
AD588
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 the turn-on settling time. Two components
normally associated with this are the time for active circuits to
settle and the time for thermal gradients on the chip to stabilize.
Figure 9 and Figure 10 show the turn-on characteristics of the
AD588. The settling is about 600 μs. Note the absence of any
thermal tails when the horizontal scale is expanded to 2 ms/cm
+V S
Output turn-on time is modified when an external noise
reduction capacitor is used. When present, this capacitor
presents an additional load to the internal Zener diode current
source, resulting in a somewhat longer turn-on time. In the case
of a 1 μF capacitor, the initial turn-on time is approximately
60 ms (see Figure 11).
Note that if the noise reduction feature is used in the ±5 V
configuration, a 39 kΩ resistor between Pin 6 and Pin 2 is
required for proper startup.
+V S
–V S
V OUT
V OUT
+V S
V OUT
Figure 9. Electrical Turn-On
Figure 10. Extended Time Scale Turn-On
Figure 11. Turn-On with CN = 1 μF
TEMPERATURE PERFORMANCE
The AD588 is designed for precision reference applications where
temperature performance is critical. Extensive temperature testing
ensures that the device’s high level of performance is maintained
over the operating temperature range.
Figure 12 shows typical output temperature drift for the
AD588BQ and illustrates the test methodology. The box in
Figure 12 is bounded on the sides by the operating temperature
extremes and on top and bottom by the maximum and
minimum output voltages measured over the operating
temperature range. The slope of the diagonal drawn from the
lower left corner of the box determines the performance grade
of the device.
SLOPE = T.C. =
V MAX – V MIN
(T MAX – T MIN ) × 10 × 1 –4
10.0013V – 10.00025V
10.002
V MAX
10.001
V MIN
10.000
(85°C – –25°C) × 10 × 10 –4
= 0.95ppm/°C
–35 –15 5 25 45
65 85
TEMPERATURE (°C)
V MIN
V MAX
Figure 12. Typical AD588BQ Temperature Drift
Rev. L | Page 10 of 20