As the performance of many handheld devices approachesthat of laptop computers, design complexity also increases.Chief among them is thermal management—how doyou meet increasing performance demands while keepinga compact and small product cool in the user’s hand?For instance, as battery capacities inevitably increase,charge currents will also increase to maintain or improvetheir charge Times. Traditional linear regulator-based batterychargers will not be able to meet the charge currentand effi ciency demands necessary to allow a product torun cool. What is needed is a switching-based chargerthat takes just about the same amount of space as a linearsolution—but without the heat.
上传时间： 2013-11-23
上传用户：lu2767
The LTC®3562 quad output step-down regulator is designedfor multicore handheld microprocessor applications thatoperate from a single Li-Ion battery. Its four monolithic, higheffi ciency buck regulators support Intel’s mobile CPU P-Stateand C-State energy saving operating modes. The outputvoltages are independently controllable via I2C, and eachoutput can be independently started and shut down. Designerscan choose from power saving pulse-skipping mode orBurst Mode® operation, or select low noise LDO mode. Thespace-saving LTC3562 is available in a 3mm &Times; 3mm QFNpackage and requires few external components.
上传时间： 2013-10-07
上传用户：1583060504
The makers of handheld medical, industrial and consumerdevices use a wide variety of high resolution, small tomedium sized color TFT LCD displays. The power supplydesigners for these displays must contend with shrinkingboard area, tight schedules, and variations in displaytypes and feature requirements. The LTC®3524 simplifi esthe designer’s job by combining a versatile, easily programmed,TFT LCD bias supply and white LED backlightdriver in a low profi le 4mm &Times; 4mm QFN package.
上传时间： 2013-10-25
上传用户：chens000
Piezoelectric motors are used in digital cameras for autofocus,zooming and optical image stabilization. Theyare relatively small, lightweight and effi cient, but theyalso require a complicated driving scheme. Traditionally,this challenge has been met with the use ofseparatecircuits, including a step-up converter and an oversizedgeneric full-bridge drive IC. The resulting high componentcount and large board space are especially problematicin the design of cameras for ever shrinking cell phones.The LT®3572 solves these problems by combining astep-up regulator and a dual full-bridge driver in a 4mm&Times; 4mm QFN package. Figure 1 shows a typical LT3572Piezo motor drive circuit. A step-up converter is usedto generate 30V from a low voltage power source suchas a Li-Ion battery or any input power source within thepart’s wide input voltage range of 2.7V to 10V. The highoutput voltage of the step-up converter, adjustable upto 40V, is available for the drivers at the VOUT pin. Thedrivers operate in a full-bridge fashion, where the OUTAand OUTB pins are the same polarity as the PWMA andPWMB pins, respectively, and the OUTA and OUTB pinsare inverted from PWMA and PWMB, respectively. Thestep-up converter and both Piezo drivers have their ownshutdown control. Figure 2 shows a typical layout
上传时间： 2013-11-18
上传用户：hulee
The LTC®3569 is a compact power solution for handhelddevices. Its tiny 3mm &Times; 3mm QFN package includesthree buck regulators with individually programmableoutput voltages. One regulator supports load currentsup to 1200mA, while the other two support currents to600mA. Two regulators can be paralleled for increasedload capability. Each current-mode regulator is internallycompensated with excellent load and line regulation. Acomplete 2- or 3-output solution requires a minimumof external passive components.
上传时间： 2013-10-11
上传用户：yxgi5
Industrial remote monitoring systems and keep-alivecircuits spend most of their time in standby mode. Manyof these systems also depend on battery power, so powersupply effi ciency in standby state is very important tomaximize battery life. The LT®8410/-1 high effi ciencyboost converter is ideal for these systems, requiringonly 8.5μA of quiescent current in standby mode. Thedevice integrates high value (12.4M/0.4M) output feedbackresistors, signifi cantly reducing input current whenthe output is in regulation with no load. Other featuresinclude an integrated 40V switch and Schottky diode,output disconnect with current limit, built in soft-start,overvoltage protection and a wide input range, all in atiny 8-pin 2mm &Times; 2mm DFN package.
上传时间： 2013-11-22
上传用户：新手无忧
锁定放大是微弱信号检测的重要手段。基于相关检测理论，利用开关电容的开关实现锁定放大器中乘法器的功能，提出开关电容和积分器相结合以实现相关检测的方法，并设计出一种锁定放大器。该锁定放大器将微弱信号转化为与之相关的方波，通过后续电路得到正比于被测信号的直流电平，为后续采集处理提供方便。测量数据表明锁定放大器前级可将10-6 A的电流转换为10-1 V的电压，后级通过带通滤波器级联可将信号放大1×105倍。该方法在降低噪声的同时，可对微弱信号进行放大，线性度较高、稳定性较好。 Abstract: Lock-in Amplifying（LIA）is one of important means for weak signal detection. Based on cross-correlation detection theory， switch in the swithched capacitor was used as multiplier of LIA， and a new method of correlation detection was proposed combining swithched capacitor with integrator. A kind of LIA was designed which can convert the weak signal to square-wave， then DC proportional to measured signal was obtained through follow-up conditioning circuit， providing convenience for signal acquisition and processing. The measured data shows that the electric current（10-6 A） can be changed into voltage（10-1 V） by LIA， and the signal is magnified 1×105 Times by cascade band-pass filter. The noise is suppressed and the weak signal is amplified. It has the advantages of good linearity and stability.
上传时间： 2013-11-28
上传用户：黑漆漆
基于单片机8&Times;8LED点阵模拟电梯，内附有Proteus仿真。
上传时间： 2013-10-25
上传用户：mahone
摘 要：给出了一种采用C8O51F02O单片机实现红外遥控电风扇的系统方案。将红外接收模块、温度采集电路、实时时钟电路、报警电路和风速控制电路置于电风扇中，通过C8051F020单片机实现电风扇风速控制、定时功能和运行模式切换功能，采用4&Times;4键盘或者遥控器完成数据和控制指令的输入，并通过TS1602 LCD 完成基本的状态数据和控制指令实时显示等。实验结果表明：本系统能够成功实现电风扇的运行模式切换、风速控制和定时功能，自动运行模式下，风速由环境温度决定，温度控制精度为土l℃ 。
上传时间： 2013-12-16
上传用户：gtf1207
16&Times;16点阵LED电子显示屏的设计
上传时间： 2013-11-02
上传用户：huannan88
