AD587
APPLICATIONS INFORMATION
+V
2
IN
USING THE AD587 WITH CONVERTERS
The AD587 is an ideal reference for a variety of 8-bit, 12-bit,
14-bit, and 16-bit ADCs and DACs. Several examples follow.
+V
IN
10V
V
OUT
6
I
=
+ I
BIAS
L
R
C
10 V Reference with Multiplying CMOS DACs or ADCs
R
500Ω
C
AD587
The AD587 is ideal for applications with 10-bit and 12-bit
multiplying CMOS DACs. In the standard hookup, shown in
Figure 18, the AD587 is paired with the AD7545 12-bit multi-
plying DAC and the AD711 high speed BiFET op amp. The
amplifier DAC configuration produces a unipolar 0 V to −10 V
output range. Bipolar output applications and other operating
details can be found in the individual product data sheets.
+15V
MIN
GND
4
Figure 20. Precision Current Source
Precision High Current Supply
For higher currents, the AD587 can easily be connected to a
power PNP or power Darlington PNP device. The circuits in
Figure 21 and Figure 22 can deliver up to 4 A to the load. The
0.1 μF capacitor is required only if the load has a significant
capacitive component. If the load is purely resistive, improved
high frequency supply rejection results can be obtained by
removing the capacitor.
+15V
R2
0.1µF
+15V
C1
33pF
0.1µF
+V
IN
V
R
FB
DD
AD587
OUT1
V
V
OUT
REF
V
AD711
OUT
AD7545
0V TO –10V
+V
10kΩ
TRIM
GND
AGND
DGND
IN
0.1µF
220Ω
DB11 TO DB0
–15V
2N6285
Figure 18. Low Power 12-Bit CMOS DAC Application
The AD587 can also be used as a precision reference for multi-
ple DACs. Figure 19 shows the AD587, the AD7628 dual DAC,
and the AD712 dual op amp hooked up for single-supply
operation to produce 0 V to −10 V outputs. Because both DACs
are on the same die and share a common reference and output
op amps, the DAC outputs will exhibit similar gain temperature
coefficients (TCs).
0.1µF
2
+V
IN
10V
V
6
OUT
I
=
L
+ I
BIAS
AD587
R
C
R
+15V
C
+15V
GND
4
0.1µF
+V
IN
RFB A
V
A
REF
OUT A
Figure 21. Precision High Current Source
V
OUT
DAC A
+V
IN
V
A =
OUT
0 TO –10V
AD587
AGND
RFB B
OUT B
DB0
DB7
DATA
GND
AD7628
AD712
INPUTS
220Ω
18
V
B
DAC B
DGND
2N6285
REF
V
B =
OUT
0 TO –10V
0.1µF
Figure 19. AD587 as a 10 V Reference for a CMOS Dual DAC
Precision Current Source
2
+V
IN
The design of the AD587 allows it to be easily configured as a cur-
rent source. By choosing the control resistor (RC) via the equation
shown in Figure 20, the user can vary the load current from the
quiescent current (2 mA typically) to approximately 10 mA.
V
OUT
+10V @ 4A
V
6
OUT
AD587
GND
4
Figure 22. Precision High Current Voltage Source
Rev. H | Page 10 of 12
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