资料介绍
This application note builds on application note AN232
Low Frequency Magnetic Transmitter Design
(DS00232). It covers the design process to implement
LF Talkback functionality. AN232 covers some of the
magnetism basics and design principles to implement
the drive circuitry. LF Talkback generally refers to the
process in which a transponder can communicate back
to a magnetic transmitter base station by loading the
generated magnetic field. By measuring the small
changes in the transmitter coil's voltage, used to gener-
ate the field, the communications’ data is extracted. LF
Talkback is commonly used in RFID, automotive
transponders, active transponders, and many other
bidirectional LF communications topologies.
This document will cover the different stages needed to
implement a typical LF Talkback system and explain
the process in choosing the different stage characteris-
tics. It explains the various performance and cost trade-
offs made for the reference design and how it can be
adapted to better suit the readers needs. AN912
Designing LF Talkback for a Magnetic Base Station
MAIN BUILDING BLOCKS
Author: Ruan Lourens
Microchip Technology Inc. Figure 1 shows the main building blocks that make up
the LF Talkback system described in this document.
The base station generates a strong magnetic field by
INTRODUCTION setting up resonance in a serial resonant tank. The
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