Datasheet

ADR1581
Rev. 0 | Page 7 of 12
OUTPUT VOLTAGE (V)
1.2488
1.2498
1.2500
1.2502
1.2504
1.2506
1.2508
1.2494
1.2496
1.2490
1.2492
V
MAX
V
MIN
SLOPE = TC =
(V
MAX
– V
O
)
(+85°C – +25°C) × 1.250V × 10
–6
SLOPE = TC =
(V
MIN
– V
O
)
(–40°C – +25°C) × 1.250V × 10
–6
V
O
–55 –35 –15 5 25 45 65 85 105 125
TEMPERATURE (°C)
06672-012
600
300
0
RESIDUAL DRIFT ERROR (ppm)
500
400
200
100
–55 –35 –15 5 25 45 65 85 105 125
TEMPERATURE (°C)
06672-013
Figure 12. Output Voltag
e vs. Temperature
Figure 13. Residual Drift Error
REVERSE VOLTAGE HYSTERESIS
For example, the ADR1581BRT initial tolerance is ±1.5 mV;
a ±50 ppm/°C temperature coefficient corresponds to an error
band of ±4.1 mV (50 × 10
−6
× 1.250 V × 65°C). Therefore, the
unit is guaranteed to be 1.250 V ± 5.6 mV over the operating
temperature range.
A major requirement for high performance industrial
eq
uipment 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 operating
at +85°C and the output voltage at +25°C after operating at −40°C.
Duplication of these results requires a combination of high
ac
curacy and stable temperature control in a test system. Evaluation
of the ADR1581 produces curves similar to those in
Figure 14 displays the hysteresis associated with the ADR1581.
This ch
aracteristic exists in all references and has been minimized
in the ADR1581.
Figure 4
a
nd Figure 12.
VOLTAGE OUTPUT NONLINEARITY VS.
TEMPERATURE
QUANTITY
0
15
20
25
30
35
40
5
10
HYSTERESIS VOLTAGE (µV)
–400 –300 –200 –100 0 100 200 300 400
06672-014
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. The usual way of showing the reference output drift is to
plot the reference voltage vs. temperature (see
Figure 12). An
al
ternative method is to draw a straight line between the
temperature endpoints and measure the deviation of the output
from the straight line. This shows the same data in a different
format. This characteristic (see
Figure 13) is generated by
n
ormalizing the measured drift characteristic to the endpoint
average drift. The residual drift error of approximately 500 ppm
shows that the ADR1581 is compatible with systems that require
10-bit accurate temperature performance.
Figure 14. Reverse Voltage Hyster
esis Distribution