MCP9700AT-E/LT Sensor

MCP9700AT-E/LT Introduction

Want a cheap, low-power way to track changes in temperature for your next project? You need the MCP9700/9700A analog temperature sensors and the MCP9701/9701A analog temperature sensors. The accuracy of these sensors is within 2 °C from 0 °C to +70 °C, and they only need 6 A to work. Instead of resistive sensors, which need an extra signal conditioning circuit, these sensors use linear active thermometer ICs. Because of this, they are a great choice for developers who want to save money and time. The MCP9700/9700A and MCP9701/9701A can also be connected directly to the ADC input of a microcontroller, giving you even more design freedom. Because they are used in hard drives, entertainment systems, and battery packs, these sensors are a must-have for anyone who wants to track changes in temperature with high accuracy and low power use.

MCP9700AT-E/LT  General Description

Linear Active Thermistor IC in MCP9700/9700A and MCP9701/9701A analog temperature sensors turn temperature into an analog voltage. The cheap, low-power sensors have a typical working current of 6 A and an accuracy of 2°C from 0°C to +70°C (MCP9700A/9701A) and 4°C from 0°C to +70°C (MCP9700/9701).

The linear active thermometer IC doesn’t need an extra signal conditioning circuit like thermistors, which are resistive sensors. You can save money using one of these cheap gadgets as a sensor instead of making a biasing circuit for a thermistor solution. A microcontroller’s ADC input can be connected directly to the Voltage Output pin (VOUT).

The temperature coefficients for the MCP9701/9701A  and MCP9700/9700A are scaled so that an 8-bit ADC with a 2.5V or 5V reference voltage can measure temperature with a resolution of 1°C/bit. For a 12-bit ADC with a 4.096V reference, the MCP9700/9700A gave out 0.1°C/bit. The MCP9700/9700A and MCP9701/9701A offer a low-cost way to measure a relative change in temperature for applications that need it. You can measure the change in temperature from 0°C to +70°C relative to +25°C with an accuracy of 1°C.

To get this level of accuracy, the system can also be set up at +25°C. These devices can handle large capacitive loads and are unaffected by parasitic capacitance. Because the device could be far from the microcontroller, there are more ways to lay out the printed circuit board (PCB). By reducing overshoots and undershoots, the transient response of the output is improved when the output capacitance is raised. But a capacitive load is unnecessary for a sensor’s output to stay stable.

Typical Applications

• Office Equipment
• General Purpose Temperature Monitoring
• Battery Packs and Portable Equipment
• Hard Disk Drives and Other PC Peripherals
• Home Appliance

Applications Information

The Linear Active ThermistorTM IC has a diode built into it, which measures temperature. A temperature coefficient is an electrical property of a diode that causes the voltage to change based on the temperature of the air around it. This temperature coefficient ranges from -40 degrees Celsius to 150 degrees Celsius. The MCP9700/9700A and the MCP9701/9701A use a temperature coefficient of 10.0 mV/°C to figure out the difference in voltage, while the MCP9701/9701A uses a temperature coefficient of 19.5 mV/°C. In the MCP9700/9700A, the typical output voltage at 0 degrees Celsius is 400 millivolts for the MCP9700/9700A and 500 millivolts for the MCP9701/9701A.

Improving Accuracy

By doing a calibration procedure at a certain temperature, you can improve the accuracy of the MCP9700/9700A and MCP9701/9701A. For example, if the system is calibrated at a temperature of +25°C, the accuracy of measurements will usually increase by 0.5°C from 0°C to +70°C. Because of this, instruments in this category that are used to track changes in the relative temperature give more accurate data.

Shutdown Using Microcontroller I/O Pin

Because their operational current is only 6 A, the MCP9700/9700A and MCP9701/9701A families are great for systems that run on batteries. This device can also get its power from an input/output (I/O) pin on a microcontroller, which is helpful when there isn’t much electricity available. Flipping the I/O pin will turn off the device. The digital switching inside the microcontroller can sometimes send noise from the power supply to the MCP9700/9700A and MCP9701/9700A. You will need a resistor in series and a decoupling capacitor to eliminate system noise and improve the accuracy of your measurements. System noise can also be caused by noise from switches.

Layout Considerations

The MCP9700/9700A and MCP9701/9701A families of sensors don’t need any extra parts to work. But a 0.1 F to 1 F decoupling capacitor should be put between the VDD and GND pins. In noisy situations, connect the power supply voltage to the VDD pin with a 200-ohm resistor and a 1F decoupling capacitor. It is best to use a high-frequency ceramic capacitor. The capacitor must be as close to the VDD and GND pins to stop the noise well. Also, avoid following digital lines that are near the sensor.

Thermal Considerations

The MCP9700/9700A and MCP9701/9701A families measure temperature by watching the voltage of a diode in the die. The pins connect the die to the PCB in a way that lets heat flow easily. So, the sensor does a good job of monitoring the PCB’s temperature. But the path for the ambient air is not as good because the plastic device package acts as a thermal barrier between the die and the air. This rule applies to silicon temperature sensors that are wrapped in plastic. The TO-92 package should be considered if the application needs to measure the air around it. The MCP9700/9700A and MCP9701/9701A sensors are made to source or sink 100 A. (max.). The amount of power lost because of the output current is not very much.

Conclusion

In conclusion, the Microchip Technology MCP9700AT-E/LT temperature and humidity sensor is a great way to measure the conditions in a room. It is a versatile and reliable part that can help your project succeed because it has an analog output and a wide temperature range. If you need a reliable distributor in China, ICRFQ can meet your needs with high-quality electronic components and support. Don’t pass up the chance to use this great tool to improve how well your project works. Get in touch with us now to find out more and get started.

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