Functional
Description
The read head signals are amplified by the
MagChip using an autoscaling amplifier. The
amplified signal is used to decode the
magnetic stripe signal (dual-frequency data
encoded using the principals of Aiken’s F2F
encoding) into a digital data format
consisting of the magnetic stripe data,
clock, and “media detect” outputs, all of
which are CMOS level signals. Additionally,
the MagChip has a automatic power-down sleep
mode that saves energy. Since the MagChips
are mounted directly on the read head, the
low amplitude analog signals are amplified
and digitized without exposure to external
“noise” for maximum noise immunity. The F2F
data rate ranges from less than 200 to
greater than 30,000 magnetic flux reversals
per second, depending upon data density and
the velocity at which the magnetic stripe is
passed across the “read” head. One clock
pulse is required for each data bit, and the
“media detect” signal is held true while
magnetic head signals are present. The
assembly’s standard confi guration consists
of the read head, one, two or three decoding
circuits, wing spring mounting, and a cable
assembly with 8-pin connector (for single or
dual track confi guration) or 10-pin
connector (for triple track).
Durability
Head life is 1,000,000 card cycles (with
media that meets ISO 7811 magnetic stripe
properties) under a non-contaminated
environment. Spring assembly is 1,000,000
card cycles as well.
Environmental
Operating: -35°C to 70°C (10% to 98%
relative humidity). Storage: -45°C to 85°C
(10% to 98% relative humidity).
Data Output
Data output is a serial stream of digital
bits, the level of which, with the
corresponding clock, represents each data
bit that was recorded on the magnetic stripe
track. No data filtering is required, as the
first 6 to 9 bits (after MagChip wake-up)
from the leading edge of a magnetic stripe
are not provided as output, as these bits
are used for circuit synchronization. A data
output high level is a ‘ZERO’ value data
bit, and a low level is a ‘ONE’ value data
bit. The data output is last-bit-first when
media is passed by the head in a reverse
direction.
Clock Output
Clocking output is normally high, and goes
low to indicate a data sample time. The data
output is stable and may be sampled on the
falling or rising edge of clock, or at any
time while the clock is low. The MagChip
clock goes low approximately 2 μsec after
the data output is valid. The clock width
changes with speed. (Please refer to the AC
Characteristics table for minimum/maximum
signal timing.) The receiving interface for
MagChip data must sense the high-to-low
clock transition and acquire the data bit
level during clock pulse. The clock width
changes with speed. (Please refer to the AC
Characteristics table.)
“Media
Detect” Output
This output indicates the presence of
encoded magnetic media passing the read
head. This signal is normally high; a low
output indicates encoded media. The output
is an open drain type with high impedance;
the outputs of several MagChip circuits can
be connected together. A pull-up resistor is
needed for proper operation of this output
if it is to be used.
Sleep Mode
Function
The MagChip will automatically enter a
power-down sleep mode when a magnetic head
signal is not present. The MagChip will
automatically wake-up when a magnetic head
signal is present. The outputs Data, Clock,
and Media Detect are at a high level during
sleep mode. |
