HTM25X0LF Measurement Specialties, HTM25X0LF Datasheet - Page 7

• Manufacturer Part Number: HTM25X0LF
• Description: Temperature And Relative Humidity Module
• Manufacturer: Measurement Specialties

HTM25X0LF – Temperature and Relative Humidity Module
HTM2530LF TEMPERATURE SENSOR: VOLTAGE OUTPUT
Concerning the temperature sensor of the HTM2530LF, it is built as the HTM2500LF temperature sensor
interface circuit. The voltage bridge divider circuit is internal. It uses only one resistor component (Rbatch) at 1%
to design HTM2530LF temperature sensor interfacing circuit.
Rbatch is chosen to be equal to NTC @25°C to get: Vout = Vcc/2 @25°C.
The difference is based on internal connections: Rbatch connected to Ground and NTC to Vcc (5Vdc). It leads
to a positive slope characteristic (Pull-Down Configuration).
SUGGESTED APPLICATION
HTM25X0LF HPC169 Rev 0
Rbatch
10kΩ
VCC
HTM2530LF NTC
10kΩ @25°C
Processing
Interface
Internal Circuit
W4 Temperature
Output Voltage
W1 Ground
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Temp (°C)
-20
-10
10
20
25
30
40
50
60
70
0
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.
68237
42506
27219
17926
12081
10000
R (Ω)
8315
5834
4161
3014
2228
Pull-Down Configuration
Vout (mV)
1280
1515
1775
2050
2330
2470
2600
2850
3070
3240
3360
July 2009