Datasheet

AD680
Rev. H | Page 8 of 12
00813-012
AD680
+V
IN
V
OUT
V
OUT
V
OUT
0V
V
L
249Ω
0.1μF
C
L
1000pF
Figure 12. Capacitive Load Transient Response Test Circuit
Figure 13 displays the output amplifier characteristics driving a
1,000 pF
, 0 mA to 10 mA load.
00813-013
V
OUT
V
L
100
90
0%
10
5μs5mV2V
Figure 13. Output Response with Capacitive Load
LOAD REGULATION
Figure 14 depicts the load regulation characteristics of
the AD680.
00813-014
V
OUT
V
L
100
90
0%
10
100μs1mV1V
Figure 14. Typical Load Regulation Characteristics
TEMPERATURE PERFORMANCE
The AD680 is designed for reference applications where tem-
perature performance is important. Extensive temperature
testing and characterization ensure that the device’s performance
is maintained over the specified temperature range.
Some confusion exists in the area of defining and specifying
r
eference voltage error over temperature. Historically, references
have been characterized using a maximum deviation per degree
centigrade, that is, ppm/°C. However, because of nonlinearities
in temperature characteristics that originated in standard Zener
references (such as “S” type characteristics), most manufac-
turers now use a maximum limit error band approach to specify
devices. This technique involves measuring the output at three
or more different temperatures to specify an output voltage
error band.
00813-015
2.501
2.500
2.498
TEMPERATURE (°C)
–50 6002040
2.499
–10–30 80 100
SLOPE = TC
=
V
MAX
– V
MIN
(T
MAX
– T
MIN
) × 2.5V × 10
–6
=
2.501 – 2.498
(85°C – (–40°C))
× 2.5V × 10
–6
= 9.6ppm/°C
VOLTS (V)
Figure 15. Typical AD680AN/AD680AR Temperature Drift
Figure 15 shows a typical output voltage drift for the AD680AN/
AD680AR and illustrates the test methodology. The box in
Figure 15 is bounded on the left and right sides by the operat-
in
g temperature extremes, and on the top and bottom by the
maximum and minimum output voltages measured over the
operating temperature range.
The maximum height of the box for the appropriate temperature
r
ange and device grade is shown in Table 4. Duplication of these
r
esults requires a combination of high accuracy and stable tem-
perature control in a test system. Evaluation of the AD680 will
produce a curve similar to that in
Figure 15, but output readings
co
uld vary depending upon the test equipment used.
Table 4. Maximum Output Change in mV
Maximum Output Change (mV)
Device Grade 0°C to 70°C −40°C to +85°C
AD680JN/AD680JR 4.375 Not applicable
AD680JT 5.250 Not applicable
AD680AN Not applicable 6.250