the chip. To arrive at 15V, you've replaced 1.23V with 1.5V in that equation.
With R1 set to 1M, the correct resistor for R2 would be 89.3k. The nearest E96 value is 88.7k, but 91k gives 14.75V, which might well be close enough. Of course, R2 doesn't have to be 1M. The bias current going into the FB pin should be 30nA, so errors caused by that should be nice and low.
