Freescale Offers Alternative with Capacitive Touch Sensors

Touch sensors have become increasingly popular as more interfaces use touch panels to reliably respond to commands. Freescale Semiconductor, a leading designer and manufacturer of sensor devices, is meeting this demand for touch-sensitive control with the introduction of two highly sensitive touch pad controllers.

Freescale’s MPR081 and MPR082 proximity capacitive touch sensor controllers are designed to detect touch by measuring capacitance. Touch sensors are becoming essential for any interface with buttons. They offer designers a low-cost alternative to mechanical push buttons for applications such as access controls, appliances, mobile phones, MP3 players, PC peripherals and remote controls. Replacing traditional push-button interfaces with touch-sensitive control ultimately makes the interface more intuitive and easier to use.

“The proliferation of touch sensor technology is making sensor-driven interfaces easier and more intuitive than ever and transforming how consumers operate their mobile electronics devices,” said Tony Massimini, chief of technology at Semico Research Corporation. “Freescale’s touch sensor controllers offer the features and pin-out design essential to implementing rotary and touch pad layouts. The devices’ flexible use of electrodes enables multiple sensing touch points for next-generation consumer electronics products.”

Freescale’s MPR081 is ideal for rotary interface applications, and the MPR082 is well suited for touch pad applications. The proximity sensors have a common pin-out, which simplifies management of control panels, switch replacements, rotary and linear sliders, and touch pad implementations. Both touch sensor devices use a digital output I2C interface to communicate. The voltage operation range is 1.8 to 3.6V, which is ideal for consumer electronics. The devices have a sound driver that provides audible feedback to simulate mechanical key clicks.

“Control panel manufacturers increasingly are designing interfaces with intelligent touch control, enabling more sophisticated functionality for portable electronics and appliances,” said Demetre Kondylis, vice president and general manager of Freescale’s Sensor and Actuator Solutions Division. “The MPR081 and MPR082 proximity sensors allow designers to evolve user interfaces, providing greater flexibility for next-generation consumer electronics.”

Proximity detection provides the latest technology for the user to interact with consumer electronics. Touch sensing is one of the most popular applications because it:

  • enables the elimination of mechanical buttons and sliders
  • enhances reliability by eliminating mechanical wear and tear
  • gives greater flexibility for product designers
  • reduces overall system costs
  • provides the ability to automate intuitively through our fingertips

For example, the MPR081 and MPR082 proximity sensors can be used in the front panel of a washing machine to replace mechanical knobs and push buttons. Users bring their fingers in proximity to an indicated command on the panel, and the washing machine begins the requested function.

Replacing mechanical buttons on smart portable electronics enables a larger LCD display and orientation placement options. Additionally, the proximity sensor electrode layouts can be changed easily, depending on the device’s portrait or landscape mode.

MPR081 and MPR082 features

  • 1.8V to 3.6V operation
  • 150 micro amps average supply current (all touch pads being monitored)
  • 1 micro amps standby current
  • MPR081 supports a 16-position rotary interface
  • MPR082 controls up to 20 touch pads
  • Proprietary false touch rejection technology
  • Ongoing pad analysis and detection not reset by EMI events
  • Sounder drive provides audible feedback to simulate mechanical key clicks
  • Digital output (I2C with custom addressing)
  • 16-pin QFN and TSSOP packages
  • -40°C to +85°C operating temperature range


  • Control panels
  • Switch replacements
  • Rotary and linear sliders
  • Touch pads

Price and Availability
Please contact Freescale sales for MPR081 and MPR082 sample availability. General availability is expected in the fourth quarter of 2007. The suggested resale price in 10,000-piece quantities starts at $1.07 (USD) for both devices. Suggested consumer product pricing is less than $1 in high volume.

Freescale offers several evaluation kits to help reduce implementation development cycle time. The KITMPR081EVM and KITMPR082EVM are available at a suggested resale price of $99 (USD) each.

About Freescale Semiconductor
Freescale Semiconductor, Inc. is a global leader in the design and manufacture of embedded semiconductors for the automotive, consumer, industrial, networking and wireless markets. The privately held company is based in Austin, Texas, and has design, research and development, manufacturing or sales operations in more than 30 countries. Freescale is one of the world’s largest semiconductor companies with 2006 sales of $6.4 billion (USD).

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