Handheld DeSIgners often grapple with ways to de-bounceand control the on/off pushbutton of portable devices.Traditional de-bounce designs use discrete logic, fl ipflops, resistors and capacitors. Other designs includean onboard microprocessor and discrete comparatorswhich continuously consume battery power. For highvoltage multicell battery applications, a high voltageLDO is needed to drive the low voltage devices. All thisextra circuitry not only increases required board spaceand design complexity, but also drains the battery whenthe handheld device is turned off. Linear Technology addressesthis pushbutton interface challenge with a pairof tiny pushbutton controllers.
上传时间： 2013-11-18
上传用户：ZJX5201314
Many system DeSIgners need an easy way to producea negative 3.3V power supply. In systems that alreadyhave a transformer, one option is to swap out the existingtransformer with one that has an additional secondarywinding. The problem with this solution is that manysystems now use transformers that are standard, offthe-shelf components, and most DeSIgners want toavoid replacing a standard, qualifi ed transformer with acustom version. An easier alternative is to produce thelow negative voltage rail by stepping down an existingnegative rail. For example, if the system already employsan off-the-shelf transformer with two secondary windingsto produce ±12V, and a –3.3V rail is needed, a negativebuck converter can produce the –3.3V output from the–12V rail.
上传时间： 2013-10-09
上传用户：Jerry_Chow
Once relegated to the hinterlands of low cost indicatorlights, the LED is again in the spotlight of the lightingworld. LED lighting is now ubiquitous, from car headlightsto USB-powered lava lamps. Car headlights exemplifyapplications that capitalize on the LED’s clear advantages—unwavering high quality light output, tough-assteelrobustness, inherent high effi ciency—while a USBlava lamp exemplifi es applications where only LEDs work.Despite these clear advantages, their requirement forregulated voltage and current make LED driver circuitsmore complex than the venerable light bulb, but some newdevices are closing the gap. For instance, the LTM®8040μModule™ LED driver integrates all the driver circuitryinto a single package, allowing DeSIgners to refocus theirtime and effort on the details of lighting design criticalto a product’s success.
上传时间： 2013-10-16
上传用户：togetsomething
DeSIgners spend much time combating thermal effects incircuitry. The close relationship between temperature andelectronic devices is the source of more design headachesthan any other consideration.
上传时间： 2013-10-17
上传用户：风之骄子
A recent trend in the design of portable devices has beento use ceramic capacitors to filter DC/DC converter inputs.Ceramic capacitors are often chosen because of theirsmall size, low equivalent series resistance (ESR) and highRMS current capability. Also, recently, DeSIgners havebeen looking to ceramic capacitors due to shortages oftantalum capacitors.
上传时间： 2013-11-05
上传用户：comer1123
When a system designer specifies a nonisolated dc/dc powermodule, considering the needed input voltage range isequally as important as considering the required performanceattributes and features. Generally, nonisolated moduleshave either a narrow or a wide input voltage range. Narrowinputmodules typically have a nominal input voltage of3.3, 5, or 12 V. For systems that operate from a tightlyregulated input bus—such as those that do not use batterybackup—a narrow-input module is often adequate sincethe input remains fairly stable.Offering greater flexibility, wide-input modules operatewithin a range of 7 to 36 V, which includes the popular12- or 24-V industrial bus. This enables a single module tobe used for generating multiple voltages. These modulesare ideal for industrial controls, HVAC systems, vehicles,medical instrumentation, and other applications that usea loosely regulated distribution bus. In addition, systemspowered by a rectifier/battery charger with lead-acidbattery backup almost always require wide-input modules.System DeSIgners who choose power supplies may wantto take a close look at the latest generation of wide-inputdc/dc modules.
标签： Wide-input modules offer dc
上传时间： 2014-12-24
上传用户：dragonhaixm
Designing Boards with Atmel AT89C51,AT89C52, AT89C1051, and AT89C2051 for Writing Flash at In-Circuit Test. Recent improvements in chips and testers have made it possible for the tester to begin taking over the role tradi-tionally assigned to the PROM program-mer. Instead of having a PROM pro- grammer write nonvolatile memories before assembling the board, the in-cir- cuit tester writes them during in-circuit testing operations. Many Teradyne Z18- series testers are now in use loading code into nonvolatile memories, micro- controllers and in-circuit programmable logic devices. The purpose of this note is to explain how the Z18 approaches the writing task for Atmel AT89C series IC’s, so that DeSIgners of boards using these chips can get the best results.
上传时间： 2013-11-17
上传用户：xiaozhiqban
IntroductionAs chip DeSIgners pack more functions into ICs,pin counts continue to grow and the space betweenpins keeps shrinking. Pin spacings of 0.5 mm and0.65 mm are not at all uncommon. The power ofthese new ICs is wonderful, to be sure, but trou-bleshooting them can be a chore because connect-ing scopes and logic analyzers has become muchmore difficult and less dependable.
标签： Agilent Probing Wedge High
上传时间： 2013-10-22
上传用户：蒋清华嗯
Designing Boards with Atmel AT89C51, AT89C52, AT89C1051, and AT89C2051 for Writing Flash at In-Circuit Test:Recent improvements in chips andtesters have made it possible for thetester to begin taking over the role traditionallyassigned to the PROM programmer.Instead of having a PROM programmerwrite nonvolatile memoriesbefore assembling the board, the in-circuittester writes them during in-circuittesting operations. Many Teradyne Z18-series testers are now in use loadingcode into nonvolatile memories, microcontrollersand in-circuit programmable logic devices. The purpose of this note is to explain how the Z18 approaches the writing task for Atmel AT89C series IC’s,so that DeSIgners of boards using these chips can get the best results.
标签： Designing Boards Atmel with
上传时间： 2013-11-20
上传用户：lijianyu172
I2C interface, is a very powerful tool for system DeSIgners. Theintegrated protocols allow systems to be completely software defined.Software development time of different products can be reduced byassembling a library of reusable software modules. In addition, themultimaster capability allows rapid testing and alignment ofend-products via external connections to an assembly-line computer.The mask programmable 87LPC76X and its EPROM version, the87LPC76X, can operate as a master or a slave device on the I2Csmall area network. In addition to the efficient interface to thededicated function ICs in the I2C family, the on-board interfacefacilities I/O and RAM expansion, access to EEPROM andprocessor-to-processor communications.
标签： microcontro Using 76X LPC
上传时间： 2013-12-30
上传用户：Artemis
