Understanding the Specifications–AD589
VOLTAGE VARIATION VS. TEMPERATURE
DYNAMIC PERFORMANCE
Some confusion exists in the area of defining and specifying
reference voltage error over temperature. Historically, references
have been characterized using a maximum deviation per degree
Centigrade; i.e., 10 ppm/°C. However, because of nonlinearities
in temperature characteristics, which originated in standard
Zener references (such as “S” type characteristics) most
manufacturers have begun to use a maximum limit error band
approach to specify devices. This technique involves measure-
ment of the output at 3, 5 or more different temperatures to
guarantee that the output voltage will fall within the given error
band. The temperature characteristics of the AD589 consis-
tently follows the curve shown in Figure 1. Three-point
measurement guarantees the error band over the specified
temperature range. The temperature coefficients specified on
the previous page represent the slopes of the diagonals of the
error band from +25°C to T
MIN
and +25°C to T
MAX
.
1.2370
Many low power instrument manufacturers are becoming
increasingly concerned with the turn-on characteristics of the
components being used in their systems. Fast turn-on compo-
nents often enable the end user to keep power off when not
needed, and yet respond quickly when the power is turned on
for operation. Figure 3 displays the turn-on characteristics of the
AD589. This characteristic is generated from cold-start opera-
tion and represents the true turn-on waveform after an extended
period with the supplies off. The figure shows both the coarse
and fine transient characteristics of the device; the total settling
time to within
±
1 millivolt is about 25
µs,
and there is no long
thermal tail appearing after that point.
200mV
100
90
10mV
10µs
1.2365
OUTPUT VOLTAGE – V
10
0%
1.2360
1.2355
+V
Figure 3. Output Settling Characteristics
1.2350
R1
Q5
R5
R6
1.2345
–50
–25
0
+25
+50
+75
+100
+125
Q8
R2
R7
Q3
R3
Q4
C1
Q9
TEMPERATURE – °C
Figure 1. Typical AD589 Temperature Characteristics
1000
Q1
R4
Q7
Q2
Hz
–V
NOISE SPECTRAL DENSITY – nV/
100
Figure 4. Schematic Diagram
10
0
10
100
1k
10k
FREQUENCY – Hz
100k
1M
Figure 2. Noise Spectral Density
REV.B
–3–
AD [ ANALOG DEVICES ]
