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AS3932

8 Detailed Description

The AS3932 is a three-dimensional low power low-frequency wakeup receiver. The AS3932 is capable to detect the presence of an inductive

coupled carrier and extract the envelope of the On-Off-Keying (OOK) modulated carrier. In case the carrier is Manchester coded the clock is

recovered from the transmitted signal and the data can be correlated with a programmed pattern. If the detected pattern corresponds to the

stored one a wake-up signal (IRQ) is risen up. The pattern correlation can be bypassed in case and the wake-up detection is based only on the

frequency detection.

The AS3932 is made up by three independent receiving channels, one envelop detector, one data correlator, one Manchester decoder, 8

programmable registers with the main logic and a real time clock.

The digital logic can be accessed by an SPI. The real time clock can be based on a crystal oscillator or on an internal RC one. In case the

second is used to improve its accuracy a calibration can be performed.

8.1 Block Diagram

Figure 10. Block Diagram

LF1P

LF2P

LF3P

LFN

GND

CL_DAT

DAT

CS

SDO

SDI

SCL

IRQ

VCC

Amp Out

RSSI

Channel

Amplifier 1

Amp Out

RSSI

Channel

Amplifier 2

Amp Out

RSSI

Channel

Amplifier 3

Wakeup

Main

Logic

SDI

Channel

Selector

Envelope Detector /

Data Slicer

Correlator

Manchester

Decoder

I/V

Bias

Xtal RTC

RC RTC

AS3932