Semiconductor Overview

The most linear temperature sensors for commercial HVAC applications

Semiconductor Description

BAPI semiconductors are designed to exhibit a defined current output directly proportional to the absolute temperature (°K). This property makes them the most linear of all the common commercial HVAC sensing elements. By putting this current output across a resistor, a proportional output voltage is produced.

The AD592 semiconductor temperature sensor supplied with BAPI products provides a two wire 248 to 378 micro amp output or a three wire 2.48 to 3.78 volt output over a range of -13 to 221 °F (-25 to 105 °C). These units are offset using equipment traceable to the National Institute of Standards and Technology (NIST). Each unit is then labeled with the actual temperature and the corresponding offset.

Definition of Specification Terms

Interchangeability Tolerance (Accuracy)

The maximum amount that sensors following the same curve will differ from each other.

Repeatability

A measure of a sensor's ability to repeat the same output value for a given input value.

Custom Offset Definition and Example

This is how BAPI calculates the offset value provided on the sensor label:

Therm Reading

The actual temperature reading according to a thermometer that is certified traceable to recognized standards by the National Institute of Standards and Technology (NIST).

Sensor Reading

The temperature reading according to the AD592 sensor, using the output in either µA or mV and converting the output to a Fahrenheit temperature.

Offset

The difference between the Thermometer Reading and the Sensor Reading

To maximize the sensor accuracy, simply add the offset value of the sensor reading into the controller.

e.g. Therm Reading 74.6Sensor Reading 73.0Offset +1.6

Correction: Add (+1.6) °F to the sensor for an accurate reading: 73 + 1.6 = 74.6°F

e.g. Therm Reading 75.4Sensor Reading 77.2Offset -1.8

Correction: Add (-1.8) °F to the sensor for an accurate reading: 77.2 + (-1.8) = 75.4°F

Semiconductor Specifications

Interchangeability Tolerance (Accuracy)

Offset to 0.1 °C (0.18 °F)

NIST Traceable

Offset Requirement

Required to achieve maximum accuracy. Each sensor includes a custom offset listed on each sensor.

Repeatability

± 0.10 °C (± 0.18°F)

Linearity

± 0.15 °C max

from 0 to 70 °C (32 to 158°F)

Sensor Range

-25 to 105 °C

(-13 to 221 °F) [248 to 378 °K]

Bias Voltage

5 to 30 VDC

Accuracy Reference

298.2 mA @ 25°C or 2.982 V @ 25°C

Temperature Output Coefficient

2 wire: 1 µA/°C (0.556 µA/°F) [1 µA/°K]
3 wire: 10 mV/°C (5.556 mV/°F) [10 mV/°K]

Typical Semiconductor Output Curve

Typical Semiconductor Output showing Current (µA) and Voltage (V) vs Temperature

Figure 1 - Typical Semiconductor Temperature Output

Semiconductor Output Tables

AD592 Standard Semiconductor Output Table

Standard AD592 current (µA) and voltage (V) output vs temperature

°F	°C	µA	Volts
-40	-40	233.2	2.332
-38	-38.89	234.311	2.343
-36	-37.78	235.42	2.354
-34	-36.67	236.53	2.365
-32	-35.56	237.646	2.376
-30	-34.44	238.76	2.388
-28	-33.33	239.87	2.399
-26	-32.22	241.98	2.41
-24	-31.11	242.09	2.421
-22	-30	243.2	2.432
-20	-28.89	244.31	2.443
-18	-27.78	245.42	2.454
-16	-26.67	246.53	2.465
-14	-25.56	247.64	2.476
-12	-24.44	248.76	2.488
-10	-23.33	249.87	2.499
-8	-22.22	250.98	2.51
-6	-21.11	252.09	2.521
-4	-20	253.2	2.532
-2	-18.89	254.31	2.543
0	-17.78	255.42	2.554
2	-16.67	256.53	2.565
4	-15.56	257.64	2.576
6	-14.44	258.76	2.588
8	-13.33	259.87	2.599
10	-12.22	260.98	2.61
12	-11.11	262.09	2.621
14	-10	263.2	2.632
16	-8.89	264.31	2.643
18	-7.78	265.42	2.654
20	-6.67	266.53	2.665
22	-5.56	267.64	2.676
24	-4.44	268.76	2.688
26	-3.33	269.87	2.699
28	-2.22	270.98	2.71
30	-1.11	272.09	2.721
32	0	273.2	2.732
34	1.11	274.31	2.743

°F	°C	µA	Volts
36	2.22	275.42	2.754
38	3.33	276.53	2.765
40	4.44	277.64	2.776
42	5.56	278.76	2.788
44	6.67	279.87	2.799
46	7.78	280.98	2.81
48	8.89	282.09	2.821
50	10	283.2	2.832
52	11.11	284.31	2.843
54	12.22	285.42	2.854
56	13.33	286.53	2.865
58	14.44	287.64	2.876
60	15.56	288.75	2.888
62	16.67	289.87	2.899
64	17.78	290.98	2.91
66	18.89	292.09	2.921
68	20	293.2	2.932
70	21.11	294.31	2.943
72	22.22	295.42	2.954
74	23.33	296.53	2.965
76	24.44	297.64	2.976
78	25.56	298.76	2.988
80	26.67	299.87	2.999
82	27.78	300.98	3.01
84	28.89	302.09	3.021
86	30	303.2	3.032
88	31.11	304.31	3.043
90	32.22	305.42	3.054
92	33.33	306.53	3.065
94	34.44	307.64	3.076
96	35.56	308.76	3.088
98	36.67	309.87	3.099
100	37.78	310.98	3.11
102	38.89	312.09	3.121
104	40	313.2	3.132
106	41.11	314.31	3.143
108	42.22	315.42	3.154
110	43.33	316.53	3.165

°F	°C	µA	Volts
112	44.44	317.64	3.176
114	45.56	318.76	3.188
116	46.67	319.87	3.199
118	47.78	320.98	3.21
120	48.89	322.09	3.221
122	50	323.2	3.232
124	51.11	324.31	3.243
126	52.22	325.42	3.254
128	53.33	326.53	3.265
130	54.44	327.64	3.276
132	55.56	328.76	3.288
134	56.67	329.87	3.299
136	57.78	330.98	3.31
138	58.89	332.09	3.321
140	60	333.2	3.332
142	61.11	334.31	3.343
144	62.22	335.42	3.354
146	63.33	336.53	3.365
148	64.44	337.64	3.376
150	65.56	338.76	3.388
152	66.67	339.87	3.399
154	67.78	340.98	3.41
156	68.89	342.09	3.421
158	70	343.2	3.432
160	71.11	344.31	3.443
162	72.22	345.42	3.454
164	73.33	346.53	3.465
166	74.44	347.64	3.476
168	75.56	348.76	3.488
170	76.67	349.87	3.499
172	77.78	350.98	3.51
174	78.89	352.09	3.521
176	80	353.2	3.532
178	81.11	354.31	3.543
180	82.22	355.42	3.554
182	83.33	356.53	3.565
184	84.44	357.64	3.576
186	85.56	358.76	3.588

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