Abstract: A resistive feedback network is often used to set the output voltage of a power supply. A mechanical potentiometer (pot)conveniently solves the problem of adjusting a power supply. For easier automatic calibration, a mechanical pot can be replaced witha digital pot. This application note presents a calibration solution that uses a digital pot, because digipots are smaller, do not movewith age or vibration, and can be recalibrated remotely. This proposed solution reduces the susceptibility of the system to thetolerance of the digital pot's end-to-end resistance, making the solution optimal fordesigners. This application note also explainssome of the equations required to calculate the resistor chain values and to use a digital pot in this way. A spreadsheet withstandard reisistor values is available for easy calculations.
標(biāo)簽： 電源供應(yīng)器 數(shù)字電位器 應(yīng)用筆記 校準(zhǔn)
上傳時(shí)間： 2013-10-31
上傳用戶：caiguoqing
Abstract: Rail splitting is creating an artificial virtual ground as a reference voltage. It is used to set the signalto match the op amp's "sweet spot." An op amp has the most linear- and distortion-free qualities at that sweetspot. Typically, the sweet spot occurs near the center between the single power rail and ground. In the case ofa number of signals, the virtual ground can control channel DC errors when multiplexing or switching thesignals.
標(biāo)簽： 電源調(diào)整 虛擬地
上傳時(shí)間： 2013-10-23
上傳用戶：wushengwu
AN22 details the theoretical and application aspects of the LT1088 thermal RMS/DC converter. The basic theory behind thermal RMS/DC conversion is discussed and design details of the LT1088 are presented. Circuitry for RMS/DC converters, wideband input buffers and heater protection is shown.
標(biāo)簽： 100 MHz RMS 轉(zhuǎn)換
上傳時(shí)間： 2013-10-16
上傳用戶：china97wan
Telecommunication, satellite links and set-top boxes allrequire tuning a high frequency oscillator. The actualtuning element is a varactor diode, a 2-terminal device thatchanges capacitance as a function of reverse bias voltage.1 The oscillator is part of a frequency synthesizingloop, as detailed in Figure 1. A phase locked loop (PLL)compares a divided down representation of the oscillatorwith a frequency reference. The PLL’s output is levelshifted to provide the high voltage necessary to bias thevaractor, which closes a feedback loop by voltage tuningthe oscillator. This loop forces the voltage controlledoscillator (VCO) to operate at a frequency determined bythe frequency reference and the divider’s division ratio.
標(biāo)簽： 開關(guān)穩(wěn)壓器 低噪聲 上傳時(shí)間： 2013-12-20
上傳用戶：ABCDE
鎖定放大是微弱信號檢測的重要手段。基于相關(guān)檢測理論，利用開關(guān)電容的開關(guān)實(shí)現(xiàn)鎖定放大器中乘法器的功能，提出開關(guān)電容和積分器相結(jié)合以實(shí)現(xiàn)相關(guān)檢測的方法，并設(shè)計(jì)出一種鎖定放大器。該鎖定放大器將微弱信號轉(zhuǎn)化為與之相關(guān)的方波，通過后續(xù)電路得到正比于被測信號的直流電平，為后續(xù)采集處理提供方便。測量數(shù)據(jù)表明鎖定放大器前級可將10-6 A的電流轉(zhuǎn)換為10-1 V的電壓，后級通過帶通濾波器級聯(lián)可將信號放大1×105倍。該方法在降低噪聲的同時(shí)，可對微弱信號進(jìn)行放大，線性度較高、穩(wěn)定性較好。 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.
標(biāo)簽： 開關(guān)電容 鎖定放大器
上傳時(shí)間： 2013-11-29
上傳用戶：黑漆漆
應(yīng)用 APPLICATIONS·電視機(jī)、錄像機(jī)、音頻設(shè)備、顯示器、復(fù)印機(jī)、打印裝置、游戲機(jī)及計(jì)算機(jī)等。·用于開關(guān)電源線性濾波器。·削除 TV、VTR、VCR及監(jiān)聽器泄漏雜音。·用于OA 設(shè)備、通信設(shè)備和其它器件。·TV set, recorder, sound-frequency equipment, show-scope, photocopy-scope, typewrite equipment, recreation-scope, computer etc.·For line filters of switching power supplies.·Eliminates incoming/leaking noise of TVs, VTRs/VCRs and audio equipment .·For OA equipment, communications equipment and other electronic devices.
標(biāo)簽： FILTERS POWER LINE 電源濾波器
上傳時(shí)間： 2013-10-23
上傳用戶：shizhanincc
在理論分析循環(huán)碼編碼和譯碼基本原理的基礎(chǔ)上，提出了基于單片機(jī)系統(tǒng)的(24，16)循環(huán)碼軟件實(shí)現(xiàn)編碼、譯碼的方案。仿真結(jié)果表明(24，16)循環(huán)碼能有效地克服來自通訊信道的干擾，保證數(shù)據(jù)通信的可靠及系統(tǒng)的穩(wěn)定，使誤碼率大幅度降低。本論文對(24，16)循環(huán)碼的研究結(jié)果表明，可以有效地降低錯(cuò)誤概率和提高系統(tǒng)的吞吐量，實(shí)現(xiàn)糾錯(cuò)僅需要在接收端增加有限的存儲空間和計(jì)算復(fù)雜度，具有一定的實(shí)用價(jià)值。 Abstract: Based on analyzing the theory of encoding and decoding of cyclic code， this paper showed the schemes of encoding and decoding of(24，16)cyclic code by the software and based on microcontroller. Simulation results show that using (24，16) cyclic codes can effectively overcome the interference from communication channel， ensure the reliability and stability of data communication systems， and reduce the bit error rate greatly. The results of this paper show that by using the (24，16) cyclic code， the error rate can be reduced and the system throughput can be improved. Meanwhile， the system only needs to enlarge limited storage space and computation the complexity at the receiving end to realize error correction. Thus the (24，16) cyclic code has a practical value.
標(biāo)簽： 24 16 單片機(jī)系統(tǒng) 循環(huán)碼
上傳時(shí)間： 2013-11-09
上傳用戶：gaoliangncepu
為了提高傳統(tǒng)溫度控制系統(tǒng)的性能，將PID控制理論與嵌入式系統(tǒng)相結(jié)合，采用瑞薩電子公司的H8S/2166作為核心處理器，AD公司的AD7705以及熱敏電阻溫度傳感器作為溫度檢測單元，利用4×6小鍵盤、LCD顯示器和S1D13305液晶控制器達(dá)到良好的人機(jī)交互，設(shè)計(jì)出了一個(gè)應(yīng)用于化工領(lǐng)域的嵌入式實(shí)時(shí)溫度控制系統(tǒng)。相比于傳統(tǒng)溫度控制系統(tǒng)，該系統(tǒng)提供了更強(qiáng)的計(jì)算能力和可擴(kuò)展能力，采用增量PID控制算法實(shí)現(xiàn)復(fù)雜控制。通過實(shí)驗(yàn)，該系統(tǒng)能達(dá)到0.1 ℃的溫度控制精度以及小于120 s的溫度穩(wěn)定時(shí)間。 Abstract: In order to improve the performance of conventional temperature control system， combining PID control theory with embedded systems， using the Renesas Electronics Corp. H8S/2166 micro-controller as a core processors， AD7705 and thermistor temperature sensor as a temperature detection unit and 4×6 small keyboard， LCD and S1D13305 LCD controller as a good human-computer interaction， this paper designed an embedded real-time temperature control system which is applied in chemical industry. Compared with conventional temperature control system， this system provides more computing power and extensibility， and adopts PID control algorithm for complex control. Through the experiment， the system can reach temperature control accuracy of 0.1 ℃ and temperature stabilization time of less than 120 seconds.
標(biāo)簽： 瑞薩電子 微控制器 溫度控制 系統(tǒng)設(shè)計(jì)
上傳時(shí)間： 2014-12-26
上傳用戶：003030
針對目前使用的RS232接口數(shù)字化B超鍵盤存在PC主機(jī)啟動(dòng)時(shí)不能設(shè)置BIOS，提出一種PS2鍵盤的設(shè)計(jì)方法。基于W78E052D單片機(jī)，采用8通道串行A/D轉(zhuǎn)換器設(shè)計(jì)了8個(gè)TGC電位器信息采集電路，電位器位置信息以鍵盤掃描碼序列形式發(fā)送，正交編碼器信號通過XC9536XL轉(zhuǎn)換為單片機(jī)可接收的中斷信號，軟件接收到中斷信息后等效處理成按鍵。結(jié)果表明，在滿足開機(jī)可設(shè)置BIOS同時(shí)，又可實(shí)現(xiàn)超聲特有功能，不需要專門設(shè)計(jì)驅(qū)動(dòng)程序，接口簡單，成本低。 Abstract: Aiming at the problem of the digital ultrasonic diagnostic imaging system keyboard with RS232 interface currently used couldn?蒺t set the BIOS when the PC boot， this paper proposed a design method of PS2 keyboards. Based on W78E052D microcontroller，designed eight TGC potentiometers information acquisition circuit with 8-channel serial A/D converter， potentiometer position information sent out with keyboard scan code sequentially.The control circuit based on XC9536 CPLD is used for converting the mechanical actions of the encoders into the signals that can be identified by the MCU， software received interrupt information and equivalently treatmented as key. The results show that the BIOS can be set to meet the boot， ultrasound specific functionality can be achieved at the same time， it does not require specially designed driver，the interface is simple and low cost.
標(biāo)簽： 單片機(jī) B超 數(shù)字化 鍵盤設(shè)計(jì)
上傳時(shí)間： 2013-10-10
上傳用戶：asdfasdfd
以C8051F020為核心處理器，設(shè)計(jì)無線傳感器網(wǎng)絡(luò)數(shù)據(jù)采集系統(tǒng)。系統(tǒng)采用SZ05-ADV型無線通訊模塊組建Zigbee無線網(wǎng)絡(luò)，結(jié)合嵌入式系統(tǒng)的軟硬件技術(shù)，完成終端節(jié)點(diǎn)的8路傳感器信號的數(shù)據(jù)采集。現(xiàn)場8路信號通過前端處理后，分別送入C8051F020的12位A/D轉(zhuǎn)換器進(jìn)行轉(zhuǎn)換。經(jīng)過精確處理、存儲后的現(xiàn)場數(shù)據(jù)，通過Zigbee無線網(wǎng)絡(luò)傳送到上位機(jī)，系統(tǒng)可達(dá)到汽車試驗(yàn)中無線測試的目的。 Abstract: This paper designs a wireless sensor network system for data acquisition with C8051F020 as core processors.The system used SZ05-ADV wireless communication module，set up a Zigbee wireless network， combined with hardware and software technologies of embedded systems，completed the end-node 8-locale sensor signal data acquisition.Eight locale signals were sent separately into the 12-bit ADC of C8051F020 for conversion through front treatment.After accurate processing and storage，the locale data was transmitted to the host computer through Zigbee wireless.The system achieves the purpose of wireless testing in vehicle trial.
標(biāo)簽： C8051F020 Zigbee 汽車測試 系統(tǒng)設(shè)計(jì)
上傳時(shí)間： 2013-11-23
上傳用戶：dsgkjgkjg
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