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Application Notes

Local Interconnect Network (LIN) Provides Multiplexed Communication in Automotive Networks

AN-1138: LINB DLL Programmer's Guide

This 20-page Application Note describes the library functions available in the LINBWSD.dll library. These functions can be used to create a USB-to-LIN downloader for integrated battery sensor devices. LINBWSD.dll uses Protocol 6 for Flash/EE memory programming via LIN. Protocol 6 is explained in detail in Application Note AN-946. LINBWSD.dll can be used for LIN programming with the following IBS devices: ADuC7032-8L, ADuC7033, ADuC7036DCPZ, and ADuC7039.

Controller Area Network Provides Robust Communications and Fault Handling

AN-1123: Controller Area Network (CAN) Implementation Guide

The controller area network (CAN) standard for distributed communications, which has built-in fault handling, is specified for the physical and data link layers of the open systems interconnection (OSI) model in ISO-11898. CAN has been widely adopted in industrial and instrumentation applications and the automotive industry due to the inherent strengths of its communication mechanisms. This 16-page Application Note considers various aspects of CAN implementations in industrial applications.

Converting the Output of an Accelerometer to an Angle of Inclination

AN-1057: Using an Accelerometer for Inclination Sensing

Inclination sensing uses the gravity vector and its projection on the axes of the accelerometer to determine the tilt angle. Because gravity is a dc acceleration, any forces that result in an additional dc acceleration corrupt the output signal and result in an incorrect calculation. Sources of dc acceleration include the period of time when a vehicle is accelerating at a constant rate and rotating devices that induce a centripetal acceleration on the accelerometer. In addition, rotating an accelerometer through gravity causes an apparent ac acceleration as the projection of gravity on the axes of interest changes. Any filtering of the acceleration signal before calculating the inclination affects how quickly the output settles to the new static value. This 8-page Application Note discusses the basic principles for converting the output of an accelerometer to an angle of inclination. This discussion includes how to calculate the ideal inclination angle for a single-axis, dual-axis, or triple-axis solution. In addition, some basic information about calibration is included to reduce error from offset and sensitivity mismatch.

Circuits from the Lab

Automotive SENT Interface-Based Thermocouple Temperature Sensor with Cold Junction Compensation Using the ADuC7060/ADuC7061 Precision Analog Microcontroller (CN0281)

This circuit uses the ADuC7060 or the ADuC7061 precision analog microcontroller in an accurate thermocouple temperature monitoring application. The microcontrollers integrate dual 24-bit sigma-delta (Σ-Δ) analog-to-digital converters (ADCs), dual programmable current sources, a 14-bit digital-to-analog converter (DAC), and a 1.2 V internal reference—as well as an ARM7 core, 32 KB flash, 4 KB SRAM, UART, timers, serial peripheral interface (SPI), I2C interfaces, and various other digital peripherals. The ADuC7060/ ADuC7061 are connected to a thermocouple and a 100-Ω platinum resistance temperature detector (RTD), which is used for cold-junction compensation. As an extra option, the ADT7311 digital temperature sensor can measure the cold-junction temperature instead of the RTD.

A Robust Video Receiver with Input Short-to-Battery Protection (CN0263)

This circuit provides a robust solution for receiving CBVS video signals in harsh environments, including integrated overvoltage protection. It uses the ADA4830-1 low-power differential receiver to convert a fully differential or pseudo differential video signal to a single-ended signal before being digitized by the ADV7180 video decoder.The ADA4830-1 eliminates the common-mode noise and phase noise caused by the ground potential differences between an incoming video signal source and the receive circuit. The circuit operates in the harsh automotive environment, detecting short-to-battery events and protecting from them.

Fully Isolated Lithium Ion Battery Monitoring and Protection System (CN0235)

Lithium ion (Li-Ion) battery stacks contain a large number of individual cells that must be monitored correctly in order to enhance the battery efficiency, prolong the battery life, and ensure safety. The 6-channel AD7280A devices in this circuit act as the primary monitor, providing accurate voltage measurement data to the System Demonstration Platform (SDP-B) evaluation board; the 6-channel AD8280 devices act as the secondary monitor and protection system. Both devices can operate from a single wide supply range of 8 V to 30 V and operate over the industrial temperature range of −40°C to +105°C. The AD7280A contains an internal ±3-ppm reference that allows a cell voltage measurement accuracy of ±1.6 mV. The ADC resolution is 12 bits and allows conversion of up to 48 cells within 7 μs. The AD8280 functions independently of the primary monitor and provides alarm functions, indicating out of tolerance conditions. It contains its own reference and LDO, both of which are powered from the battery cell stack. The reference, in conjunction with external resistor dividers, is used to establish overvoltage/undervoltage trip points. Each channel contains programmable deglitching circuitry to avoid alarming from transient input levels. The AD7280A and AD8280, which reside on the high voltage side of the battery management system, have a daisy-chain interface, allowing up to eight AD7280A’s and eight AD8280’s to be stacked together and 48 Li-Ion cell voltages to be monitored. Adjacent AD7280As and AD8280s can communicate directly, passing data up and down the stack without the need for isolation. The master devices on the bottom of the stack use the SPI interface and GPIOs to communicate with the SDP-B evaluation board. High-voltage galvanic isolation is required to protect the low-voltage side of the SDP-B board at this interface. The ADuM1400 and ADuM1401 digital isolators and the ADuM5404 digital isolator with integrated dc-to-dc converter combine to provide the required eleven channels of isolation in a compact, cost effective solution. The ADuM5404 also provides isolated 5 V to the VDRIVE input of the lower AD7280A and the VDD2 supply voltage for the ADuM1400 and ADuM1401 isolators.

New Product Briefs

July 2014

Analog Front-End for radar receive path includes ADC, 4-channel LNA/PGA/AAF

ad8285The AD8285 analog front-end for radar receive paths includes four channels of low-noise amplifier (LNA), programmable-gain amplifier (PGA), and antialiasing filter (AAF), plus a direct-to-ADC channel, a 5-channel multiplexer, and a 12-bit ADC. Each channel has a 16-dB to 34-dB gain range in 6-dB increments; and the ADC converts at up to 72 MSPS. The combined input referred noise voltage of the entire channel is 3.5 nV/√Hz at maximum gain. Designed for low cost, low power, compact size, flexibility, and ease of use, the device is optimized for dynamic performance and low power in applications where a small package size is critical. Operating on 1.8-V and 3.3-V supplies, the AD8285 dissipates 185 mW in normal mode and 5 mW in power-down mode. Available in a 72-lead power LFCSP package, it is specified from –40°C to +105°C and priced at $8.33 in 1000s.

Technical Articles

Ben Wang, Reduced Integration Time Improves Accuracy in Dead Reckoning Navigation Systems, Analog Dialogue, 2013-07-02

David Krakauer, Digital isolators deliver automotive-grade quality, reliability, EE Times, 2013-04-02

Peter Hall, New ICs, topologies beat the automotive data-net bottleneck, EE Times, 2013-03-04

Paul Slattery, Enabling HDMI in the automotive segment, Automotive Electronics News, 2012-11-16

Don Nisbett, Looking Back on Safety, Design Solutions, 2012-10-15

Jim Stegen, Digital Isolators: Solving design challenges in automotive xEV applications, Automotive Electronics News, 2012-10-04

Don Nisbett, Rearward detection mandate presents rearview video design challenges, Automotive Electronics News, 2012-07-05

Don Nisbett, Diagnostic Technique Detects Open and Short Circuits in Wiring Harnesses, Analog Dialogue, 2012-07-02

Peter Voss and Benno Kusstatscher, Camera based ADAS for mass deployments, EE Times Europe, 2012-06-21

Javier Salcedo and Jean-Jacques Hajjar, Bidirectional Devices for Automotive-Grade Electrostatic Discharge Applications, IEEE Electron Devices Journal, 4/9/12

Jeff Watson and Gustavo Castro, High-Temperature Electronics Pose Design and Reliability Challenges, Analog Dialogue, 4/4/12

Darwin Tolentino, Simple Circuit Provides Adjustable CAN-Level Differential-Output Signal, Analog Dialogue, 4/4/12

Webinars and Tutorials

Implementing video surveillance - This webcast will present the two forms of video surveillance systems prevalent in the market today and the individual form of end equipment used in each. The major focus will be the edge devices or cameras and will review two image processing challenges and one power management challenge along with associated solutions to aid the design and implementation of video surveillance systems. Co-sponsored by Arrow Electronics.

 

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