SNVS039J June 2000 – April 2015 LM1086
PRODUCTION DATA.
The LM1086 adjustable version develops a 1.25-V reference voltage, (VREF), between the output and the adjust terminal. As shown in Figure 16, this voltage is applied across resistor R1 to generate a constant current I1. This constant current then flows through R2. The resulting voltage drop across R2 adds to the reference voltage to sets the desired output voltage.
The current IADJ from the adjustment terminal introduces an output error . But since it is small (120uA max), it becomes negligible when R1 is in the 100 Ω range.
For fixed voltage devices, R1 and R2 are integrated inside the devices.