AD586

Rev. G | Page 8 of 16

50

µS

200

µV

Figure 8. Effect of 1 µF Noise Reduction Capacitor on Broadband Noise

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 9, Figure 10, and Figure 11 show the

turn-on characteristics of the AD586. It shows the settling to be

about 60 µs to 0.01%. Note the absence of any thermal tails

when the horizontal scale is expanded to l ms/cm in Figure 10.

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% (see Figure 11).

10V

1mV

20

µS

Figure 9. Electrical Turn-On

10V

5V

1mS

Figure 10. Extended Time Scale

10V

1mV

100mS

DYNAMIC PERFORMANCE

The output buffer amplifier is designed to provide the AD586

with static and dynamic load regulation superior to less com-

plete references.

Many ADCs and DACs present transient current loads to the

reference, and poor reference response can degrade the per-

formance of the converter.

Figure 12, Figure 13, and Figure 14 display the characteristics of

the AD586 output amplifier driving a 0 mA to 10 mA load.

AD586

5V

0V

500

Ω

3.5V

Figure 12. Transient Load Test Circuit