New Top

All Products By Category

TMP421 Temp Sensor


In stock

SKU: MD0540 Category:


The Temp Sensor is an I2C sensor  Arduino is capable of turning the Arduino into an instant thermometer, plugging directly into Arduino Duemilanove or Uno Analog Pins 2-5, or just breaking out the native Arduino I2C pins (4 & 5) and powering the chip from anther source.

The TMP421 chip is a 12 bit I2C chip that works from minus – 40 to 125 degrees C, and the sensor is able to resolve .04 degrees C per bit. The absolute accuracy is guaranteed to be +/- 1 degree C. The relative resolution should make the sensor useful for a range of higher resolution activities such as sniffing out drafts around windows.

The Temp Sensor comes with a 4-pin male header (unsoldered) and 8 total pin-outs to allow for maximal flexibility in project use. With a small, narrow form factor, it’s easy to set up multiple Temp Sensors for local temperature monitoring as well.

A ready-to-go Arduino library is also available free for download  and off-the-shelf integration with any Arduino project.

The chip communicates via I2C and also has an onboard remote temperature sensing capability as well.


  • TMP421 chip
  • 4-pin male header included (unsoldered)
  • Communicates over I2C protocol
  • 1 Bi-directional data pin
  • 1 Clock pin
  • Ranges from – 40C to +125C with +/ – 1C accuracy
  • Optional remote temperature probe input
  • I2C Digital Interface
  • Arduino Pin Compatible
  • +5V Tolerant I/O

Arduino Pin Mapping

Analog 2 = Ground
Analog 3 = Vin
Analog 4 = Data
Analog 5 = Clock


Additional information

Weight 45 g
Dimensions .5 × 1 × .1 in