Instructions

UM-0085-B09 DT80 Range User Manual Page 321
RG
Temperature – LM35 Series IC Sensors
LM35 series sensors are 3-terminal semiconductor devices which produce a voltage output that is proportional to
temperature. Supply voltage is typically 4-30V.
Channel Types
The following channel types are supported:
Channel Types
Description
Range
LM34
10mV/°F -50 – +300 °F
LM35
10mV/°C
-55 – +150 °C
LM45
10mV/°C
-20 – +100 °C
LM50
10mV/°C + 500mV -40 – +125 °C
LM60
6.25mV/°C + 424mV
-40 – +125 °C
TMP35
10mV/°C -40 – +125 °C
TMP36
10mV/°C + 500mV
-40 – +125 °C
TMP37
20mV/°C
-40 – +125 °C
The devices with a voltage offset (LM50, LM60 and TMP36) allow negative temperatures to be read without additional
components.
Channel Options
The following channel options are sometimes used when measuring LM35 series devices:
• the excitation options specify how the sensor is powered:
V (use internal 4.5V voltage source; default), E
(external supply connected to EXT* terminal) or
N (external supply).
•
MDn (measurement delay) specifies that the DT80 should wait n ms (default 10ms) after selecting a channel
before starting the actual measurement. This can be useful in conjunction with the
E or V option, as it allows the
sensor some time to stabilise after power is applied to it.
• the channel factor specifies an offset adjustment, in °C
•
GLx, ESn, as for voltage measurements
Calibration
For LM35 series sensors, the channel factor is an offset correction, in °C. So if the sensor reads 25.4°C when the actual
temperature is 25.0°C (an error of +0.4°C) then the channel factor would simply be specified as:
4+LM35(0.4)
IC2 – LM35-Series Inputs
In this wiring configuration the sensor is powered by the DT80’s 4.5V voltage excitation. This single-ended supply means
that the sensor’s output voltage will not be able to go below about 100mV. For devices with no offset voltage (e.g. LM35)
this restricts the minimum usable temperature to 10°C (for LM35).
Accuracy can be improved by replacing the link wire between the # and – terminals with a wire from the – terminal of the
logger to the – terminal of the sensor. This will compensate for voltage drops due to cable resistance, similar to a 4-wire
resistance measurement.
Figure 147: L2 Wiring for LM35 series input – restricted temperature range
To measure
Use the command
temperature
1LM35