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EM4022 Schematic ( PDF Datasheet ) - EM Microelectronic - MARIN SA

Teilenummer EM4022
Beschreibung Multi Frequency Contactless Identification Device Anti-Collision compatible
Hersteller EM Microelectronic - MARIN SA
Logo EM Microelectronic - MARIN SA Logo 




Gesamt 15 Seiten
EM4022 Datasheet, Funktion
EM MICROELECTRONIC - MARIN SA
EM4022www.DataSheet4U.com
Multi Frequency Contactless Identification Device
Anti-Collision compatible with BTG's Supertag Category Protocols
Description
The EM4022 (previously named P4022) chip implements
patented anti-collision protocols for both high frequency
and low frequency applications. It is even possible to
identify transponders with identical codes, thereby
making it possible to count identical items. The chip is
typically used in “passive” transponder applications, i.e. it
does not require a battery power source. Instead, it is
powered up by an electromagnetic energy field or beam
transmitted by the reader, which is received and rectified
to generate a supply voltage for the chip. A pre-
programmed code is transmitted to the reader by varying
the amount of energy that is reflected back to the reader.
This is done by modulating an antenna or coil, thereby
effectively varying the load seen by the reader.
Typical Applications
Access control
Animal tagging
Asset control
Sports event timing
Licensing
Electronic keys
Auto-tolling
Features
Implements all BTG anti-collision protocols:
Fast SWITCH-OFF, SLOW-DOWN, and
FREE-RUNNING
Can be used to implement low frequency
inductive coupled transponders, high frequency
RF coupled transponders or bi-frequency
transponders
Reading 500 transponders in less than one
second for high frequency applications
Factory programmed 64 bit ID number
Data rate options form 4 kbit/s to 64 kbit/s
Manchester data encoding
Any field frequency: Typically 125 kHz, 13.56
MHz inductive and 100 MHz to 2.54 GHz RF
Data transmission done by amplitude
modulation
Trimmed 110 pF ± 3% on-chip resonant
capacitor
On-chip oscillator, rectifier and voltage limiter
Low power consumption
Low voltage operation : down to 1.5 V at
ambient temperature
-40 to +85 °C operating temperature range
Pin Assignment
EM 4 0 2 2
1
2
34 5
6
11
10
9
78
Fig. 1
Pad N°
1
2
3
4
5
6
7
8
9
10
11
Name
XCLK
VDD
M
MTST
COIL1
COIL2
VSSTST
VSS
GAP
SI
TMC
Function
external test clock input
positive supply
connection to antenna
test output
Coil terminal 1
Coil terminal 2
negative test supply output
negative supply
GAP input
Serial test data input (pull down)
Test mode control (pull down)
Copyright 2002, EM Microelectronic-Marin SA
1
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EM4022 Datasheet, Funktion
ACK timing diagram
Clock
ACK timing
Bit n
Data
HF ACK
LF ACK
T1
GAP Detection Algorithm
The GAP detection logic contains two main controllers,
one for detecting the ACK signal, and one for detecting
the MUTE and WAKE-UP signals. The WAKE-UP signal
is also called an asynchronous ACK, as it is really an
ACK meant for another chip. It also contains a pre-
processor for low frequency GAP signals.
Refer to the timing diagrams in Figure 6 and 7 for the
following detailed description of the GAP detection
algorithms.
ACK
The controller checks for a LOW 1.75 bit periods after
the last bit of code has been transmitted. It then checks
for a HIGH 3 bits later, a LOW 3 bits later and finally a
HIGH a further 3 bits later.
The reader should synchronise itself to the frequency of
the received code, check the CRC and then send two
GAPs so that the above pattern is matched. Ideally to
achieve the lowest error rate, the GAPS should be as
narrow as possible and situated 4.75 and 7.75 bits after
the last bit of code.
In practice allowance must be made for the fact that the
on-chip oscillator can drift in the time between when the
last code bit is transmitted and when the GAPs are
expected. One reason for the drift is that the oscillator is
supply voltage dependent, and the supply voltage will
typically be rising during this time, since the transponder
will not be modulating its coil or antenna.
The slope of the rising and falling edges of the GAPs can
also be adjusted to reduce reader power bandwidth. In
the case of high frequency GAPs the envelope is used
directly. Low frequency GAPs have to be pre-processed.
They are detected by checking for high periods lasting
longer than one bit period. For this reason there is a set-
up time of 1 bit. The minimum GAP width is therefore 1
bit period (T1 in the timing diagram).
EM4022www.DataSheet4U.com
T1
Fig. 6
MUTE
The MUTE signal is received asynchronously by the
transponder. The controller checks for a HIGH less than
7 bits wide after pre-processing (T2 in the timing
diagram). As in the case of the ACK, low frequency
MUTE GAPs must be at least one bit wide (T1 in the
timing diagram), but high frequency GAPs can be
arbitrarily narrow.
When transmitting a MUTE, the reader must take into
account that there could be a spread in the clock
frequencies of all the receiving transponders.
The reader should therefor limit the width of a MUTE to
be less than 5 bits of the nominal bit rate (T4 in the timing
diagram). A low frequency MUTE should also be wider
than 1.5 bits of the nominal bit rate (T3 in the timing
diagram).
The MUTE should be sent as early as possible after a
code transmission has been detected, while still making
sure that it is a code transmission and not just noise. The
earlier the MUTE is sent, the more time the reader has to
recover before the SYNCH and code bits arrive, and the
smaller the probability that another transponder has
started a colliding transmission
Copyright 2002, EM Microelectronic-Marin SA
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EM4022 pdf, datenblatt
Protocol combinations
The free-running and the two basic bi-directional
protocols, switch-off and slow-down, can all be combined
with the Fast protocol to give six different protocols, i.e.
Normal free-running, slow-down, Normal switch-off, Fast
free-running, slow-down, and Fast switch-off.
The following should be noted about the different
protocols:
1) The switch-off protocols must be used for counting
applications.
2) All the protocols except the switch-off protocols have
built in redundancy because of the fact that they can
transmit a code more than once.
3) Normal free-running is the only unidirectional
protocol. It has the lowest power spectrum requirement
because the reader transmits a CW wave.
4) Fast switch-off and Fast slow-down are the fastest
protocols, and should be used where speed is important,
or where the data rate limits the reading rate. Fast slow-
down is slightly slower, but theoretically has a lower error
rate.
5) For 125 kHz inductive applications using a 4 kbit/s
data rate, Fast slow-down is probably the best overall
protocol.
6) For RF applications using a 64 kbit/s data rate,
normal free-running protocol is probably the best
protocol.
Reader determined protocols
If the reader does not send MUTE signals to
transponders that were programmed for one of the FAST
protocols, the protocol merely reverts to the equivalent
normal protocol. Similarly, if the reader does not send
ACK signals to transponders that were programmed for
SLOW-DOWN or SWITCH-OFF, the protocol reverts to
a FREE-RUNNING protocol. In this manner, the reader
can determine the protocol that is used.
Note, however, that unless a transponder was
specifically programmed for the free-running protocol, its
GAP input must be pulled down. This happens
automatically in low frequency inductive applications,
where the GAP input is pulled down by the internal GAP
detector diode. In RF applications, however, the GAP
input will have to be pulled down explicitly.
EM4022www.DataSheet4U.com
Protocol saturation
As the number of transponders in a reader beam is
increased, the number of collisions increase, and it takes
longer to read all the tags. This process is not linear. To
read twice as many transponders could take more than
twice as long. This effect is called protocol saturation.
The normal free-running protocol saturates the easiest of
all the protocols, because it does not have any means of
reducing the transmitting population. The Fast protocols,
on the other hand, are virtually immune against
saturation, as they prevent collisions by muting all
transponders except the transmitting one.
One way of delaying the onset of saturation, is to reduce
the initial repeat rate (not data rate) at which
transponders transmit their codes. This is done by
increasing the maximum random delay between
transmissions.
Figure 14 and 15 below show's reading times for some
possible versions
Optimum repeat delay settings
The following table lists the optimum repeat delay
settings for each of the protocols vx number of
transponders in a group.
Protocol
Free-running
Slow-down
Switch-off
Fast Free-running
Fast Slow-down
Fast Switch-off
Number of transponders
3 10 30 100
1k 4k 16k 64k
1k 1k 4k 16k
1k 1k 4k 16k
256 1k 1k 4k
256 256 1k
1k
256 256 1k
1k
Copyright 2002, EM Microelectronic-Marin SA
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