Datasheet

AD680
Rev. H | Page 7 of 12
00813-007
500μV
100
90
0%
10
50μs500μV
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.
00813-008
V
IN
V
OUT
100
90
0%
10
10μs5V 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-
ac
teristics 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
c
apacitive in nature, or the load may be connected to the
AD680 by a long capacitive cable.
00813-009
AD680
+V
IN
V
OUT
V
OUT
V
OUT
0V
V
L
249Ω
0.1μF
Figure 9. Transient Load Test Circuit
00813-010
V
OUT
V
L
100
90
0%
10
5μs50mV2V
Figure 10. Large Scale Transient Response
00813-011
V
OUT
V
IN
100
90
0%
10
5μs5mV2V
Figure 11. Fine Scale Settling for Transient Load