at88rf1354 ATMEL Corporation, at88rf1354 Datasheet - Page 31

• Manufacturer Part Number: at88rf1354
• Description: 13.56 Mhz Type B Rf Reader Specification
• Manufacturer: ATMEL Corporation

A.9.
A.10.
8547A−RFID−10/08
Magnetic Field Strength
ISO/IEC 14443 part 2 defines the minimum and maximum operating magnetic field strength as Hmin and Hmax. A
credit card sized (ID-1) PICC is required to operate at all magnetic field strengths between Hmin = 1.5 A/m rms and
Hmax = 7.5 A/m rms. The PCD is not allowed to generate magnetic fields in excess of Hmax = 7.5 A/m rms. The
PICC is not required to function outside the operating envelope defined by Hmin and Hmax.
The magnetic field strength requirements of ISO/IEC 14443 part 2 apply only to systems utilizing ID-1 size PICCs,
which have an antenna area of approximately 3000 square millimeters. The magnetic field strength required to
operate tags with antennas larger than ID-1 is less than the limits specified in the standard. For tags with antennas
smaller than ID-1 size, a higher magnetic field strength is required. The field strength required is inversely
proportional to the area of the tag antenna.
See amendment 4 to ISO/IEC 10373-6 for the definition of an ID-1 “Class 1” PICC antenna. Any PICC antenna
falling within the “Class 1” dimensions is considered an ID-1 antenna for the purpose of this specification. PCD
antennas for ISO/IEC 14443 have not been standardized by the WG8 working group responsible for ISO/IEC 14443
because PCD performance requirements are application specific.
Magnetic field strength is measured with a single turn antenna coil. For ID-1 cards the test method and measurement
coil are described in ISO/IEC 10373-6 section 6. For larger or smaller tags the measurement coil must be sized
similarly to the tag for the magnetic field strength to be relevant. Measurements with coils larger or smaller than the
PICC antenna dimensions are misleading since they do not measure the magnetic flux that the PICC antenna will
actually see.
Warning: Exposure to magnetic fields in excess of 30 A/m rms may be hazardous to your health.
Communication Range and Interoperability
The ISO/IEC 14443 standards do not guarantee that any compliant PCD will operate with any compliant PICC. The
standards define the communication interface between a card and reader for contactless smartcard applications.
This interface definition allows the industry to develop compliant card or tag products that can communicate with
compliant readers. The standards reduce development cost and technical risk for manufacturers and users of the
protocol. Cards from multiple manufacturers can communicate with readers from other manufacturers.
The ISO/IEC 14443 standards do not specify or guarantee the distance over which a compliant PICC will
communicate with a compliant PCD. The magnetic field strength requirements described in Appendix A.9 defines the
operating envelope of ID-1 PICCs and allows the PCD manufacturer to measure and specify the volume surrounding
the reader antenna where the ID-1 PICC operating requirements are satisfied. In other words, the developer of a
reader for ID-1 cards is expected to specify the operating volume where all requirements of the standard have been
met so that the customer knows if the reader is appropriate for the application.
Since ISO/IEC 14443 explicitly defines the field strength and other requirements for ID-1 cards it is easy for the
reader manufacturer and the system developer to discuss the operating characteristics of a system for ID-1 cards
using the requirements in the standards.
Unfortunately there are no corresponding definitions of the operating conditions for PICCs that are smaller or larger
than the ID-1 format.
antennas. Small tags will not operate reliably with large reader antennas. Large tags will not operate reliably with
small reader antennas. If the tag and reader antennas are the same size, then the tag will not operate correctly at
close range due to excessive mutual inductance.
Discussion of the numerous factors impacting the performance of ISO/IEC 14443 systems is beyond the scope of this
document. One rule of thumb estimates that the reliable operating range of a tag is approximately equal to the
outside diameter of the tag antenna when the tag and reader antennas are parallel and the antenna centers are
aligned. This rule assumes that the reader antenna is larger than the tag antenna, but is appropriately sized, and that
the reader has no significant design flaws.
A reliable ISO/IEC 14443 system uses PICCs and PCDs matched to the application, with appropriately sized
13.56 MHz Type B RF Reader
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