AD1580 View Datasheet(PDF) - Analog Devices
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AD1580 Datasheet PDF : 12 Pages
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AD1580
designer can easily determine the maximum total error from
the initial tolerance plus temperature variation.
1.2258
1.2256
SLOPE = TC =
(VMAX – VO)
(+85°C – +25°C) × 1.225 × 10–6
1.2254
VMAX
1.2252
1.2250
VO
1.2248
1.2246
1.2244
1.2242
1.2240
1.2238
–55
SLOPE = TC =
(VMIN – VO)
(–40°C – +25°C) × 1.225 × 10–6
VMIN
–35 –15
5 25 45 65
TEMPERATURE (°C)
85 105 125
Figure 13. Output Voltage vs. Temperature
For example, the AD1580BRT initial tolerance is ±1 mV;
a ±50 ppm/°C temperature coefficient corresponds to an error
band of ±4 mV (50 × 10–6 × 1.225 V × 65°C). Thus, the unit is
guaranteed to be 1.225 V ± 5 mV over the operating
temperature range.
Duplication of these results requires a combination of high
accuracy and stable temperature control in a test system.
Evaluation of the AD1580 produces a curve similar to that in
Figure 5 and Figure 13.
VOLTAGE OUTPUT NONLINEARITY VS.
TEMPERATURE
When a reference is used with data converters, it is important to
understand how temperature drift affects the overall converter
performance. The nonlinearity of the reference output drift
represents additional error that is not easily calibrated out of the
system. This characteristic (see Figure 14) is generated by
normalizing the measured drift characteristic to the end point
average drift. The residual drift error of approximately 500 ppm
shows that the AD1580 is compatible with systems that require
10-bit accurate temperature performance.
600
500
REVERSE VOLTAGE HYSTERESIS
A major requirement for high performance industrial
equipment manufacturers is a consistent output voltage at
nominal temperature following operation over the operating
temperature range. This characteristic is generated by
measuring the difference between the output voltage at +25°C
after operation at +85°C and the output, at +25°C after
operation at −40°C. Figure 15 displays the hysteresis associated
with the AD1580. This characteristic exists in all references and
has been minimized in the AD1580.
40
35
30
25
20
15
10
5
0
–400 –300 –200 –100 0
100 200 300 400
HYSTERESIS VOLTAGE (µV)
Figure 15. Reverse Voltage Hysteresis Distribution
OUTPUT IMPEDANCE VS. FREQUENCY
Understanding the effect of the reverse dynamic output
impedance in a practical application may be important to
successfully apply the AD1580. A voltage divider is formed by
the AD1580 output impedance and the external source
impedance. When an external source resistor of about 30 kΩ
(IR = 100 μA) is used, 1% of the noise from a 100 kHz switching
power supply is developed at the output of the AD1580.
Figure 16 shows how a 1 μF load capacitor connected directly
across the AD1580 reduces the effect of power supply noise to
less than 0.01%.
1k
100
CL = 0
400
10
300
ΔIR = 0.1IR
IR = 100µA
1
CL = 1µF
200
IR = 1mA
100
0
–55 –35 –15 5
25 45 65 85
TEMPERATURE (°C)
Figure 14. Residual Drift Error
105 125
0.1
10
100
1k
10k
100k
1M
FREQUENCY (Hz)
Figure 16. Output Impedance vs. Frequency
Rev. C | Page 7 of 12
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