AS3931 Datasheet

austriamicrosystems AG
is now
ams AG
The technical content of this austriamicrosystems datasheet is still valid.
Contact information:
Headquarters:
ams AG
Tobelbaderstrasse 30
8141 Unterpremstaetten, Austria
Tel: +43 (0) 3136 500 0
e-Mail: ams_sales@ams.com
Please visit our website at www.ams.com
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
Error tolerant digital pattern correlator that detects a given code
sequences in the received data signal and generates a wakeup
signal.
1 General Description
2 Key Features
Programmable Serial Data Interface
Flexible carrier frequencies
The product is available in 16-pin TSSOP package.
The AS3931 contains:
Antenna rotation switch
Three axis wakeup pattern detection
Three axis LF field strength measurement
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
Input attenuator
al
id
Sophisticated power management logic that powers down the
correlator if no data is received.
am
lc s
on A
te G
nt
st
ill
v
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.
16-pin TSSOP package
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.
Receiving Antennas
Te
Transmitting
Antenna
VCC
CBAT
RP
CREG
VCC
VREG
LF1N
RSSI
RSSI
LF1P
SDA
DATA
SCL
CLOCK
LF2N
LF2P
AS3931
ch
ni
ca
Figure 1. Typical Application Diagram
CHIP SEL
CS
LF3N
WAKE
LF3P
XOUT
GND
XIN
WAKE
XTAL
CA
www.austriamicrosystems.com/AS3931
Revision 6.2
CB
1 - 30
AS3931
Datasheet - C o n t e n t s
Contents
1 General Description
.................................................................................................................................................................. 1
2 Key Features
............................................................................................................................................................................ 1
3 Applications
.............................................................................................................................................................................. 1
....................................................................................................................................................................... 4
4.1 Pin Descriptions
................................................................................................................................................................................... 4
5 Absolute Maximum Ratings
6 Electrical Characteristics
...................................................................................................................................................... 5
.......................................................................................................................................................... 6
7 Typical Operating Characteristics
7.1 RSSI Characteristic
al
id
4 Pin Assignments
............................................................................................................................................. 9
.............................................................................................................................................................................. 9
7.2 Temperature Dependence of RSSI
am
lc s
on A
te G
nt
st
ill
v
.................................................................................................................................................... 10
7.3 Supply Voltage Dependence of RSSI
7.4 Frequency Dependence of RSSI
................................................................................................................................................ 11
....................................................................................................................................................... 12
8 Detailed Description
............................................................................................................................................................... 13
8.1 Block Diagram
.................................................................................................................................................................................... 13
8.2 Block Description
............................................................................................................................................................................... 13
8.2.1 Antenna Rotator ......................................................................................................................................................................... 13
8.2.2 Input Attenuator ......................................................................................................................................................................... 13
8.2.3 Input Shortcutting ....................................................................................................................................................................... 13
8.2.4 Input Protection Circuit .............................................................................................................................................................. 13
8.2.5 Logarithmic Envelope Amplifiers ............................................................................................................................................... 14
8.2.6 Detectors ................................................................................................................................................................................... 14
8.2.7 Digital Correlators ...................................................................................................................................................................... 14
8.2.8 Wake Generator ........................................................................................................................................................................ 14
8.2.9 Crystal Oscillator ........................................................................................................................................................................ 14
8.2.10 Regulator ................................................................................................................................................................................. 14
8.2.11 Power On Reset (POR) ........................................................................................................................................................... 14
8.3 Basic Operation
.................................................................................................................................................................................. 15
LF Transmission Protocol .......................................................................................................................................................... 15
Wake Up Detection .................................................................................................................................................................... 16
WAKE Signal Clearing ............................................................................................................................................................... 16
WAKE Signal After POR ............................................................................................................................................................ 16
RSSI Operation .......................................................................................................................................................................... 16
ca
8.3.1
8.3.2
8.3.3
8.3.4
8.3.5
ni
8.4 Serial Programming Interface Timing
8.5 Input Signal Waveform Definition
9 Configuring the Product
....................................................................................................................................................... 17
.......................................................................................................................................................... 18
ch
9.1 Serial Programming Interface
9.2 Power On Register
................................................................................................................................................. 16
............................................................................................................................................................ 18
............................................................................................................................................................................. 18
Te
9.2.1 P0, P1, P2 (Channel Enable) ..................................................................................................................................................... 19
9.2.2 P3 (Regulator Enable) ............................................................................................................................................................... 19
9.2.3 P4, P5 (Antenna Rotator/Input Shortcut) ................................................................................................................................... 19
9.3 RSSI Channel Select Register
9.3.1
9.3.2
9.3.3
9.3.4
........................................................................................................................................................... 19
C0, C1 (RSSI Channel Select) .................................................................................................................................................. 20
C2, C3 (RSSI Output Mode) ...................................................................................................................................................... 20
C4 (Channel Attenuator) ............................................................................................................................................................ 20
C5 (WAKE Clear) ....................................................................................................................................................................... 21
www.austriamicrosystems.com/AS3931
Revision 6.2
2 - 30
AS3931
Datasheet - C o n t e n t s
9.4 Test Mode Register
9.4.1
9.4.2
9.4.3
9.4.4
9.4.5
............................................................................................................................................................................ 21
T0 (Test Mode Enable) .............................................................................................................................................................. 21
T1, T2 (Test Mode Select) ......................................................................................................................................................... 21
T3 ............................................................................................................................................................................................... 22
T4 (RSSI Step Select) ............................................................................................................................................................... 22
T5 (Wake Generator On/Off) ..................................................................................................................................................... 22
9.5 Correlator Mode Register
................................................................................................................................................................... 22
al
id
M0 (Correlator Off) ..................................................................................................................................................................... 23
M1 (Single/Double Wake Pattern) ............................................................................................................................................. 23
M2, M3 (Zero-Half-Bit Detection Mode) ..................................................................................................................................... 23
M4 (Detector Time Constant) .................................................................................................................................................... 23
M5 .............................................................................................................................................................................................. 23
10 Extended Operation
.............................................................................................................................................................. 24
am
lc s
on A
te G
nt
st
ill
v
9.5.1
9.5.2
9.5.3
9.5.4
9.5.5
10.1 Power Management
10.1.1
10.1.2
10.1.3
10.1.4
10.1.5
10.1.6
10.1.7
......................................................................................................................................................................... 24
Sleep Mode .............................................................................................................................................................................. 24
Standby Mode .......................................................................................................................................................................... 24
Receive Mode .......................................................................................................................................................................... 24
Regulator On/Off ...................................................................................................................................................................... 24
Typical Current Consumption in Different Modes .................................................................................................................... 24
RSSI Step ................................................................................................................................................................................ 24
Antenna Rotation ..................................................................................................................................................................... 24
10.2 Input Attenuation and Input Shortcutting
10.3 WAKE Signal at the RSSI Pin
10.4 Single WAKE Operation
.......................................................................................................................................... 24
.......................................................................................................................................................... 25
................................................................................................................................................................... 25
10.5 Using the Wake Generator
............................................................................................................................................................... 25
10.6 Direct DATA Mode
............................................................................................................................................................................ 26
10.7 Correlator Modes
............................................................................................................................................................................. 26
10.8 Threshold Adaptation Filter Time Constant
10.9 RSSI and WAKE Pin Modes
11 Package Drawings and Markings
......................................................................................................................................... 27
............................................................................................................................................................. 29
Te
ch
ni
ca
12 Ordering Information
...................................................................................................................................... 26
............................................................................................................................................................ 26
www.austriamicrosystems.com/AS3931
Revision 6.2
3 - 30
AS3931
Datasheet - P i n A s s i g n m e n t s
4 Pin Assignments
VCC
1
16
VREG
LF1N
2
15
RSSI
LF1P
3
14
SDA
LF2N
4
13
SCL
LF2P
5
12
CS
LF3N
6
11
WAKE
LF3P
7
10
XOUT
GND
8
9
XIN
am
lc s
on A
te G
nt
st
ill
v
AS3931
al
id
Figure 2. Pin Assignments 16-pin TSSOP Package
4.1 Pin Descriptions
Pin Name
VCC
LF1N
LF1P
LF2N
LF2P
LF3N
LF3P
GND
XIN
XOUT
WAKE
CS
Pin
Number
1
2
3
4
5
6
7
8
9
10
11
12
13
ni
SCL
Pin
Type
Supply Input
Analog Input
Analog Input
Analog Input
Analog Input
Analog Input
Analog Input
Ground
Analog Input
Analog Output
Open Drain
Digital Input with
Pulldown
Digital Input with
Pulldown
Digital Input with
Pulldown
Analog/Digital
output
Analog Output
Description
Positive Supply Voltage
Channel 1 negative input
Channel 1 positive input
Channel 2 negative input
Channel 2 positive input
Channel 3 negative input
Channel 3 positive input
Negative Supply Voltage
Crystal Oscillator Pin 1
Crystal Oscillator Pin 2
Wake Up Detect output/Reset output
ca
Table 1. Pin Descriptions
14
RSSI
15
VREG
16
Serial Clock
Serial Data
Received Signal Strength Indicator signal/
Digital Test mode signal output
Regulator Output Voltage
Te
ch
SDA
Chip Select
www.austriamicrosystems.com/AS3931
Revision 6.2
4 - 30
AS3931
Datasheet - A b s o l u t e M a x i m u m R a t i n g s
5 Absolute Maximum Ratings
Stresses beyond those listed in Table 2 may cause permanent damage to the device. These are stress ratings only. Functional operation of the
device at these or any other conditions beyond those indicated in Section 6 Electrical Characteristics on page 6 is not implied. Exposure to
absolute maximum rating conditions for extended periods may affect device reliability.
Table 2. Absolute Maximum Ratings
Max
Units
Positive supply voltage
(VCC)
-0.5
5.5
V
Analog ground
(GND)
0
0
V
Voltage at any pin except pin 2 to pin 7 (VIN)
GND-0.5
VCC+0.5
V
Notes
al
id
Min
am
lc s
on A
te G
nt
st
ill
v
Parameter
Voltage at Pin 2 to Pin 7
(VIN)
GND-0.5
GND+0.5
V
Input current (Latchup Immunity)
(Iin)
-100
+100
mA
JEDEC 78
Electrostatic discharge
(VESD)
1000
V
Norm: MIL 883 E method 3015
HBM: R=1.5 kΩ, C=100 pF
Total power dissipation
(Ptot)
300
mW
125
ºC
Storage temperature
(Tstg)
-55
Package body temperature
(Tbody)
Humidity non-condensing
5
Moisture Sensitive Level
Operating Ambient Temperature Range
(TAMB)
+260
ºC
85
%
3
-20
The reflow peak soldering temperature (body
temperature) specified is in accordance with IPC/
JEDEC J-STD-020 “Moisture/Reflow Sensitivity
Classification for Non-Hermetic Solid State
Surface Mount Devices”.
The lead finish for Pb-free leaded packages is
matte tin (100% Sn).
Represents a maximum floor life time of 168h
+65
ºC
ca
Recommended Operating Conditions
2.6
5.5
V
Regulator used
Positive supply voltage
(VCC)
2.4
3.5
V
Regulator not used
Analog Ground
(GND)
0
0
V
Te
ch
ni
Positive supply voltage
(VCC)
www.austriamicrosystems.com/AS3931
Revision 6.2
5 - 30
AS3931
Datasheet - E l e c t r i c a l C h a r a c t e r i s t i c s
6 Electrical Characteristics
TAMB = -20° to +65° C, VCC = 3.0 V, fIN = 20 kHz, register settings as after POR, CS = low, transmission protocol according to Figure 15,
Figure 16 and application circuit according to Figure 1 unless otherwise specified.
Table 3. Electrical Characteristics
Parameter
Conditions
Min
Typ
General
fIN
LF input carrier frequency
range
BR
Half-bit rate
BM
Manchester Bit Rate
W
Manchester Code Word
NPRE
Preamble half-bits
VREG
Regulator Voltage
TPOR
Power On Reset time
19
1
4
kHz
2.758
kB/s
1.379
kB/s
6
VCC = 2.6 V to 5.5 V
2.30
VCC = 2.4 V to 5.5 V
5
regulator off,
VCC = 2.4V to
3.5V;
TAMB = 27° C
operating current
ca
regulator on,
RSSI-step =
low;
TAMB = 27° C
RSSI buffer operating
IBUF
7
ni
current
8
ch
VCC transient compliance
Te
Differential small sig. input
impedance
crystal oscillator frequency
www.austriamicrosystems.com/AS3931
hex
8
regulator on,
TAMB = 27° C
fXTAL
1.365
150
96
5
ICC
ZIN
1.352
3
regulator off,
VCC = 2.4 V;
TAMB = 27° C
ΔVCC
2.731
Units
am
lc s
on A
te G
nt
st
ill
v
2
2.704
Max
al
id
Symbol
2.4
2.60
V
ms
sleep mode
0.3
µA
standby mode
6.5
µA
receive mode
6.7
µA
sleep mode
0.5
standby mode
6.8
sleep mode
0.8
1.5
µA
standby mode
7.0
8.8
µA
receive mode
7.2
9
µA
standby mode
6.6
No load at RSSI-Pin
2
8
recovery time = 10 ms; regulator on ,
2.6 V < VCC < 5.5 V for VCC after step
8
recovery time = 10 ms; regulator off ;
2.4 V < VCC < 5.5 V for VCC before step
µA
2
V
0.3
V
normal operation; TAMB = 27º
2
MΩ
input attenuator active;
TAMB = 27º
1.5
kΩ
input shortcutting active;
TAMB = 27º
0.5
kΩ
32.768
kHz
Crystal type: CC4 from MicroCrystal
Revision 6.2
9
6 - 30
AS3931
Datasheet - E l e c t r i c a l C h a r a c t e r i s t i c s
Table 3. Electrical Characteristics
Symbol
Parameter
Conditions
Min
Typ
Max
Units
WAKEUP
Vin,max
maximum differential input
voltage for wake
up
10
detection
IWAKE
WAKE pin current
VRSSI
RSSI output voltage range
VRSSI0
RSSI output voltage
(RSSI offset)
350
NPRE = 8
trise,tfall < 150 µs;
10
detection
VREG = 2.4 V to 3.5 V
µVpp
11
al
id
minimum differential input
voltage for wake up
Vin,min
Voltage at WAKE pin:
VOL < 0.4 V;
11
Vpp
0.33
mA
am
lc s
on A
te G
nt
st
ill
v
VREG = 2.4 V to 3.5 V
1
RSSI
0.5
12
VIN = 0;
0.5
0.76
VIN = 1 mVpp;
100
290
0.3
VSTEP
RSSI output voltage step
VLOG
logarithmic input voltage
range
VIN = 1 mVpp, RSSI step = high
SRSSI
RSSI slope in log. range
RSSI step = high
CRSSI
cap. loading of RSSI pin
IRSSI
RSSI buffer output current
Tstep
RSSI voltage step time
13
ca
RSSI Ripple Voltage
1.2
V
mV
12
Input signal amplitude
100 mVpp; CS from low to high
(Buffer activation in presence of
a strong input signal);
mV
mV/dB
10
pF
5
µA
350
µs
350
µs
channel switching from ChA(100
mVpp) to
14
VRIP
V
300
RSSI buffer active
CL = 10 pF,
RL = 1 MΩ;
1.7
ChB (0 mVpp) ,
with CS deactivation of
10 µs
RSSI buffer active, CL = 10 pF, RL = 1 MΩ;
VIN = 1 mVpp ;
70
mV
Digital input L level
ch
VIL
ni
Serial Programming Interface
Te
VIH
IIH
Digital input H level
Digital Input current
Pins SCL, SDA, CS;
11
VREG = 2.4 V to 3.5 V
Pins SCL, SDA, CS
11
VREG
0.7 *
VREG = 2.4 V to 3.5 V
VREG
Pins SCL, SDA, CS
VIH = 2.4 V;
30
11
VREG = 2.4 V to 3.5 V
V
11
60
100
µA
2
µs
11
500
ns
11
500
ns
Clock period
VREG = 2.4 V to 3.5 V
TCH
Clock high duration
VREG = 2.4 V to 3.5 V
TCL
Clock low duration
VREG = 2.4 V to 3.5 V
Revision 6.2
V
11
TCLK
www.austriamicrosystems.com
0.3 *
11
7 - 30
AS3931
Datasheet - E l e c t r i c a l C h a r a c t e r i s t i c s
Table 3. Electrical Characteristics
Parameter
Conditions
Min
TDVCH
Data valid to pos. Clock
edge
VREG = 2.4 V to 3.5 V
TCHDI
pos. Clock edge to Data
invalid
VREG = 2.4 V to 3.5 V
TSHCH
Select active to pos. Clock
edge
VREG = 2.4 V to 3.5 V
TCHSL
pos. Clock to Select
inactive
VREG = 2.4 V to 3.5 V
TSL
Select low time
VREG = 2.4 V to 3.5 V
11
Max
100
11
100
11
100
11
500
Units
ns
100
11
ns
ns
ns
ns
am
lc s
on A
te G
nt
st
ill
v
1. The half-bit rate correlates with the crystal oscillator clock frequency fclk as follows: BR = fCLK/12
Typ
al
id
Symbol
2. The Manchester bit rate correlates with the Half-Bit Rate as follows: BM = BR/2
3.
4.
5.
6.
Code word can be changed by metal option
8 preamble half-bits are equivalent to 4 manchester bits
VREG output may not be used as a supply for other circuits
This is the internal Power on Reset time generated by the chip. To ensure proper start-up conditions, the supply voltage VCC must be
ramped up to its final value during TPOR
7. This is the additional operating current when the RSSI buffer is activated without load
8. ΔVCC means a hard step of the supply voltage down to a lower value by an amount of ΔVCC; after such a step, the analog circuits in the
chip take some time to recover for working properly again. The maximum step value is listed.
9. Crystal tolerance: 100ppm
10.Values refer to production test
11.If regulator is on, then VREG = 2.4 V; If regulator is off, then VREG = VCC, where VCC = 2.4 V to 3.5 V
Te
ch
ni
ca
12.The RSSI step is the change of the RSSI output voltage when the input signal amplitude changes from 0 to specified value
13.Time to step from initial RSSI value to 95% of the final value
14.ChA may be any channel 1 – 3, whereas ChB may be any other remaining channel.
www.austriamicrosystems.com
Revision 6.2
8 - 30
AS3931
Datasheet - Ty p i c a l O p e r a t i n g C h a r a c t e r i s t i c s
7 Typical Operating Characteristics
All graphs refer to Tab = 27°C and VREG = 2.4 V, unless otherwise stated.
7.1 RSSI Characteristic
Figure 3. RSSI-Characteristic VRSSI [V] vs Vin [Vpp]
al
id
1.70
1.60
am
lc s
on A
te G
nt
st
ill
v
1.50
1.40
1.30
1.20
1.10
1.00
900m
800m
100µ
10m
100m
1
Te
ch
ni
ca
1m
www.austriamicrosystems.com/AS3931
Revision 6.2
9 - 30
AS3931
Datasheet - Ty p i c a l O p e r a t i n g C h a r a c t e r i s t i c s
7.2 Temperature Dependence of RSSI
Figure 4. RSSI-step [V] @ Vin = 1 mVpp and 2 mV
vs temp [deg C]
Figure 5. RSSI-step [V] @ Vin = 300 µVpp and offset
vs. temp [deg C]
410m
920m
390m
900m
880m
370m
al
id
860m
350m
840m
330m
820m
800m
310m
70.0m
290m
am
lc s
on A
te G
nt
st
ill
v
69.0m
270m
68.0m
250m
67.0m
230m
210m
66.0m
-20
-10
0.0
10
20
30
temp
40
50
60
70
-20
Figure 6. RSSI-step [V] @ Vin = 1 mV and 2 mV vs.
temp [deg C], reduced step
290m
65.0m
-10
0.0
10
20
30
40
50
60
70
Figure 7. RSSI-step [V] @ Vin=300µ Vpp and offset
vs. temp [deg C], reduced step
1.020
1.010
1.000
270m
VIN = 0 (offset)
990.0m
980.0m
250m
970.0m
960.0m
230m
950.0m
45.0m
210m
44.0m
190m
170m
VIN = 300µ VPP
43.0m
-10
0.0
10
20
30
temp
40
50
60
70
42.0m
-20
-10
0.0
10
20
30
40
50
60
70
Te
ch
ni
-20
ca
150m
www.austriamicrosystems.com/AS3931
Revision 6.2
10 - 30
AS3931
Datasheet - Ty p i c a l O p e r a t i n g C h a r a c t e r i s t i c s
7.3 Supply Voltage Dependence of RSSI
Figure 8. RSSI-step [V] @ Vin = 1 mVpp and 2 mV
vs. VCC [V]
410m
Figure 9. RSSI-step [V] @ Vin = 300 µVpp and offset
vs. VCC [V]
87.0m
83.0m
390m
79.0m
370m
al
id
75.0m
71.0m
350m
67.0m
330m
2.00m
1.80m
310m
am
lc s
on A
te G
nt
st
ill
v
1.60m
290m
1.40m
1.20m
270m
1.00m
250m
800m
2.40
2.60
2.80
3.00
3.20
3.40
3.60
Figure 10. RSSI-step [V] @ Vin = 1 mVpp and 2 mV vs
VCC [V], reduced stepvs. VCC [V], reduced step
280m
2.40
2.60
2.80
3.00
3.20
3.40
3.60
Figure 11. RSSI-step [V] @ Vin =300 µVpp and offset
57.0m
55.0m
53.0m
260m
51.0m
49.0m
240m
47.0m
45.0m
43.0m
220m
2.10
1.90
200m
1.70
1.50
180m
1.30
2.80
3.00
3.20
3.40
3.60
900m
2.40
2.60
2.80
3.00
3.20
3.40
3.60
Te
ch
ni
2.60
ca
1.10
160m
2.40
www.austriamicrosystems.com/AS3931
Revision 6.2
11 - 30
AS3931
Datasheet - Ty p i c a l O p e r a t i n g C h a r a c t e r i s t i c s
7.4 Frequency Dependence of RSSI
Figure 12. RSSI-step [V] @ Vin = 1 mVpp vs. fin [Hz],
RSSI high step and low step
280m
260m
al
id
240m
220m
200m
180m
am
lc s
on A
te G
nt
st
ill
v
160m
140m
120m
100m
80.0m 10.k
1M
Te
ch
ni
ca
100.k
www.austriamicrosystems.com/AS3931
Revision 6.2
12 - 30
AS3931
Datasheet - D e t a i l e d D e s c r i p t i o n
8 Detailed Description
8.1 Block Diagram
LF3N
Log. Env. Amp 3
Detector3
Correlator3
Wake
WAKE
Multiplexer
Input
Attenuator3
LF3P
Correlator2
Wake3
Input
Protection3
Detector2
RSSI3
LF2N
Log. Env. Amp 2
am
lc s
on A
te G
nt
st
ill
v
LF2P
AS3931
al
id
Input
Attenuator2
RSSI2
Input
Protection2
Wake1
Detector1
LF1N
Correlator1
Wake2
Log. Env. Amp 1
Data1
LF1P
Input
Attenuator1
Data2
Antenna Rotator
Data3
Input
Protection1
RSSI1
Figure 13. Block Diagram
Control Logic
Data
Multiplexer
RSSI
Buffer
POR
XOUT
Regulator
VREG
GND
Regulator
XIN
VCC
RSSI
RSSI
Multiplexer
CS
SCL
SDA
Multiplexer
Wake Generator
8.2 Block Description
8.2.1
Antenna Rotator
Input Attenuator
ni
8.2.2
ca
In order to achieve an optimum assignment of the antennas to the receiving channels, the connection of the antennas to the channels can be
changed cyclically with a multiplexed (antenna rotator), which is controlled by an internal register. The register setting can be changed by the
serial interface.
ch
Input signal attenuation is provided for each channel by means of connecting a 1.5 kΩ resistor across the differential inputs. An internal register
controls attenuation.
8.2.3
Input Shortcutting
Te
The differential inputs can be shortened by register settings to measure the RSSI offset. In this case, the resistance between the differential
inputs is reduced to approximately 500 Ω.
8.2.4
Input Protection Circuit
Each signal input has a powerful input overload protection circuit consisting of two anti-parallel protection diodes connected to ground (see
Figure 14). This connection ensures that the differential input voltage can never exceed the supply voltage of the chip. To obtain proper
operation, the differential input receiving circuits (resonant RLC-circuits) must be floating and shall be grounded nowhere (see Figure 1)
www.austriamicrosystems.com/AS3931
Revision 6.2
13 - 30
AS3931
Datasheet - D e t a i l e d D e s c r i p t i o n
Figure 14. Input Protection Circuit
LFN
al
id
LFP
GND
8.2.5
Logarithmic Envelope Amplifiers
8.2.6
Detectors
am
lc s
on A
te G
nt
st
ill
v
The logarithmic envelope amplifiers amplify the ASK coded LF input signals. They generate Received Signal Strength Indicator (RSSI) signals,
which are proportional to the logarithm of the received field strengths within the specified dynamic range. These signals are used for data
detection and distance measurements. The RSSI signals are bandwidth limited to reduce noise influence. The slope of the amplifiers in the low
signal range can be controlled by register settings: a high slope for increased sensitivity but also increased current consumption and a weak
slope with reduced current consumption are possible.
The detectors convert the logarithmic envelope signal containing ASK coded data into digital signals. Each detector consists of a lowpass filter
for generation of an adaptive threshold and a slicing comparator. A preamble is required for a proper adaptation of the threshold prior to the
decision of the first valid data bit. A constant positive threshold offset is included in the comparator to ensure no data output in case of no input
signal. This increases the overall system noise immunity.
8.2.7
Digital Correlators
The AS3931 uses a 16-bit digital wakeup pattern. Digital correlators perform the identification of this pattern. They use a sophisticated detection
algorithm that provides high immunity against noise injection as a result of stochastic and periodic interference’s. The AS3931 provides the
possibility to double the length of the wake pattern to 32 bit. This is useful in environments with high noise levels to reduce the possibility of
spurious (parasitic) wakeups. In this case the usual wake pattern must be sent twice before a wake up is recognized and a WAKE signal is
generated. This active low WAKE signal is generated after successful pattern identification. Otherwise WAKE is high. Setting a register bit via the
serial-programming interface resets the correlators. In order to save power the correlators are stopped when no data has been received for a
specified amount of time. The correlators can be configured regarding their error tolerance by register settings.
8.2.8
Wake Generator
Crystal Oscillator
ni
8.2.9
ca
A counter, clocked by the 32 kHz crystal oscillator, generates an artificial wake up app. every 2 hours. This wake up can be used to manage the
quiescent current consumption of the AS3931. The idea behind is, to switch off one or more of the receiving channels in case of no true wake up
detection for long times; that is when only parasitic wakeups or no wakeup at all is detected. An external controlling unit (µC) can identify this
case by counting the parasitic wake ups and powering down one or more of the receiver channels to save current. When no wake ups are
detected at all, e.g. if the application device is stored in a stock, then the wake generator’s artificial parasitic wakeups (every 2 hours) can be
used to identify the situation.
ch
The crystal oscillator generates the clock signal for the digital correlators. It has been optimized for a 32.768 kHz quartz crystal connected to pins
XIN and XOUT. The oscillator provides extremely low current consumption, so it can be operated permanently by a battery.
8.2.10 Regulator
Te
A regulator is implemented to provide the amplifiers and digital circuits with a stable and clean supply. The regulator can be switched off; in this
case the external supply voltage is bypassed to the amplifiers and digital circuits. The regulator shall always be used for external supply voltages
higher then 3.3V, otherwise the current consumption is significantly increased. The regulated voltage can be seen at the VREG pin, but may not
be used to supply any other external circuits.
8.2.11 Power On Reset (POR)
A power on reset circuit guarantees proper circuit operation after power supply starts up. All internal registers are reset to their default states
after power on. After the Power On Reset time, the active low WAKE output is activated and set to low (Power On Wake Up). During the Power
On Reset time, the WAKE output pin is set to high. By this, it is ensured that this triggers the Power On Wake Up triggered only when the internal
registers are reset and ready to be programmed.
www.austriamicrosystems.com/AS3931
Revision 6.2
14 - 30
AS3931
Datasheet - D e t a i l e d D e s c r i p t i o n
8.3 Basic Operation
8.3.1
8.3.1.1
LF Transmission Protocol
Data Pattern
8.3.1.2
al
id
The AS3931 identifies a 16 half-bit binary coded data pattern, which is ASK-modulated on a LF carrier. The pattern must contain 8 LOGIC 0 halfbits and 8 LOGIC 1 half-bits in order to be DC free. Furthermore, for a proper detector threshold adaptation it has to be ensured that there are no
long groups of LOGIC 0 and LOGIC 1 half-bits. Therefore coding of the 16 half-bit binary data to 8 Manchester bits is common. This means that
8 consecutive half-bit pairs are grouped to Manchester bits whereas a Manchester bit 1 is a HIGH to LOW transition and a Manchester bit 0 is a
LOW to HIGH transition. The AS3931 supports the Manchester bit pattern 96 [hex] which in binary code is: 10 01 01 10 01 10 10 01. MSB is
transmitted first. The Manchester bit pattern i.e. the binary DATA pattern can be changed on demand by a metal mask modification.
Double Data Pattern
8.3.1.3
Wake Up Frame
am
lc s
on A
te G
nt
st
ill
v
To increase the immunity against parasitic wakeups, the data pattern necessary for a successful wakeup can be doubled by programming the
AS3931: if the double data pattern is used, the pattern 96 has to be sent twice; after recognition of the first data pattern, the second data pattern
has to be sent immediately after the first one, otherwise no WAKE signal is generated. For the timing see Wake Up Frame on page 15. Setting
the bit M1 to 1 can program the double data pattern feature.
The Wake Up Frame of AS3931 consists of a preamble used for detector threshold adaptation followed by the DATA pattern once (normal or
single Wake Up) or twice (double Wake Up) to be identified. We recommend a transmission protocol as shown on Figure 15 and Figure 16. The
preamble consists of a half-bit pattern 1010... with a specified number NPRE of half-bits (NPRE must be an even number in order to get complete
1/0 pairs). NPRE depends on the application and has influence on the wakeup and overload sensitivity. We recommend a minimum of NPRE = 8
half-bits (according to 4 manchester bits “1”).
Figure 15. Wake Up Frame of AS3931 with Single WAKE Data Pattern
LF Carrier
Amplitude
Preamble
NPRE half- bits
ca
WAKE
Data 96
5.86 ms (16 half-bits)
ni
Figure 16. Wake Up Frame of AS3931 with Double WAKE Data Pattern
Te
ch
LF Carrier
Amplitude
Preamble
NPRE half-bits
Data 96
5.86 ms (16 half-bits)
Data 96
5.86 ms (16 half-bits)
WAKE
www.austriamicrosystems.com/AS3931
Revision 6.2
15 - 30
AS3931
Datasheet - D e t a i l e d D e s c r i p t i o n
8.3.2
Wake Up Detection
A WAKE signal is generated if and only if all 8 LOGIC 1 half-bits and a predefined number of LOGIC 0 half-bits have been identified as correct.
The wakeup detection criteria can be changed: the number of invalid zero half-bits can be programmed from 0 to 3. A valid Wake Up Frame can
be detected at only one of the 3 channels or at more then one channel simultaneously. The single WAKE signals of each channel are ored
together to a common WAKE signal Figure 13.
WAKE Signal Clearing
am
lc s
on A
te G
nt
st
ill
v
8.3.3
al
id
In case of using the double wake up feature, the settings of the allowed zero half-bit errors apply for each of the sent data pattern individually.
E.g. if you configure the AS3931 to allow 2 zero half-bit errors, the first data pattern can contain up to two invalid zero half-bits as well as the
second data pattern, but it is not possible that the first pattern contains 3 and the second data pattern contains one zero half-bit error (what in
total would give the same number of allowed zero half-bit errors as before). Note that a Double-Wake-Pattern detection is possible also if the two
consecutive Single-Wake-Patterns are assigned to different channels: e.g. if the first pattern is recognized at channel 2 and the second pattern is
recognized at channel 3, then a Double-Wake-Pattern is recognized and the WAKE Pin is activated. All channel combinations are possible. In
case of different channels, it is not possible to decide which channel received the first and which channel received the second data pattern.
After a Wake Up detection, the WAKE output signal must be reset via the Serial Programming Interface. This is done by toggling the bit C5 in the
Channel Select register from low to high and vice versa. This is valid for both cases the Single Wake pattern and the Double Wake pattern
detection. Furthermore, it is also valid for an internal generated Artificial Wakeup (see Extended Operation on page 24).
8.3.4
WAKE Signal After POR
After a power on reset (POR), the WAKE signal is activated (LOW). Therefore, after startup the WAKE signal must be cleared as if a valid Wake
Up would have been detected.
8.3.5
RSSI Operation
The RSSI signal of a selected channel can be measured at the RSSI pin. Each channel can be selected by register settings. To calibrate the
RSSI measurement, the LF inputs can be shortcutted with approximately 500 Ω by internal register settings. Doing so, the RSSI voltage offset
can be measured. The RSSI – signal is buffered at the RSSI pin. The buffer can be deactivated by register settings; in this case the RSSI pin is
tristated (high impedance). However, if the CS signal is not activated, the RSSI pin is tristated. This has to be kept in mind when programming
the AS3931 via the Serial Programming Interface (the CS signal is used to latch the serial data into the selected register at the falling edge of
CS).
8.4 Serial Programming Interface Timing
Figure 17. SPI Timing Waveforms
TSHCH
TCLK
SCL
ca
TDVCH
TCL
ni
TCH
TCHSL
ch
TCHDI
A0
A1
D4
Te
SDA
D5
TSL
CS
www.austriamicrosystems.com/AS3931
Revision 6.2
16 - 30
AS3931
Datasheet - D e t a i l e d D e s c r i p t i o n
8.5 Input Signal Waveform Definition
Figure 18. Input Signal Waveform
Vin
tfall
0.9*Vin
Te
ch
ni
ca
am
lc s
on A
te G
nt
st
ill
v
0.1*Vin
al
id
trise
www.austriamicrosystems.com/AS3931
Revision 6.2
17 - 30
AS3931
Datasheet - C o n f i g u r i n g t h e P r o d u c t
9 Configuring the Product
9.1 Serial Programming Interface
The AS3931 is programmed via an unidirectional three wire Serial Programming Interface.The 3 lines are:
CS: Chip Select, used for selecting AS3931 and for data latching
SCL: Serial Clock
al
id
SDA: Serial Data
A block of 8 bit data starting with the LSB is sent according to the diagram shown in Figure 19. The received block of 8 bit data is shifted into an
8 bit latch. The two LSBs are register address bits and the remaining 6 bits are data bits. The register address bits A1 and A0 are decoded and
the 6 data bits are stored into one of three 6 bit registers with the falling edge of CS.
CS
am
lc s
on A
te G
nt
st
ill
v
Figure 19. Protocol of 8 Bit Data Serial Transmission
ADDRESS
SDA
SCL
A0
DATA
A1
D0
D1
D2
D3
D4
D5
D = P : POWER ON REGISTER
D = C : CHANNEL SELECT REGISTER
D = T : TEST MODE REGISTER
D = M: CORRELATOR MODE REGISTER
9.2 Power On Register
Bit
P0
P1
P2
P3
Description
1
Enable Channel 1
1
Enable Channel 2
ni
P4
POR state
ca
Table 4. Register Data
P5
1
Enable Channel 3
1
Enable Regulator
0
Antenna Rotator Bit 1
0
Antenna Rotator Bit 2
Te
ch
Table 5. Register Address
Bit
Value
A0
0
A1
0
www.austriamicrosystems.com/AS3931
Revision 6.2
18 - 30
AS3931
Datasheet - C o n f i g u r i n g t h e P r o d u c t
9.2.1
P0, P1, P2 (Channel Enable)
If the bit P0, P1 or P2 is set to 1, the related channel is enabled. That means, the logarithmic envelope amplifier and the correlator are enabled
and ready to receive a Wake Up Frame. When disabled, the channel is off, taking no current except for the bias cell to the amplifier. After a power
on, all channels are enabled.
Note: Shaded cells show POR-states
9.2.2
P0, P1, P2
Mode
0
Channel Disabled
1
Channel Enabled
al
id
Table 6. P0, P1, P2 Bit Mode
P3 (Regulator Enable)
Table 7. P3 Bit Mode
9.2.3
am
lc s
on A
te G
nt
st
ill
v
Bit P3 enables the regulator (VREG 2.4 V) or switches off the regulator (VREG = VCC). If the regulator is switched off, then the voltage at Pin
VCC is bypassed unregulated to the internal circuits. After a power on, the regulator is on.
P3
Mode
0
Regulator Disabled
1
Regulator Enabled
P4, P5 (Antenna Rotator/Input Shortcut)
Bits P4 and P5 are used to set the Antenna Connection Mode or to shortcut the differential inputs of each amplifier. See Table 28 for the
description of the rotator modes.
Table 8. P4, P5 Bit Mode
P4
P5
Mode
0
Connection Mode1
0
Connection Mode2
1
Connection Mode3
1
Amplifier Inputs Shorted
Connection Mode1
Connection Mode2
Connection Mode3
Antenna 1 → Channel 1
Antenna 2 → Channel 1
Antenna 3 → Channel 1
Antenna 2 → Channel 2
Antenna 3 → Channel 2
Antenna 1 → Channel 2
Antenna 3 → Channel 3
Antenna 1 → Channel 3
Antenna 2 → Channel 3
Bit
POR state
Description
C0
0
RSSI select Bit 1
C1
0
RSSI select Bit 2
C2
0
RSSI output mode Bit 1
C3
0
RSSI output mode Bit 2
C4
0
Channel attenuator
C5
0
WAKE clear
0
1
0
1
ni
ca
Table 9. Antenna Rotation Modes
ch
9.3 RSSI Channel Select Register
Te
Table 10. Register Data
www.austriamicrosystems.com/AS3931
Revision 6.2
19 - 30
AS3931
Datasheet - C o n f i g u r i n g t h e P r o d u c t
Table 11. Register Address
9.3.1
Bit
Value
A0
1
A1
0
C0, C1 (RSSI Channel Select)
Table 12. C0, C1 Bit Mode
C1
Mode
0
0
Channel 1
0
1
am
lc s
on A
te G
nt
st
ill
v
C0
1
9.3.2
al
id
Bits C0 and C1 are used to select the channel whose RSSI signal is multiplexed to the RSSI pin. In case of both bits C0 and C1 set to 1, a
bandgap voltage VBG (1.25 V) appears at the RSSI pin. After power on, channel 1 is selected.
0
Channel 2
1
Channel 3
1
VBG (T0=0), WAKE (T0=1)
C3
RSSI Pin Function
0
high Z
0
Analog output: RSSI of selected channel or
VBG
1
Digital output: WAKE,
single WAKE or DATA
1
not used
C2, C3 (RSSI Output Mode)
Bits C2 and C3 define the RSSI pin function.
Table 13. C2, C3 Bit Mode
C2
0
1
0
1
Note: The RSSI pin function also depends on the signal CS. If CS = 0, the RSSI pin is always in the high impedance state. This is also the
case after power on.
9.3.3
ca
The WAKE or single WAKE function is selected together with bits T0 – T2 and C0 – C1. For more information see Extended Operation
on page 24
C4 (Channel Attenuator)
ni
When bit C4 is set, a resistor (app. 1.5 kΩ) is connected across the differential inputs of each channel. This resistor reduces the Q-factor of the
antenna resonant circuit; therefore the received signal is reduced too. The amount of damping depends on the Q-factor of the antenna circuit.
C4
Mode
0
Input attenuators disabled
1
Input attenuators enabled
Te
ch
Table 14. C4 Bit Mode
www.austriamicrosystems.com/AS3931
Revision 6.2
20 - 30
AS3931
Datasheet - C o n f i g u r i n g t h e P r o d u c t
9.3.4
C5 (WAKE Clear)
Bit C5 is used to reset the active low WAKE pin after the pin has been set as a result of receiving a valid code word (single or double wake
pattern) by one of the 3 channels, a POR or an internally generated Wakeup. Setting Bit C5 to 1, the WAKE pin is reset to high and held in high
state, to enable the channels for the next wake up signal, the bit C5 must be toggled to 0 afterwards. After power on, the WAKE-pin is activated
and the bit C5 has to be toggled high and low after a power on.
C5
Mode
0
no effect
1
WAKE=H
al
id
Table 15. C5 Bit Mode
Table 16. Register Data
Bit
T0
T1
T2
T3
T4
T5
Table 17. Register Address
9.4.1
am
lc s
on A
te G
nt
st
ill
v
9.4 Test Mode Register
POR state
Description
0
Test mode enable
0
Test mode select Bit 1
0
Test mode select Bit 2
0
not used
1
RSSI step
0
WAKE Generator on/off
Bit
Value
A0
0
A1
1
T0 (Test Mode Enable)
Bit T0 is used to define the pin function of the WAKE pin. When bit T0 is reset to 0, the WAKE pin is used for normal Wake Up detection (Single
or Double Wakeup from the receiver channels or internally generated wakeup). When bit T0 is set to 1, testmode signals are multiplexed to the
WAKE pin according to the selected test mode (T1, T2). After power on, the normal wake up detection mode is selected.
ca
Table 18. T0 Bit Mode
WAKE Pin function
0
WAKE
1
Test Mode Signals
ni
9.4.2
T0
T1, T2 (Test Mode Select)
ch
When bit T0 is set to 1, the following signals can be mapped to the WAKE pin. For signal description (see Figure 13).
DATA: received bit stream of the selected channel
WAKE: detected wake up of the selected channel
Te
For the DATA and WAKE signal select the desired channel by setting Bits C0 and C1.
Table 19. T1, T2 Bit Mode
T1
T2
WAKE Pin Function
0
0
DATA of selected channel
1
0
WAKE of selected channel
www.austriamicrosystems.com/AS3931
Revision 6.2
21 - 30
AS3931
Datasheet - C o n f i g u r i n g t h e P r o d u c t
Table 19. T1, T2 Bit Mode
9.4.3
T1
T2
WAKE Pin Function
0
1
not used
1
1
not used
T3
9.4.4
al
id
Not used; must always be programmed to 0 by the user!
T4 (RSSI Step Select)
Bit T4 is used to switch between a high and a low RSSI step. For more information on RSSI steps see Extended Operation on page 24.
Table 20. T4 Bit Mode
Mode
0
Low RSSI step
1
High RSSI step
am
lc s
on A
te G
nt
st
ill
v
9.4.5
T4
T5 (Wake Generator On/Off)
Bit T5 is used to activate the Wake Generator. If activated, an artificial parasitic wakeup is generated every 2 hours.
Table 21. T5 Bit Mode
T5
Mode
0
Wake Generator off
1
Wake Generator on
9.5 Correlator Mode Register
Table 22. Register Data
Bit
M0
M1
M2
M4
M5
ca
M3
POR state
Description
0
Correlator Off
0
single/double wake pattern
0
Zero-Bit Detection Mode bit1
1
Zero-Bit Detection Mode bit2
1
detector threshold τ select
0
not used
Bit
Value
A0
1
A1
1
Te
ch
ni
Table 23. Register Address
www.austriamicrosystems.com/AS3931
Revision 6.2
22 - 30
AS3931
Datasheet - C o n f i g u r i n g t h e P r o d u c t
9.5.1
M0 (Correlator Off)
Bit M0 is used to simultaneously turn off all 3 correlators. This is done by turning off the correlator clocks. This can be used to reduce power
consumption when the Direct Data Mode is used.
9.5.2
M0
Mode
0
Low RSSI step
1
High RSSI step
M1 (Single/Double Wake Pattern)
Bit M1 selects the number of data patterns that are necessary for wakeup detection.
9.5.3
am
lc s
on A
te G
nt
st
ill
v
Table 25. M1 Bit Mode
al
id
Table 24. M0 Bit Mode
M1
Mode
0
Single Data pattern
1
Double Data pattern
M2, M3 (Zero-Half-Bit Detection Mode)
Bits M2 and M3 select the number of Zero-Half-bits that are allowed to be invalid. A high level of allowed invalid Zero-Half-bits increases the error
tolerance related to noise or interference’s, that means that the probability for the detection of a valid WAKE pattern increases. Note that in turn
the immunity against parasitic wakeups (WAKE detection when no data has been sent, due to noise or interference’s) is reduced.
Table 26. M2, M3 Bit Mode
M2
0
1
0
1
9.5.4
M3
WAKE Pin Function
0
3 invalid Zero-bits allowed
0
2 invalid Zero-bits allowed
1
1 invalid Zero-bits allowed
1
0 invalid Zero-bits allowed
M4 (Detector Time Constant)
Bit M4 is used to switch between a large and a small τ of the detector threshold adoption filter. A large τ is recommended, because it increases
the noise margin. A small τ can be used to improve the wake sensitivity when non-specified wake-patterns are used.
ca
Table 27. M4 Bit Mode
M5
Mode
0
small τ
1
large τ
ni
9.5.5
M4
Te
ch
Not used; must always be programmed to 0 by the user!
www.austriamicrosystems.com/AS3931
Revision 6.2
23 - 30
AS3931
Datasheet - E x t e n d e d O p e r a t i o n
10 Extended Operation
10.1 Power Management
10.1.1 Sleep Mode
al
id
In sleep mode, all channels are switched off, taking no current except for the bias cells of the amplifiers. Sleep mode is entered by register
setting, bits P0, P1, P2 set to 0. The remaining elements that take current are the oscillator and the regulator (if used). The Serial Programming
Interface remains active also in the sleep mode.
10.1.2 Standby Mode
10.1.3 Receive Mode
am
lc s
on A
te G
nt
st
ill
v
In standby mode, selected channels are switched on, ready to receive data. The amplifier of the selected channel is on, whereas the correlator is
powered down as long as no input signal is detected at the input. Enabling the related channel when setting bits P0, P1 or P3 enters the standby
mode. In the standby mode, the current consumption increases by the amplifier currents compared to the sleep mode.
An enabled channel automatically changes from the standby mode to the receive mode as soon as an input signal is detected. The channel
stays in receive mode as long as an input signal is detected. In receive mode, the correlator of the channel is active, scanning the input signal
waveform for a valid wake up pattern. The channel goes back to standby mode if no input signal is detected for more then a fixed timeout period.
The timeout period is approximately 3.3 ms. by this operating principle it is guaranteed, that the correlators are only active and taking current as
long as it is really necessary.
10.1.4 Regulator On/Off
The regulator can be switched off to reduce the current consumption. When switching off, the supply voltage is bypassed unregulated to the
internal circuits, so VREG = VCC. Otherwise, the internal voltage is regulated to 2.4 V. Switching off the regulator saves about 1 µA of current.
The regulator should only be switched off, when VCC is not higher then 3.3 V, otherwise the current consumption is increased because the
internal circuits will then take more current.
10.1.5 Typical Current Consumption in Different Modes
The Table 28 gives an overview of the typical current consumptions in the different modes. All three channels are used in this case. Power
consumption of course can be further reduced when not all three channels are enabled.
Table 28. Typical Current Consumption
Operating Mode
Regulator on, VCC = 3 V
Regulator off, VCC = 2.4 V
Sleep
0.8 µA
0.3 µA
7.0 µA
6.5 µA
7.2 µA
6.8 µA
6.6 µA
6.1 µA
Standby
ca
Receive
Standby & RSSI low step
10.1.6 RSSI Step
ch
ni
The RSSI step is defined as the change in the RSSI signal voltage if the input amplitude steps from zero to a defined (small) value. For example
when changing the input signal amplitude from zero to 1 mVpp, the RSSI signal makes a step of app. 175 mV if the bit T4 is set to 1 (compare to
Figure 8 on page 21). If not needed, this step can be reduced to a lower value (T4 = 0), which decreases the current consumption of each
channel by app. 120 nA.
10.1.7 Antenna Rotation
Te
The 3 possible input signals can be distributed to the 3 channels in 3 different connection modes. Using this feature, the differences between the
individual antenna voltages and also the differences of the individual RSSI-voltages of the channels can be handled. For example to eliminate
the differences of the RSSI-voltages it is possible to use only one channel and to multiplex it to each antenna. The Bits P4 and P5 select the
Antenna Rotation Modes.
10.2 Input Attenuation and Input Shortcutting
All differential LF-inputs are each shorted by approximately 500 Ω when setting Bits P4 and P5 both to 1. This can be used to measure the
RSSI-voltage with no input signal present; therefore the RSSI offset can be calibrated. It should be taken into account that the shortcut
resistance can not be made zero due to design restrictions, so the input signal cancellation is not 100% (depending on the antenna circuit).
www.austriamicrosystems.com/AS3931
Revision 6.2
24 - 30
AS3931
Datasheet - E x t e n d e d O p e r a t i o n
Similar to the input shortcutting option, a 1.5 kΩ resistor can be connected across the differential inputs when setting bit C4 to 1. This input
attenuation allows handling of very strong input signals by damping the antenna circuit. The damping depends on the Q-factor of the receiver
circuits.
10.3 WAKE Signal at the RSSI Pin
C3 = 1 and C2 = 0 in the Channel Select Register (RSSI output mode digital)
C0 = 1 and C1 = 1 in the Channel Select Register
Note: The RSSI pin is only active if the CS signal is active (CS = 1), otherwise RSSI is high Z.
10.4 Single WAKE Operation
al
id
The WAKE signal, which is normally available at the WAKE pin, can be mapped to the RSSI pin additionally, which then becomes a digital output.
To do this, set the following bits:
am
lc s
on A
te G
nt
st
ill
v
The single WAKE signals of each channel can be mapped to the WAKE pin. Normally, the 3 WAKE signals are “ored” together and mapped to
the WAKE pin, so the channel with the strongest input signal will generate a WAKE signal. To map a single WAKE signal to the WAKE pin, follow
the steps:
1. Enable Test Mode: set T0 = 1 in Test Mode Register
2. Select Test Mode: set T1 = 1 and T2 = 0 in Test Mode Register
3. Select Channel: set C0 and C1 in the Channel Select Register
The single WAKE signals can also be mapped to the RSSI pin, which then becomes a digital output pin. To do this, make this step:
Select RSSI output mode digital:set C2 = 0 and C3 = 1 in the Channel Select Register
The RSSI pin is only active if the CS signal is active (CS = 1), otherwise RSSI is high Z.
It is possible to operate the WAKE pin in the normal mode first (that is all three single WAKE signals ored together) and after a wake up
detection, to use the Single WAKE mode to check which channel received the wake pattern. This must be done before clearing the WAKE pin. It
is also possible to operate the WAKE pin in normal WAKE mode and simultaneously to operate the RSSI-pin in single WAKE mode.
10.5 Using the Wake Generator
The wake generator generates artificial parasitic wakeup’s every 2 hours as a time base for an external-controlling unit to identify situations
where no true wakeup’s can be detected for a long time. For this purpose the external controlling unit must be able to distinguish between a true
wakeup (generated by one of the receiving channels) or an Artificial Wakeup. This is done by checking the receiving channels using the single
WAKE operation (see Single WAKE Operation on page 25). If a wakeup has occurred and no one of the receiving channels can be identified as
the trigger for the wake up, then the Wake Generator has triggered the wakeup. In this case, the WAKE signal has to be cleared as if a receiving
channel would have triggered the Wake Up.
ca
Note: The internal counter, that generates the internal wakeup by an overflow, can not be reset by clearing the wake pin or other actions.
The time between two artificial wakeups is approximately 2 hours (2h 16min 32sec); however, the first artificial wakeup generated by the Wake
Generator after activation of the feature (by setting bit T5 = 1) may come earlier then in 2:16:32 hours. This time is not defined. After the first
artificial wakeup, the time between two wake ups is then 2 hours.
Te
ch
ni
The Wake Generator must be activated by programming the bit T5 = 1 in the Test Mode Register.
www.austriamicrosystems.com/AS3931
Revision 6.2
25 - 30
AS3931
Datasheet - E x t e n d e d O p e r a t i o n
10.6 Direct DATA Mode
In Direct Data Mode, the received DATA of a selected channel can be mapped to the WAKE pin. The DATA signal is the digital output of the
detector and is normally fed to the correlator, where it is scanned for the WAKE pattern (see Figure 13). To get the DATA signal at the WAKE pin,
follow the steps:
al
id
1. Enable Test Mode: set T0 = 1 in Test Mode Register
2. Select Test Mode: set T1 = 0 and T2 = 0 in Test Mode Register
3. Select Channel: set C0 and C1 in the Channel Select Register
The Direct DATA signals can also be mapped to the RSSI pin, which then becomes a digital output pin. To do this, make this step:
Select RSSI output mode digital:set C2 = 0 and C3 = 1 in the Channel Select Register
Note: The RSSI pin is only active if the CS signal is active (CS = 1), otherwise RSSI is high Z.
am
lc s
on A
te G
nt
st
ill
v
10.7 Correlator Modes
Operation of the correlators can be modified regarding the error tolerances for the Zero-Half-Bits. In this case, the number of Zero-Half-Bits that
is allowed to be invalid can be set from 0 to 2. Please take into account that an increased error tolerance also reduces the immunity against
parasitic wakeups (WAKE detection when no data has been sent, due to noise or interferences).
10.8 Threshold Adaptation Filter Time Constant
Bit M4 is used to switch between a large and a small τ of the detector threshold adaptation filter. A large τ is recommended, because it increases
the noise margin. A small τ can be used to improve the wake sensitivity when non-specified Wake-Patterns are used.
10.9 RSSI and WAKE Pin Modes
This table gives an overview of the different signals that can be mapped to the RSSI and WAKE pin and how to program it.
RSSI Output Mode 2
RSSI Output Mode 1
Channel Select 2
Channel Select 1
WAKE Test Mode Enable
Test Mode Select 2
Test Mode Select 1
CS
C3
C2
C1
C0
T0
T2
T1
WAKE-Pin: WAKE
X
X
X
X
X
0
X
X
WAKE-Pin: DATA1
X
X
X
0
0
1
0
0
WAKE-Pin: DATA2
X
X
X
0
1
1
0
0
WAKE-Pin: DATA3
X
X
X
1
0
1
0
0
Bit/Pin
Chip Select Pin
Table 29. RSSI/WAKE-Pin Modes
ni
ca
Mode
X
X
X
0
0
1
0
1
WAKE-Pin: WAKE2
X
X
X
0
1
1
0
1
WAKE-Pin: WAKE3
X
X
X
1
0
1
0
1
RSSI-Pin: WAKE
1
1
0
1
1
X
X
X
RSSI-Pin: DATA1
1
1
0
0
0
X
0
0
RSSI-Pin: DATA2
1
1
0
0
1
X
0
0
RSSI-Pin: DATA3
1
1
0
1
0
X
0
0
RSSI-Pin: WAKE1
1
1
0
0
0
X
0
1
RSSI-Pin: WAKE2
1
1
0
0
1
X
0
1
RSSI-Pin: WAKE3
1
1
0
1
0
X
0
1
Te
ch
WAKE-Pin: WAKE1
www.austriamicrosystems.com/AS3931
Revision 6.2
26 - 30
AS3931
Datasheet - P a c k a g e D r a w i n g s a n d M a r k i n g s
11 Package Drawings and Markings
The product is available in 16-pin TSSOP package.
al
id
Figure 20. 16-pin TSSOP Package
am
lc s
on A
te G
nt
st
ill
v
AS3931
YYWWMZZ
Max
1.20
0.15
1.05
0.30
0.20
5.10
4.50
0.75
-
Te
Symbol
R
R1
S
Θ1
Θ2
Θ3
aaa
bbb
ccc
ddd
N
ca
Nom
1.00
5.00
6.40 BSC
4.40
0.65 BSC
0.60
1.00 REF
ni
Min
0.05
0.80
0.19
0.09
4.90
4.30
0.45
-
ch
Symbol
A
A1
A2
b
c
D
E
E1
e
L
L1
Min
0.09
0.09
0.20
0º
-
Nom
-
12 REF
12 REF
0.10
0.10
0.05
0.20
16
Max
8º
-
Notes:
1. Dimensioning & tolerancing conform
to ASME Y14.5M-1994.
2. All dimensions are in millimeters.
Angles are in degrees.
Marking: YYWWMZZ.
YY
WW
M
ZZ
Year (i.e. 10 for 2010)
Manufacturing Week
Assembly plant identifier
Assembly traceability code
www.austriamicrosystems.com/AS3931
Revision 6.2
27 - 30
AS3931
Datasheet - R e v i s i o n H i s t o r y
Revision History
Table 30. Revision History
Owner
6.1
Apr 22, 2010
6.2
Apr 14, 2011
Description
Changed to new template
dhe
Updated the Ordering table Table 31
Updated Absolute Maximum Ratings, Package Drawings and Markings.
al
id
Date
Te
ch
ni
ca
am
lc s
on A
te G
nt
st
ill
v
Revision
www.austriamicrosystems.com/AS3931
Revision 6.2
28 - 30
AS3931
Datasheet - O r d e r i n g I n f o r m a t i o n
12 Ordering Information
Table 31.
Ordering
Device
ID Information
Part Number
AS3931-TPD
Description
AS3931-ZTST
AS3931-ZTSM
1
Delivery Form
Tape and Reel
Tape and Reel
Package
16-pin TSSOP
16-pin TSSOP
lid
1. Dry pack sensitivity level = 3, according to IPC/JEDEC J-STD-033A
Where:
T = Temperature range
va
P = Package Type
D = Delivery Form
Z = Others
TS = TSSOP
am
lc s
on A
te G
nt
st
ill
M = Tape & Reel (500 pcs / reel)
T = Tape & Reel (4500 pcs / reel)
Note: All products are RoHS compliant and Pb-free.
Buy our products or get free samples online at ICdirect: http://www.austriamicrosystems.com/ICdirect
Te
ch
ni
ca
For further information and requests, please contact us mailto:sales@austriamicrosystems.com
or find your local distributor at http://www.austriamicrosystems.com/distributor
www.austriamicrosystems.com/AS3931
Revision 6.2
29 - 30
AS3931
Datasheet - C o p y r i g h t s
Copyrights
Copyright © 1997-2011, austriamicrosystems AG, Tobelbaderstrasse 30, 8141 Unterpremstaetten, Austria-Europe. Trademarks Registered ®.
All rights reserved. The material herein may not be reproduced, adapted, merged, translated, stored, or used without the prior written consent of
the copyright owner.
All products and companies mentioned are trademarks or registered trademarks of their respective companies.
al
id
Disclaimer
am
lc s
on A
te G
nt
st
ill
v
Devices sold by austriamicrosystems AG are covered by the warranty and patent indemnification provisions appearing in its Term of Sale.
austriamicrosystems AG makes no warranty, express, statutory, implied, or by description regarding the information set forth herein or regarding
the freedom of the described devices from patent infringement. austriamicrosystems AG reserves the right to change specifications and prices at
any time and without notice. Therefore, prior to designing this product into a system, it is necessary to check with austriamicrosystems AG for
current information. This product is intended for use in normal commercial applications. Applications requiring extended temperature range,
unusual environmental requirements, or high reliability applications, such as military, medical life-support or life-sustaining equipment are
specifically not recommended without additional processing by austriamicrosystems AG for each application. For shipments of less than 100
parts the manufacturing flow might show deviations from the standard production flow, such as test flow or test location.
The information furnished here by austriamicrosystems AG is believed to be correct and accurate. However, austriamicrosystems AG shall not
be liable to recipient or any third party for any damages, including but not limited to personal injury, property damage, loss of profits, loss of use,
interruption of business or indirect, special, incidental or consequential damages, of any kind, in connection with or arising out of the furnishing,
performance or use of the technical data herein. No obligation or liability to recipient or any third party shall arise or flow out of
austriamicrosystems AG rendering of technical or other services.
Contact Information
ca
Headquarters
ni
austriamicrosystems AG
Tobelbaderstrasse 30
A-8141 Unterpremstaetten, Austria
Tel: +43 (0) 3136 500 0
Fax: +43 (0) 3136 525 01
ch
For Sales Offices, Distributors and Representatives, please visit:
Te
http://www.austriamicrosystems.com/contact
www.austriamicrosystems.com/AS3931
Revision 6.2
30 - 30