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FM50
Analog Temperature Sensor
Features
• Analog output: 10 mV/°C
• Range: -40 to 125°C range:
• Accuracy: ±1°C at 25°C
• Supply Current, 170 µA max.
• Output Drive, 25 µA
• Self-heating < 0.1°C
• Operating Voltage: +2.4V to +6V
Applications
• Mobile Phones
• Computers
• Battery Management
• Office Equipment
•HVAC
• Power Supply Modules
• Disk Drives
• Automotive
Thermal Response
Description
As a precision CMOS temperature sensor, the FM50 is
cost-effective for accurate low-power temperature monitoring applications. Output voltage versus temperature is
extremely linear. With no load, the supply current is
typically 130µA. For normal operation, the load on V
should be 100K Ω or less.
In a typical application, a remotely mounted FM50 is
monitored by a microcontroller with an analog A/D
converter input. Alternatively, the FM50 can drive a
comparator with a high impedance input.
Accuracy is typically ± 0.5°C at room temperature; and
better than ±2°C from 0 to 75°C.
Package is a 3-pin SOT-23
V
(mV)
OUT
OUT
1750
750
500
100
-50 -40
-25 25
Temperature ( C) =
FM50 Output Voltage vs. Temperature
0
Temperature ( C)
V
OUT
10 mV/ C
50 75
- 500 mV
100
125
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FM50 PRODUCT SPECIFICATION
Pin Assignments
GND
3
FM50
12
VDD
VOUT
Pin Descriptions
Pin Name Pin No. Type Function
V
OUT
V
DD
GND 3 Power
2 Analog Output Temperature Sense. Analog output voltage indicating temperature.
V
= 500+10T(°C) mV
OUT
1Power Supply Voltage. 2.4 to 6.0V
Ground.
2
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≤
PRODUCT SPECIFICATION FM50
Absolute Maximum Ratings
1
Parameter Min. Typ. Max. Units
Supply Voltage +7 V
Output Voltage V
+ 0.5 V
DD
Output Current 10 µA
Operating Temperature Range
2
-50 +150 °C
Storage Temperature Range -60 +150 °C
Lead Soldering Temperature 220 °C
2
ESD
Human Body Model
Machine Model
Notes:
1. Absolute maximum ratings are limits beyond which operation may cause permanent damage to the device. These are stress
ratings only; functional operation at or above these limits is not implied.
2. Operating ratings are conditions for which the device is intended to be functional without specific guaranteed performance
limits. For guaranteed specifications and test conditions refer to Electrical Characteristics.
3. Human Body Model: 100pF capacitor discharged through a 1.5kOhm resistor into each pin. Machine Model: 200pF capacitor
discharged directly into each pin.
Electrical Characteristics
Limits apply for -40°C ≤ T
+125°C and V
A
4
= +5.0V unless otherwise noted.
DD
2000
250
V
V
Parameter Symbol Conditions Min Typ Max Units
Transfer Characteristic
Sensitivity A
OUT
9.7 10 10.3 mV/°C
Output at 25°C 740 750 760 mV
Accuracy
5
T
= +25°C
A
T
= -40°C (T
A
T
= +125°C (T
A
MIN
MAX
-1
)
)
-3.5
-3
±0.5
±1
±1
+1
+3.5
+3
°C
°C
°C
Temperature Range -40 +125 °C
Non-Linearity
6
-0.8 +0.8 °C
Output
Output Voltage Range 100 1500 mV
Output Current Source I
I
Output Current Sink I
ONSN
ONSG
OL
Sensing 25 µA
Surge mA
50 µA
Output resistance 100k Ω load at 25°C 1 10 k Ω
Load regulation mV/mA
Power
Supply Voltage V
Quiescent Current I
DD
S
No output load 170 µA
2.4 6.0 V
Package
Thermal Resistance 260 °C/W
Notes:
4. These specifications are guaranteed only for the test conditions listed.
5. Accuracy (expressed in °C) = Difference between calculated output voltage and measured output voltage. Calculated output
voltage = 10mV/°C multiplied by the device’s case temperature at specified conditions of temperature, voltage and power
supply, added to 500mV.
6. Non-linearity is defined as the deviation of the output-voltage-versus-temperature curve from the best-fit straight line, over the
device’s rated temperature range.
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FM50 PRODUCT SPECIFICATION
Typical Performance Characteristics
4.0
upper spec limit
lower spec limit
Temperature (°C)
Accuracy (°C)
3.0
2.0
1.0
0.0
-1.0
-2.0
-3.0
-4.0
-50
Figure 1. Accuracy vs. Temperature
100
VDD = +5V
150500
140.0
120.0
100.0
80.0
60.0
40.0
Supply Current (uA)
20.0
0.0
-50 -30 -10 10 30 50 70 90 110 130
Temperature (°C)
Figure 2. Typical IDD versus Temperature Figure 3. Typical Sensitivity to Supply Voltage
Description
Within the FM50 are a thermal diode, calibration circuits
and amplifiers. Since the FM50 is calibrated at 33°C,
the nominal output in mV is:
V
where T is the thermal junction temperature expressed in °C.
At 33°C, the tolerances are as follows:
OUT
830 10 T 33–()•+=
5.0
4.0
3.0
2.0
1.0
0.0
VOUT Deviation from 5V Value (mV)
-1.0
2.5 3.0 3.5 4.0 4.5 5.0 5.5 6.0 6.5
VDD Volts
These values accommodate the specified accuracies at -40,
25 and +125°C.
Output structure of the FM50 is an n-channel CMOS transistor driving a p-channel load. Available current is typically 50
µA to ground. Series resistance is typically 7 k Ω , charging
and 2 k Ω , discharging through a capacitor connected from
V
to ground.
OUT
Following application of power to V
DD
, V
is accurate
OUT
following a delay of approximately 80 msec.
1. Offset is ±3mV
2. Slope, ±0.3mV/°C
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PRODUCT SPECIFICATION FM50
Applications Information
Although the FM50 is a simple device, care must be taken to
ensure that temperature is measured accurately. There are
two major sources of errors:
3. Voltage errors.
4. Thermal Delay Errors.
5. Location errors
Voltage Errors
VDD
FM50
GND(power)
Figure 4. Recommended Electrical Connections
VOUT
GND(sense)
A Kelvin connection is recommended to avoid errors due to
voltage drops in the ground connections. Although the
typical 130µA supply current draw of the FM50 will only
cause a 130µV error if the series resistance is 1 Ω , a 100 mA
current supply to adjacent circuits can cause a 10mV drop
across 100m Ω (10m Ω is a typical value for soldered joints or
contact resistance), leading to a 1°C error. For this reason,
the FM50 should be Kelvin connected as shown in Figure 4.
Thermal Delay Errors
For measurement accuracy of the order of tenths of 1°C,
adequate settling time must be allowed. For a typical circuit
board installation, 15 minutes should be allowed to elapse
following reading of temperature within 1 - 2°C of the
expected final value. Once V
is stable (with or without about ±0.1°C noise) for about 5
minutes, temperature can be calculated.
has ceased to slew and
OUT
Location Errors
Position is another source of error. Even within a controlled
thermal environment, changing location by a few inches can
lead to errors of several tenths of 1°C
Mounting
The FM50 can be easily mounted by gluing or cementing it
to a surface. In this case, its temperature will be within about
0.2°C of the temperature of the surface it is attached to if the
ambient air temperature is almost the same as the surface
temperature. If the air temperature is much higher or lower
than the surface temperature, the actual temperature of the
FM50 die will be at an intermediate temperature between the
surface temperature and the air temperature.
To ensure good thermal conductivity, the backside of the
FM50 die is directly attached to the GND pin. The lands and
traces to the FM50 will, of course, be part of the printed
circuit board, which is the object whose temperature is being
measured. These printed circuit board lands and traces will
not cause the FM50’s temperature to deviate from the
desired temperature.
Alternatively, the FM50 can be mounted inside a sealed-end
metal tube, and can then be dipped into a bath or screwed
into a threaded hole in a tank. As with any IC, the FM50 and
accompanying wiring and circuits must be kept insulated and
dry to avoid leakage and corrosion. This is especially true if
the circuit may operate at cold temperatures where condensation can occur. Printed-circuit coatings and varnishes such
as Humiseal and epoxy paint or dips can be used to ensure
that moisture cannot corrode the FM50 or its connections.
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FM50 PRODUCT SPECIFICATION
Typical Applications Circuits
3.9K
FM50
FM50
U1
1µF
V
100K
10K
TEMP
FB
Adjustable
Shunt Voltage
Reference
IN
REF
1.75V
U2
Serial
Analog-to-Digital
Converter
U3
Figure 4. Serial Output Temperature to Digital Converter (Full Scale = +125°C)
5V
30K
8
U3
U1
1µF
V
TEMP
5K
15K
IN
Parallel Output
Analog-to-Digital
Converter
U2
+
1.75V
V
REF
SERIAL
DATA OUT
CLOCK
ENABLE
PARALLEL
DATA
OUTPUT
INTR
CS
RD
WR
Figure 5. Parallel Output Temperature to Digital Converter (Full Scale = +125°C)
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PRODUCT SPECIFICATION FM50
Typical Applications (continued)
Shunt
Voltage
Reference
V+
R4
V+
U3
4.1V
FM50
R1
0.1µF
V
U2
R2
TEMP
V
T
Figure 6. Thermostat/Fan Controller
R3
-
V
U1
+
OUT
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FM50 PRODUCT SPECIFICATION
Mechanical Dimensions
SOT-23 FS Package Code AU
0.110 (2.800)
0.120 (3.040)
0.047 (1.20)
0.055 (1.40)
PIN 1
0.070 (1.780)
0.081 (2.050)
0.035 (0.890)
0.044 (1.120)
0.0005 (0.013)
0.004 (0.100)
inches (millimeters) unless otherwise noted
0.083 (2.100)
0.104 (2.640)
0.035 (0.890)
0.041 (1.030)
0.017 (0.450)
0.024 (0.600)
0.015 (0.370)
0.020 (0.510)
SEATING
PLANE
0.015 (0.085)
0.007 (0.180)
10°
0°
0.0217 REF (0.55) REF
Ordering Information
Part Number Package Temperature Range Shipping
FM50S3X 3-Pin SOT-23 -40°C to +125°C Tape and Reel, 3000 units/reel
DISCLAIMER
FAIRCHILD SEMICONDUCTOR RESERVES THE RIGHT TO MAKE CHANGES WITHOUT FURTHER NOTICE TO
ANY PRODUCTS HEREIN TO IMPROVE RELIABILITY, FUNCTION OR DESIGN. FAIRCHILD DOES NOT ASSUME
ANY LIABILITY ARISING OUT OF THE APPLICATION OR USE OF ANY PRODUCT OR CIRCUIT DESCRIBED HEREIN;
NEITHER DOES IT CONVEY ANY LICENSE UNDER ITS PATENT RIGHTS, NOR THE RIGHTS OF OTHERS.
LIFE SUPPORT POLICY
FAIRCHILD’S PRODUCTS ARE NOT AUTHORIZED FOR USE AS CRITICAL COMPONENTS IN LIFE SUPPORT DEVICES
OR SYSTEMS WITHOUT THE EXPRESS WRITTEN APPROVAL OF THE PRESIDENT OF FAIRCHILD SEMICONDUCTOR
CORPORATION. As used herein:
1. Life support devices or systems are devices or systems
which, (a) are intended for surgical implant into the body,
or (b) support or sustain life, and (c) whose failure to
perform when properly used in accordance with
instructions for use provided in the labeling, can be
reasonably expected to result in a significant injury of the
user.
2. A critical component in any component of a life support
device or system whose failure to perform can be
reasonably expected to cause the failure of the life support
device or system, or to affect its safety or effectiveness.
www.fairchildsemi.com
9/12/02 0.0m 003
2002 Fairchild Semiconductor Corporation
Stock#DS30000050
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