Datasheet

AD580
Rev. B | Page 6 of 8
The consistent voltage versus temperature performance of a
typical AD580 is shown in Figure 7. Note that the characteristic
is quasi-parabolic, not the possible S type characteristics of
classical Zener references. This parabolic characteristic permits
a maximum output deviation specification over the device’s full
operating temperature range, rather than just at 3 to 5 discrete
temperatures.
2.51
2.50
2.49
2.48
2.47
2.46
–55 –30 0 25 50 75 100 125
00525-B-007
TEMPERATURE (°C)
OUTPUT VOLTAGE (V)
MAXIMUM
VOLTAGE CHANGE
FROM 0°C TO 70°C
Figure 7. Typical AD580K Output Voltage vs. Temperature
The AD580M guarantees a maximum deviation of 1.75 mV
over the 0°C to 70°C temperature range. This can be shown to
be equivalent to 10 ppm/°C average maximum; i.e.,
averageCppm
V
C
m
V
max/10
5.2
1
70
ma
x
75.1
°=×
°
The AD580 typically exhibits a variation of 1.5 mV over the
power supply range of 7 V to 30 V. Figure 8 is a plot of AD580
line rejection versus frequency.
NOISE PERFORMANCE
Figure 9 represents the peak-to-peak noise of the AD580 from
1 Hz (3 dB point) to a 3 dB high end shown on the horizontal
axis. Peak-to-peak noise from 1 Hz to 1 MHz is approximately
600 µV.
140
130
0
10
20
30
40
50
60
70
80
90
100
110
120
10 100 1k 10k 100k
00525-B-008
LINE FREQUENCY (Hz)
E
OUT
, p-p (mV)
AD580
k e OUT p-p
e = 23V p-p
E = 18.5V
E IN COMPOSITE (17V
≤ V
IN
≤ 30V)
Figure 8. AD580 Line Rejection Plot
1mV
100µV
10µV
0
100 1k 10k 100k 1M
00525-B-009
FREQUENCY (Hz)
PEAK-TO-PEAK NOISE
Figure 9. Peak-to-Peak Output Noise vs. Frequency
00525-B-010
5V
500µA
Figure 10. Input Current vs. Input Voltage (Integral Loads)
THE AD580 AS A CURRENT LIMITER
The AD580 represents an excellent alternative to current limiter
diodes that require factory selection to achieve a desired
current. This approach often results in temperature coefficients
of 1%/C. The AD580 approach is not limited to a specially
selected factory set current limit; it can be programmed from
1 mA to 10 mA with the insertion of a single external resistor.
The approximate temperature coefficient of current limit for the
AD580 used in this mode is 0.13%/°C for I
LIM
= 1 mA and
0.01%/°C for I
LIM
= 13 mA (see Figure 11). Figure 10 displays
the high output impedance of the AD580 used as a current
limiter for I
LIM
= 1, 2, 3, 4, and 5 mA.
00525-B-011
BOTTOM VIEW OF
2.5V PRECISION
REFERENCE CIRCUIT
IN TO-52 CASE
AD580
V+
V–
OUTPUT
R
LOAD
2.5V
2.5V
R
i
≅ + 1mA
Figure 11. A Two-Component Precision Current Limiter