AD680

Rev. H | Page 7 of 12

500

μV

100

90

0%

10

50

μs

500

μV

Figure 7. Broadband Noise at 300 kHz

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 components

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. The turn-on settling time of the AD680 is about 20 μs

to within 0.025% of its final value, as shown in Figure 8.

100

90

0%

10

10

μs

5V

1mV

Figure 8. Turn-On Settling Time

The AD680 thermal settling characteristic benefits from its

compact design. Once initial turn-on is achieved, the output

linearly approaches its final value; the output is typically within

0.01% of its final value after 25 ms.

DYNAMIC PERFORMANCE

The output stage of the amplifier is designed to provide the

AD680 with static and dynamic load regulation superior to

less complete references. Figure 9 to Figure 11 display the char-

acteristics of the AD680 output amplifier driving a 0 mA to

10 mA load. Longer settling times result if the reference is

forced to sink any transient current.

In some applications, a varying load may be both resistive and

capacitive in nature, or the load may be connected to the

AD680 by a long capacitive cable.

AD680

0V

249

Ω

0.1

μF

Figure 9. Transient Load Test Circuit

100

90

0%

10

5

μs

50mV

2V

Figure 10. Large Scale Transient Response

100

90

0%

10

5

μs

5mV

2V

Figure 11. Fine Scale Settling for Transient Load