AD669BR 데이터 시트보기 (PDF) - Analog Devices
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AD669BR Datasheet PDF : 12 Pages
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AD669
allows 5 V, 8.192 V and 10.24 V ranges to be used. For ex-
ample, by using the AD586 5 V reference, outputs of 0 V to
+5 V unipolar or ± 5 V bipolar can be realized. Using the
AD586 voltage reference makes it possible to operate the
AD669 off of ± 12 V supplies with 10% tolerances.
Figure 5 shows the AD669 using the AD586 5 V reference in
the bipolar configuration. This circuit includes two optional po-
tentiometers and one optional resistor that can be used to adjust
the gain, offset and bipolar zero errors in a manner similar to
that described in the BIPOLAR CONFIGURATION section.
Use –5.000000 V and +4.999847 as the output values.
2
+VCC
AD586
VOUT 6
GND
4
TRIM 5
50Ω
R1
100Ω
R2
10kΩ
(MSB)
DB15
7
6 CS
5 L1
(LSB)
DB0
22
SPAN/BIP 26
OFFSET
23 LDAC
25
27 REF IN
AD669
28 REF OUT
–VEE +VCC
1
2
+V LL
3
24
4
OUTPUT
GND
USING THE AD669 WITH THE AD688 HIGH PRECISION
VOLTAGE REFERENCE
The AD669 is specified for gain drift from 15 ppm/°C to
25 ppm/°C (depending upon grade) using its internal 10 volt
reference. Since the internal reference contributes the vast ma-
jority of this drift, an external high precision voltage reference
will greatly improve performance over temperature. As shown in
Figure 6, the +10 volt output from the AD688 is used as the
AD669 reference. With a 3 ppm/°C drift over the industrial
temperature range, the AD688 will improve the gain drift by a
factor of 5 to a factor of 8 (depending upon the grade of the
AD669 being used). Using this combination may result in ap-
parent increases in initial gain error due to the differences
between the internal reference by which the device is laser
trimmed and the external reference with which the device is ac-
tually applied. The AD669 internal reference is specified to be
10 volts ± 20 mV whereas the AD688 is specified as 10 volts
± 5 mV. This may result in an additional 5 mV (33 LSBs) of ap-
parent initial gain error beyond the specified AD669 gain error.
The circuit shown in Figure 6 also makes use of the –10 V
AD688 output to allow the unipolar offset and gain to be ad-
justed to zero in the manner described in the UNIPOLAR
CONFIGURATION section.
Figure 5. Using the AD669 with the AD586 5 V Reference
7
6
43
RS
A1
A3
R4 AD688
R1
R2
R5
A4
R6
R3
A2
5 9 10
8 12 11 13
1
R1
100Ω
14
15
2 +VCC
16 –VEE
CS 6
L1 5
LDAC 23
27
28
(MSB)
DB15
7
(LSB)
DB0
22
16-BIT LATCH
16-BIT LATCH
10k
16-BIT DAC
10V REF
AD669
1
-VEE
2
+VCC
3
+VLL
10k
10.05k
AMP
4
R3
20k
26
R2
100Ω
25
24
R4
10kΩ
OUTPUT
0 TO +10V
GND
Figure 6. Using the AD669 with the AD688 High Precision ±10 V Reference
REV. A
–7–
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