TK5561A-PP
Rev. A2, 04-Oct-00
1 (8)
Read/Write Crypto Transponder for Short Cycle Time
Description
The TK5561A-PP is a complete transponder integrating
all important functions for immobilizer and identification
systems. It consists of a plastic cube which accommo-
dates the crypto IDIC
*)
e5561A and the antenna
realized as tuned LC-circuit. The TK5561A-PP is a R/W
crypto transponder for applications which demand higher
security levels than those which standard R/W transpond-
ers can fulfil. For this reason, the TK5561A-PP has an
additional encryption algorithm block which enables a
base station to authenticate the transponder. Any attempt
to fake the base station with a wrong transponder will be
recognized immediately. For authentication, the base
station transmits a challenge to the TK5561A-PP. This
challenge is encrypted by both IC and base station. Both
should possess the same secret key. Only then the result
be expected to be equal.
For detailed technical information about functions, con-
figurations etc., please refer to the e5561 data sheet.
Fea
tures
D 65 ms cycle time for crypto algorithm programmable
D Encryption time < 10 ms, < 30 ms optional
D Identification transponder in plastic cube
D Contactless read/write data transmission
D High-security crypto algorithm optional
D Inductive coupled power supply at 125 kHz
D Basic component R/W e5561 IDIC
D Built-in coil and capacitor for circuit antenna
D Starts with cyclical data read out
D Self-adapting resonance frequency (optionally)
D 128-bit user-programmable EEPROM
D Typical < 50 ms to write and verify a block
D Read/write protection by lock bits
D Options set by EEPROM
Bitrate [bit/s]:
Rf/32; Rf/64
Modulaton:
Manchester; Biphase
Application
D Car immobilizers with higher security level
D High-security identification systems
Transponder TK5561APP
RF field
Response
e5561A
(e5561A + coil + C in plastic cube)
Base station
U2270B read/write IC
MARC4 series
mC
Coil
Power
C
ID
Challenge
Figure 1. Transponder and base station
*)
IDIC
stands for IDentification Integrated Circuit and is a trademark of Atmel Wireless & Microcontrollers.
TK5561A-PP
Rev. A2, 04-Oct-00
2 (8)
Coil1
Coil2
MODULATOR
ANALOG FRONT END
INPUT REGISTER
WRITE
DECODER
BITRATE
GENERATOR
64 or 128 bit ID code
CONTROLLER
TESTLOGIC
MODE REGISTER
HV GENERATOR
CRYPTO CIRCUIT
POR
Testpads
crypto control
OPcode detect
EEPROM control
read/write control
crypto key
ADAPT
V
DD
V
SS
Memory
(320 bit EEPROM)
Figure 2. Block diagram
General
The transponder is the mobile part of the closed coupled
identification system (see figure 1), whereas the
read/ write base station is based on the U2270B or on dis-
crete solutions, and the read/write transponder is based on
the e5561A IDIC
.
The transponder is a plastic-cube device consisting of the
following parts:
D The transponder antenna, realized as tuned LC-circuit
D Read/write IDIC
(e5561A) with EEPROM
The Transponder Antenna
The antenna consists of a coil and a capacitor for tuning
the circuit to the nominal carrier frequency of 125 kHz.
The coil has a ferrite core for improving the distance of
read, write and programming operations.
Read-Write Crypto Identification
The e5561A is a member of the Atmel Wireless & Micro-
controllers' contactless IDentification IC (IDIC)
family, which are used in applications where information
has to be transmitted without contacts. The IDIC
is
connected to a tuned LC circuit for power supply and
bidirectional data communication (Read/Write) to a base
station.
The on-chip non-volatile memory of the 320-bit
EEPROM (10 blocks 32 bits each) can be read and written
blockwise by a read/write base station, e.g. basing on the
U2270B. Up to four blocks consisting of the user pro-
grammable ID code, the crypto key and configurations
are stored in six blocks. The crypto key and the ID code
can be individually protected against overwriting.
The typical operational frequency of the TK5561A-PP is
125 kHz. Two data bit rates are programmable: Rf/32 and
Rf/64. During the reading operation the incoming RF
field is damped bit-wise by an on-chip load. This
AM-modulation is detected by the field generating base
station unit. Data transmission starts after power-up with
the transmission of the ID code and continues as long as
the TK5561A-PP is powered.
Writing is carried out by means of Atmel Wireless & Mi-
crocontrollers' writing method (patented). To transmit
data to the TK5561A-PP the read/ write base station has
to interrupt the RF field for a short time to create a field
gap. The information is encoded in the number of clock
cycles between two subsequent gaps.
See e5561A data sheet for detailed information of the
IDIC
.
TK5561A-PP
Rev. A2, 04-Oct-00
3 (8)
Electrical Characteristics
Absolute Maximum Ratings
Parameters
Symbol
Value
Unit
Operating temperature range
T
amb
40 to +85
C
Storage temperature range
T
stg
40 to +125
C
Maximum assembly temperature, t < 5 min.
T
ass
170
C
Magnetic field strength at 125 kHz
H
pp
1000
A/m
Operating Characteristics Transponder
T
amb
= 25
C, f = 125 kHz if not otherwise noted
Parameters
Test Conditions / Pins
Symbol
Min.
Typ.
Max.
Unit
Inductance
L
4.2
mH
LC circuit, H
PP
= 20 A/m
Resonance frequency
Tamb = 40 to +85
C
f
r
121
125
129
kHz
Quality factor
Q
LC
5
8
11
Magnetic field strength (H)
Parameters
Test Conditions / Pins
Symbol
Min.
Typ.
Max.
Unit
Max. field strength where
transponder does not
modulate
No influence to other trans-
ponders in the field
H
pp not
5
A/m
Minimum field strength
Read mode
T
amb
= 40
C
H
pp 40
24
A/m
T
amb
= 25
C
H
pp 25
18
A/m
T
amb
= 85
C
H
pp 85
15
A/m
Programming mode
T
amb
= 40
C
H
ppp 40
30
A/m
T
amb
= 25
C
H
ppp 25
35
A/m
T
amb
= 85
C
H
ppp 85
40
A/m
Lowest adapt frequency
f
LA
118
121
124.5
kHz
Highest adapt frequency
f
HA
125
128
131.5
kHz
Data retention EEPROM
T = 25
C
t
retention
10
Years
Programming cycles
EEPROM
100,000
Programming time / block
RF = 125 kHz
t
p
16
ms
Maximum field strength
H
pp max
600
A/m
TK5561A-PP
Rev. A2, 04-Oct-00
4 (8)
0.0
0.1
0.2
0.3
0.4
0.5
0
20
40
60
80
100
120
DV
(V)
H
pp
(A/m)
Figure 3. Typical curve for degree of modulation
V2
V1
m
+ V1 * V2
V1
) V2
Figure 4. Measurement of the degree of modulation
Measurement Assembly
All parameters are measured in a Helmholtz-arrangement which generates a homogenous magnetic field (see figure 5
and 6). A function generator drives the field generating coils, so the magnetic field can be varied in frequency and field
strength.
SUBTRACTOR
FUNCTION
GENERATOR
OUTPUT
VOLTAGE
AMPLIFIER
1:10
FIELD GENERATING
COILS ( IN PHASE )
REFERENCE COIL ( IN PHASE )
SENSING COILS ( IN PHASE )
REFERENCE COIL
( IN PHASE )
TK5561A-PP
Figure 5. Testing application
TK5561A-PP
Rev. A2, 04-Oct-00
5 (8)
l = 30 mm
5 mm
22 mm
d = 60 mm
SENSING COIL
REFERENCE COIL
FIELD GENERATING COIL
SENSING COIL
REFERENCE COIL
FIELD GENERATING COIL
Transponder
16524
Figure 6. Testing geometry
Writing Data into the TK5561A-PP
A write sequence of the TK5561A-PP is shown below.
Writing data into the transponder occurs by interrupting
the RF field with short gaps. After the start gap the write
op-code (10) is transmitted. The next 32 bits contain the
actual data. The last 4 bits denote the destination block
address. If the correct number of bits have been received,
the actual data is programmed into the specified memory
block.
Standard op-code
Address bits (e.g. block 2)
0
1
Read mode
Write mode
Start gap
> 64 clocks
0
1
0
32 bit
12444
RF field
0
Figure 7. Write protocol to program the EEPROM
Write Data Decoding
The time elapsing between two detected gaps is used to
encode the information. As soon as a gap is detected, a
counter starts counting the number of field clock cycles
until the next gap will be detected. Depending on how
many field clocks elapse, the data is regarded as '0' or '1'.
The required number of field clocks is shown in figure 8.
A valid '0' is assumed if the number of counted clock
periods is between 16 and 32, for a valid '1' it is 48 or 64
respectively. Any other value being detected results in an
error and the device exits write mode and returns to read
mode.
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