AS3931 3D Low Power LF Wakeup Receiver0 pages

Datasheet
AS3931
3 D L o w P o w e r Wa k e u p R e c e i v e r

1 General Description
The AS3931 is an ultra low power, three channel LF ASK receiver
designed to operate in various applications such as LF identifications
systems and LF tag receivers. AS3931 detects a low frequency
ASK-modulated signal by looking for a digital wakeup pattern and
generates a WAKE signal after successful pattern detection. The
device incorporates an intelligent pattern detection algorithm that
provides reliable operation in presence of strong interference. An
RSSI signal can be generated at the RSSI pin for each receiver
channel.

Error tolerant digital pattern correlator that detects a given code
sequences in the received data signal and generates a wakeup
signal.
Sophisticated power management logic that powers down the
correlator if no data is received.

2 Key Features
Programmable Serial Data Interface
Flexible carrier frequencies

The product is available in 16-pin TSSOP package.

Three axis wakeup pattern detection

The AS3931 contains:

Three axis LF field strength measurement

Antenna rotation switch

Antenna rotation for easy calibration

Three independent LF receiver chains

High sensitivity and high dynamic range

Wakeup output combining the three receiver chains

Wide operating frequency range

Low power 32.768kHz crystal oscillator circuit

Reliable, interference resistant wakeup decoding

Serial programming interface

Highly protected differential inputs

Voltage regulator with 2.4V output, on/off switchable

Ultra low power consumption

Each independent LF receiver chain contains:

Automotive qualified

Input overload protection

16-pin TSSOP package

Input attenuator
Ultra low power LF amplifier with logarithmic envelope output
Robust data detector with adaptive slicing threshold that
translates the logarithmic envelope into a digital data signal.

3 Applications
The device is ideal for LF identification systems, LF tag receivers,
three dimensional LF field strength measurement systems, and Ultra
low power wake up systems.

Figure 1. Typical Application Diagram
VCC

CBAT

RP
CREG

Receiving Antennas

Transmitting
Antenna

VREG

LF1N

RSSI

RSSI

LF1P

SDA

DATA

SCL

CLOCK

LF2N
LF2P

AS3931

VCC

CHIP SEL

CS

LF3N
LF3P

XOUT

GND

WAKE

WAKE

XIN

XTAL

CA

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Revision 6.2

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