Philips Semiconductors

Product Profile

PCF7991AT

May 1998

Advanced Basestation IC, ABIC

Features

• Extended system operating range due to powerful

AM/PM demodulation technique

• Ideally suited for "Intelligent Antenna" and "Active

Antenna" architectures

• High antenna drive capabilities, CW: 200mAp

• Low antenna driver output resistance, 3.5 Ω

• Excellent receiver sensitivity, 2mVpp

• Large receiver dynamic range

• Programmable clock divider, modulator, receiver

gain and filter characteristics

• Fast "read after write" receiver settling

characteristics

• On-chip receive EMI filter

• Antenna failure mode detection

• Few external components

• Operating supply voltage: 4.5 to 5.5 V

• Power down mode: 7µA @ 5.5 V

• 14-pin SO package

General Description

The PCF7991 is a highly integrated and powerful

advanced basestation IC, ABIC, ideally suited for

vehicle immobilisation applications. The device

incorporates all necessary functions to facilitate reading

and writing of transponders.

The ABIC, PCF7991 employs a unique AM/PM

demodulation technique that extends the system

operating range compared with simple envelope

detection.

Optimised to operate with the Philips transponder family

(PCF79xx), the ABIC can be used in combination with

commonly available transponder that employ ASK

modulation. ASK modulation and receive characteristics

are widely programmable for powerful system

adaptation. The ABIC fits "Intelligent Antenna" as well

as "Active Antenna" applications.

The carrier frequency can be derived from an on-chip

oscillator or an external clock source. A wide range of

clock frequencies can be applied due to the

programmable on-chip clock divider circuitry.

The device enables system diagnostic functions by

antenna fail detection features.

Communication with the device and the transponder is

provided via the serial microcontroller interface.

Employing CMOS technology, the device features low

power operation and supports Idle and Powerdown

modes.

Minimum Application Circuitry

Modulation

Pulse Gen.

Antenna

Driver

Synchron

Demodulator

SC Filter

Amplifier

Control

Unit

Clk Divider

Timing

Oscillator

Serial

Interface

Register

DIN

CLK

DOUT

XTAL2

XTAL1

RX

TX1

TX2

VDD

VSS

QGND

CEXT

EMI

Filter

PCF 7991

4.5 ... 5.5 V

To microcontroller