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MCP9808T-E/MS: A Digital Temperature Sensor for Consumer Electronics

Have you ever passed by a car and its horn started blaring? It can be scary and you may have wondered why that happened. More often than not, the car’s horn blares when it “senses” that someone or an object is coming closer to it. The same scenario plays out when a vehicle is in motion and depending on the customization, it swerves a little to avoid a collision.

All those and many other examples go to prove how sensitive consumer electronics have become. Sensors are now a part and parcel of these products and you have to take note of how each of these sensors work. The temperature sensor is one of the most outstanding but that doesn’t mean that there are no other options out there. We also have variants like the:

  • Position sensors
  • Force sensors
  • Strain gauges
  • Pressure sensors
  • Motion sensors
  • Radio Frequency (RF) sensors
  • Optical sensors
  • Ultrasonic sensors

What is a Temperature Sensor?


Generally, it is a type of sensor that “senses” or takes note of the change in a consumer electronics’ device. However, there are more meaning to that and we will break those down.

A temperature sensor is a dedicated sensor that detects and measures the amount of coldness and heat that is generated in a consumer electronics. The idea of detecting these is to correlate the outcome to the predefined values to ensure that the current temperature is not below or above those values.

Once the detection is made, the temperature sensor typically releases the value in the form of a digital or analog output.

In addition, the digital temperature sensor is one of the most-used, because of the simplicity. According to Analog Devices Incorporated, a digital temperature sensor like MCP9808T-E/MS tends to have a feasible interface, which could be either the I2C interface or the Serial Peripheral Interface (SPI).

MCP9808T-E/MS’s Maximum Accuracy

If there is one feature to look for in a digital temperature sensor, it has to be the accuracy of the signal. MCP9808T-E/MS’s accuracy is maximum and can be typically projected up to ±0.5˚C.

Although temperature sensors are noted for the limited range, that of MCP9808T-E/MS can go a long way to transmit the converted signals in good time. As per the information in the datasheet, it can convert temperatures between -20˚C and +100˚C to a digital word of ±0.5˚C.

MCP9808T-E/MS Supports Multiple Interfaces

It is better for a digital temperature sensor to work in unison with other supported peripherals and interfaces, as that could facilitate the speed of temperature sensor. Therefore, we are delighted to see that MCP9808T-E/MS supports multiple interfaces.

This support is rendered via the industry-standard, 400 kHz, 2-wire, SMBus/I2C-compatible serial interface. This interface standard allows the sensor to establish connections of up to sixteen (16) sensors – and all these would be controlled with the same serial bus.

MCP9808T-E/MS is User-Programmable

Given the many options in the market today, most consumers prefer going for the electronics and related products that can be easily fixed. In that regard, we are looking at electronics that are flexible enough for these users.

In the same light, MCP9808T-E/MS has been configured along those lines. It has a wide range of user-programmable registers, which provide the much-needed flexibility for temperature sensing and conversion.

Here are some of the techniques involved:

1. User-Selectable Settings

The users are allowed to program and reprogram the MCP9808T-E/MS digital temperature sensor as per the specifications of each application. The user-programmable settings include the specifications of the temperature critical output limits and the temperature alert window.

The users, or the digital circuit designer, can also program the power options/settings, such as the low-power and the shutdown modes.

2. User-Programmable Temperature Limits

The temperature at which the MCP9808T-E/MS functions or operates is also another programmable setting offered. Here, the users get to program the sensor with the critical temperature and the temperature window limits.

How this plays out is that the MCP9808T-E/MS gives out an alert signal anytime the temperature changes beyond or goes above the specified boundary limits.

When that happens, the users have the option to reprogram or reset these limits, especially the alert output signal polarity. It is up to the users to either set the polarity as an active-high or an active-low comparator output if it were to be used for the thermostat’s operation.

Otherwise, it would be a great idea to reset the polarity to temperature alert interrupt input if it is for the microprocessor-based systems.

MCP9808T-E/MS’s Pins

MCP9808T-E/MS supports up to five (5) pin configurations and each of those pins are optimized to work in a certain way.

Here are some of them:

  • Power Pin: Also known as the VDD pin, the power pin is the primary pin that powers the MCP9808T-E/MS digital temperature sensor. For accurate performance, it is to be connected in line with the operating voltage range specified in the DC.
  • Serial Data Line: It is also known as the SDA. The Serial Data Line is the pin configuration that serves as a bidirectional input and output pin. It works best with a pull-up resistor and is primarily used to make a serial transmission/transfer of data to and from the host controller.
  • Temperature Alert, Open-Drain Output: This is MCP9808T-E/MS’s Alert pin. It works by giving out a signal (alert) when the predefined temperature value or ambient range of the MCP9808T-E/MS goes beyond the original value.
  • Serial Clock Line: Clock performance is also required for a digital temperature sensor to work accurately. MCP9808T-E/MS’s clocking is regulated by the Serial Clock Line (SCL). Either of the master controller or the host controller located in the serial bus generate the clock. The Serial Clock Line (SCL)’s primary function is to make the timing and communication of the digital temperature sensor to be relative to the signal in the pin/line.

Final Words

MCP9808T-E/MS doubles as a local and digital temperature sensor type with a local sensing temperature of 125˚C, maximum. It has a 10-b resolution, supports up to 5.5 volts of supply voltage and includes a wide range of features, including shutdown mode, output switch, programmable resolution and programmable limit.