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Local Interconnect Network (LIN) Provides Multiplexed Communication in Automotive Networks
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
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
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.
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.
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.
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.
4-channel Sigma-Delta ADC for automotive audio
The ADAU1979 includes four high-performance ADCs, a voltage regulator, a band gap reference, and a PLL to provide an analog front-end for automotive audio applications. The ADC inputs accept 4.5 V rms, fully differential, ac-coupled signals. The multibit, continuous-time sigma-delta architecture achieves low EMI, 109-dB dynamic range, and –95-dB THD+N. The on-chip PLL, which can derive the master clock from an external clock or frame clock, eliminates the need for a separate high-frequency master clock. Operating on 1.8-V and 3.3-V supplies, the ADAU1979 dissipates 56 mW in normal mode and 1 mW in power-down mode. Available in a 40-lead LFCSP package, it is specified from –40°C to +105°C and priced at $4.06 in 1000s.
Supervisory Circuits with watchdog and manual reset
The ADM8316, ADM8318, ADM8319, ADM8320, ADM8321, and ADM8322 supervisory circuits monitor power supply voltage levels and code execution integrity in microprocessor-based systems. An on-chip watchdog timer provides power-on reset signals and resets the microprocessor if it fails to strobe within a preset timeout period. The reset signal can also be asserted by an external push button through a manual reset input. The six devices feature different combinations of watchdog input, manual reset input, and output stage configuration, as shown in the table. Each device is available in a choice of 26 reset threshold options ranging from 2.5 V to 5 V in 100-mV increments. Four reset timeout options of 1 ms, 20 ms, 140 ms, and 1120 ms (minimum) and four watchdog timeout options of 6.3 ms, 102 ms, 1600 ms, and 25.6 sec (typical) provide additional flexibility. Available in 5-lead SOT-23 packages, the ADM831x are specified from –40°C to +125°C and priced at $0.69 in 1000s.
Supervisory Circuits with windowed watchdog and manual reset
The ADM8323 and ADM8324 supervisory circuits monitor power supply voltage levels and code execution integrity in microprocessor-based systems. An on-chip watchdog timer checks for activity within a preset timeout window. The watchdog timeout period is measured from the falling edge of the watchdog input. A failure, which can be triggered by watchdog pulses that are too close or an absence of watchdog pulses, results in a low output on the reset pin. A reset signal can also be asserted by an external push button through a manual reset input. The reset output is push-pull on the ADM8323 and open-drain on the ADM8324. Each device is available in a choice of 26 reset threshold options from 2.5 V to 5 V in 100-mV increments. Four reset timeout options of 1 ms, 20 ms, 140 ms, and 1120 ms (minimum) increase flexibility. Available in 5-lead SOT-23 packages, the ADM8323/24 are specified from –40°C to +125°C and priced at $0.79 in 1000s.
AD8418 high-voltage, high-resolution
current-sense amplifier measures bidirectional currents across a shunt
resistor in a variety of applications, including motor control, battery
management, and solenoid control. Its buffered output directly interfaces
with most ADCs. It features 100-dB common-mode rejection from −2 V to +70 V,
a gain of 20, and ±0.15% max gain error over temperature. Its zero-drift
core achieves ±200 μV offset, with 0.1-μV/°C offset drift over temperature
and common-mode range. Fully qualified for automotive applications, it
includes EMI filters and patented circuitry that ensures output accuracy
with pulse-width modulated common-mode voltages. Operating with a 2.7-V to
5.5-V supply, the AD8418 draws 2.6 mA. Specified from
High-performance 12-/16-channel, 24-bit, 192-kHz Differential-Output DACs
The ADAU1962A and ADAU1966A high-performance digital audio circuits comprise 12/16 multibit Σ-Δ DACs with single-ended or differential outputs, plus digital filters and volume controls. The DACs provide 114-dB dynamic range and –97-dB total harmonic distortion plus noise (THD+N) in differential mode. A microcontroller can adjust volume and other parameters, and read the temperature of the on-chip temperature sensor, via an SPI/I2C port. For low EMI, the on-chip PLL derives the master clock from an external left/right frame clock—eliminating the need for a separate high-frequency master clock and allowing the DACs to be used with or without a bit clock. The continuous-time architecture and low-voltage operation combine to further minimize EMI, power consumption, and digital waveform amplitudes. The ADAU1962AW/66AW use two separate power sources or a single analog supply with an on-chip regulator producing the digital supply. Operating with a 2.25-V to 3.46-V digital supply and 3.14-V to 3.46-V analog supply, they consume 299 mW in normal mode and 15 µW in power-down mode. Available in 80-lead LQFP packages, they are specified from –40°C to +105°C, release to automotive (RTA) qualified, and priced at $5.08/$6.34 in 1000s.
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
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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