SMT-160-30-220 SMARTEC, SMT-160-30-220 Datasheet - Page 6

• Manufacturer Part Number: SMT-160-30-220
• Description: IC, TEMP SENSOR, TO-220-3, 160
• Manufacturer: SMARTEC

Specifications of SMT-160-30-220

• Ic Output Type: Voltage
• Sensing Accuracy Range: ± 1.7°C
• Supply Current: 200µA
• Supply Voltage Range: 4.75V To 7.2V
• Sensor Case Style: TO-220
• No. Of Pins: 3
• Operating Temperature Max: 130°C
• Operating: RoHS Compliant
• Temperature Sensing Range: -45°C To +130°C
• Rohs Compliant: Yes

SMT16030
Version 7/2005
SMARTEC B.V, Delpratsingel 26
4811 AP Breda, The Netherlands
General operation
A simple way of measuring a duty cycle is to use a microcontroller. The sensor output can be
directly connected to a microcontroller input. The microcontroller can determine the duty-
cycle value by sampling the sensor output. If the microcontroller is not fast enough to
determine the temperature accurately enough within one sensor output cycle, the sampling can
be extended over multiple periods. This method has the advantage to filter out noise. From the
theory of signal processing it can be derived that there is a fixed ratio between the sensors
signal frequency, the sampling rate and the sampling noise. This sampling noise limits the
accuracy and amounts to:
Microcontrollers can sample at a high frequency so with a simple program it is possible to
measure the sensor's duty cycle within 50 ms and a resolution of .01 °C.
condition
mounted in an alu block of a certain
temperature (mean value of different measurements)
in a bath filled with oil that was stirred
(mean value of different measurements)
Moving air with a speed of about 3 m/s
- without heatsink
- with heatsink
Non moving air
-without heatsink
-with heatsink
Overview of time constants in different conditions
T
t
t
t
s
m
p
error
= measurement error (= standard deviation of the sampling noise)
= microcontrollers sampling rate
= total measurement time
= output signal periodicity of the sensor
T
error
= 200 * t
- 6 –
s /sqrt(
6*t
m
*t
p)
timeconstant
(s) (TO18)
13.5
100
0.6
1.4
60
5
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