Philips Semiconductors
Analog voice scrambler/descrambler
Product specification
PCD4440T
1 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.
2 APPLICATIONS
• Cordless telephones
• Security telephones
• Portable phones
• Private Mobile Radio (PMR).
3 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.
4 ORDERING INFORMATION
TYPE
NUMBER
PCD4440T
NAME
SO8
PACKAGE
DESCRIPTION
plastic small outline package; 8 leads; body width 7.5 mm
VERSION
SOT176-1
1996 Dec 20
3