Datasheet

Data Sheet AD5781
Rev. D | Page 25 of 28
Gain of Two Configuration
Figure 52 shows an output amplifier configured for a gain of
two. The gain is set by the internal matched 6.8 kΩ resistors,
which are exactly twice the DAC resistance, having the effect
of removing an offset from the input bias current of the external
amplifier. In this configuration, the output spans from 2 × V
REFN
−
V
REFP
to V
RE F P.
This configuration is used to generate a bipolar
output span from a single-ended reference input, with V
REFN
=
0 V. For this mode of operation, the RBUF bit of the control
register must be cleared to Logic 0.
A1
6.8kΩ
6.8kΩ
R
1
R
FB
18-BIT
DAC
V
REFPS
V
REFPF
V
REF
P
V
REFN
= 0V
V
REFNS
AD5781
1/2
AD8676
1/2
AD8676
V
REFNF
R
FB
INV
V
OUT
09092-056
10pF
AD8675,
ADA4898-1,
ADA4004-1
V
OUT
Figure 52. Output Amplifier in Gain of Two Configuration