PCF7991AT datasheet(3/19 Pages) ETC2

3 / 19 page

printed 1998 Apr 20

Philips Semiconductors

Product Speciﬁcation (Rev. 1998 Apr 20)

Advanced Basestation IC

PCF7991AT

FEATURES

• Fully integrated single chip basestation

• Compatible with PCF79xx transponder family

• Robust antenna coil power driver stage with modulator

• High performance adaptive sampling time AM/PM

demodulator (patent pending)

• Read and write function

• Programmable modulator/demodulator characteristics

• On-chip clock oscillator and divider in the case of

external clock reference

• Antenna rupture and short circuit detection

• Low power consumption

• Very low power stand-by mode

• Low external component count

• Small package (SO14).

GENERAL DESCRIPTION

The PCF7991AT is a fully integrated Advanced

Basestation IC, ABIC, designed for car immobilizer

systems providing read and write access to an

identification transponder. The device is intended for use

with the Philips transponder family (PCF79xx) as well as

other transponder types operating at 125 kHz and

employing ASK, Amplitude Shift Keying for write and

AM/PM for the read operation. The receiver characteristics

(amplifier gain, filter cutoff frequencies) can be optimized

to system and transponder requirements. The

PCF7991AT IC is designed for easy integration into

immobilizer read/write and read-only systems featuring a

high degree of integration and very low external

component count. The device integrates a powerful

antenna driver/modulator, a low-noise adaptive sampling

time demodulator, programmable filters/amplifier and

digitizer, required to design high-performance

basestations. A three wire microcontroller interface is

provided for programming the PCF7991AT as well as for

the bidirectional communication with the transponder. The

three-wire interface can be configured for two wire

operation by connecting the data input and the data

output.

The device employs a unique Adaptive Sampling Time

(AST) demodulation technique, that extends the system

operation range and eliminates the effect of a zero

amplitude modulation response from the transponder, as a

result of resonance frequency tolerances.

ORDERING INFORMATION

EXTENDED

TYPE NUMBER

PACKAGE

TEMPERATURE

RANGE (

°C)

NAME

DESCRIPTION

VERSION

PCF7991AT/1081

SO14

plastic small outline package; 14 leads

SOT108-1

−40 to +85

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