Linear Technology offers a variety of devices that simplifyconverting power from a USB cable, but the LTC®3455represents the highest level of functional integration yet. The LTC3455 seamlessly manages power flowbetween an AC adapter, USB cable and Li-ion battery,while complying with USB power standards, all from a4mm × 4mm QFN package. In addtion, two high efficiencysynchronous buck converters generate low voltage railswhich most USB-powered peripherals require. TheLTC3455 also provides power-on reset signals for themicroprocessor, a Hot SwapTM output for poweringmemory cards as well as an uncommitted gain blocksuitable for use as a low-battery comparator or an LDOcontroller. The PCB real estate required for the entire USBpower control circuit and two DC/DC converters is only225mm2.
One of the fi rst lessons in a basic electronics coursecovers the symbols for resistors, capacitors, inductors,voltage sources and current sources. Althougheach symbol represents a functional component of areal-world circuit, only some of the symbols have directphysical counterparts. For instance, the three discretepassive devices—resistors, capacitors, inductors—canbe picked off a shelf and placed on a real board muchas their symbolic analogs appear in a basic schematic.Likewise, while voltage sources have no direct 2-terminalanalog, a voltage source can be easily built with an offthe-shelf linear regulator.
介紹一種以Atmel公司的Attiny13為處理器的投影儀防盜器設計方案。該防盜器具有功耗低，功能完整，防盜效果良好等特點，除具有報警功能外，防盜器還具有以無線方式向主機發送報警信號的功能。采用315MHz發射模塊實現無線信號發送。該投影儀防盜器可適應眾多廠家生產的防盜器主機。
Abstract:
This paper introduces the design scheme of overhead projector's anti-theft device which users ATMEL company’s Attiny13as processor.This anti-theft device features low powerloss，functional integrity，good effect of anti-theft.In addition to its own with alarm functions，the anti-theft device also has alarm function which can send alarm signal to the host through wireless way.It sends wireless signal using315MHz transmitting module，so this overhead projector’s anti-theft device is adapted to anti-theft device host produced by many manufacturers.
該系統由單片機89S52控制模塊，程控寬帶放大模塊，整形模塊，FPGA內頻率、相位差測量模塊等構成，采用等精度測頻法測出頻率和周期，可測量有效值為0.01～5V，頻率范圍1Hz～20MHz信號的頻率、周期信號，精度高達10-6。采用計數法測量相位差，該系統可測量有效值0.5～5V，頻率10Hz～100kHz信號的相位差，精度為1°。系統功能由按鍵控制，測量結果實時顯示，人機界面友好。
Abstract:
The system consists of the following functional blocks:89S52microcontroller controlling module,programmable amplifier module,comparator module,frequency and phase difference testing module in the FPGA.The system use the equal accuracy frequency-examining technique it measures frequency and circle of signal which its ranges is from1Hz to20MHz and the amplitude of which its range is from0.01Vrms to5Vrms,precision is up to10-6.Using of count method,the system detects the phase difference of signal,the amplitude of whic its range is from0.5Vrms to5Vrms and the frequency of which its ranges is from10Hz to100kHz,precision is up to1°,The system functions is controlled by certain keys,measurement results are displayed in real-time and it is friendly interface.
介紹一種多功能音樂播放器，它是以AT89S52單片機為核心，并輔有一些外圍器件，采用匯編語言編寫程序，實現多功能音樂播放，歌曲自動循環播放和使用琴鍵自編曲目功能。此外，彩燈顯示歌曲節奏，按鍵跳轉到喜愛曲目，液晶顯示當前播英文曲目。并給出了系統軟硬件設計。
Abstract:
It introduces a multifunctional music player,taking AT89S52 single-chip microcomputer as hardware control core and using some peripheral elements.Programmes are compiled in assembly language to act as expected.There are two functional modes in this system.One is to make the music play automatically and consecutively,the other is to compose new songs through keys.In addition,lights show the pace of music and the English names can be displayed in the liquid crystal screen.With perfect combination of hardware and software,the music player can meet many music lovers’needs for multifunctional music player.And the hardware and software of the system are given.
針對當前安檢力學試驗機所能完成的試驗種類單一、自動化程度低等問題，提出一種以ATmega128單片機為核心控制器的安檢力學試驗機的設計。詳細闡述了該安檢力學試驗機各個組成部分的設計原理和方案，并且給出了各部分的軟件設計思想和操作流程。經過大量測試試驗表明：設計的安檢力學試驗機可以完成多達十余種的力學安檢試驗，完全符合相關國家標準，并且具有數據采集精度高、傳輸速度快、操作安全簡便等特點，實現了安檢設備的多功能化、數字化和自動化。
Abstract:
Currently， many mechanical security testing machines have only one function. The degree of automation of them is low. To solve those problems， a new kind of mechanical security testing machine， using ATmega128 micro-controller as its core controller， has been advanced. It describes the components of the machine. The principles and the scheme in the designing processes are presented in detail， and the software architecture and the operation processes of each part are given. After having done many testing， we have reached the following conclusions: the mechanical security testing machine presented can do over ten mechanical security tests complying with related national standards. It has high data acquisition accuracy and high transmission speed. The operation of the machine is simple and safe. In general， this machine is a multi-functional， highly automatic， digitalized security testing device.
