AD589U AD [Analog Devices], AD589U Datasheet - Page 3

• Manufacturer Part Number: AD589U
• Description: Two-Terminal IC 1.2 V Reference
• Manufacturer: AD [Analog Devices]

VOLTAGE VARIATION VS. TEMPERATURE
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
REV.B
Figure 1. Typical AD589 Temperature Characteristics
1.2370
1.2365
1.2360
1.2355
1.2350
1.2345
1000
100
10
0
10
–50
Figure 2. Noise Spectral Density
–25
100
0
TEMPERATURE – °C
MIN
FREQUENCY – Hz
1k
+25
and +25 C to T
+50
10k
+75
100k
MAX
+100
.
+125
1M
Understanding the Specifications–AD589
–3–
DYNAMIC PERFORMANCE
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 s, and there is no long
thermal tail appearing after that point.
+V
–V
Figure 3. Output Settling Characteristics
Q1
R2
R3
R1
100
90
0%
10
Figure 4. Schematic Diagram
Q3
200mV
R4
Q5
R5
Q4
10mV
Q2
R7
10µs
C1
Q8
Q7
R6
Q9