feature

Analog output, -11.77mV/℃

Range -55 to 130 °C

Accuracy, ±1°C at 25°C

Supply current, 9µA typical

Output driver, 1µA

Self-heating <0.021°C

Operating Voltage: +2.4V to +6V

application

Cell Phones. Computers. Battery Management. Office Equipment. HVAC. Power Modules. Disk Drives. Automotive

illustrate

As a precision CMOS temperature sensor, the FM20 is a cost-effective low-power accurate temperature monitoring application. The output voltage is very linear with temperature. At no load, the supply current is typically 1µA. For normal operation, the load on VOUT should be less than or equal to 5MΩ. In a typical application, a remotely mounted FM20 monitors the converter input with an analog A/D microcontroller. Alternatively, the FM20 can drive a high impedance input comparator. Accuracy is typically ±1°C at room temperature; and better over ±2.5°C from 0 to 50°C. Available packages are surface mount 5-pin SC70 and 3-pin SET 23.

Absolute Maximum Ratings1

notes:

1. Absolute maximum ratings are limits beyond which operation may cause permanent damage to the device. These are pressure ratings only; no functional operation at or above these limits is implied.

2. Human Body Model: A 100pF capacitor discharges into each pin through a 1.5kΩ resistor. Machine model: 200pF capacitors are drained directly to each pin.

Electrical Characteristics 3

Unless otherwise stated, limits apply for -55°C≤TA≤+130°C and VDD=+5.0V

notes:

3. These specifications are guaranteed only under the test conditions listed.

4. Accuracy (in °C) = difference between calculated output voltage and measured output voltage. Calculated output voltage = -11.77mV/°C multiplied by the device's case temperature at 0°C for the specified temperature, voltage and power conditions, plus an offset of 1863.9 mV from the power supply.

5. Nonlinearity is defined as the output voltage versus temperature curve over the rated temperature range of the device.

6. The lowest output current should be the goal; higher currents result in more self-heating of the device.

7. High capacitive loads can be driven by the output in quiescent mode, but a delay time may be required to allow the RC time constant of the capacitor to charge before the initial power read.

Application Information Installation

The FM20 can be easily mounted to a surface by gluing or gluing. In this case, it's about the same temperature if the ambient air temperature is about 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 mold will be at the surface temperature and air temperature. To ensure good thermal conductivity, connect the FM20 die directly to the GND pin. Land and of course, the traces to the FM20 will become part of the printed circuit board, the temperature of which is carefully considered. Traces on these printed circuit boards will not cause the temperature of the FM20 to deviate from the desired value. Alternatively, the FM20 can be installed in a sealed end metal tube, which can then be submerged in a bathtub or screwed into a threaded hole in a tank. As with any IC, the FM20 and accompanying wiring and circuitry must be kept insulated and dry to avoid leakage and corrosion.

Especially if the circuit is likely to operate at low temperatures where condensation can occur. Printed circuit coatings and varnishes such as humic acid and epoxy paints or impregnants can be used to ensure that moisture does not corrode the FM20 or its connections. Loading the FM20 will handle bulk capacitive loads up to 300pF without any special consideration. In a very noisy local environment it is recommended to minimize the noise in the output voltage. It is also recommended to add a 0.1µF bypass capacitor between the supply voltage and ground. This is due to the instantaneous current demand caused by switching CMOS transistors. Usually, it is not advisable to throw a large enough supply (especially when being able to handle the dynamic current of CMOS transistors. It is a simpler solution to use a bypass capacitor during this brief period of demand.

In particularly noisy environments, it may be necessary to install the device. As shown below, in addition to the output impedance of the device and a 200Ω series resistor for the low pass filter, it will pass the slow thermal time constant of the FM20 while filtering higher frequency noise. This filter affects the response time network of the FM20, so a value of CFILTER < 1500pF is recommended.

Example Application Circuit

typical application

(The full scale of an A-to-D converter is typically limited to the number of bits available in a +125°C conversion. The FM20 can still achieve full output swing.)

Typical Applications (continued)