Abstract: This tutorial discusses proper printed-circuit board (PCB) grounding for mixed-signal designs. Formost applications a simple method without cuts in the ground plane allows for successful PCB layouts withthis kind of IC. We begin this document with the basics: where the current flows. Later, we describe how toplace compOnents and route signal traces to minimize problems with crosstalk. Finally, we move on toconsider power supply-currents and end by discussing how to extend what we have learned to circuits withmultiple mixed-signal ICs.
Abstract: Most magnetic read head data sheets do not fully specify the frequency-dependent compOnents andare often vague when specifying other key parameters. In some cases, the specifications of two very similarheads from two different manufacturers might be quite different in terms of parameters specified and omitted.The limitations in the data sheets make designing an optimum card reading system unnecessarily difficult andtime consuming. This document outlines a strategy to overcome the above shortcomings and offers guidelinesto overcome the noise issues.
Maxim Analog Essentials are a series of plug-in peripheral modules that allow engineers to quickly test, evaluate, and integrate Maxim compOnents into their hardware/software designs. The modules electrically and physically conform to the Digilent Pmod™ interface specification and are compatible with any Digilent Pmod-compatible header.
Abstract: Perfection is relative and application specific. The perfect race car is not the car we use to commute to work.
We need products for everyday use that are high quality, affordable, and solidly reliable. There will be times when we
must use compOnents that are not perfect, and this is when calibration becomes important. Calibration techniques reduce
tolerances in imperfect manufacturing equipment while maintaining affordability.
High input impedance and a wide input range are twohighly desirable features in a precision analog-to-digitalconverter, and the LTC®2449 delta-sigma ADC has both.With just a few external compOnents, the LTC2449 formsan exceptional measurement system with very high inputimpedance and an input range that extends 300mV beyondthe supply rails.
This application note features 8-, 10-, and 12-bit dataacquisition compOnents in various circuit configurations.The circuits include battery monitoring, temperature sensing,isolated serial interfaces, and microprocessor andmicrocontroller serial and parallel interfaces. Also includedare voltage reference circuits (Application Note 42contains more voltage reference circuits).
One of the most critical compOnents in a step-up design like Figure 1 is the transformer. Transformers have parasitic compOnents that can cause them to deviate from their ideal characteristics, and the parasitic capacitance associated with the secondary can cause large resonating current spikes on the leading edge of the switch current waveform.
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.
This document provides practical, common guidelines for incorporating PCI Express interconnect
layouts onto Printed Circuit Boards (PCB) ranging from 4-layer desktop baseboard designs to 10-
layer or more server baseboard designs. Guidelines and constraints in this document are intended
for use on both baseboard and add-in card PCB designs. This includes interconnects between PCI
Express devices located on the same baseboard (chip-to-chip routing) and interconnects between
a PCI Express device located “down” on the baseboard and a device located “up” on an add-in
card attached through a connector.
This document is intended to cover all major compOnents of the physical interconnect including
design guidelines for the PCB traces, vias and AC coupling capacitors, as well as add-in card
edge-finger and connector considerations. The intent of the guidelines and examples is to help
ensure that good high-speed signal design practices are used and that the timing/jitter and
loss/attenuation budgets can also be met from end-to-end across the PCI Express interconnect.
However, while general physical guidelines and suggestions are given, they may not necessarily
guarantee adequate performance of the interconnect for all layouts and implementations.
Therefore, designers should consider modeling and simulation of the interconnect in order to
ensure compliance to all applicable specifications.
The document is composed of two main sections. The first section provides an overview of
general topology and interconnect guidelines. The second section concentrates on physical layout
constraints where bulleted items at the beginning of a topic highlight important constraints, while
the narrative that follows offers additional insight.
Abstract: The DS1875 features a pulse-width modulation (PWM) controller that can be used to control aDC-DC converter. The DC-DC converter can then be used to generate the high bias voltages necessaryfor avalanche photodiodes (APDs). This application note describes the operation of a boost converterthat uses the DS1875. Discussion covers the selection of the inductor and switching frequency, and theselection of compOnents that improve the efficiency of the converter. Test data are presented.
