page 33
The
LM35
is a low-cost precision
integrated-circuit temperature sensor,
whose output voltage is linearly
proportional to the Celsius (Centigrade)
temperature. The LM35 thus has an
advantage over linear temperature
sensors calibrated in ° Kelvin, as the
user is not required to subtract a large
constant voltage from its output to
obtain convenient Centigrade scaling.
The LM35 does not require any external
calibration or trimming to provide
typical accuracies of ±¼°C at room
temperature and ±¾°C over a full -55
to +150°C temperature range. It has
a linear + 10.0 mV/°C scale factor
and less than 60 μA current drain. As
it draws only 60 μA from its supply, it
has very low self-heating,
less than 0.1°C in still air.
mikromedia
™
workStation
v7 provides a separate socket
(
TS2
) for the LM35 sensor in
TO-92 plastic packaging. Readings
are done with microcontroller using
single analog input line, which is
selected with a
J4
jumper.
D
AT
A BUS
R5
1K
C3
100nF
G0.0
G0.3
Figure 13-5: LM35 connected to G0.0 pin
mikromedia
™
workStation v7 enables you to get analog readings from the LM35
sensor using
G0.0
or
G0.3
microcontroller pins. The selection of either of those
two lines is done using
J4
jumper. When placing the sensor in the socket make
sure that half-circle on the board’s silkscreen markings matches the rounded
part of the LM35 sensor. If you accidentally connect the sensor the other way,
it can be permanently damaged and you might need to replace it with another
one. During the sensor readings make sure that no other device is using the
selected analog line, as that may interfere with the readings.
Figure 13-1:
LM35 not
connected
Figure 13-2:
LM35 placed
in socket
Figure 13-3:
LM35
connected
to G0.3 pin
Figure 13-4:
LM35
connected
to G0.0 pin
Enabling LM35 Sensor
1
2
3
4
LM35 - Analog
Temperature Sensor
other modules
