HTM2500LF – Temperature and Relative Humidity Module
HTM2500LF HPC169 Rev C www.meas-spec.com October 2012
1/9
•
Hermetic Housing
• Humidity calibrated within +/-2% @55%RH
• Temperature measurement through NTC
10kOhms +/-1% direct output
• Small size product
• Typical 1 to 4 Volt DC output for 0 to 100%RH
at 5Vdc
DESCRIPTION
Based on the rugged HTS2035SMD humidity / temperature sensor, HTM2500LF is a dedicated humidity and
temperature transducer designed for OEM applications where a reliable and accurate measurement is needed.
Direct interface with a micro-controller is made possible with the module’s humidity linear voltage output.
FEATURES
• Full interchangeability
• High reliability and long term stability
• Not affected by water immersion
• Ratiometric to voltage supply
• Suitable for 3 to 10 Vdc supply
voltage
Humidity Sensor Specific Features
• Instantaneous de-saturation after long periods in saturation
phase
• Fast response time
• High resistance to chemicals
• Patented solid polymer structure
Temperature Sensor Specific Features
• Stable
• High sensitivity
APPLICATIONS
•
Industrial
• Process control
• Hygrostat
• Data logger
…
HTM2500LF – Temperature and Relative Humidity Module
HTM2500LF HPC169 Rev C www.meas-spec.com October 2012
2/9
PERFORMANCE SPECS
MAXIMUM RATINGS
Ratings Symbol Value Unit
Storage Temperature
Tstg
-
40 to
8
5
°C
Storage Humidity
RHstg
0 to 100
% RH
Supply Voltage (Peak)
Vs
12
Vdc
Humidity Operating Range
RH
0 to 100
% RH
Temperature Operating Range
Ta
-
40 to
8
5
°C
Peak conditions: less than 10% of the operating time
ELECTRICAL CHARACTERISTICS
(Ta=23°C, Vs=5Vdc +/-5%, R
L
>1MΩ unless otherwise stated)
Humidity Characteristics Symbol Min Typ Max Unit
Humidity Measuring Range
RH
1
99
%RH
Relative Humidity Accuracy (10 to 95% RH)
RH
+/
-
3
+/
-
5
%RH
Supply Voltage
Vs
4.75
5.00
5.25
Vdc
Nominal Output @55%RH (at 5Vdc)
Vout
2.4
2
2.48
2.54
V
Current consumption
Ic
1.
0
1.
2
mA
Temperature Coefficient (10 to 50°C)
Tcc
+0.1
%RH/°C
Average Sensitivity from 33% to 75%RH
∆Vout/∆RH
+2
6
mV/%RH
Sink Current Capability (R
L
=15kΩ)
Is
300
µA
Recovery time after 150 hours of con
densation
tr
10
s
Humidity Hysteresis
+/
-
1.5
%RH
Long term stability
T
+/
-
0.5
%RH/yr
Time Constant (at 63% of signal, static) 33% to 76%RH
(1)
τ
5
s
Output Impedance
Z
70
Ω
(1) At 1m/s air flow
(Ta=25°C)
* For temperature upper than 60°C, specific high te mperature cable is required: HTM2500LFL products
Temperature Characteristics
Symbol
Min
Typ
Max
Unit
Nominal Resistance @25°C R 10 kΩ
Beta value: B25/50 β 3347 3380 3413 K
Temperature Measuring Range* Ta -40 85 °C
Nominal Resistance Tolerance @25°C R
N
1 %
Beta Value Tolerance β 1 %
Response Time τ 10 s
HTM2500LF – Temperature and Relative Humidity Module
HTM2500LF HPC169 Rev C www.meas-spec.com October 2012
3/9
TYPICAL PERFORMANCE CURVES
HUMIDITY SENSOR
• Typical response look-up table (Vs = 5V)
RH (%)
Vout (mV)
RH (%)
Vout (mV)
10 1235 55 2480
15 1390 60 2605
20 1540 65 2730
25 1685 70 2860
30 1825 75 2990
35 1960 80 3125
40 2090 85 3260
45 2220 90 3405
50 2350 95 3555
• Modeled linear voltage output (Vs = 5V)
• Linear Equations
Vout = 26.65 * RH + 1006
RH = 0.0375 * Vout – 37.7
with Vout in mV and RH in %
• Polynomial Equations
Vout = 1.05E
-3
*
RH
3
- 1.76E
-1
*
RH
2
+ 35.2 * RH + 898.6
RH = -1.92E
-9
*
Vout
3
+ 1.44E
-5
*
Vout
2
+ 3.4E
-3
*
Vout – 12.4
with Vout in mV and RH in %
• Measurement Conditions
HTM2500LF is specified for accurate measurements within 10 to 95% RH.
Excursion out of this range (<10% or >95% RH, including condensation) does not affect the reliability of
HTM2500LF characteristics.
1000
1500
2000
2500
3000
3500
4000
0 10 20 30 40 50 60 70 80 90 100
Relative Humidity (%RH)
Output Voltage (mV)
0
10
20
30
40
50
60
70
80
90
100
1000 1500 2000 2500 3000 3500 4000
Output Voltage (mV)
Relative Humidity (%RH)
HTM2500LF – Temperature and Relative Humidity Module
HTM2500LF HPC169 Rev C www.meas-spec.com October 2012
4/9
• Error Budget at 23°C
HTM2500LF Error Limits:
Temperature coefficient compensation:
HTM2500LF Linearity Error:
Non-linearity and temperature compensation:
with Vout in mV, RH in % and Ta in °C
( )
ET
a
out
V
E
out
V
E
Vout
E
RH
3
3
2
5
3
9
4.2231
4.12421.3437.19206.1
%
−
−−−
×−+
−++−
=
(
)
(
)
E
T
RH
RH
areadCor
3
4.2231%%
−
×−−×=
HTM2500LF – Temperature and Relative Humidity Module
HTM2500LF HPC169 Rev C www.meas-spec.com October 2012
5/9
HTM2500LF TEMPERATURE SENSOR: DIRECT NTC OUTPUT
• Typical temperature output
Depending on the needed temperature measurement range and associated accuracy, we suggest two methods
to access to the NTC resistance values.
R
T
NTC resistance in Ω at temperature T in K
R
N
NTC resistance in Ω at rated temperature T in K
T, T
N
Temperature in K
β Beta value, material specific constant of NTC
e Base of natural logarithm (e=2.71828)
The exponential relation only roughly describes the actual characteristic of an NTC thermistor can, however,
the material parameter β in reality also depend on temperature. So this approach is suitable for describing a
restricted range around the rated temperature or resistance with sufficient accuracy.
For practical applications, a more precise description of the real R/T curve may be required. Either more
complicated approaches (e.g. the Steinhart-Hart equation) are used or the resistance/temperature relation as
given in tabulation form. The below table has been experimentally determined with utmost accuracy for
temperature increments of 1 degree.
Actual values may also be influenced by inherent self-heating properties of NTCs. Please refer to MEAS-France
Application Note HPC106 “Low power NTC measurement”.
• Temperature look-up table
Temp (°C)
R (Ω)
Temp (°C)
R (Ω)
-40
195652
25
10000
-35
148171
30
8315
-30
113347
35
6948
-25
87559
40
5834
-20
68237
45
4917
-15
53650
50
4161
-10
42506
55
3535
-5
33892
60
3014
0
27219
65
2586
5
22021
70
2228
10
17926
75
1925
15
14674
80
1669
20
12081
85
1452
−
×=
N
TT
NT
eRR
11
β
HTM2500LF – Temperature and Relative Humidity Module
HTM2500LF HPC169 Rev C www.meas-spec.com October 2012
6/9
• Steinhart-Hart coefficients
According to the equation below, the Steinhart-Hart coefficients for the operating temperature range for
HTM2500LF thermistor are:
)ln(*)ln(*)ln(*)ln(*
1RRRCRba
T
++=
R
NTC resistance in Ω at temperature T in K
T Temperature in K
a Constant value (a = 8.54942E-04)
b Constant value (b = 2.57305E-04)
c Constant value (c = 1.65368E-07)
• Temperature Interface Circuit
Concerning the temperature sensor of the HTM2500LF, the following measuring method described below is
based on a voltage bridge divider circuit. It uses only one resistor component (Rbatch) at 1% to design
HTM2500LF temperature sensor interfacing circuit.
Rbatch is chosen to be equal to NTC @25°C to get: Vout = Vcc/2 @25°C.
The proposal method connects Rbatch to Vcc (5Vdc) and NTC to Ground. It leads to a negative slope
characteristic (Pull-Up Configuration).
Temp (°C) R (Ω)
Pull
-
up Configuration
Vout (mV)
-40
195652
4757
-30
113347
4595
-20
68237
4361
-10
42506
4048
0
27219
3657
10
17926
3210
20
12081
2736
25
10000
2500
30
8315
2270
40
5834
1842
50
4161
1469
60
3014
1158
70
2228
911
80
1669
715
W4
NTC Resistance output
HTM2500LF NTC
10kΩ @25°C
Vout (mV)
W2
VCC
Rbatch
10kΩ
W1
Ground
)()( )(*)(
)(
2500
2500
Ω+Ω
Ω
=
LFHTMbatch
LFHTM
OUT
NTCR NTCmVVcc
mVV
HTM2500LF – Temperature and Relative Humidity Module
HTM2500LF HPC169 Rev C www.meas-spec.com October 2012
7/9
SUGGESTED APPLICATION
QUALIFICATION PROCESS
RESISTANCE TO PHYSICAL AND CHEMICAL STRESSES
• HTM2500LF has passed through qualification processes of MEAS-France including vibration, shock,
storage, high temperature and humidity, ESD.
• Additional tests under harsh chemical conditions demonstrate good operation in presence of salt
atmosphere, SO2 (0.5%, H2S (0.5%), 03, NOx, NO, CO, CO2, Softener, Soap, Toluene, acids (H2SO4,
HNO3, HCI), HMDS, Insecticide, Cigarette smoke, this is not an exhaustive list.
• HTM2500LF is not light sensitive.
SPECIFIC PRECAUTIONS
• HTM2500LF is not protected against reversed polarity - Check carefully when connecting the device.
• If you wish to use HTM2500LF in a chemical atmosphere not listed above, consult us.
Steps of 1% RH are achievable by
using 8-bit A/D.
If more resolution is required, a 10-
bit A/D needs to be used and a third
display will be added, giving steps of
0.2% RH.
HTM2500LF – Temperature and Relative Humidity Module
HTM2500LF HPC169 Rev C www.meas-spec.com October 2012
8/9
PACKAGE OUTLINE
HTM2500LF weight: 17.5g
HTM2500LFL weight: 50g
HTM2500LF wire characteristics: AWG 24 for W1, W2, W3 and W4 / AWG 16 for W5
HTM2500LFL wire characteristics: AWG 24 for W1, W2, W3 and W4 / AWG 16 for W5
Dim Min (mm) Max (mm)
A 53 55
B 74.3 76.3
C 11.2 11.6
D*
(HTM2500LF) 200 250
D*
(HTM2500LFL) 1450 1550
*Specific length available on request
For operating temperature upper than 60°C, specific high temperature
cable is required
(1500mm long)
Wire Cable Color
HTM2500LF
Cable Color
HTM2500LFL Function
W1 Brown Black Ground
W2 White Orange Supply Voltage
W3 Yellow Yellow Humidity Voltage Output
W4 Green Purple Temperature Output
(NTC Direct)
W5 Black (thick) Black (thick) Shield
HTM2500LF – Temperature and Relative Humidity Module
HTM2500LF HPC169 Rev C www.meas-spec.com October 2012
9/9
ORDERING INFORMATION
HPP809A031 : HTM2500LF
HUMIDITY VOLTAGE OUTPUT + NTC (TEMPERATURE DIRECT OUTPUT)
HPP809A033 : HTM2500LFL
HUMIDITY VOLTAGE OUTPUT + NTC (TEMPERATURE DIRECT OUTPUT) WITH LONG CABLE
(MULTIPLE PACKAGE QUANTITY OF 10 PIECES)
Customer Service contact details
Measurement Specialties, Inc - MEAS France
Impasse Jeanne Benozzi
CS 83 163
31027 Toulouse Cedex 3
FRANCE
Tél: +33 (0)5 820 822 02
Fax: +33(0)5 820 821 51
Sales: humidity.sales@meas-spec.com
Revision Comments Who Date
0 Document creation D. LE GALL July 09
A Temperature operating range updated, HTM25X0LFL
references added D. LE GALL December 09
B New MEAS template, Temperature operating range
updated, RH polynomial equation modified, package
outline
paragraph updated
D. LE GALL January 12
C New combined RH/Temp sensor implemented,
HTM2530LF product reference deleted D. LE GALL October 12
The information in this sheet has been carefully reviewed and is believed to be accurate; however, no responsibility is assumed for
inaccuracies. Furthermore, this information does not convey to the purchaser of such devices any license under the patent rights to the
manufacturer. Measurement Specialties, Inc. reserves the right to make changes without further notice to any product herein. Measurement
Specialties, Inc. makes no warranty, representation or guarantee regarding the suitability of its product for any particular purpose, nor does
Measurement Specialties, Inc. assume any liability arising out of the application or use of any product or circuit and specifically disclaims
any and all liability, including without limitation consequential or incidental damages. Typical parameters can and do vary in different
applications. All operating parameters must be validated for each customer application by customer’s technical experts. Measurement
Specialties, Inc. does not convey any license under its patent rights nor the rights of others.
