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汽车电子
应用笔记
增强EMC保护，同时保持电容数字转换精度
AN-1055：AD7746的EMC保护
AD7746电容数字转换器(CDC)可直接测量浮地式电容传感器的电容，即传感器直接连接至AD7746输入引脚。电磁干扰会扭曲容性传感器周围的电场，从而改变电容测量结果。可以通过外部滤波保护AD7746，使之不受电磁干扰影响，但在信号路径中增加滤波器会降低转换精度。这篇20页的应用笔记讨论AD7746引脚上的外部滤波器可以实现的EMC性能，以及滤波器对AD7746精度的影响。
将加速度计的输出转换为倾斜角度
AN-1057：利用加速度计进行倾斜检测
倾斜检测利用重力矢量及其在加速度计轴上的投影来确定倾斜角度。由于重力是直流加速度，任何产生额外直流加速度的力均会破坏输出信号，导致计算错误。直流加速度的来源包括车辆在一定时间内以恒定速率加速，以及旋转器件在加速度计上产生向心加速度。此外，通过重力旋转加速度计，随着目标轴上的重力投影变化，会引起明显的交流加速度。在计算倾斜之前，对加速度信号进行任何形式的滤波都会影响建立输出新静态值的速度。这篇8页的应用笔记讨论将加速度计输出转换为倾斜角度的基本原理。讨论内容包括如何计算单轴、双轴或三轴解决方案的理想倾斜角度。此外还包括一些关于校准的基本信息，以减少失调和灵敏度失配所引起的误差。
实验室电路
用于AD2S1210旋变数字参考信号输出的高电流驱动器(CN0192)
RDC与旋转传感器配合使用，以便检测电机轴的位置和转速。在这种应用中，旋变器利用正弦波参考信号进行激励。初级绕组上的旋变器激励参考信号转换为两个正弦差分输出信号：正弦和余弦。正弦和余弦信号的幅度取决于实际的旋变器位置、旋变器转换比和激励信号幅度。RDC同步采样两个输入信号，以便向数字引擎（即所谓Type II跟踪环路）提供数字化数据。Type II跟踪环路负责计算位置和速度。
新产品简介
June 2011
Lithium-ion Battery-Monitoring System
 The
AD7280A lithium-ion battery-monitoring system
contains all of the functions required for monitoring battery stacks in
hybrid electric vehicles, power tools, and power-supply backups.
Multiplexing six voltage inputs and six temperature inputs into a 12-bit,
1-Msps ADC, it monitors up to six cells. Functionally complete, it includes
a 2.5-V, ±3-ppm/°C voltage reference, channel sequencer, alert function,
cell-balancing interface, and self-test feature, which applies a known
voltage to the ADC inputs. Its daisy-chain interface allows up to eight
devices to be stacked without the need for individual device isolation,
enabling conversion of up to 48 cell voltages within 7 μs. Operating with an
8‑V to 30-V supply, the AD7280A dissipates 170 mW during conversion, 75 mW
in software power-down mode, and 54 µW in full power-down
mode. Available in a 48-lead LQFP package, it is automotive qualified to
AECQ100, specified from –40°C to +105°C, and priced at $4.33 in 1000s.
SHARC Processors
 The
ADSP-21478 and
ADSP-21479 fourth-generation
low-power SHARC® processors offer increased performance,
hardware-based filter accelerators, audio- and application-focused
peripherals, and up to 5 Mbits of SRAM, making them ideal for professional
and automotive audio applications. Their single-instruction, multiple-data
(SIMD) core supports 32-bit fixed-point and 32-/40-bit floating-point
arithmetic formats—performing up to 1800 MFLOPS with a 300-MHz clock. The
variable instruction-set architecture (VISA) allows code to be decreased by
20% to 30%, increasing the available memory. Application-specific
peripherals simplify hardware design, minimize design risks, and reduce time
to market. The software-programmable signal routing unit (SRU) enables
flexible routing of digital applications interface (DAI) blocks. Peripherals
connected through the SRU include serial ports, SPI ports, S/PDIF
transceiver, and an 8-channel asynchronous sample-rate-converter block. The
digital peripheral interface (DPI) includes a UART and a two-wire interface.
FIR, IIR, and FFT accelerators increase the total system performance. The
DMA controller can transfer data from the serial ports to external 16-bit
SDR SDRAMs through a glueless interface. All SHARC processors are pin- and
code compatible. Specified from 0°C to +70°C (K-grade) or –40°C to +85°C
(B-grade), the ADSP-21478/79 are available in 100-lead LQFP and 196-ball
CSP-BGA packages and priced from $7.99 in 1000s.
Blackfin Embedded Processor
 The
ADSP-BF592 Blackfin processors—optimized for
cost-sensitive industrial, automotive, and medical applications—combine the
multimedia signal-processing power of a single-instruction, multiple-data
(SIMD) DSP with the control capabilities of a RISC microcontroller. With two
16-bit MACs, two 40-bit ALUs, four 8-bit video ALUs, and 132K bytes of
core-addressable memory, they operate at up to 400 MHz. 64K bytes of
factory-programmed instruction ROM contains VDK RTOS and C-runtime
libraries. Peripherals include four timer/counters (three with PWM); two
full-duplex synchronous serial ports (SPORTs) that support eight channels of
I2S stereo audio; two SPI ports; one UART with IrDA support; a
parallel peripheral interface (PPI) that supports ITU-R 656 video formats; a
two-wire interface (TWI) controller; nine peripheral DMAs; two
memory-to-memory DMA channels, an event handler, 32 GPIOs, a JTAG debugging
interface, and a PLL. Specified from 0°C to +70°C (K-grade) or –40°C to
+85°C (B-grade), the ADSP-BF592 is available in a 64-lead LFCSP package and
priced from $3.56 in 1000s.
技术文章
Ben Wang,
利用SigmaDSP将汽车音频系统的噪声和功耗降至最低, Analog Dialogue, 3/1/2011
Fionn Hurley,
汽车应用需要快速模拟视频切换, ECN,
12/21/2010
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