Data Sheet
AD588
In some applications, a varying load can be both resistive and
DYNAMIC PERFORMANCE
capacitive in nature or can be connected to the AD588 by a long
capacitive cable. Figure 25 and Figure 26 display the output
amplifier characteristics driving a 1000 pF, 0 mA to 10 mA load.
The output buffer amplifiers (A3 and A4) are designed to
provide the AD588 with static and dynamic load regulation
superior to less complete references. Many analog-to-digital and
digital-to-analog converters present transient current loads to
the reference, and poor reference response can degrade converter
performance. Figure 21 and Figure 22 display the characteristics
of the AD588 output amplifier driving a 0 mA to 10 mA load.
A3 OR A4
V
OUT
C
L
1kΩ
10V
1000pF
10V
V
L
0V
A3 OR A4
Figure 25. Capacitive Load Transient Response Test Circuit
V
OUT
I
1kΩ
10V
L
L
10V
V
0V
Figure 21. Transient Load Test Circuit
C
= 0
L
C
= 1000pF
L
V
L
V
OUT
Figure 26. Output Response with Capacitive Load
V
L
Figure 27 and Figure 28 display the crosstalk between output
amplifiers. The top trace shows the output of A4, dc-coupled
and offset by 10 V, while the output of A3 is subjected to a 0 mA
to 10 mA load current step. The transient at A4 settles in about
1 μs, and the load-induced offset is about 100 μV.
Figure 22. Large-Scale Transient Response
Figure 23 and Figure 24 display the output amplifier
characteristics driving a 5 mA to 10 mA load, a common
situation found when the reference is shared among multiple
converters or is used to provide a bipolar offset current.
A4
V
OUT
A3
1kΩ
10V
+
+
A3 OR A4
10V
–
10V
–
V
L
0V
V
OUT
I
2kΩ
10V
2kΩ
L
L
Figure 27. Load Crosstalk Test Circuit
+
10V
–
V
0V
Figure 23. Transient and Constant Load Test Circuit
V
OUT
1mV/CM
V
OUT
V
OUT
200mV/CM
V
L
Figure 28. Load Crosstalk
V
L
Figure 24. Transient Response 5 mA to10 mA Load
Rev. M | Page 13 of 20
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