The STM32F10xxx microcontroller family embeds up to three advanced 12-bit ADCs (depending on the device) with a conversion time down to 1 μs. A self-calibration feature is provided to enhance ADC accuracy versus environmental condition changes.
上传时间： 2014-12-23
上传用户：eastimage
PCB 被动组件的隐藏特性解析 传统上，EMC一直被视为「黑色魔术（black magic）」。其实，EMC是可以藉由数学公式来理解的。不过，纵使有数学分析方法可以利用，但那些数学方程式对实际的EMC电路设计而言，仍然太过复杂了。幸运的是，在大多数的实务工作中，工程师并不需要完全理解那些复杂的数学公式和存在于EMC规范中的学理依据，只要藉由简单的数学模型，就能够明白要如何达到EMC的要求。本文藉由简单的数学公式和电磁理论，来说明在印刷电路板（PCB）上被动组件（passivecomponent）的隐藏行为和特性，这些都是工程师想让所设计的电子产品通过EMC标准时，事先所必须具备的基本知识。导线和PCB走线导线（wire）、走线（trace）、固定架……等看似不起眼的组件，却经常成为射频能量的最佳发射器（亦即，EMI的来源）。每一种组件都具有电感，这包含硅芯片的焊线（bond wire）、以及电阻、电容、电感的接脚。每根导线或走线都包含有隐藏的寄生电容和电感。这些寄生性组件会影响导线的阻抗大小，而且对频率很敏感。依据LC 的值（决定自共振频率）和PCB走线的长度，在某组件和PCB走线之间，可以产生自共振（self-resonance），因此，形成一根有效率的辐射天线。在低频时，导线大致上只具有电阻的特性。但在高频时，导线就具有电感的特性。因为变成高频后，会造成阻抗大小的变化，进而改变导线或PCB 走线与接地之间的EMC 设计，这时必需使用接地面（ground plane）和接地网格（ground grid）。导线和PCB 走线的最主要差别只在于，导线是圆形的，走线是长方形的。导线或走线的阻抗包含电阻R和感抗XL = 2πfL，在高频时，此阻抗定义为Z = R + j XL j2πfL，没有容抗Xc = 1/2πfC存在。频率高于100 kHz以上时，感抗大于电阻，此时导线或走线不再是低电阻的连接线，而是电感。一般而言，在音频以上工作的导线或走线应该视为电感，不能再看成电阻，而且可以是射频天线。
上传时间： 2013-10-08
上传用户：时代将军
Abstract: We don't expect manufacturers to produce clothes that in one size that fits everyone. In thesame way, one ESD component can't solve all issues—each application has different ESD requirements.Knowing that "one size fits all" cannot apply to power design, the power designer, or the engineering"super hero," must consider all the potential disruptions to a steady flow of power and thenvarious waysto mitigate them. This tutorial describes voltage- and current-limiting devices and risetime reducers tomanage the power. It also points to free and low-cost software tools to help design lowpass filters, checkcapacitor self-resonance, and simulate circuits.
上传时间： 2013-11-17
上传用户：zhouxuepeng1
In this paper, two types of MMIC voltage controlled oscillators have been successfully demonstrated. The first chip with single tuning diode shows the excellent tuning linearity. The second chip with two tuning diodes can improve the tuning bandwidth.
上传时间： 2013-10-17
上传用户：xjz632
Avalanche photo diode (APD) receiver modules arewidely used in fi ber optic communication systems. AnAPD module contains the APD and a signal conditioningamplifi er, but is not completely self contained. It stillrequires signifi cant support circuitry including a highvoltage, low noise power supply and a precision currentmonitor to indicate the signal strength. The challenge issqueezing this support circuitry into applications withlimited board space. The LT®3482 addresses this challengeby integrating a monolithic DC/DC step-up converter andan accurate current monitor. The LT3482 can supportup to a 90V APD bias voltage, and the current monitorprovides better than 10% accuracy over four decades ofdynamic range (250nA to 2.5mA).
上传时间： 2014-01-18
上传用户：wenyuoo
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.
上传时间： 2013-12-20
上传用户：ABCDE
Tuning the nRF24xx matching network VICKY TEL:0755-26674773 E-mail:nrf800@freqchina.com
上传时间： 2013-10-26
上传用户：gaoqinwu
The CAT93C46 is a 1 kb Serial EEPROM memory device which isconfigured as either 64 registers of 16 bits (ORG pin at VCC) or 128registers of 8 bits (ORG pin at GND). Each register can be written (orread) serially by using the DI (or DO) pin. The CAT93C46 features aself−timed internal write with auto−clear. On−chip Power−On Resetcircuit protects the internal logic against powering up in the wrongstate.
上传时间： 2013-11-19
上传用户：ynzfm
Bootloader是微处理器上电时运行的第一段代码，它可以通过通信接口实现对微处理器内部应用程序的更新升级，为网络化嵌入式产品的应用程序升级带来极大的便利。由于目前没有统一嵌入式系统的Bootloader。基于NEC 78K0系列单片机自编程原理，设计出一个适用于78K0/Fx2系列单片机的Bootloader，并能够通过单片机串口在线升级应用程序。 Abstract: Bootloader is the first piece of code executed after microprocessor startup. It makes the embedded product’s firmware update conveniently through communication interface. However， no unified bootloader is available for all kinds of microprocessor products. Based on the principle of self-programming NEC 78K0s’ series， a useful Bootloader which is suitable for 78K0/Fx2s’ series MCU is designed，the design can update the application through serial ports.
标签： Bootloader MCU 自编程
上传时间： 2013-10-25
上传用户：fang2010
FEATURES400 MSPS internal clock speedIntegrated 10-bit DAC32-bit tuning wordPhase noise ≤ –120 dBc/Hz @ 1 kHz offset (DAC output)Excellent dynamic performance>75 dB SFDR @ 160 MHz (±100 kHz offset) AOUTSerial I/O control1.8 V power supplySoftware and hardware controlled power-down48-lead TQFP/EP packageSupport for 5 V input levels on most digital inputsPLL REFCLK multiplier (4× to 20×)Internal oscillator; can be driven by a single crystalPhase modulation capabilityMultichip synchronization
上传时间： 2014-12-04
上传用户：axin881314
