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參數(shù)資料
| 型號： | MCRF250 |
| 廠商： | Microchip Technology Inc. |
| 英文描述： | 125 kHz microID Passive RFID Device with Anti-Collision |
| 中文描述： | 125千赫microID無源RFID設(shè)備與反碰撞 |
| 文件頁數(shù)： | 4/24頁 |
| 文件大小： | 395K |
| 代理商： | MCRF250 |
MCRF250
DS21267F-page 4
2003 Microchip Technology Inc.
2.0
FUNCTIONAL 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, V
DD
(operating voltage), and
high-voltage clamping to prevent excessive voltage
from being applied to the device. This section also
generates a system clock from the incoming carrier
signal and modulates the carrier signal to transmit data
to the reader.
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 V
DD
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
IRQ DETECTOR
This circuitry detects an interrupt in the continuous
electromagnetic field of the interrogator. An IRQ
(interrupt request) is defined as the absence of the
electromagnetic field for a specific number of clock
cycles. Detection of an IRQ will trigger the device to
enter the Anti-collision mode. This mode is discussed
in detail in
Section 5.0 “Anti-Collision”
.
2.1.5
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 (V
A
and V
B
). 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.
MODULATION CIRCUIT
FIGURE 2-1:
MODULATION SIGNAL AND MODULATED SIGNAL
MCRF250
V
A
Modulation
Signal
V
B
Modulation
Transistor
Modulation Signal
Modulated RF Signal
(across V
A
and V
B
)
L
C
Amplitude
t
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| MCRF250-I/P | 制造商:MICROCHIP 制造商全稱:Microchip Technology 功能描述:125 kHz microID Passive RFID Device with Anti-Collision |
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