ADR380/ADR381
Rev. C | Page 13 of 16
PRECISION HIGH CURRENT VOLTAGE SOURCE
In some cases, the user may want higher output current delivered
to a load and still achieve better than 0.5% accuracy from the
ADR380/ADR381. The accuracy for a reference is normally
specified on the data sheet with no load. However, the output
voltage changes with load current.
The circuit in Figure 30 provides high current without compromis-
ing the accuracy of the ADR380/ADR381. By op amp action,
V
OUT
follows V
REF
with very low drop in R1. To maintain circuit
equilibrium, the op amp also drives the N-Channel MOSFET
Q1 into saturation to maintain the current needed at different
loads. R2 is optional to prevent oscillation at Q1. In such an
approach, hundreds of milliamps of load current can be achieved,
and the current is limited by the thermal limitation of Q1. V
IN
=
V
OUT
+ 300 mV.
GND
V
OUT
V
IN
3
V
OUT
21
8V TO 15V
R
L
IN
A1
–V
+V
AD820
U1
ADR380/
ADR381
Q1
2N7002
R2
100Ω
R1
100kΩ
C1
0.001µF
02175-030
Figure 30. ADR380/ADR381 for Precision High Current Voltage Source
