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Details, datasheet, quote on part number:FM20S3X
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Datasheet text preview:
www.fairchildsemi.com
FM20
Ultra-Low-Power Analog Temperature Sensor
Features
· · · · · · · Analog Output, -11.77mV/°C Range, -55 to 130°C Accuracy, ±1°C at 25°C Supply Current, 9µA typical Output Drive, 1µA Self-heating < 0.021°C Operating Voltage: +2.4V to +6V
Description
As a precision CMOS temperature sensor, the FM20 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 1µA. For normal operation, the load on VOUT should be 5M or less. In a typical application, a remotely mounted FM20 is monitored by a microcontroller with an analog A/D converter input. Alternatively, the FM20 can drive a comparator with a high impedance input. Accuracy is typically ±1°C at room temperature; and better than ±2.5°C from 0 to 50°C. Available packages are surface mount 5-pin SC70 and 3-pin SOT-23.
Applications
· · · · · · · · Mobile Phones Computers Battery Management Office Equipment HVAC Power Supply Modules Disk Drives Automotive
Thermal Response
VOUT (mV)
1863.9
391 -50 -40 -25 0 25 50 75 100 125
Temperature (°C)
Temperature (°C) =
VOUT 1863.9mV 11.77mV/°C
FM20 Output Voltage vs. Temperature
REV. 1.0.6 1/9/03
FM20
PRODUCT SPECIFICATION
Pin Assignments
VOUT 3 GND 2 N/C 1 GND 3
FM20
4 VDD 5 GND
FM20
1 VDD 2 VOUT
Pin Descriptions
Pin No. Pin Name SC-70 SOT-23 VOUT 3 2 Type Analog Output Function Temperature Sense. Analog output voltage indicating temperature. VOUT = 1863.9 11.77 T(°C) mV Supply Voltage. 2.4 to 6.0V Ground.
VDD GND
4 2, 5
1 3
Power Power
2
REV. 1.0.6 1/9/03
PRODUCT SPECIFICATION
FM20
Absolute Maximum Ratings1
Parameter Supply Voltage Output Voltage Output Current Storage Temperature Range Lead Soldering Temperature ESD2 Human Body Model Machine Model Min. Typ. Max. +7 VDD + 0.5 -20/+1 +150 220 2000 250 Units V V µA °C °C V V
-60
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. Human Body Model: 100pF capacitor discharged through a 1.5k resistor into each pin. Machine Model: 200pF capacitor discharged directly into each pin.
Electrical Characteristics3
Limits apply for -55°C TA +130°C and VDD = +5.0V unless otherwise noted. Parameter Transfer Characteristic Sensitivity Output at 0°C Accuracy4 Symbol Conditions Min Typ -11.77 1863.9 ±1 ±2 ±2 Max Units mV/°C mV °C °C °C °C °C mV µA mA µA k mV/mA pF V µA µA °C °C
TA = +25°C TA = -55°C (TMIN) TA = +130°C (TMAX)
Temperature Range Non-Linearity5 Output Output Voltage Range Output Current Source6 Output Current Sink6 Output resistance Load regulation Capacitive Load7 Power Supply Voltage Quiescent Supply Current Output Floating Package Self Heating
-2 -3 -5 -55 -0.5 300
+2 +3 +5 +130 +0.2 2550
IONSN IONSG IOL
VOUT < VDD Sensing Surge TA = 25°C
1 20
CL VDD IDD
100 2.4 TA = +25°C -55°C TA +130°C SOT-23 SC70 9 9
1000 6.0 11.5 14 0.02016 0.02082
Notes: 3. These specifications are guaranteed only for the test conditions listed. 4. Accuracy (expressed in °C) = Difference between calculated output voltage and measured output voltage. Calculated output voltage = -11.77mV/°C multiplied by device's case temperature at specified conditions of temperature, voltage and power supply plus an offset of 1863.9 mV at 0°C. 5. 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. 6. Lowest output current should be targeted; higher currents result in more self-heating of the device. 7. High capacitive loads may be driven by the output in a static mode, but it may require a delay time before initial read at power up to allow for the RC time constant of the charging capacitor. REV. 1.0.6 1/9/03
3
FM20
PRODUCT SPECIFICATION
Typical Performance Characteristics
Quiescent Current (µA) 12 11 10 9 8 7 6 -50 -25 0 25 50 75 100 125 VDD = +5V
Temperature (°C)
Figure 1. Quiescent Current vs. Temperature
3 2 Accuracy (°C) 1 0 -1 -2 -3 -4 -5 -50 0 lower spec limit 50 Temperature (°C)
VDD =+5V upper spec limit
100
Figure 2. Accuracy vs. Temperature
Applications Information
Mounting
The FM20 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 FM20 die will be at an intermediate temperature between the surface temperature and the air temperature. To ensure good thermal conductivity, the backside of the FM20 die is directly attached to the GND pin. The lands and traces to the FM20 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 FM20's temperature to deviate from the desired temperature. Alternatively, the FM20 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 FM20 and 4 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 FM20 or its connections.
Loading
The FM20 will handle sizable capacitive loads up to 300pF without any special considerations. In an extremely noisy environment it may be advisable to add some filtering to minimize noise in the output voltage. It is also recommended that a 0.1µF bypass capacitor be added between the supply voltage and ground. This is due to the instant current demand caused by switching CMOS transistors. Normally it is unadvisable to put a sufficiently large supply (particularly in portable electronics) to be able to handle the dynamic currents of CMOS transistors. It is a much simpler solution to use a bypass capacitor to sustain the supply voltage during this short demand period.
REV. 1.0.6 1/9/03
PRODUCT SPECIFICATION
FM20
In environments that are particularly noisy it may be necessary to add a low-pass filter network to the output of the device. As shown below, a 1µF capacitor in addition to the output impedance of the device and a 200 series resistor for a low-pass filter that will pass the slow thermal time con-
stant of the FM20, while filtering the higher frequency noise. The response time of the FM20 can be affected by this filter network, therefore values for CFILTER < 1500pF are recommended.
GND 0.1µF Bypass Cap VDD VOUT
CFILTER RFILTER
CL
GND 0.1µF Bypass Cap VDD VOUT RFILTER
CFILTER
CL
Figure 3. FM20 with Filter Network for Noisy Environments or for Capacitive Loads Greater than 300pF
Table 1. Resistor/Capacitor Combinations for Filter Network
RFILTER 200 470 680 1000 10k 100k CFILTER 1µF 0.1µF 0.01µF 1000pF 100pF 10pF
REV. 1.0.6 1/9/03
5
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