AD587
TURN-ON TIME
100ms
10V
1V
Upon application of power (cold start), the time required for
the output voltage to reach its final value within a specified
error band is defined as the turn-on settling time. Two compo-
nents normally associated with this are the time for the active
circuits to settle and the time for the thermal gradients on the
chip to stabilize. Figure 7, Figure 8, and Figure 9 show the turn-
on characteristics of the AD587. These figures show the settling
to be about 60 μs to 0.01%. Note the absence of any thermal tails
when the horizontal scale is expanded to 1 ms/cm in Figure 8.
+V
IN
100
90
V
OUT
10
0%
Output turn-on time is modified when an external noise reduc-
tion capacitor is used. When present, this capacitor acts as an
additional load to the current source of the internal Zener
diode, resulting in a somewhat longer turn-on time. In the case
of a 1 μF capacitor, the initial turn-on time is approximately
400 ms to 0.01%, as shown in Figure 9.
Figure 9. Turn-On with 1 μF CN
DYNAMIC PERFORMANCE
The output buffer amplifier is designed to provide the AD587
with static and dynamic load regulation that is superior to less
complete references.
1mV
10V
Many ADCs and DACs present transient current loads to the
reference, and poor reference response can degrade the con-
verter’s performance.
+V
IN
100
90
Figure 11 and Figure 12 display the characteristics of the AD587
output amplifier driving a 0 mA to 10 mA load.
V
OUT
V
10
0%
OUT
7.0V
1kΩ
20µs
10V
0V
V
L
Figure 7. Electrical Turn-On
AD587
1ms
20V
10V
Figure 10. Transient Load Test Circuit
+V
IN
100
90
10V
50mV
1µs
V
V
100
90
L
OUT
V
OUT
10
0%
10
0%
Figure 8. Extended Time Scale
Figure 11. Large-Scale Transient Response
Rev. H | Page 7 of 12
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