AD580
1mV
100µV
10µV
0
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
MAXIMUM
VOLTAGE CHANGE
FROM 0°C TO 70°C
100
1k
10k
100k
1M
FREQUENCY (Hz)
Figure 9. Peak-to-Peak Output Noise vs. Frequency
–55
–30
0
25
50
75
100
125
TEMPERATURE (°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.,
500µA
1.75mV max
70°C
1
2.5V
5V
×
=10 ppm/ °C max average
Figure 10. Input Current vs. Input Voltage (Integral Loads)
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.
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 ILIM = 1 mA and
0.01%/°C for ILIM = 13 mA (see Figure 11). Figure 10 displays
the high output impedance of the AD580 used as a current
limiter for ILIM = 1, 2, 3, 4, and 5 mA.
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
e = 23V p-p
120
110
100
90
80
70
60
50
40
30
20
10
0
k
e OUT p-p
E = 18.5V
AD580
E IN COMPOSITE (17V
≤
V
≤
30V)
IN
V+
AD580
OUTPUT
2.5V
2.5V
R
i
≅
+ 1mA
R
LOAD
V–
BOTTOM VIEW OF
2.5V PRECISION
REFERENCE CIRCUIT
IN TO-52 CASE
10
100
1k
LINE FREQUENCY (Hz)
10k
100k
Figure 8. AD580 Line Rejection Plot
Figure 11. A Two-Component Precision Current Limiter
Rev. B | Page 6 of 8
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