AD587
ΔV
(µV)
OUT
10V
1mV
2µs
1000
V
L
100
90
500
2
LOAD (mA)
4
6
8
10
–6
–4
–2
0
V
OUT
–500
–1000
10
0%
Figure 15. Typical Load Regulation Characteristics
Figure 12. Fine-Scale Setting for Transient Load
TEMPERATURE PERFORMANCE
In some applications, a varying load may be both resistive and
capacitive in nature, or the load may be connected to the
AD587 by a long capacitive cable.
The AD587 is designed for precision reference applications
where temperature performance is critical. Extensive tempera-
ture testing ensures that the device’s high level of performance is
maintained over the operating temperature range.
Figure 14 displays the output amplifier characteristics driving a
1000 pF, 0 mA to 10 mA load.
Some confusion exists in the area of defining and specifying
reference voltage error over temperature. Historically, references
have been characterized using a maximum deviation per degree
Celsius, such as ppm/°C. However, because of nonlinearities in
temperature characteristics that originated in standard Zener
references (such as S-type characteristics), most manufacturers
have begun to use a maximum limit error-band approach to
specify devices. This technique involves the measurement of the
output at three or more temperatures to specify an output
voltage error band.
V
OUT
C
L
7.0V
1000pF
1kΩ
10V
0V
V
L
AD587
Figure 13. Capacitive Load Transient/Response Test Circuit
10V
200mV
1µs
C
= 0
L
100
90
10
0%
C
= 1000pF
L
V
L
Figure 14. Output Response with Capacitive Load
LOAD REGULATION
The AD587 has excellent load regulation characteristics.
Figure 15 shows that varying the load several milliamperes
changes the output by only a few microvolts.
Rev. H | Page 8 of 12
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