AD822AR-REEL Analog Devices Inc, AD822AR-REEL Datasheet - Page 19
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AD822AR-REEL
Manufacturer Part Number
AD822AR-REEL
Description
IC,Operational Amplifier,DUAL,BIPOLAR/JFET,SOP,8PIN,PLASTIC
Manufacturer
Analog Devices Inc
Datasheet
1.AD822ARMZ-REEL.pdf
(24 pages)
Specifications of AD822AR-REEL
Rohs Status
RoHS non-compliant
Design Resources
16-Bit Fully Isolated 4 mA to 20 mA Output Module Using AD5662, ADuM1401, and External Amplifiers (CN0064)
Amplifier Type
General Purpose
Number Of Circuits
2
Output Type
Rail-to-Rail
Slew Rate
3 V/µs
Gain Bandwidth Product
1.9MHz
-3db Bandwidth
1.9MHz
Current - Input Bias
2pA
Voltage - Input Offset
400µV
Current - Supply
1.4mA
Current - Output / Channel
20mA
Voltage - Supply, Single/dual (±)
3 V ~ 36 V, ±1.5 V ~ 18 V
Operating Temperature
-40°C ~ 85°C
Mounting Type
Surface Mount
Package / Case
8-SOIC (3.9mm Width)
Lead Free Status / RoHS Status
Figure 45 is a plot of noise gain vs. capacitive load that results in
a 20° phase margin for the AD822. Noise gain is the inverse of
the feedback attenuation factor provided by the feedback
network in use.
100
0%
90
10
5
4
3
2
1
300
. . . .
. . . .
Figure 45. Noise Gain vs. Capacitive Load Tolerance
Figure 44. Small Signal Response of AD822 as
. . . .
. . . .
CAPACITIVE LOAD FOR 20° PHASE MARGIN (pF)
20mV
Unity-Gain Follower Driving 350 pF
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
1k
R1
R
F
3k
2µs
10k
C
L
30k
Rev. I | Page 19 of 24
Figure 46 shows a method for extending capacitance load drive
capability for a unity-gain follower. With these component
values, the circuit drives 5000 pF with a 10% overshoot.
SINGLE-SUPPLY VOLTAGE-TO-FREQUENCY
CONVERTER
The circuit shown in Figure 47 uses the AD822 to drive a low
power timer that produces a stable pulse of width t
going output pulse is integrated by R1 and C1 and used as one
input to the AD822 that is connected as a differential integrator.
The other input (nonloading) is the unknown voltage, V
AD822 output drives the timer trigger input, closing the overall
feedback loop.
Typical AD822 bias currents of 2 pA allow MΩ range source
impedances with negligible dc errors. Linearity errors on the
order of 0.01% full scale can be achieved with this circuit. This
performance is obtained with a 5 V single supply that delivers
less than 1 mA to the entire circuit.
FULL SCALE
C5
0.1µF
Figure 46. Extending Unity-Gain Follower Capacitive Load Capability
0V TO 2.5V
V
3
IN
V
IN
10V
4
2
Figure 47. Single-Supply Voltage-to-Frequency Converter
499kΩ
5
0.01µF
6
499kΩ
R1
1%
V
REF
REF02
2%
1%
C2
R2
U4
R
10kΩ
= 5V
SCALE
+
–
20kΩ
AD822
1/2
+
AD822B
–
8
4
V+
V–
U1
NOTES
1. f
2. R3 = 1% METAL FILM <50ppm/°C TC.
3. R
4. t
1/2
OUT
1
SCALE
0.01µF
CMOS
74HCO4
4
= 33µF FOR f
0.01µF
0.01µF, 2%
20pF
Beyond 350 pF
U3B
= V
= 25kHz
C1
= 10% 20T FILM <100ppm/°C TC.
IN /
3
(V
REF ×
116kΩ
f
S
U3A
2
OUT
100Ω
AS SHOWN.
R3
t
1
= 20kHz @ V
), t
6
2
7
1
1
= 1.1
THR
DIS
TR
R
4
U2
CMOS 555
GND
×
R3
1
C
IN
OUT
V+
L
CV
×
1
8
= 2.0V.
C3
0.1 µF
. The positive
C6.
3
5
V
OUT
AD822
C4
0.01µF
IN
OUT2
OUT1
. The