Document order number: MC34940

Rev 2.0, 2/2006

Freescale Semiconductor

Technical Data

© Freescale Semiconductor, Inc., 2006. All rights reserved.

Electric Field Imaging Device

The 34940 is intended for cost-sensitive applications where non-contact

sensing of objects is desired. When connected to external electrodes, an

electric field is created. The 34940 detects objects in this electric field. The IC

generates a low-frequency sine wave, which is adjustable by using an external

resistor and is optimized for 120 kHz. The sine wave has very low harmonic

content to reduce harmonic interference. The 34940 also contains support

circuits for a microcontroller unit (MCU) to allow the construction of a two-chip

E-field system.

Features

•

Supports up to 7 Electrodes

•

Shield Driver for Driving Remote Electrodes Through Coaxial

•

High-Purity Sine Wave Generator Tunable with External Resistor

•

Response Time Tunable with External Capacitor

•

Can support up to 28 touch pad sensors

•

Pb-Free and RoHS compliant

Typical Applications

•

Appliance Control Panels and Touch Sensors

•

Linear and Rotational Sliders

•

Spill Over Flow Sensing Measurement

•

Refrigeration Frost Sensing

•

Industrial Control and Safety Systems Security

•

Proximity Detection for Wake-Up Features

•

Touch Screens

•

Garage Door Safety Sensing

•

PC Peripherals

•

Patient Monitoring

•

Point of Sale Terminals

•

Size Detection

•

Liquid Level Sensing

ORDERING INFORMATION

Device Name

Temperature

Range

Drawing

Package

MC34940EG/R2

0 to 90°C

98ASB42564B

SOICW-24

34940

ELECTRONIC FIELD

IMAGING DEVICE

24 LEAD (PB-FREE)

SOICW

98ASB42344B

Figure 1. Pin Connections

N/C

E7

E6

E5

E4

E3

E2

E1

TEST

GND

SHIELD

AGND

DGND

N/C

SHIELDEN

C

B

A

LEVEL

LPCAP

ROSC

VDDCAP

VPWR

VCCCAP