VRE3021AD 데이터 시트보기 (PDF) - Thaler Corporation
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VRE3021AD Datasheet PDF : 8 Pages
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TEMPERATURE PERFORMANCE
The VRE3050 is designed for applications where the
initial error at room temperature and drift over
temperature are important to the user. For many
instrument manufacturers, a voltage reference with a
temperature coefficient less than 1ppm/°C makes it
possible to not perform a system temperature calibration,
a slow and costly process.
Of the three TC specification methods (slope, butterfly,
and box), the box method is most commonly used. A box
is formed by the min/max limits for the nominal output
voltage over the operating temperature range. The
equation follows:
( ) T
.C.
=
Vmax
Vnominal •
− Vmin
Tmax −
Tmin
• 106
THERMAL HYSTERISIS
A change in output voltage as a result of a temperature
change. When references experience a temperature
change and return to the initial temperature, they do not
always have the same initial voltage. Thermal hysterisis
is difficult to correct and is a major error source in
systems that experience temperature changes greater
than 25°C. Reference vendors are starting to include this
important specification in their datasheets.
This method corresponds more accurately to the
method of test and provides a closer estimate of actual
error than the other methods. The box method
guarantees limits for the temperature error but does not
specify the exact shape and slope of the device under
test.
A designer who needs a 14-bit accurate data
acquisition system over the industrial temperature range
(-40°C to +85°C), will need a voltage reference with a
temperature coefficient (TC) of 1.0ppm/°C if the reference
is allowed to contribute an error equivalent to 1LSB. For
1/2LSB equivalent error from the reference you would
need a voltage reference with a temperature coefficient of
0.5ppm/°C. Figure 4 shows the required reference TC vs.
delta T change from 25°C for resolution ranging from 8
bits to 20 bits.
10000
1000
ReferenceTC
(ppm/°C)
100
8 BIT
10
10 BIT
12 BIT
1
14 BIT
16 BIT
0.1
18 BIT
0.01
1
20 BIT
10
100
Reference TC vs. ∆T change from 25°C for 1 LSB change
VRE3050DS REV. D JULY 2000
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