GENERAL DESCRIPTION

The PCD4440T is a silicon gate CMOS integrated circuit intended to be used in cordless telephony, radio, and line telecommunications products utilizing a microcontroller for the control functions. The purpose of the device is to prevent unauthorized ‘listening-in’ on conversations. A major application is protection of the vulnerable radio link between a CT0 type cordless handset and its base unit. Analog scrambling/descrambling is based on the split frequency method realized in a sophisticated switched-capacitor technology. The PCD4440T is compatible with most microcontrollers and communicates via a two line bidirectional I2C-bus.

FEATURES

• Scrambler or descrambler function

• Scrambling in frequency domain

• Selectable split frequency (up to 10 selections per second)

• Telephony-band filtering included

• No increase in bandwidth

• No external components required

• Small signal delay

• Insensitive to distortion and group delay of transmission channel

• Control via serial I2C-bus

• Low transfer loss of speech

• Mute option

• Transparent mode

• High signal input impedance

• Low signal output impedance

• Low power consumption.

APPLICATIONS

• Cordless telephones

• Security telephones

• Portable phones

• Private Mobile Radio (PMR).