I'm looking to create the simple adjustable voltage regulator below
However, I am confused by the input-output voltage relationship. Looking at the LM317 data sheet (https://www.onsemi.com/pub/Collateral/LM317-D.PDF, pages 1,2 and 7 in particular), the Vref (the voltage across resistor R1) is specified as being a constant 1.25V.
Page 2 under characteristics of Vref states "Reference Voltage, 3.0 V ≤ VI−VO ≤ 40 V ... "
- What is the input-output relationship in the LM317?
- Can Vin be any voltage as long as Vout is between 1.25 - 37V but the difference between Vin and Vout (Vin - Vout) cannot be greater than 40V or less than 3V?
- is Vin - 3 the maximum allowed Vout?