AD565AJRZ 查看數據表（PDF） - Analog Devices
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AD565AJRZ Datasheet PDF : 12 Pages
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AD565A
CONNECTING THE AD565A FOR BUFFERED VOLTAGE
OUTPUT
The standard current-to-voltage conversion connections using an
operational amplifier are shown in Figures 1, 2, and 3 with the
preferred trimming techniques. If a low offset operational amplifier
(OP77, AD741L, OP07) is used, excellent performance can be
obtained in many situations without trimming (an op amp with
less than 0.5 mV max offset voltage should be used to keep offset
errors below 1/2 LSB). If a 50 Ω fixed resistor is substituted for
the 100 Ω trimmer, unipolar zero is typically within ± 1/2 LSB
(plus op amp offset) and full-scale accuracy is within 0.1%
(0.25% max). Substituting a 50 Ω resistor for the 100 Ω bipo-
lar offset trimmer gives a bipolar zero error typically within
± 2 LSB (0.05%).
The AD509 is recommended for buffered voltage-output
applications that require a settling time to ± 1/2 LSB of
1 μs. The feedback capacitor is shown with the optimum value
for each application; this capacitor is required to compen-
sate for the 25 pF DAC output capacitance.
FIGURE 1. UNIPOLAR CONFIGURATION
This configuration provides a unipolar 0 V to 10 V output
range. In this mode, the bipolar terminal, Pin 8, should be
grounded if not used for trimming.
R2
100⍀
REF
IN
REF
GND
REF
OUT
VCC
100k⍀
100⍀
BIPOLAR OFF
+15V
R1
50k⍀
–15V
5k⍀
9.95k⍀
10V
AD565A 5k⍀
19.95k⍀
20k⍀
0.5mA
IREF
POWER
GND
IO 8k⍀
DAC
IOUT =
4 ؋ IREF
؋ CODE
CODE
INPUT
20V SPAN
10V SPAN
DAC
OUT
10pF
AD509
OUTPUT
0V TO
+10V
2.4k⍀
–VEE
MSB
LSB
Figure 1. 0 V to 10 V Unipolar Voltage Output
R2
100⍀
REF
IN
REF
GND
R1
REF
OUT
VCC
100⍀
BIPOLAR OFF
5k⍀
9.95k⍀
10V
AD565A 5k⍀
19.95k⍀
20k⍀
0.5mA
IREF
POWER
GND
IO 8k⍀
DAC
IOUT =
4 ؋ IREF
؋ CODE
CODE
INPUT
20V SPAN
10V SPAN
DAC
OUT
10pF OUTPUT
–5V TO
+5V
AD509
2.4k⍀
–VEE
MSB
LSB
Figure 2. ±5 V Bipolar Voltage Output
STEP I . . . OFFSET ADJUST
Turn OFF all bits. Adjust 100 Ω trimmer R1 to give –5.000 V
output.
STEP II . . . GAIN ADJUST
Turn ON all bits. Adjust 100 Ω gain trimmer R2 to give a
reading of +4.9976 V.
Please note that it is not necessary to trim the op amp to obtain
full accuracy at room temperature. In most bipolar situations,
an op amp trim is unnecessary unless the untrimmed offset drift
of the op amp is excessive.
FIGURE 3. OTHER VOLTAGE RANGES
The AD565A can also be easily configured for a unipolar 0 V to
+5 V range or ± 2.5 V and ± 10 V bipolar ranges by using the
additional 5 kΩ application resistor provided at the 20 V span R
terminal, Pin 11. For a 5 V span (0 V to +5 V, or ± 2.5 V), the
two 5 kΩ resistors are used in parallel by shorting Pin 11 to Pin 9
and connecting Pin 10 to the op amp output and the bipolar
offset either to ground for unipolar or to REF OUT for the
bipolar offset either to ground for unipolar or to REF OUT for
the bipolar range. For the ± 10 V range (20 V span) use the 5 kΩ
resistors in series by connecting only Pin 11 to the op amp output
and the bipolar offset connected as shown. The ± 10 V option is
shown in Figure 3.
STEP I . . . ZERO ADJUST
Turn all bits OFF and adjust zero trimmer R1 until the output
reads 0.000 V (1 LSB = 2.44 mV). In most cases, this trim is not
needed, but Pin 8 should then be connected to Pin 12.
STEP II . . . GAIN ADJUST
Turn all bits ON and adjust 100 Ω gain trimmer R2 until the
output is 9.9976 V. (Full scale is adjusted to 1 LSB less than
nominal full scale of 10.000 V.) If a 10.2375 V full scale is desired
(exactly 2.5 mV/bit), insert a 120 Ω resistor in series with the gain
resistor at Pin 10 to the op amp output.
FIGURE 2. BIPOLAR CONFIGURATION
This configuration provides a bipolar output voltage from
–5.000 V to +4.9976 V, with positive full scale occurring with
all bits ON (all 1s).
R2
100⍀
REF
IN
REF
GND
R1
REF
OUT
VCC
100⍀
BIPOLAR OFF
20V SPAN
5k⍀
9.95k⍀
10V
AD565A 5k⍀
19.95k⍀
20k⍀
0.5mA
IREF
IO 8k⍀
DAC
IOUT =
4 ؋ IREF
؋ CODE
10V SPAN
DAC
OUT
10pF
AD509
OUTPUT
–10V TO
+10V
3.0k⍀
POWER
GND
CODE
INPUT
–VEE
MSB
LSB
Figure 3. ±10 V Voltage Output
–8–
REV.F
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