MCRF200 データシートの表示（PDF） - Microchip Technology

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MCRF200

125 kHz microID Passive RFID Device

Microchip Technology 

MCRF200

2.0 FUNCTION DESCRIPTION

The device contains three major building blocks. They

are RF front-end, configuration and control logic, and

memory sections. The Block Diagram is shown on

page 1.

2.1 RF Front-End

The RF front-end of the device includes circuits for

rectification of the carrier, VDD (operating voltage) and

high-voltage clamping. This section also includes a

clock generator and modulation circuit.

2.1.1 RECTIFIER – AC CLAMP

The rectifier circuit rectifies RF voltage on the external

LC antenna circuit. Any excessive voltage on the tuned

circuit is clamped by the internal circuitry to a safe level

to prevent damage to the IC.

2.1.2 POWER-ON RESET

This circuit generates a Power-on Reset when the tag

first enters the reader field. The Reset releases when

sufficient power has developed on the VDD regulator to

allow correct operation.

2.1.3 CLOCK GENERATOR

This circuit generates a clock based on the carrier

frequency from the reader. This clock is used to derive

all timing in the device, including the baud rate and

modulation rate.

2.1.4 MODULATION CIRCUIT

The device sends the encoded data to the reader by

AM-modulating the coil voltage across the tuned LC

circuit. A modulation transistor is placed between the

two antenna coil pads (VA and VB). The transistor turns

on and off based on the modulation signal. As a result,

the amplitude of the antenna coil voltage varies with the

modulation signal. See Figure 2-1 for details.

FIGURE 2-1:

MODULATION SIGNAL AND MODULATED SIGNAL

MCRF200

VA Modulation

Signal

L

C

Amplitude

Modulation

Transistor

VB

Modulation Signal

Modulated RF Signal

t

(across VA and VB)

DS21219H-page 4

 2003 Microchip Technology Inc.

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