THERMOPILE
OTP-538U
Thermopile Sensor
OTP-538U
Revision Date: 2009/09/09
Introduction
The OTP-538U is a thermopile sensor in classic TO-46 housing. The sensor is composed of 116
elements of thermocouple in series on a floating micro-membrane having an active diameter of 545
μm and with blacken surface to absorb the incident thermal infrared radiation, which induces a
voltage response at output terminals. The sensor chip is fabricated by a unique front-surface bulk
micromachining technology, which result in smaller size and faster to response ambient
temperature change.
The IR window is a bandpass filter having its 50% cut-on wavelength at 5 μm, and cut-down at
14μm. The sensor responses proportionally to the incident IR radiation and has a constant signal
response up to its cut-off frequency, which is limited by the sensor thermal time constant of tens
millisecond range.
The OTP-538U thermopile sensor provides nearly Johnson-noise-limited performance, which can
be calculated by its ohmic series resistance. A thermistor element, with a lead connected to
ground, is also provided inside the TO package for ambient temperature reference
.
Features
Non-contact temperature detection
Voltage output, easy to take signal
Zero power consumption
Wide detection temperature range
Applications
Medical Application: Ear thermometers
Home Facility: Microwave oven, Hair dryer, Safety system, Home security, Refrigerator & Air
conditioner
Industry Application: Process monitor and controller, Infrared non-contact thermometers
Automobile Application: Thermal sensing system
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THERMOPILE
Table of Contents
1 General Characteristics
1.1 Absolute Maximum Ratings
1.2 Handling Guidelines
2 Device Characteristics
2.1 Device Descriptions
2.2 Sensor Characteristics
2.3 Signal Output Characteristics
2.4 Frequency Response
2.5 Thermistor Characteristics
2.6 Optical Characteristics
2.7 Filter Characteristics
2.8 Mechanic Drawing and Pin Assignment
3 Liability Statement
OTP-538U
List of Figures
Figure 1: Typical output voltage versus object temperature with sensor at 25° C
Figure 2: Frequency response
Figure 3: Field of view curve
Figure 4: Typical spectral transmittance curve
Figure 5: Mechanical drawing and pin assignment
List of Tables
Table 1: Absolute maximum ratings
Table 2: Device characteristics
Table 3: Thermopile sensor characteristics
Table 4: Typical numerical data of Thermopile’s output voltage (sensor at 25° C)
Table 5: Thermistor information
Table 6: Tabulated thermistor data
Table 7: Optical characteristics
Table 8: Filter parameters
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THERMOPILE
OTP-538U
1. General Characteristics
1.1 Absolute Maximum Rating
Table 1: Absolute maximum rating
Parameter Min. Typ. Max. Unit
Ambient Operating Temperature -20 100
Storage Temperature -40 100
℃
℃
1.2 Handling Guidelines
Stresses above the absolute maximum ratings may cause damages to the device.
Do not expose the sensor to aggressive detergents such as Freon, Trichloroethylene, etc.
Avoid touching or cleaning of the window. If necessary, do cleaning only very carefully with alcohol and
cotton swab.
Hand soldering and wave soldering may be applied by a maximum temperature of 260° C for a dwell time
less than 10 s. Reflow soldering is not recommended.
2. Device Characteristics
2.1 Device Descriptions
The materials of OTP-538U are lead-free and fully complied with the RoHS regulations.
Table 2: Device characteristics
Parameter Description
Cap Metal cap with integrated IR window
Header TO 46
Leads (3 isolated + 1 ground) pins with solderable gold coating
Filter Si-based IR filter
Insulation gas sealing The sensor is sealed hermetically in a nitrogen environment.
2.2 Sensor Characteristics
Table 3: Thermopile sensor characteristics
Parameter Min Typ Max Unit Conditions
T
=25℃
Output Voltage 0.77 1.44 mV
Sensitivity 70 85 100 V/W *
T
amb.
=50℃
obj.
TC of sensitivity 0.10 0.11 0.12 %/K Typical
Sensitivity area in
diameter
Resistance of thermopile 50 65 80
TC of resistance --- 0.09 --- %/K Typical
Time constant --- 16 --- ms *
Noise voltage 28 32 36 nV/Hz
NEP 0.28 0.36 0.48 nW/Hz
Normalized detectivity (D*) 1.0*108 1.3*10
Notes: * All optical performances are measured at 1 Hz chopper frequency using a blackbody
radiator of 500K temperature with filtered spectrum ranging from 5 to 14μm.
Distance between packaged thermopile and blackbody is 11cm.
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--- 545 ---
8
1.7*108 cm*Hz
μm
KΩ 25℃
1/2
1/2
1/2
/W *
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9.03 厘米
2.3 Signal Output Characteristics
6.00
5.00
4.00
3.00
2.00
1.00
0.00
Thermopile Signal [mV]
-1.00
-2.00
-30 -20 -10 0 10 20 30 40 50 60 70 80 90 100 110 120 130
Object Temperature [℃]
OTP-538U
Figure 1: Typical output voltage versus object temperature with sensor at 25° C.
Table 4: Typical numerical data of Thermopile’s output voltage (sensor at 25° C)
Temp. (℃)
-20
-10
0
10
20
25
30
40
Note: Blackbody source size: 250 x 250mm
Distance from sensor to source: 110mm
V_out (mV)
-1.29
-1.06
-0.80
-0.51
-0.18
0.00
0.19
0.59
Temp. (℃)
50
60
70
80
90
100
110
120
V_out (mV)
1.02
1.49
1.99
2.52
3.09
3.69
4.33
5.00
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THERMOPILE
Frequency Response
2.4
OTP-538U
Figure 2: Frequency response
2.5 Thermistor Characteristics
Table 5: Thermistor information
Parameter Min Typ Max Unit Conditions
Resistance 97 100 103
β value
Table 6: Tabulated thermistor data
Resistance (KΩ) Resistance (KΩ)
Temp.(oC) Min Center Max. Temp.(oC) Min Center Max.
-20 882.3 919.7 957.9 45 42.68 44.18 45.69
-15 668.9 696.3 724.2 50 35.23 36.50 37.78
-10 511.7 532.0 552.5 55 29.23 30.31 31.41
-5 394.8 409.8 425.1 60 24.36 25.29 26.23
0 307.0 318.3 329.8 65 20.41 21.20 22.01
5 240.5 249.1 257.7 70 17.17 17.85 18.55
10 189.8 196.3 202.9 75 14.51 15.10 15.70
15 150.7 155.7 160.7 80 12.31 12.82 13.34
20 120.5 124.4 128.3 85 10.48 10.93 11.38
25 97.0 100.0 103.0 90 8.960 9.347 9.742
30 78.32 80.83 83.34 95 7.685 8.023 8.369
35 63.61 65.72 67.83 100 6.615 6.911 7.214
40 51.96 53.73 55.51 105 5.712 5.972 6.238
3944 3964 3984 K
KΩ 25℃
25℃/100℃
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2.6 Optical Characteristics
Table 7: Optical characteristics
Parameter Min Typ Max Unit Conditions
Field of view 66 degree At 50% target signal
OTP-538U
Figure 3: Field of view curve
2.7 Filter Characteristics
Table 8: Filter parameters
Parameter Min Typ Max Unit Conditions
Cut on wavelength 4.7 5.0 5.3
100
90
80
70
60
50
40
Transmittance (%)
30
20
10
0
μm
At 25℃,
50% transmittance
234567891011121314151617
Wavelength (um)
Figure 4: Typical spectral transmittance curve
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THERMOPILE
2.8 Mechanic Drawing and Pin Assignment
OTP-538U
Dimensions in mm
Figure 5: Mechanic drawing and pin assignment
3. Liability Statement
The contents of this document are subject to change without notice and customers should consult with
Oriental System Technology (OST) sales representatives before ordering. Customers considering the use of
OST thermopile devices in applications where failure may cause personal injury or property damage, or where
extremely high levels of reliability are demanded, are requested to discuss their concerns with OST sales
representatives before such use. The Company’s responsibility for damages will be limited to the repair or
replacement of defective product. As with any semiconductor device, thermopile sensors or modules have a
certain inherent rate of failure. To protect against injury, damage or loss from such failures, customers are
advised to incorporate appropriate safety design measures into their product.
Oriental System Technology Inc.
2F., No. 25 Industry E. Road 9th,
Hsinchu Science Park,
Hsinchu 30075, Taiwan
Tel: 886-3-5785177
Fax: 886-3-5787070
sales@orisystech.com
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