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전자부품 데이터시트 검색엔진 |
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전자부품 데이터시트 검색엔진 |
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MCRF250 데이터시트(PDF) 4 Page - Microchip Technology |
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MCRF250 데이터시트(HTML) 4 Page - Microchip Technology |
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4 / 24 page  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, VDD (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 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 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 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 MCRF250 Modulation Signal VA VB Modulation Modulation Signal Modulated RF Signal (across VA and VB) LC Amplitude t Transistor |
유사한 부품 번호 - MCRF250 |
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유사한 설명 - MCRF250 |
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