5962-8958101PA Datasheet, PDF (17/20 Pages) Analog Devices – Precision 2.5 V, 5.0 V, and 10.0 V Voltage References

BIPOLAR VOLTAGE REFERENCE
Many applications require both a positive and reference voltage
of the same magnitude. A simple method of generating such a
bipolar reference is shown in Figure 42.
V+
U1 2
V_IN
6
V_OUT
REF03
100kΩ
+2.5V
GND
4
100kΩ
U2
2
7
OP97 ⁶
3
4
–2.5V
V–
Figure 42. Bipolar Voltage Reference
In this configuration, the negative rail is generated simply
with an inverting amplifier with a gain of −1. A low offset
op amp should be used to minimize the voltage error at the
negative output.
REF01/REF02/REF03
ADJUSTABLE REFERENCE WITH POSITIVE AND
NEGATIVE SWING
The output voltage of the REF0x references can be readily
adjusted via a simple trim circuit (explained in the Output
Adjustment section). The circuit shown in Figure 43 extends
the negative range of adjustment beyond that obtainable with
the simple trim circuit by employing a precision op amp with
a potentiometer feeding the op amp’s noninverting input.
V+
U1 2
V_IN
6
V_OUT
REF03
50kΩ
GND
4
50kΩ
50kΩ
2
+15V
7
OP97 ⁶
3
U2
4
V+
V_OUT
–2.5V TO +2.5V
Figure 43. Negatively Adjustable Reference
The voltage output from the op amp can be adjusted by
changing the value of the potentiometer: as shown, the op
amp outputs +2.5 V when the pot is pulled completely high,
and −2.5V when pulled completely low. In this configuration,
the load current is sourced by the op amp; therefore, a low
offset op amp with a current rating that meets or exceeds the
current requirements of the load should be used.
Rev. K | Page 17 of 20