EM4450
EM4550
Timing Characteristics
V
DD
=2.5V, V
SS
=0V , f
coil
= 125 kHz Sine wave, V
coil
= 1V
pp
,
T
op
= 25°C
unless otherwise specified
All timings are derived from the field frequency and are specified as a number of RF periods..
Parameter
Symbol
Conditions
Value
Unit
Opt64
Option : 64 clocks per bit
Read Bit Period
t
rdb
64
RF periods
LIW/ACK/NACK pattern duration
t
patt
320
RF periods
Read 1 Word Duration
t
rdw
including LIW
3200
RF periods
Processing Pause Time
t
pp
64
RF periods
Write Access Time
t
wa
64
RF periods
Initialization Time
t
init
2112
RF periods
EEPROM write time
t
wee
V
DD
= 3V
3200
RF periods
Opt32
Option : 32 clocks per bit
Read Bit Period
t
rdb
32
RF periods
LIW/ACK/NACK pattern duration
t
patt
160
RF periods
Read 1 Word Duration
t
rdw
including LIW
1600
RF periods
Processing Pause Time
t
pp
32
RF periods
Write Access Time
t
wa
32
RF periods
Initialization Time
t
init
1056
RF periods
EEPROM write time
t
wee
V
DD
= 3V
2624
RF periods
RF periods represent periods of the carrier frequency emitted by the transceiver unit. For example, if 125 kHz is used :
The Read bit period (Opt64) would be : 1/125'000*64 = 512 µs, and the time to read 1 word : 1/125'000*3200 = 25.6 ms.
The Read bit period (Opt32) would be : 1/125'000*32 = 256 µs, and the time to read 1 word : 1/125'000*1600 = 12.8 ms.
ATTENTION
Due to amplitude modulation of the coil-signal, the clock-extractor may miss clocks or add spurious clocks close
to the edges of the RF-envelope. This desynchronisation will not be larger than ±3 clocks per bit and must be
taken into account when developing reader software.
Functional Description
General
The EM4450/4550 is supplied by means of an electromagnetic field induced on the attached coil. The AC voltage is rectified
in order to provide a DC internal supply voltage. When the DC voltage crosses the Power-On level, the chip enters the
Standard Read Mode and sends data continuously. The data to be sent in this mode is user defined by storing the first and
last addresses to be output. When the last address is sent, the chip will continue with the first address until the transceiver
sends a request. In the read mode, a Listen Window (LIW) is generated before each word. During this time, the
EM4450/4550 will turn to the Receive Mode (RM) if it receives a valid RM pattern. The chip then expects a valid command.
Mode of Operation
Pow er-On
Init
Standard
Read Mode
Get Command
NO
Receive
Mode
request ?
YES
Execute Command
Login
Write Word
Write Password
Selective Read
Send w ord
Reset
Fig. 4
Copyright
2003, EM Microelectronic-Marin SA
4
www.emmicroelectronic.com
EMMICRO [ EM MICROELECTRONIC - MARIN SA ]
