AD587

Rev. H | Page 7 of 12

TURN-ON TIME

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.

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.

100

10

0%

10V

1mV

90

20µs

Figure 7. Electrical Turn-On

100

90

10

0%

10V

1ms

20V

Figure 8. Extended Time Scale

100

90

10

0%

1V

100ms

10V

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.

Many ADCs and DACs present transient current loads to the

reference, and poor reference response can degrade the con-

verter’s performance.

Figure 11 and Figure 12 display the characteristics of the AD587

output amplifier driving a 0 mA to 10 mA load.

AD587

7.0V

1kΩ

10V

0V

Figure 10. Transient Load Test Circuit

100

90

10

0%

50mV

1µs

10V

Figure 11. Large-Scale Transient Response