R
EM4100
Block Diagram
CLOCK
EXTRACTOR
a
Logic
Clock
COIL1
VDD
AC1
+
Cres
Csup
FULL WAVE
RECTIFIER
MEMORY
ARRAY
SEQUENCER
-
AC2
VSS
COIL2
Serial
Data Out
DATA
MODULATOR
DATA
ENCODER
Modulation
Control
a: open only for PSK version
Fig. 5
Data Modulator
Functional Description
The data modulator is controlled by the signal Modulation
Control in order to induce a high current in the coil. In the
PSK version, only COIL2 transistor drives this high current.
In the other versions, both coil1 and coil2 transistors drive it
to Vdd. This will affect the magnetic field according to the
data stored in the memory array.
General
The EM4100 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 last bit is sent, the chip will continue with the first
bit until the power goes off.
Resonance Capacitor
Full Wave Rectifier
This capacitor can be trimmed in factory by 0.5pf steps to
achieve the absolute value of 74pf typically. This option,
which is on request, allows a smaller capacitor tolerance on
the whole of the production.
The AC input induced in the external coil by an incident
magnetic field is rectified by a Graetz bridge. The bridge
will limit the internal DC voltage to avoid malfunction in
strong fields.
Clock Extractor
One of the coil terminals (COIL1) is used to generate the
master clock for the logic function. The output of the clock
extractor drives a sequencer.
Sequencer
The sequencer provides all necessary signals to address
the memory array and to encode the serial data out.
Three mask programmed encoding versions of logic are
available. These three encoding types are Manchester,
biphase and PSK. The bit rate for the first and the second
type can be 64 or 32 periods of the field frequency. For the
PSK version, the bit rate is 16.
The sequencer receives its clock from the COIL1 clock
extractor and generates every internal signal controlling the
memory and the data encoder logic.
Copyright © 2004, EM Microelectronic-Marin SA
4
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EMMICRO [ EM MICROELECTRONIC - MARIN SA ]
