High performance 1-Wire network driver

This document describes a microcontroller-based 1-Wire® master interface for reliable operation of small, medium, and large 1-Wire networks. This is accomplished using careful impedance matching, intelligent (software-controlled) active pullup, and slew-rate control. Software flow charts are included to assist the user in generating the correct 1-Wire timing for reset pulse, presence detect, write one, write zero, and read time slots using any suitable microcontroller. Scope traces illustrate the timing performance of the driver as well as transmission line effects as they appear with long cables.

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Lower cost, improved performance HDTV active reconstruction filters

In order to preserve the quality of HDTV and progressive DVD video, a bank of three (RGB/YPbPr), 5-pole reconstruction filters are used to set the 30MHz bandwidth and to provide the >40dB selectivity required by EIA770-3.

Application of 3V DAC in ±10V

Many modern systems have the majority of their electronics powered by 3.3V or lower, but must drive external loads with ±10V, a range that is still very common in industrial applications. There are digital to analog converters (DACs) available that can drive loads with ±10V swings, but there are reasons to use a 3.3V DAC and amplify the output voltage up to ±10V.

Flexible fault protection

A flexible circuit is shown that limits current or removes power in response to a command from the user or other fault-indicating signal. It accommodates manual-reset (MR), over-temperature, and protection in hot-swap applications. Residing on either the backplane/host side or the removable-card/remote-device side of the backplane connectors, it guards against start-up faults when a card or board is inserted into a rack or host with the main power supply turned on.

Active video filter

Originally, video filters were passive LC circuits surrounded by amplifiers. Smaller, more efficient designs can currently be achieved by combining the amplifier with an RC filter. Sensitivity analysis and predistortion methods developed in the 1960s have, moreover, overcome the poor performance that gave early video filters a bad reputation.

Use of MAX4090 with reconstruction filter

In most video applications, the video signal generated from the DAC requires a reconstruction filter to smooth out the signal and attenuate the sampling aliases. The MAX4090 is a direct, DC-coupled output driver, which can be used after the reconstruction filter to drive the video signal. The driving load from the video DAC can be varied from 75Ω to 300Ω. A low input impedance (< 100Ω) is required by the MAX4090 in normal operation, special care must be taken when a reconstruction filter is used in front of the MAX4090.

Positive temperature coefficient compensation for PT100 temperature sensor

This article reviews the basic characteristics of common temperature sensors, describes the RTD PT100 temperature transducer, and explains a simple analog approach for linearizing and conditioning the output of that device.

Wiring Guidelines for Parametric Measurement Units (PMU)

This application note discusses ways to help system designers apply proper layout techniques and signal routing. The layout and component descriptions will minimize noise pick-up and manage the thermal dissipation in applications using PMUs.

Using negative voltage charge pumps and analog switches to build DirectDrive video filter amplifiers in audio/video applications

The MAX9503/MAX9505 DirectDrive™ video filter amplifiers integrate an analog switch (MAX9505 only) and a negative charge pump that can be used to improve performance for audio/video applications.

Use a simple voltage regulator circuit to provide a constant voltage to a high-side current monitor

In a typical photodiode current-monitoring application, the voltage drop between the current monitor and the avalanche photodiode (APD) varies with the temperature and current flowing through it, thereby changing the overall gain. This application note describes a regulator circuit that solves this problem by maintaining a constant voltage drop across the current monitor and APD.

Verification and implementation of I²C bus

This application note briefly reviews the history of the I2C bus. It then presents I2C configurations proven to ensure easy communication between the master and slaves on the bus. Examples include schematics and code. Appendix 1 contains helpful definitions of terms used in this article.

Simplifying lithium-ion (Li+) battery charger testing

Because the charging process for Li+ batteries can take an hour or longer, testing a Li+ battery charger using its natural load (i.e., a battery) is time consuming and inconvenient. This application note presents a simple circuit for simulating the behavior of a Li+ battery, thus providing a more convenient method for testing Li+ battery chargers than using real batteries.

Support high-gain applications using rejustors and precision instrumentation amplifiers

This article shows how to use a zero-drift, precision, instrumentation amplifier with a pair of rejustors (passive electrically-adjustable resistors) and gain-setting resistors to ensure high accuracy. The MAX4208 precision instrumentation amplifier serves as the example device. Experiments are described and test results presented.

Laptop VGA signal switching reference design

This application shows how the MAX4885E low-capacitance VGA switch can be used to perform the switching function in a laptop computer. The MAX4885E draws nearly zero current, fits into a 4mm x 4mm package, and incorporates most of the switches and active components used in a discrete implementation. All device outputs are protected to ±15kV Human Body Model (HBM) so that the designer can eliminate many ESD components, thereby reducing cost and saving board space. An application circuit shows the MAX4885E used for VGA signal switching between a laptop and docking station.

PC-Based Oscilloscope Reference Design

This article presents a reference design for a PC-based oscilloscope. The MAX1393 ADC and MAX1396 EV (evaluation) kit are featured. Schematics, software, and explanation of software functions are all provided.

PC-based temperature measurement system reference design

This application note is a reference design for a PC-based temperature measurement system. It uses the MAX1396 and MAX6603EVKITs, a MAXQ2000 microcontroller, and MAX6603 signal conditioner. The design presents an easy way to obtain the temperature readings from the MAX6603 without requiring complicated conversion formulas. Schematics, block diagrams, and software are all provided.

Signal conditioning in industrial multi-channel data acquisition systems using Σ-Δ ADCs

This application note will help the designer of a high-performance, multichannel data acquisition system (DAS) configure the proper interface between industrial sensors and high-performance ADCs. The example used is a power-grid monitoring system. The article explains advantages of the MAX11040K ADC's sigma-delta architecture, and how to select the proper schematic and components to achieve optimum system performance.

VGA 8:1 Multiplexer Reference Design Using the MAX4885

This reference design (RD) features a fully assembled and tested surface-mount printed circuit board (PCB). The RD board utilizes the MAX4885 1:2 or 2:1 multiplexer and other ICs to implement a complete video graphics array (VGA) 8:1 multiplexer. VGA input/output connections are provided to easily interface the MAX4885 RD board with VGA-compatible devices. The RD board gives the option to use a single 5V DC power supply (V+), or this RD board can be powered from any one of the eight VGA sources.

High-precision temperature measurement using advanced thermocouples and high-resolution Σ-Δ ADCs

Many industrial and medical applications require temperature measurements with accuracies of ±1°C or better, performed with reasonable cost over a wide range of temperatures (-270°C to +1750°C), and often with low power consumption. Properly selected, Standardized, modern thermocouples paired with high-resolution ADC data acquisition systems (DASs) can cover this wide temperature range and ensure reproducible measurements, even in the harshest industrial environments.