AS2870
Basic Adjustable Regulator
VIN
VOUT
AS2870
R1
R2
VREF
IADJ
50µA
*
ADJ R2
(1 + R2 ) + I
R1
VOUT = VREF
*
Fig.2 Basic Adjustable Regulator
Output Voltage
Consider Figure 2. The resistance R1 generates a constant current flow, normally the specified load current of 10mA. This current will
go through the resistance R2 to set the overall output voltage. The current IADJ is very small and constant. Therefore its contribution to
the overall output voltage is very small and can generally be ignored
Load Regulation
Parasitic line resistance can degrade load regulation. In order not to affect the behavior of the regulator, it is best to connect directly
the R1 resistance from the resistor divider to the case, and not to the load. For the same reason, it is best to connect the resistor R2 to
the Negative side of the load.
RP Parasitic Line
Resistance
VIN
AS2870
Connect R 1 to
Case of Regulator
R1
RL
R2
Connect R 2 to Load
Fig.3 Basic Adjustable Regulator
Rev. 9/29/00
SIPEX [ SIPEX CORPORATION ]
