**PERFORMANCE OF THE AD590 TEMPERATURE TRANSDUCER AT LOW TEMPERATURE**

Test Report

Richard Patterson

NASA Glenn Research Center

&

Scott Gerber

ZIN Technologies

&

Ahmad Hammoud

QSS Group, Inc.

NASA Glenn Research Center

Cleveland, Ohio

August 10, 2001

**Performance Of The AD590 Temperature Transducer At Low Temperature**

**Device Description**

The AD590 is a two-terminal integrated circuit (voltage in/current out)
temperature transducer that produces an output current proportional to
absolute temperature. In addition to temperature measurement, this
device can be used in applications that include flow rate measurements,
correction of discrete components, temperature compensation, biasing
proportional to absolute temperature, level detection of fluids and
anemometry.

**Effort Objective**

Temperature transducers are commonly used in electronic systems in
almost all of NASA missions. The simple design of the AD590, which
requires no support circuitry, makes it particularly useful in remote
sensing applications \[1\]. Unlike other conventional transducers, the
AD590 does not require any linearization circuitry, precision voltage
amplifiers, resistance measurement circuit, or cold junction
compensation. Its simple design and high accuracy render it a good
candidate for use in many of NASA space exploration missions.

**Device Specifications**

The AD590 temperature transducer is made by Analog Devices, Inc. and
Harris Corporation. The device comes in different grades with ceramic
package or metal can options. The specifications of some of these
packages are listed in Table I.

Table I. Some of the manufacturer specifications of the devices tested
\[2,3\].

  ------------------------------- ------------- ------------- -------------
                                  **AD590LF**   **AD590JF**   **AD590JH**

  Input Voltage (V)               +4 to +30     +4 to +30     +4 to +30

  Linear Current Output (μA/K)    1             1             1

  Temperature Range (°C)          -55 to +150   -55 to +150   -55 to +150

  Maximum Nonlinearity (°C)       ±0.4          ±1.5          ±1.5

  Maximum Absolute Error (°C)     ±3            ±10           ±10

  Maximum Calibration Error       ±1            ±5            ±5
  \@R.T. (°C)                                                 

  Maximum Repeatability (°C)      ±0.1          ±0.1          ±0.1

  Package                         Ceramic       Ceramic       Metal
  ------------------------------- ------------- ------------- -------------

**Test Procedure**

Three different versions of the AD590 were evaluated in terms of output
response and linearity as a function of temperature. A total of 61
devices were characterized in the temperature range of 293K (+20 °C) to
80K (-193 °C). The data were initially gathered at room temperature,
then at successive test temperatures down to 80K, and again at room
temperature after low temperature was completed. At a given test
temperature, the device under test was allowed to soak for 20 minutes so
that thermal equilibrium was reached before any measurement was made. To
investigate the effect of low temperature exposure on the packaging,
devices with ceramic packaging and metal cans were used in this work.
Each device was characterized in its output current, which is
proportional to absolute temperature, as a function of temperature and
its input or supply voltage. After the last measurement was taken at the
lowest temperature, i.e. ‑190 °C, data was then obtained at room
temperature.

**Test Results**

A total of 61 devices were evaluated in this work. These comprised of
ceramic-packaged (LF and JF versions) and metal-canned (JH version)
units. While the first batch (six) of the LF‑series was about seven
years old, the rest of the devices (55) were recently acquired. An
overall summary on the performance of the devices tested is shown in
Table II.

Table II. Summary of performance of the various AD590 devices.

+------+-------+------+----------+-----------------------------------+
| **V  | *     | **Qu | **Manufa | **Performance with Temperature**  |
| ersi | *Pack | anti | cturer** |                                   |
| on** | age** | ty** |          |                                   |
+------+-------+------+----------+-----------------------------------+
| LF   | Ce    | 6    | Analog   | 5 devices showed good performance |
|      | ramic |      | Devices  | down to 90 - 80K                  |
|      |       |      |          |                                   |
|      |       |      | (old)    | 1 device had good performance     |
|      |       |      |          | down to only 144K                 |
+------+-------+------+----------+-----------------------------------+
|      |       | 6    | Analog   | 5 devices showed good performance |
|      |       |      | Devices  | down to 170 - 140K                |
|      |       |      |          |                                   |
|      |       |      |          | 1 device exhibited deviation in   |
|      |       |      |          | performance below 220K            |
+------+-------+------+----------+-----------------------------------+
| JF   | Ce    | 30   | Analog   | 9 devices exhibited good          |
|      | ramic |      | Devices  | performance down to 120 - 80K     |
|      |       |      |          |                                   |
|      |       |      |          | 19 devices showed good            |
|      |       |      |          | performance down to ∼130K         |
|      |       |      |          |                                   |
|      |       |      |          | 2 devices started to drift in     |
|      |       |      |          | performance below 170K            |
+------+-------+------+----------+-----------------------------------+
| JH   | Metal | 10   | Analog   | All devices performed well down   |
|      |       |      | Devices  | to only 120K                      |
+------+-------+------+----------+-----------------------------------+
|      |       | 9    | Harris   | All devices exhibited poor        |
|      |       |      |          | performance between 220-170K      |
+------+-------+------+----------+-----------------------------------+

It can be clearly seen from Table II that a wide variation in
performance was exhibited by the various versions of the AD590
temperature transducer. In fact, discrepancies in output behavior with
temperature were even observed for devices from the same series. For
example, the first batch (old six) of the ceramic LF-series exhibited,
in general, much better performance with temperature than those acquired
recently. It is not readily clear why such unexpected outcome is
observed. However, it can be postulated that different production lots
and possibly new manufacturing processes or design modifications might
have contributed to this behavior.

Most of the JF-series devices exhibited good performance down to about
140 to 130K. While nine of the remaining devices performed relatively
well with temperature down to about 120 to 80K, two devices exhibited
good operation only down to 170K. It is important to note that all of
the devices were able to generate some output beyond the aforementioned
good low temperature cut-offs. The produced output, however, did not
reflect an accurate representation of the temperature to be measured.

The metal-can packaged devices were obtained from two manufacturers. The
ten Analog Devices units displayed good and consistent behavior from
room temperature down to 120K. The Harris devices, nine of them,
however, exhibited behavior that was different from one device to
another from the same batch. While some of these devices operated quite
well down to 170K, others exhibited irregularity in their output at
temperatures as low as 220K.

A detailed listing of the devices tested along with their corresponding
good low temperature limit, below which deviation in the output was
observed, is given in Table III.

Table III. Approximate working low temperature of devices tested.

  -------------- ----------- ----------- ------------ ---------- -----------
  **Device       **Device    **Temp.     **Device     **Device   **Temp.
  Type**         #.**        (K)**       Type**       #.**       (K)**

  AD590LF(old)   1           80          AD590JF      4          123

                 2           80                       5          123

                 3           144                      6          102

                 29          80                       7          144

                 30          80                       8          144

                 31          90                       9          123

  AD590LF(new)   56          170                      32         100

                 57          220                      33         110

                 58          150                      34         170

                 59          140                      35         140

                 60          150                      36         130

                 61          140                      37         130

  AD590JH        10          120                      38         130

  Analog         11          120                      39         140

                 12          120                      40         80

                 13          120                      41         140

                 14          130                      42         130

                 15          120                      43         130

                 16          120                      44         130

                 17          120                      45         120

                 18          120                      46         130

                 19          120                      47         130

  AD590JH        20          220                      48         130

  Harris         21          220                      49         120

                 22          170                      50         170

                 23          220                      51         140

                 24          220                      52         130

                 25          170                      53         130

                 26          220                      54         140

                 27          170                      55         130

                 28          220                                 
  -------------- ----------- ----------- ------------ ---------- -----------

Graphical representations of the data obtained on each device are
followed in the same sequence as were presented in Table II. The
parameters depicted in each figure include the supply input voltage (a
test variable) and the specific test temperatures at which measurements
were made. The corresponding output current, which was measured at
various temperatures, is plotted along the coordinate. This measurement
can also be read as temperature in Kelvins since the AD590 temperature
transducer provides an output of 1μA/K.

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To illustrate the effect of low temperature exposure on the linearity of
these temperature transducers, data pertaining to six selected devices
are plotted in the following figures. The data shows the linearity
curves for devices 1 and 56 of the LF-series, 10 and 22 of the
JH-series, and 6 and 52 of the JF-series. For a given device, the figure
depicts the output current corresponding to a certain temperature at
various supply voltage levels. It can be clearly seen that all devices
exhibit some non-linearity as the temperature is decreased. These
effects become more apparent at extreme low temperatures and at high
supply voltage levels. The severity of these changes are, however,
dependent on the series-type of the device, its manufacturer as well as
production lot.

![](media/image12.emf){width="5.602083333333334in"
height="7.220833333333333in"}

**Conclusion**

Temperature transducers are widely used in electronic systems for remote
sensing applications. Design simplicity of the AD590 device, which does
not require any supporting circuitry, makes it an attractive candidate
for use in NASA missions. A large number of these devices were
investigated in this work for suitability for use in low temperature
environment. Ceramic-packaged and metal-canned devices, with different
accuracy ratings, were included in this investigation to determine if
the low temperature exposure has any effect on the packaging material of
these components.

Although these devices are rated for only -55 °C (218K), this effort was
undertaken to determine their operation limit at low temperature. All
devices exhibited variation in their operational behavior with
temperature. While some of these devices displayed good performance with
temperature all the way down to 80K (around liquid nitrogen
temperature), others started to deviate in their output response at
temperatures below 220K (manufacturer rating). It is important to note
that although the majority of the devices exhibited changes, with
varying degrees, in their output linearity with decreasing temperature,
none underwent any catastrophic failure due to exposure to the low
temperature environment. This is evident from the full recovery in
performance exhibited by all the devices tested upon their thermal
stabilization back to room temperature. As far as the packaging material
is concerned, the results of this preliminary work preclude any decisive
assessment of the effects induced by the low temperature exposure. More
comprehensive testing is, therefore, required to fully characterize the
behavior of these devices and to determine their suitability for use and
limitation in low temperature environments. Issues such as thermal
cycling, non-linearity, and low temperature operation capability need to
be addressed for designing efficient and reliable electronic systems for
space and terrestrial applications.

**Acknowledgment**

This work has been performed at the NASA Glenn Research Center under
SETAR and GESS Tasks. Support was also provided by the Jet Propulsion
Laboratory through the NASA Electronic Parts and Packaging (NEPP)
Program.

**References**

\[1\]. M. P. Timko, "A Two-Terminal IC Temperature Transducer", IEEE
Journal of solid-state circuits, Vol. SC-11, No. 6, December 1976.

\[2\]. Analog Devices, Inc. product data sheet.

\[3\]. Harris/Intersil Corporation product data sheet.