OTP-538U

Thermopile Sensor

OTP-538U

Revision Date: 2009/04/16

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 & Air conditioner

Industry Application:Process monitor and controller, Infrared non-contact thermometers

Automobile Application:Thermal sensing system

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

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

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

Output Voltage 0.77 1.44 mV T amb.=25℃T obj. =50℃

Sensitivity 70 85 100 V/W * TC of sensitivity 0.10 0.11 0.12 %/K Typical Sensitivity area in

diameter

--- 545 --- μm

Resistance of thermopile 50 65 80 KΩ 25℃TC of resistance --- 0.09 --- %/K Typical

Time constant --- 16 --- ms *

Noise voltage 28 32 36 nV/Hz1/2

NEP 0.28 0.36 0.48 nW/Hz1/2

Normalized detectivity (D*) 1.0*108 1.3*108 1.7*108cm*Hz1/2/W* 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.

2.3 Signal Output Characteristics

Table 4: Typical numerical data of Thermopile’s output voltage (sensor at 25° C) Temp. (℃) V_out (mV) Temp. (℃) V_out (mV) -20 -1.29 50 1.02

-10 -1.06 60 1.49

0 -0.80 70 1.99

10 -0.51 80 2.52

20 -0.18 90 3.09

25 0.00 100 3.69

30 0.19 110 4.33

40 0.59 120 5.00

Note: Blackbody source size: 250 x 250mm

Distance from sensor to source: 110mm

2.4 Frequency Response

Figure 2: Frequency response

2.5 Thermistor Characteristics

Table 5: Thermistor information

Parameter Min Typ Max Unit Conditions

Resistance 97 100 103 KΩ 25℃

β value 3944 3964 3984 K 0℃/50℃

Table 6: Tabulated thermistor data

(K?)

(K?) Resistance Resistance

Temp.(o C) Min Center Max.Temp.(o C)Min Center Max.

-20 882.3 919.7 957.94542.6844.18 45.69

-15 668.9 696.3 724.25035.2336.50 37.78

-10 511.7 532.0 552.55529.2330.31 31.41

-5 394.8 409.8 425.16024.3625.29 26.23

0 307.0 318.3 329.86520.4121.20 22.01

5 240.5 249.1 257.77017.1717.85 18.55

10 189.8 196.3 202.97514.5115.10 15.70

15 150.7 155.7 160.78012.3112.82 13.34

20 120.5 124.4 128.38510.4810.93 11.38

25 97.0 100.0 103.0908.9609.347 9.742

30 78.32 80.83 83.34957.6858.023 8.369

35 63.61 65.72 67.83100 6.615 6.911 7.214

40 51.96 53.73 55.51105 5.712 5.972 6.238

2.6 Optical Characteristics

Table 7: Optical characteristics

Parameter

Min

Typ Max Unit Conditions Field of view

66

degree

At 50% target signal

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

μm

At 25℃,

50% transmittance

Figure 4: Typical spectral transmittance curve

2.8 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.