AD592CN Analog Devices Inc, AD592CN Datasheet - Page 5

• Manufacturer Part Number: AD592CN
• Description: IC TEMP TRANSDUCER 2-TERM TO92-3
• Manufacturer: Analog Devices Inc

Specifications of AD592CN

• Rohs Status: RoHS non-compliant
• Sensing Temperature: -25°C ~ 105°C
• Output Type: Current
• Voltage - Supply: 4 V ~ 30 V
• Accuracy: ±0.3°C
• Package / Case: TO-226-3, TO-92-3 (TO-226AA)
• Termination Type: Through Hole
• Mounting Type: Through Hole
• Operating Temperature Range: -25°C To +105°C
• Peak Reflow Compatible (260 C): No
• Ic Function: Temperature Sensor IC
• Leaded Process Compatible: No
• Temperature Sensor Function: Temp Sensor
• Package Type: TO-92
• Operating Temperature (min): -25C
• Operating Temperature Classification: Commercial
• Operating Supply Voltage (min): 4V
• Operating Supply Voltage (typ): 5/9/12/15/18/24V
• Operating Supply Voltage (max): 30V
• Lead Free Status / Rohs Status: Not Compliant

To trim the circuit the temperature must be measured by a ref-
erence sensor and the value of R should be adjusted so the out-
put (V
procedure should be implemented as close as possible to the
temperature highest accuracy is desired for. In most applications
if a single temperature trim is desired it can be implemented
where the AD592 current-to-output voltage conversion takes
place (e.g., output resistor, offset to an op amp). Figure 5 illus-
trates the effect on total error when using this technique.
If greater accuracy is desired, initial calibration and scale factor
errors can be removed by using the AD592 in the circuit of
Figure 6.
With the transducer at 0 C adjustment of R1 for a 0 V output
nulls the initial calibration error and shifts the output from K to
by adjusting R2 trims out scale factor error. The only error
remaining over the temperature range being trimmed for is
nonlinearity. A typical plot of two trim accuracy is given in
Figure 7.
REV. A
Figure 4. Basic Voltage Output (Single Temperature Trim)
C. Tweaking the gain of the circuit at an elevated temperature
Figure 5. Effect of Scale Factor Trim on Accuracy
AD1403
OUT
+1.0
+0.5
–0.5
–1.0
) corresponds to 1 mV/K. Note that the trim
Figure 6. Two Temperature Trim Circuit
0
–25
+5V
8.66k
100
7.87k
950
R
+V
AFTER SINGLE
TEMPERATURE
CALIBRATION
AD592
TEMPERATURE –
AD592
1k
R1
+25
V
V–
OUT
97.6k
WITHOUT TRIM
= 1mV/K
ACCURACY
o
C
AD741
5k
R2
V
OUT
= 100mV/
+105
o
C
–5–
SUPPLY VOLTAGE AND THERMAL ENVIRONMENT
EFFECTS
The power supply rejection characteristics of the AD592 mini-
mizes errors due to voltage irregularity, ripple and noise. If a
supply is used other than 5 V (used in factory trimming), the
power supply error can be removed with a single temperature
trim. The PTAT nature of the AD592 will remain unchanged.
The general insensitivity of the output allows the use of lower
cost unregulated supplies and means that a series resistance of
several hundred ohms (e.g., CMOS multiplexer, meter coil
resistance) will not degrade the overall performance.
The thermal environment in which the AD592 is used deter-
mines two performance traits: the effect of self-heating on accu-
racy and the response time of the sensor to rapid changes in
temperature. In the first case, a rise in the IC junction tempera-
ture above the ambient temperature is a function of two vari-
ables; the power consumption level of the circuit and the
thermal resistance between the chip and the ambient environ-
ment (
ing the power dissipation by
vary widely for surroundings with different heat sinking capaci-
ties it is necessary to specify
I shows how the magnitude of self-heating error varies relative
to the environment. In typical free air applications at +25 C
with a 5 V supply the magnitude of the error is 0.2 C or less. A
common clip-on heat sink will reduce the error by 25% or more
in critical high temperature, large supply voltage situations.
Medium
Still Air
Moving Air
Fluorinert Liquid
Aluminum Block**
NOTES
**With thermal grease.
* is an average of five time constants (99.3% of final value). In cases where the
thermal response is not a simple exponential function, the actual thermal re-
sponse may be better than indicated.
Without Heat Sink
With Heat Sink
Without Heat Sink
With Heat Sink
JA
+2.0
+1.0
–1.0
–2.0
). Self-heating error in C can be derived by multiply-
0
–25
Figure 7. Typical Two Trim Accuracy
Table I. Thermal Characteristics
0
TEMPERATURE –
+25
JA
JA
. Because errors of this type can
under several conditions. Table
175
130
60
40
35
30
JA
( C/watt)
o
C
+75
AD592
+105
60
55
12
10
5
2.4
(sec)*