AD586
22V TO 46V
2
5 V REFERENCE WITH MULTIPLYING
CMOS DACs OR ADCs
V
IN
The AD586 is ideal for applications with 10- and 12-bit
multiplying CMOS DACs. In the standard hookup, as shown
in Figure 20, the AD586 is paired with the AD7545 12-bit
multiplying DAC and the AD711 high speed BiFET op amp.
The amplifier DAC configuration produces a unipolar 0 V to
−5 V output range. Bipolar output applications and other
operating details can be found in the individual product data
sheets.
6
5
V
15V
OUT
TRIM
GND
AD586
10kΩ
4
2
V
IN
6
5
V
10V
5V
OUT
AD586
10kΩ
TRIM
R2
68Ω
+15V
+15V
GND
2
4
V
+15V
0.1µF
IN
2
C1
33pF
6
5
V
18
20
V
IN
OUT
TRIM
GND
AD586
R
V
FB
DD
AD586
10kΩ
7
1
2
2
OUT 1
6
5
19
V
V
REF
OUT
V
AD711K
4
6
OUT
0V TO–5V
4
3
10kΩ
AGND
TRIM
AD7545K
0.1µF
DGND
3
GND
4
Figure 22. Multiple AD586s Stacked for Precision 5 V, 10 V, and 15 V Outputs
DB11TODB0
–15V
PRECISION CURRENT SOURCE
Figure 20. Low Power 12-Bit CMOS DAC Application
The design of the AD586 allows it to be easily configured as a
current source. By choosing the control resistor RC in Figure 23,
the user can vary the load current from the quiescent current
(typically, 2 mA) to approximately 10 mA. The compliance volt-
age of this circuit varies from about 5 V to 21 V, depending on
the value of VIN.
The AD586 can also be used as a precision reference for multi-
ple DACs. Figure 21 shows the AD586, the AD7628 dual DAC,
and the AD712 dual op amp hooked up for single-supply opera-
tion to produce 0 V to −5 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 TCs.
+V
IN
+15V
+15V
2
2
17
3
V
IN
V
IN
RFB A
V
A
5V
REF
OUT A
6
I
=
+ I
BIAS
V
V
AD586
2
6
4
L
OUT
OUT
R
C
R
DAC A
C
V
A=
(500Ω MIN)
OUT
0TO–5V
GND
4
AD586
AGND
RFB B
14
7
1
DB0
DATA
INPUTS
GND
4
AD7628
AD712
DB7
19
20
OUT B
Figure 23. Precision Current Source
4
V
B
DAC B
REF
V
B=
OUT
0TO–5V
PRECISION HIGH CURRENT SUPPLY
DGND
5
For higher currents, the AD586 can easily be connected to a
power PNP or power Darlington PNP device. The circuit in
Figure 24 and Figure 25 can deliver up to 4 amps 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.
Figure 21. AD586 as a 5 V Reference for a CMOS
STACKED PRECISION REFERENCES FOR
MULTIPLE VOLTAGES
Often, a design requires several reference voltages. Three
AD586s can be stacked, as shown in Figure 22, to produce
5.000 V, 10.000 V, and 15.000 V outputs. This scheme can be
extended to any number of AD586s, provided the maximum
load current is not exceeded. This design provides the addi-
tional advantage of improved line regulation on the 5.0 V
output. Changes in VIN of 18 V to 50 V produce output changes
that are below the noise level of the references.
Rev. G | Page 11 of 16
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