Datasheet AD708 (Analog Devices) - 10

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AD708 Data Sheet THEORY OF OPERATION CROSSTALK PERFORMANCE
The AD708 exhibits very low crosstalk as shown in Figure 25,
A VOUTA VIN = ±10V 2kΩ
Figure 26, and Figure 27. Figure 25 shows the offset voltage induced on Side B of the AD708 when Side A output is moving
10kΩ
slowly (0.2 Hz) from −10 V to +10 V under no load. This is the least stressful situation to the part because the overall power in
B VOUTB
the chip does not change. Only the location of the power in the
10Ω 10Ω
output device changes. Figure 26 shows the input offset voltage change to Side B when Side A is driving a 2 kΩ load. Here the power changes in the chip with the maximum power change
2V
occurring at 7.5 V. Figure 27 shows crosstalk under the most severe conditions. Side A is connected as a follower with 0 V input, and is forced to sink and source ±5 mA of output
V
current.
/DI V 1µ
Power = (30 V)(5 mA) = 150 mW
= SB
Even this large change in power causes only an 8 μV (linear)
V O Δ
change in the input offset voltage of Side B. 026
A VOUTA V
05789-
IN = ±10V VOUTA = 2V/DIV 10kΩ
Figure 26. Crosstalk with 2 kΩ Load
IIN = ±5mA B VOUTB A 2kΩ 10Ω 10Ω VIN = ±10V 10kΩ 2V B VOUTB 10Ω 10Ω V /DI V 2V 1µ = SB V O Δ V /DI V 2µ
025
= SB
05789-
V O V Δ OUTA = 2V/DIV
Figure 25. Crosstalk with No Load 027 05789-
INA = 1mA/DIV
Figure 27. Crosstalk Under Forced Source and Sink Conditions Rev. D | Page 10 of 16 Document Outline Features Pin Configuration General Description Product Highlights Revision History Specifications Absolute Maximum Ratings ESD Caution Typical Performance Characteristics Matching Characteristics Theory of Operation Crosstalk Performance Operation with a Gain of −100 High Precision Programmable Gain Amplifier Bridge Signal Conditioner Precision Absolute Value Circuit Selection of Passive Components Outline Dimensions Ordering Guide