General Description
The LM621 is a bipolar IC designed for commutation of
brushless DC motors. The part is compatible with both
three- and four-phase motors. It can directly drive the power
switching devices used to drive the motor. The LM621 provides
an adjustable dead-time circuit to eliminate ``shootthrough''
current spiking in the power switching circuitry.
Operation is from a 5V supply, but output swings of up to
40V are accommodated. The part is packaged in an 18-pin,
dual-in-line package.
·詳細說明：MPEG4解壓縮算法源代碼，研究其中關于錯誤處理部分。-MPEG4 solution compression calculated the law origin code, studies about the error processing part. 文件列表(點擊判斷是否您需要的文件): DECORE ......\BUILD .
Abstract: Specifications such as noise, effective number of bits (ENOB), effective resolution, and noise-free resolution inlarge part define how accurate an ADC really is. Consequently, understanding the performance metrics related to noise isone of the most difficult aspects of transitioning from a SAR to a delta-sigma ADC. With the current demand for higherresolution, designers must develop a better understanding of ADC noise, ENOB, effective resolution, and signal-to-noiseratio (SNR). This application note helps that understanding.
Silicon Motion, Inc. has made best efforts to ensure that the information contained in this document is accurate andreliable. However, the information is subject to change without notice. No responsibility is assumed by SiliconMotion, Inc. for the use of this information, nor for infringements of patents or other rights of third parties.Copyright NoticeCopyright 2002, Silicon Motion, Inc. All rights reserved. No part of this publication may be reproduced, photocopied,or transmitted in any form, without the prior written consent of Silicon Motion, Inc. Silicon Motion, Inc. reserves theright to make changes to the product specification without reservation and without notice to our users
Integrated EMI/Thermal Design forSwitching Power SuppliesWei ZhangThesis submitted to the Faculty of theVirginia Polytechnic Institute and State Universityin partial fulfillment of the requirements for the degree of
Integrated EMI/Thermal Design forSwitching Power SuppliesWei Zhang(ABSTRACT)This work presents the modeling and analysis of EMI and thermal performancefor switch power supply by using the CAD tools. The methodology and design guidelinesare developed.By using a boost PFC circuit as an example, an equivalent circuit model is builtfor EMI noise prediction and analysis. The parasitic elements of circuit layout andcomponents are extracted analytically or by using CAD tools. Based on the model, circuitlayout and magnetic component design are modified to minimize circuit EMI. EMI filtercan be designed at an early stage without prototype implementation.In the second part, thermal analyses are conducted for the circuit by using thesoftware Flotherm, which includes the mechanism of conduction, convection andradiation. Thermal models are built for the components. Thermal performance of thecircuit and the temperature profile of components are predicted. Improved thermalmanagement and winding arrangement are investigated to reduce temperature.In the third part, several circuit layouts and inductor design examples are checkedfrom both the EMI and thermal point of view. Insightful information is obtained.
Abstract: The rapid build out of today's smart grid raises a number of security questions. In this article,we review two recent well-documented security breaches and a report of a security gap. These situationsinclude a 2009 smart-meter hack in Puerto Rico; a 2012 password discovery in grid distributionequipment; and insecure storage of a private key in distribution automation equipment. For each of theseattacks, we examine the breach, the potential threat, and secure silicon methods that, as part of acomplete security strategy, can help thwart the attacks.
The LTC3546 is a dual output current mode buck regulatorwith fl exible output current partitioning. Beyondthe advantages normally associated with dual outputregulators (reduced size, cost, EMI and part count, withimproved effi ciency), the LTC3546’s outputs can bepartitioned for either 3A and 1A outputs, or two 2A outputs.This increases its application range and simplifi esmultiple supply rail designs. A confi gurable Burst Mode®clamp for each output sets the current transition levelbetween Burst Mode operation and forced continuousconduction mode to optimize effi ciency over the entireoutput range. An adjustable switching frequency up to4MHz and internal power MOSFET switches allow forsmall and compact footprints.
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.
