ADVFC32芯片中文翻译
频率信号的获取方法

自动检测中获取频率信号的方法摘要:在微机测控系统中往往需要将被测信号(传感器信号)转换为频率信号。
获取频率信号的常用方法是使用集成电压/频率变换器(VFC),但集成VFC有一些明显的局限。
本文讨论了集成VFC的特点,以及在微机测控系统中获取频率信号的几种实用方法,恰当选用这些方法既能满足微机测控系统的应用需要,又能克服集成VFC的某些应用局限。
关键词:自动检测;频率信号;传感器;555定时器;锁相环Automatic detection for the method of frequency signalAbstract:It is very useful for measuring and controlling systems with microcontrollers to convert sensor signals into frequency signals. The integrated voltage-to-frequency converters are commonly used for this purpose. The integrated voltage-to-frequency converters have some significant limitations of performance and cost. In a microcomputer measurement and control system is discussed in this paper to obtain frequency signal of several practical methods (VFC) without integration and its characteristics, appropriate chooses these methods can not only meet the needs of the application of microcomputer measurement and control system, and integration of VFC some application limitation can be overcome.Key words:Automatic detection; Frequency signal; sensor; 555 timer; phase-locked loop (PLL)1 引言由于频率信号具有很多重要优点,如抗干扰性好、便于远距离传送输、送入微处理器时输入灵活、接口简单、占用I/O口资源少,因而在微机测控系统中有重要应用。
V-F与F-V转换电路

C2
VIN +15V
偏移调节 -15V
增益调节 R2 R1
R5 RIN R4
-15V 0.1μF
单稳触发器电容 +V逻辑 R3
FOUT
-IN 1
NC- 2
NC- 3 -VCC 4
5 C1 NC- 6 FOUT 7
+A -
1mA
单稳态 -VS 触发器
W1 W2 比较器
14 +IN 13 VOUT 12 +VCC
若要求输入脉冲频率FIN=10KHz时输出电压VOUT=10V,可使 R1+R2=40KΩ,C1=3650pF,C2=0.01μF。
单片机原理与应用
中ADVFC32的内部结构与引脚分布如图7.40所示,有14个引脚,采
用双列直插式结构。在联接使用时,主要外接的器件有电阻RIN、积 分电容器C2,输出电阻R3以及单稳定时器电容C1。这些器件的参数可 由下列公式计算:
C1
3.3105 Fmax
3.010小于1000pF)
C
+VS
VIN
R
IIN
A
+
VINT
比较器
W1 W2
RX CX 单稳态定时器
RL
Vo
(f)
S IR
-VS
图7.38 V/F转换器原理图
假设开始时单稳态定时器输出低电平,恒流源与反相输入端
开路。这时流过积分器的电流只有输入电流IIN。该电流对积分 电容器C充电,使积分器输出VINT下降。下降到0V时比较器翻 转,触发单稳态定时器输出宽度为t0的正脉冲,使模拟开关S闭 合,恒流源向积分电容器C反向充电(也称为电容器放电),
单片机原理与应用
频率信号的获取方法

自动检测中获取频率信号的方法摘要:在微机测控系统中往往需要将被测信号(传感器信号)转换为频率信号。
获取频率信号的常用方法是使用集成电压/频率变换器(VFC),但集成VFC有一些明显的局限。
本文讨论了集成VFC的特点,以及在微机测控系统中获取频率信号的几种实用方法,恰当选用这些方法既能满足微机测控系统的应用需要,又能克服集成VFC的某些应用局限。
关键词:自动检测;频率信号;传感器;555定时器;锁相环Automatic detection for the method of frequency signalAbstract:It is very useful for measuring and controlling systems with microcontrollers to convert sensor signals into frequency signals. The integrated voltage-to-frequency converters are commonly used for this purpose. The integrated voltage-to-frequency converters have some significant limitations of performance and cost. In a microcomputer measurement and control system is discussed in this paper to obtain frequency signal of several practical methods (VFC) without integration and its characteristics, appropriate chooses these methods can not only meet the needs of the application of microcomputer measurement and control system, and integration of VFC some application limitation can be overcome.Key words:Automatic detection; Frequency signal; sensor; 555 timer; phase-locked loop (PLL)1 引言由于频率信号具有很多重要优点,如抗干扰性好、便于远距离传送输、送入微处理器时输入灵活、接口简单、占用I/O口资源少,因而在微机测控系统中有重要应用。
adi中英文技术资料

AD中英文技术资料Ecardsh整理,2011年8月3日型号厂家功能说明AD5361 ADI 16通道、14-Bit、串行输入、电压输出型DACAD5362 ADI 八通道、14-Bit、串行输入、电压输出型DACAD5363 ADI 八通道、14-Bit、串行输入、电压输出型DACAD536A ADI Integrated Circuit True RMS-to-DC ConverterAD537 ADI Integrated Circuit Voltage-to-Frequency ConverterAD5370 ADI 40通道、16-Bit、串行输入、电压输出型DACAD5371 ADI 40通道、14-Bit、串行输入、电压输出型DACAD5372 ADI 32通道、14-Bit、串行输入、电压输出型DACAD5373 ADI 32通道、14-Bit、串行输入、电压输出型DACAD5378 ADI 32-Channel 14-Bit Serial/Parallel Bipolar D/A ConverterAD5379 ADI 40-Channel 14-Bit Bipolar Voltage-Output D/A ConverterAD537S ADI Aerospace Voltage to Frequency Converter, ±30V to 150kHzAD537S ADI Aerospace Voltage to Frequency Converter, ±30V to 150kHzAD538 ADI Real-Time Analog Computational Unit (ACU)AD5380 ADI 40-Channel 14-Bit 3 V/5 V Single-Supply Voltage-Output DACAD5381 ADI 40-Channel 12-Bit 3 V/5 V Single-Supply Voltage-Output DACAD5382 ADI 32-Channel 14-Bit 3 V/5 V Single-Supply Voltage-Output DACAD5383 ADI 32-Channel 12-Bit 3 V/5 V Single-Supply Voltage-Output DACAD5384 ADI 40-Channel, 3 V/5 V Single Supply,14-Bit, Serial Voltage-Output DAC AD539 ADI Wideband Dual-Channel Linear Multiplier/DividerAD5390 ADI 16-Channel 14-Bit 3 V/5 V Single-Supply Voltage-Output DACAD5391 ADI 16-Channel 12-Bit 3V/5V Single-Supply Voltage-Output DACAD5392 ADI 8-Channel 14-Bit Single-Supply Voltage-Output DACAD5398 ADI 120 mA、吸电流、10-Bit、具有I2C接口的数模转换器AD5398A ADI 120 mA, Current Sinking, 10-Bit, I2C DACAD5398A ADI 120 mA, Current Sinking, 10-Bit, I2C DACAD5398A ADI 120 mA, Current Sinking, 10-Bit, I2C DACAD5399 ADI Two's Complement, Dual 12-Bit DACs, Internal REFAD5405 ADI Dual 12-Bit , High Bandwidth, Multiplying DAC with 4 Quadrant Resistors and Parallel InterfaceAD5410 ADI Single Channel, 12-Bit, Serial Input, Current Source DACAD5412 ADI Single Channel, 12-Bit, Serial Input, Current Source & Voltage Output DACAD5415 ADI Dual 12-Bit,High Bandwidth,Multiplying DAC with 4 Quadrant Resistors and Serial InterfaceAD5420 ADI Single Channel, 16-Bit, Serial Input, Current Source DACAD5422 ADI 单通道,16-Bit, 串行输入, 电流源与电压输出数模转换器AD5424 ADI High Bandwidth CMOS 8-Bit Parallel Interface Multiplying D/A Converter AD5425 ADI High Bandwidth, CMOS 8-Bit Serial Interface Multiplying D/A Converter AD5426 ADI High Bandwidth CMOS 8-Bit Serial Interface Multiplying D/A Converter AD5428 ADI Dual 8-Bit, High Bandwidth Multiplying DACs with Parallel InterfaceAD5429 ADI Dual 8-Bit, High Bandwidth Multiplying D/A Converter With Serial InterfaceAD5432 ADI High Bandwidth CMOS 10-Bit Serial Interface Multiplying D/A Converter AD5433 ADI High Bandwidth CMOS 10-Bit Parallel Interface Multiplying D/A ConverterAD5439 ADI Dual 10-Bit, High Bandwidth Multiplying D/A Converter With Serial InterfaceAD5440 ADI Dual 10-Bit, High Bandwidth Multiplying DACs with Parallel Interface AD5441 ADI 12-Bit串行输入乘法型数模转换器AD5441 ADI 12-Bit串行输入乘法型数模转换器AD5443 ADI High Bandwidth CMOS 12-Bit Serial Interface Multiplying D/A Converter AD5444 ADI 12-Bit High Bandwidth Multiplying DAC with Serial InterfaceAD5445 ADI High Bandwidth CMOS 12-Bit Parallel Interface Multiplying D/A Converter AD5446 ADI 14-Bit High Bandwidth Multiplying DAC with Serial InterfaceAD5447 ADI Dual 12-Bit, High Bandwidth Multiplying DACs with Parallel InterfaceAD5449 ADI Dual 12-Bit, High Bandwidth Multiplying D/A Converter With Serial InterfaceAD5450 ADI 8-Bit High Bandwidth Multiplying DACs with Serial InterfaceAD5451 ADI 10-Bit High Bandwidth Multiplying DACs with Serial InterfaceAD5452 ADI 12-Bit High Bandwidth Multiplying DACs with Serial InterfaceAD5453 ADI 14-Bit High Bandwidth Multiplying DACs with Serial InterfaceAD548 ADI Precision, Low Power BiFET Op AmpAD549 ADI Ultralow Input-Bias Current Operational AmplifierAD5516 ADI 16-Channel 12-Bit Bipolar Voltage-Output DAC with 14-Bit Increment Mode AD5520 ADI Per-pin Parametric Measurement Unit / Source Measure UnitAD5522 ADI 集成16位电平设置DAC的四参数测量单元AD5530 ADI Serial Input, Voltage Output 12-Bit D/A ConverterAD5531 ADI Serial Input, Voltage Output14-Bit D/A ConverterAD5532 ADI 32-Channel 14-Bit Bipolar Voltage-Output DACAD5532B ADI 32-Channel 14-bit Bipolar Voltage-Output DACAD5532HS ADI 32-Channel 14-Bit bipolar DAC with High Speed 3-Wire Serial Interface AD5533 ADI 32-Channel Infinite Sample-and-HoldAD5533B ADI 32-Channel Infinite Sample-and-HoldAD5535 ADI 32-Channel, 14-Bit DAC with Fullscale Output Voltage Programmable from 50 V to 200 VAD5541 ADI 16-Bit Voltage-Output DAC in SO-8 PackageAD5542 ADI 16-Bit Bipolar-Voltage-Output DAC with Kelvin SensingAD5543 ADI 16-Bit DAC in μSOIC-8 PackageAD5544 ADI Precision QUAD 16-Bit D/A ConverterAD5545 ADI Precision DUAL 16-Bit and 14-Bit DACs in Compact TSSOP Packages AD5546 ADI Current-Output Parallel-Input, 16-Bit Digital-to-Analog Converter AD5547 ADI Dual Current-Output Parallel-Input, 16-Bit DACAD5551 ADI 5 V, Serial-Input, Voltage-Output 14-Bit DACAD5552 ADI 5 V, Serial-Input, Voltage-Output 14-Bit DAC With Bipolar Output CapabilityAD5553 ADI 14-Bit DAC in μSOIC-8 PackageAD5554 ADI Precision QUAD 14-Bit D/A ConverterAD5555 ADI Precision DUAL 16-Bit 14-Bit-DACs in Compact TSSOP Packages AD5556 ADI Current-Output Parallel-Input, 14-Bit Digital-to-Analog Converter AD5557 ADI Dual Current-Output Parallel-Input, 14-Bit DACAD5560 ADI 1.2A Programmable Device Power Supply with Integrated 16-bit Level Setting DACsAD5560 ADI 1.2A Programmable Device Power Supply with Integrated 16-bit Level Setting DACsAD5564 ADI This product is obsolete and replaced by the AD5532. (9/99) AD557 ADI DACPORT Low Cost, Complete μP-Compatible 8-Bit DACAD5570 ADI True Accuracy, 16-Bit ±12 V/±15 V, Serial Input Voltage Output D/A ConverterAD558 ADI Voltage-output 8-bit digital-to-analog converter,including output amplifier,full microprocessor interface and precisionAD5582 ADI +15 V, Quad, Parallel Input, 12-Bit D/A Converter AD5583 ADI +15V, Quad, Parallel Input, 10-Bit D/A Converter AD5590 ADI 16输入/16输出模拟I/O端口,集成放大器AD5601 ADI 2.7 V to 5.5 V,<100 μA,8-Bit <em>nano</em>DAC?,SPI Interface in SC70 PackageAD5602 ADI 2.7 V to 5.5 V, <100 μA, 8-Bit <em>nano</em>DAC? D/A Converter with I2C Compatible Interface, Tiny SC70 PackageAD561 ADI Low Cost 10-Bit Monolithic D/A ConverterAD5611 ADI 2.7 V to 5.5 V,<100 μA,10-Bit <em>nano</em>DAC?,SPI Interface in SC70 PackageAD5612 ADI 2.7 V to 5.5 V,<100 μA,10-Bit <em>nano</em>DAC? D/A Converter with I2C Compatible Interface, Tiny SC70 PackageAD561S ADI Aerospace 10-Bit, Current Output DACAD5620 ADI 3 V/5 V, 12-Bit <em>nano</em>DAC? Converter with 5 ppm/°C On-Chip Reference in Sot-23AD5621 ADI 2.7 V to 5.5 V,<100 μA,12-Bit <em>nano</em>DAC?,SPI Interface in SC70 PackageAD5622 ADI 2.7 V to 5.5 V,<100 μA,12-Bit <em>nano</em>DAC? D/A Converter with I2C Compatible Interface, Tiny SC70 PackageAD5623R ADI Dual 12-Bit <em>nano</em>DAC? with 5 ppm/°C On-Chip ReferenceAD5624 ADI 2.7 V to 5.5 V, 450 μA, Rail-to-Rail Output, Quad, 12-/16-Bit <em>nano</em>DACs?AD5624R ADI Quad,12-Bit <em>nano</em>DAC? with 5ppm/°C On-Chip Reference AD5625 ADI Quad, 12-Bit <em>nano</em>DACs?, I2C? InterfaceAD5625R ADI Quad, 12-Bit <em>nano</em>DACs? with 5 ppm/°C On-Chip Reference,I2C? InterfaceAD5626 ADI 5 V,12-Bit <em>nano</em>DAC?,串行接口,采用MSOP与LFCSP 封装AD5627 ADI Dual, 12-Bit nanoDAC? with I2C? InterfaceAD5627R ADI Dual,12-Bit nanoDAC? with 5 ppm/°C On-Chip Reference,I2C? InterfaceAD5628 ADI Octal, 12-Bit D/A Converter with 5 ppm/°C On-Chip Reference in 14-Lead TSSOPAD563 ADI ObsoleteAD5640 ADI 3 V/5 V, 14-Bit <em>nano</em>DAC? Converter with 5 ppm/°C On-Chip Reference in Sot-23AD5641 ADI 2.7 V to 5.5 V,<100 μA,14-Bit <em>nano</em>DAC,SPI Interface in SC70 PackageAD5643R ADI Dual 14-Bit <em>nano</em>DAC? with 5 ppm/°C On-Chip Reference AD5644R ADI Quad, 14-Bit <em>nano</em>DAC? with 5ppm/°C On-Chip ReferenceAD5645R ADI Quad, 14-Bit <em>nano</em>DACs? with 5 ppm/°C On-Chip Reference,I2C? InterfaceAD5647R ADI Dual,14-Bit nanoDAC? with 5 ppm/°C On-Chip Reference,I2C? InterfaceAD5648 ADI Octal, 14-Bit D/A Converter with 5 ppm/°C On-Chip Reference in 14-Lead TSSOPAD565A ADI 12-bit Digital-to-Analog Converters, with Zener ReferenceAD565S ADI Aerospace 12-Bit, Current Output, Complete High Speed DACAD5660 ADI 3 V/5 V, 16-Bit <em>nano</em>DAC? Converter with 5 ppm/°C On-Chip Reference in a Sot-23AD5662 ADI 2.7-5.5V, 16-Bit <em>nano</em>DAC? Converter in a Sot-23AD5663 ADI 2.7 V to 5.5 V, 250 μA, Rail-to-Rail Output, Dual 16-Bit <em>nano</em>DAC?AD5663R ADI Dual 16-Bit <em>nano</em>DAC? with 5 ppm/°C On-Chip ReferenceAD5664 ADI 2.7 V to 5.5 V, 450 μA, Rail-to-Rail Output, Quad, 12-/16-Bit <em>nano</em>DACs?AD5664R ADI Quad, 16-Bit <em>nano</em>DAC? with 5ppm/°C On-Chip Reference AD5665 ADI Quad, 16-Bit <em>nano</em>DACs?, I2C? InterfaceAD5665R ADI 片上带5ppm/°C基准源和I2C接口的16bit 四nanoDAC?AD5666 ADI Quad, 16 Bit D/A Converter with 10ppm/°C Max On-Chip Reference in 14-Lead TSSOPAD5667 ADI Dual, 16-Bit nanoDAC? with I2C? InterfaceAD5667R ADI Dual,16-Bit nanoDAC? with 5 ppm/°C On-Chip Reference,I2C? InterfaceAD5668 ADI Octal, 16-Bit D/A Converter with 5 ppm/°C On-Chip Reference in 16-Lead TSSOPAD567 ADI 12-Bit Current Output, Microprocessor-Compatible DACAD5678 ADI 4 x 12-Bit and 4 × 16-Bit Octal D/A Converter with On-Chip Reference in 14-Lead TSSOPAD568 ADI 12-Bit Ultrahigh Speed Monolithic D/A ConverterAD5680 ADI 5 V 18-Bit <em>nano</em>DAC? in a SOT-23AD569 ADI 16-Bit Monotonic Voltage Output D/A ConverterAD570 ADI 8-Bit Successive Approximation Analog-to-Digital ConverterAD571 ADI 10-Bit, A/D Converter, Complete with Reference and Clock AD571S ADI Aerospace 10-Bit Complete Anolog to Digital ConverterAD572 ADI 12-Bit Successive Approximation Integrated Circuit A/D ConverterAD5722 ADI Complete,Dual,12-Bit,Serial Input,Unipolar/Bipolar,Voltage Output DACAD5722 ADI Complete,Dual,12-Bit,Serial Input,Unipolar/Bipolar,Voltage Output DACAD5722R ADI Complete,Dual,12-Bit,Serial Input,Unipolar/Bipolar,Voltage Output DACAD5724 ADI Complete,Quad,12-Bit,Serial Input,Unipolar/Bipolar Voltage Output DACsAD5724 ADI Complete,Quad,12-Bit,Serial Input,Unipolar/Bipolar Voltage Output DACsAD5724R ADI Complete,Quad,12-Bit,Serial Input,Unipolar/Bipolar Voltage OutputDACAD5725 ADI 12-bit、并行输入、单极性/双极性、电压输出四DACAD5726 ADI Quad, 12-Bit, Serial Input, Unipolar/Bipolar, Voltage Output DAC AD573 ADI 10-bit successive approximation ADC.AD5732 ADI Complete,Dual,14-Bit,Serial Input,Unipolar/Bipolar,Voltage Output DACAD5732 ADI Complete,Dual,14-Bit,Serial Input,Unipolar/Bipolar,Voltage Output DACAD5732R ADI Complete,Dual,14-Bit,Serial Input,Unipolar/Bipolar,Voltage Output DACAD5734 ADI Complete,Quad,14-Bit,Serial Input,Unipolar/Bipolar Voltage Output DACAD5734 ADI Complete,Quad,14-Bit,Serial Input,Unipolar/Bipolar Voltage Output DACAD5734R ADI Complete,Quad,14-Bit,Serial Input,Unipolar/Bipolar Voltage Output DACAD5744 ADI Complete,Quad,14-Bit,High Accuracy,Serial Input,Bipolar Voltage Output D/A ConverterAD5744R ADI Complete Quad, 14-Bit, High Accuracy, Serial Input, Bipolar Voltage Output D/A ConverterAD5744R ADI Complete Quad, 14-Bit, High Accuracy, Serial Input, Bipolar Voltage Output D/A ConverterAD574A ADI Complete 12-Bit A/D ConverterAD574S ADI Aerospace 12-Bit-ADC w/Microprocessor InterfaceAD575 ADI ObsoleteAD5750 ADI AD5750 电流/电压输出驱动器,输出范围可编程,适合工业应用 AD5750 ADI AD5750 电流/电压输出驱动器,输出范围可编程,适合工业应用AD5751 ADI 电流/电压输出驱动器,单电源供电,60 V电压范围,输出范围可编程,适合工业应用AD5751 ADI 电流/电压输出驱动器,单电源供电,60 V电压范围,输出范围可编程,适合工业应用AD5752 ADI Complete,Dual,16-Bit,Serial Input,Unipolar/Bipolar,Voltage Output DACAD5752 ADI Complete,Dual,16-Bit,Serial Input,Unipolar/Bipolar,Voltage Output DACAD5752R ADI Complete,Dual,16-Bit,Serial Input,Unipolar/Bipolar,Voltage Output DACAD5754 ADI 完全4通道、16 Bit、串行输入、单极/双极性电压输出数模转换器AD5754R ADI Complete,Quad,16-Bit,Serial Input,Unipolar/Bipolar Voltage Output DACAD5762R ADI 16-Bit,双通道,高精度, 串行输入, 双极性电压输出型DAC AD5763 ADI Complete Dual, 16-Bit, High Accuracy, Serial Input, ±5V DACsAD5764 ADI Complete Quad, 16-Bit, High Accuracy, Serial Input, Bipolar Voltage Output DACsAD5764R ADI Complete Quad, 16-Bit, High Accuracy, Serial Input, Bipolar Voltage Output D/A ConverterAD5764R ADI Complete Quad, 16-Bit, High Accuracy, Serial Input, Bipolar Voltage Output D/A ConverterAD5765 ADI Complete Quad, 16-Bit, High Accuracy, Serial Input, ±5V DACs AD580 ADI High Precision 2.5 V IC ReferenceAD581 ADI High Precision 10 V IC ReferenceAD582 ADI Low-Cost Sample-and-Hold AmplifierAD5821 ADI 120 mA, Current Sinking, 10-Bit, I2C? DACAD5821A ADI 120 mA, Current Sinking, 10-Bit, I2C DACAD5821A ADI 120 mA, Current Sinking, 10-Bit, I2C DACAD5821A ADI 120 mA, Current Sinking, 10-Bit, I2C DACAD583 ADI ObsoleteAD584 ADI Pin Programmable Precision Voltage ReferenceAD584S ADI Aerospace Pin Programmable Precision Voltage ReferenceAD585 ADI Complete Monolithic SHA Circuit.AD585S ADI Aerospace High Speed, Precision Sample-and-Hold AmplifierAD586 ADI High Precision 5 V ReferenceAD587 ADI High Precision 10 V ReferenceAD588 ADI High Precision Voltage ReferenceAD589 ADI Two-Terminal IC 1.2 V ReferenceAD589S ADI Aerospace Precision 1.2 Volt IC ReferenceAD590 ADI Two Terminal IC Temperature TransducerAD590S ADI Aerospace 2 Terminal Temperature Transducer, 1uA/°KAD592 ADI Current Output – Precision IC Temperature TransducerAD5930 ADI Programmable Frequency Sweep and Output Burst Waveform Generator AD5932 ADI 可编程单扫描波形发生器AD5933 ADI 1 MSPS,12 bit阻抗转换器和网络分析器AD5934 ADI 250 kSPS 12-Bit Impedance Converter Network AnalyzerAD594 ADI Monolithic Thermocouple Amplifier with Cold Junction Compensation Pretrimmed for Type J ThermocouplesAD595 ADI Monolithic Thermocouple Amplifier with Cold Junction Compensation Pretrimmed for Type K ThermocouplesAD596 ADI Thermocouple Conditioner and Setpoint Controller Operates with Type J ThermocoupleAD597 ADI Thermocouple Conditioner and Setpoint Controller Operates with Type K ThermocoupleAD598 ADI LVDT Signal ConditionerAD600 ADI Dual, Low Noise, Wideband Variable Gain Amplifier, 0 dB To +40 dB GainAD602 ADI Dual,Low Noise,Wideband Variable Gain Amplifier,-10 dB To +30 dB GainAD6021 ADI Othello One ET? Quad Band EDGE Transmit ModulatorAD603 ADI Low Noise, 90 MHz Variable Gain AmplifierAD604 ADI Dual, Ultralow Noise Variable Gain AmplifierAD605 ADI Dual, Low Noise, Single-Supply Variable Gain AmplifierAD606 ADI 50 MHz, 80 dB Demodulating Logarithmic Amplifier with Limiter Output AD607 ADI Low Power Mixer/AGC/RSSI 3V Receiver IF SubsystemAD608 ADI Low Power Mixer/Limiter/RSSI 3 V Receiver IF SubsystemAD620 ADI Low Drift, Low Power Instrumentation Amp with Set Gains of 1 to 10000 AD621 ADI Low Drift, Low Power Instrumentation Amp with fixed gains of 10 and 100 AD622 ADI 低成本仪表放大器AD623 ADI Single Supply, Rail-Rail, Low Cost Instrumentation AmplifierAD624 ADI High Precision, Low Noise Instrumentation AmplifierAD625 ADI Programmable Gain Instrumentation AmplifierAD626 ADI Low Cost, Single-Supply Differential AmplifierAD627 ADI 微功耗,单电源/双电源,轨到轨仪表放大器AD628 ADI High Common-Mode Voltage, Programmable Gain Difference Amplifier AD629 ADI High Common-Mode Voltage, Difference AmplifierAD630 ADI Balanced Modulator/DemodulatorAD632 ADI Internally Trimmed Precision IC MultiplierAD633 ADI Low Cost Four-Quadrant Analog MultiplierAD636 ADI Low Level, True RMS-to-DC ConverterAD637 ADI High Precision, Wideband RMS-to-DC ConverterAD640 ADI 120 MHz, 50 dB Demodulating Logarithmic AmplifierAD641 ADI 250 MHz, 44 dB Demodulating Logarithmic AmplifierAD6411 ADI DECT RF TransceiverAD648 ADI Dual Precision, Low Power BiFET Op AmpAD6488 ADI ADSL2+ CPE Analog Front EndAD648S ADI Aerospace Dual Precision, Low Power BiFET Op AmpAD650 ADI Voltage-to-Frequency and Frequency-to-Voltage ConverterAD651 ADI ObsoleteAD652 ADI Monolithic Synchronous Voltage-to-Frequency ConverterAD6524 ADI GSM Multi-Band SynthesizerAD6534 ADI Othello One Single-Chip Direct-Conversion GSM/GPRS/EDGE RFICAD6538 ADI Othello One Plus? Direct Conversion GSM/GPRS/EDGE Transceiver with Integrated LO VCOAD6539 ADI Othello One TV? Single Chip Direct Conversion GSM/GPRS Transceiver with Integrated TX VCOsAD654 ADI Low Cost Monolithic Voltage-to-Frequency ConverterAD660 ADI Monolithic 16-Bit Serial/Byte DACPORTAD6600 ADI Diversity Receiver ChipsetAD6620 ADI 65MSPS Digital Receive Signal ProcessorAD6622 ADI 65 MSPS, Quad Transmit Signal Processor (TSP)AD6623 ADI 104 MSPS, Four-Channel Digital Transmit Signal Processor (TSP) AD6624 ADI 80 MSPS, Quad Receiver Signal ProcessorAD6624A ADI Four-Channel, 100 MSPS Digital Receive Signal Processor (RSP) AD6630 ADI Differential, Low Noise IF Gain Block with Output ClampingAD6633 ADI Multi-channel (Digital) Transmit Signal Processor (TSP) with VersaCREST? Crest Reduction EngineAD6634 ADI 80 MSPS, Dual-Channel, WCDMA Receive Signal Processor (RSP) AD6635 ADI Four-Channel, 80 MSPS WCDMA Receive Signal Processor (RSP) AD6636 ADI 150 MSPS Wideband (Digital) Receive Signal Processor (RSP)AD664 ADI Monolithic 12-Bit Quad DACAD6640 ADI Multi-Channel, Multi-Mode Receiver ChipsetAD6644 ADI 14-Bit, 40 MSPS/65 MSPS Analog-to-Digital ConverterAD6645 ADI 14-Bit, 80 MSPS/105 MSPS A/D ConverterAD6645-MILADI 14-Bit, 80 MSPS Analog to Digital ConverterAD6650 ADI Diversity IF-to-Baseband GSM/EDGE Narrow-Band ReceiverAD6652 ADI 12-Bit, 65 MSPS IF to Base Band Diversity ReceiverAD6653 ADI IF Diversity ReceiverAD6654 ADI 14-Bit, 92.16 MSPS, 4 & 6-Channel Wideband IF to Base Band ReceiverAD6655 ADI IF Diversity ReceiverAD667 ADI Microprocessor-Compatible 12-Bit D/A ConverterAD667S ADI Aerospace 12-Bit Microprocessor Compatible DACAD668 ADI 12-Bit Ultrahigh Speed Multiplying D/A ConverterAD669 ADI Monolithic 16-Bit DACPORTAD670 ADI 8-Bit Signal Conditioning ADC.AD670S ADI Aerospace 8-Bit Low Cost Signal Conditioning Single Supply AD673 ADI 8-bit Successive Approximation, ADCAD674B ADI Complete 12-Bit A/D ConvertersAD676 ADI 16-Bit Parallel 100 kSPS Sampling ADCAD677 ADI 16-Bit, Serial, 100 kSPS Sampling ADC.AD678 ADI 12-Bit 200 kSPS Complete Sampling ADCAD679 ADI 14-Bit 128 kSPS Complete Sampling ADCAD680 ADI Bandgap, Low Power 2.5v ReferenceAD682 ADI ObsoleteAD684 ADI Monolithic Quad Sample-and-hold Amplifier (SHA)AD688 ADI High Precision ±10 V ReferenceAD689 ADI ObsoleteAD693 ADI Loop-Powered 4-20 mA Sensor TransmitterAD694 ADI 4-20mA Monolithic Current TransmitterAD698 ADI Universal LVDT Signal ConditionerAD7011 ADI CMOS, ADC pi/4 DQPSK Baseband Transmit PortAD704 ADI Quad Picoampere Input Current Bipolar Op AmpAD706 ADI Dual Picoampere Input Current Bipolar Op AmpAD708 ADI Ultralow Offset Voltage Dual Op AmpAD71028 ADI Dual Digital BTSC Encoder with Integrated DACAD711 ADI Precision, Low Cost, High Speed, BiFET Op Amp AD7111 ADI Monolithic Multiplying DAC Featuring Wide Dynamic RangeAD7112 ADI Dual CMOS Multiplying DAC with Anti-Log Transfer Function for Audio Volume Control ApplicationsAD712 ADI Dual Precision, Low Cost, High Speed, BiFET Op Amp AD713 ADI Quad Precision, Low Cost, High Speed, BiFET Op Amp AD7142 ADI 电容式触摸传感器专用可编程控制器AD7143 ADI 电容式触摸传感器专用可编程控制器AD7147 ADI CapTouch?单电极电容式传感器专用可编程控制器AD7148 ADI AD7148 可编程触摸控制器,用于单电极电容传感器AD7150 ADI 用于近程传感的超低功耗双通道电容式转换器。
常用芯片资料

MAX038 0.1Hz-20MHz单片函数发生器
MAX232 "5V电源多通道RS232驱动器/接收器 " +5V-Powered,Multichannel RS232 Drivers/Receivers
Microchip "PIC系列单片机RS232通讯应用 " Microchip PIC系列单片机与数字温度计的RS232通讯应用,内有典型应用电路图、源程序等,可供你作为单片机与RS232通讯方面的应用参考。
MM5369 3.579545MHz-60Hz 17级分频振荡器 常用于LM8361、LM8362、LM8365等电子钟电路将3.579545MHz晶体振荡分频到60Hz
LM431 "可调电压基准电路 "
LM567/LM567C "锁相环音频译码器 "
LM741 "运算放大器 " LM741A/LM741E/LM741/LM741C 运算放大器
LM831 "双低噪声音频功率放大器 "
LM833 "双低噪声音频放大器 "
MC145407 "RS232驱动器/接收器 " EIA-232/V.28 CMOS Driver/Receiver,5V Only, 3 x 3
MC145583 "RS232驱动器/接收器 " 3.3V - 5.0V EIA-232/V.28 CMOS Driver/Receiver, 3 x 5
MC2833 "低功率调频发射系统 " Low Power FM Tranmistter System
高精度电压频率和频率电压转换器ADVFC32的性能及应用

电压频率和频率电压转换器ADVFC32及应用一、概述ADVFC32是ADI公司生产的一种低成本的单片集成的实现电压频率转换或频率电压转换的器件。
它具有很好的线性(10KHz时的最大误差时0.01%),最大的工作频率可以达到0.5MHz。
只需要外接很少的器件就可以把输入的正、负电压或电流转换为与之成比例的频率。
频率电压转换的模式所用的器件与电压频率转换的相同,只是要有一个简单的逻辑偏压或网络组合来保证输入逻辑电平有较大的范围。
在V/F模式下用一个开放的输出频率收集器可以实现TTL和CMOS兼容。
上拉电阻可以接到30V、15V的电压,或者5V标准CMOS和TTL逻辑电平。
应选取这个电阻值限制输出集电极的电流不超过8毫安。
低输入电压失调漂移,仅有满度的3ppm/℃。
ADVFC32具有以下的一些优点:1、ADVFC32采用的是电荷平衡电路技术,这使得它的电压频率转换具有很高的精度。
它的工作频率的范围仅仅由一个精密电阻和电容决定,其它的元件对频率范围影响不大。
所以可以采用比较便宜的,精度±20%的电阻和电容,这样并不会影响线性和温度漂移。
2、ADVFC32可以很容易满足系统工作范围要求。
选择不同的输入电阻可以实现不同的输入电压缩放比。
输入电阻还可以在最大的输入电压时使输入电流达到0.25mA。
3、频率电压转换的模式所用的器件与电压频率转换的相同,只是要有一个简单的逻辑偏置、网络相加和重新组合即可。
4、ADVFC32和其它公司生产的VFC32具有引脚的兼容性。
5、ADVFC32与军用标准MIL_STD_883兼容。
二、封装结构ADVFC32有两种封装方式:一种是14管脚的双列直插式,另一种是10管脚的金属罐式。
图1(A)给出的是ADVFC32的14脚封装结构及引脚排布,图1(B)给出的是ADVFC32的10脚封装结构及引脚排布。
(A):14引脚封装结构(B ):10引脚封装结构图1:ADVFC32的两种封装结构三、工作原理及应用设计ADVFC32应用广泛,除了用于电压频率转换和频率电压转换,还可以用于微处理器控制的A/D 转换及其他的电路。
VFC32 压频转换芯片数据资料

2VFC32SPECIFICATIONSAt T A = +25°C and V CC = ±15V, unless otherwise noted.V Specification the same as VFC32KP.NOTES: (1) A 25% duty cycle (0.25mA input current) is recommended for best linearity. (2) Adjustable to zero. See Offset and Gain Adjustment section. (3) Linearity error is specified at any operating frequency from the straight line intersecting 90% of full scale frequency and 0.1% of full scale frequency. See Discussion of Specifications section. Above 200kHz,it is recommended all grades be operated below +85°C. (4) ±0.015% of FSR for negative inputs shown in Figure 5. Positive inputs are shown in Figure 1. (5) FSR = Full Scale Range (corresponds to full scale frequency and full scale input voltage). (6) Exclusive of external components’ drift. (7) Positive drift is defined to be increasing frequency with increasing temperature. (8) For operations above 200kHz up to 500kHz, see Discussion of Specifications and Installation and Operation sections. (9) One pulse of new frequency plus 1µs.5VFC32APPLICATION INFORMATION Figure 1 shows the basic connection diagram for frequency-to-voltage conversion. R 1 sets the input voltage range. For a 10V full-scale input, a 40k Ω input resistor is recommended.Other input voltage ranges can be achieved by changing the value of R 1.R 1should be a metal film type for good stability. Manufac-turing tolerances can produce approximately ±10% variation in output frequency. Full-scale output frequency can be trimmed by adjusting the value of R 1—see Figure 3.The full-scale output frequency is determined by C 1. Values shown in Figure 1 are for a full-scale output frequency of 10kHz. Values for other full-scale frequencies can be read from Figure 2. Any variation in C 1—tolerance, temperature drift, aging—directly affect the output frequency. Ceramic NPO or silver-mica types are a good choice.For full-scale frequencies above 200kHz, use larger capaci-tor values as indicated in Figure 2, with R 1 = 20k Ω.The value of the integrating capacitor, C 2, does not directly influence the output frequency, but its value must be chosen within certain bounds. Values chosen from Figure 2 produce approximately 2.5Vp-p integrator voltage waveform. If C 2’s value is made too low, the integrator output voltage can exceed its linear output swing, resulting in a nonlinear response. Using C 2 values larger than shown in Figure 2 is acceptable.Accuracy or temperature stability of C 2 is not critical be-cause its value does not directly affect the output frequency.For best linearity, however, C 2 should have low leakage and low dielectric absorption. Polycarbonate and other film capacitors are generally excellent. Many ceramic types are adequate, but some low-voltage ceramic capacitor types may degrade nonlinearity. Electrolytic types are not recom-mended.FREQUENCY OUTPUT PIN The frequency output terminal is an open-collector logic output. A pull-up resistor is usually connected to a 5V logic supply to create standard logic-level pulses. It can, however,be connected to any power supply up to +V CC . Output pulses have a constant duration and positive-going during the one-shot period. Current flowing in the open-collector output transistor returns through the Common terminal. This termi-nal should be connected to logic ground.(1)FIGURE 1. Voltage-to-Frequency Converter Circuit.R 1=V FS 0.25mA6VFC32PRINCIPLES OF OPERATION The VFC32 operates on a principle of charge balance. The signal input current is equal to V IN /R 1. This current is integrated by input op amp and C 2, producing a downward ramping integrator output voltage. When the integrator out-put ramps to the threshold of the comparator, the one-shot is triggered. The 1mA reference current is switched to the integrator input during the one-shot period, causing the integrator output ramp upward. After the one-shot period,the integrator again ramps downward.The oscillation process forces a long-term balance of charge (or average current) between the input signal current and the reference current. The equation for charge balance is:Where:f O is the output frequencyt OS is the one-shot period, equal tot OS = 7500 C 1 (Farads)(4)The values suggested for R 1 and C 1 are chosen to produce a 25% duty cycle at full-scale frequency output. For full-scale frequencies above 200kHz, the recommended values pro-duce a 50% duty cycle.FREQUENCY-TO-VOLTAGE CONVERSIONFigure 4 shows the VFC32 connected as a frequency-to-voltage converter. The capacitive-coupled input network C 3,R 6 and R 7 allow standard 5V logic levels to trigger the comparator input. The comparator triggers the one-shot on the falling edge of the frequency input pulses. Threshold voltage of the comparator is approximately –0.7V. For frequency input waveforms less than 5V logic levels, the R 6/R 7 voltage divider can be adjusted to a lower voltage to assure that the comparator is triggered.The value of C 1 is chosen from Figure 2 according to the full-scale input frequency. C 2 smooths the output voltage waveform. Larger values of C 2 reduce the ripple in the output voltage. Smaller values of C 2 allow the output voltage to settle faster in response to a change in input frequency.Resistor R 1 can be trimmed to achieve the desired output voltage at the full-scale input frequency.I IN =I R(AVERAGE)(2)V IN R 1=f O t OS (1mA)(3)FIGURE 2. Capacitor Value Selection.FIGURE 3. Gain and Offset Voltage Trim Circuit.7VFC32FIGURE 4. Frequency-to-Voltage Converter Circuit.FIGURE 5. V/F Converter—Negative Input Voltage.。
各厂家IC封装命名规则

各国品牌IC封装及命名规则DIP英文简称:DIP英文全称:Double In-line Package中文解释:双列直插式封装。
插装型封装之一,引脚从封装两侧引出,封装材料有塑料和陶瓷两种。
DIP是最普及的插装型封装,应用范围包括标准逻辑IC,存贮器LSI,微机电路等。
PLCC英文简称:PLCC英文全称:Plastic Leaded Chip Carrier中文解释:PLCC封装方式,外形呈正方形,32脚封装,四周都有管脚,外形尺寸比DIP封装小得多。
PLCC封装适合用SMT表面安装技术在PCB上安装布线,具有外形尺寸小、可靠性高的优点。
PQFP英文简称:PQFP英文全称:Plastic Quad Flat Package中文解释: PQFP封装的芯片引脚之间距离很小,管脚很细,一般大规模或超大规模集成电路采用这种封装形式,其引脚数一般都在100以上。
SOP英文简称:SOP英文全称:Small Outline Package中文解释: 1968~1969年菲为浦公司就开发出小外形封装(SOP)。
以后逐渐派生出SOJ(J型引脚小外形封装)、TSOP(薄小外形封装)、VSOP(甚小外形封装)、SSOP(缩小型SOP)、TSSOP(薄的缩小型SOP)及SOT(小外形晶体管)、SOIC(小外形集成电路)等。
IC 封装及命名规则---TI逻辑器件的产品名称器件命名规则SN 74 LVC H 16 2 244 A DGG R1 2 3 4 5 6 7 8 9 101. 标准前缀示例:SNJ -- 遵从MIL-PRF-38535 (QML)2. 温度范围54 -- 军事74 -- 商业3. 系列4. 特殊功能空= 无特殊功能C -- 可配置Vcc (LVCC)D -- 电平转换二极管(CBTD)H -- 总线保持(ALVCH)K -- 下冲-保护电路(CBTK)R -- 输入/输出阻尼电阻(LVCR)S -- 肖特基钳位二极管(CBTS)Z -- 上电三态(LVCZ)5. 位宽空= 门、MSI 和八进制1G -- 单门8 -- 八进制IEEE 1149.1 (JTAG)16 -- Widebus™(16 位、18 位和20 位)18 -- Widebus IEEE 1149.1 (JTAG)32 -- Widebus™(32 位和36 位)6. 选项空= 无选项2 -- 输出串联阻尼电阻4 -- 电平转换器25 -- 25 欧姆线路驱动器7. 功能244 -- 非反向缓冲器/驱动器374 -- D 类正反器573 -- D 类透明锁扣640 -- 反向收发器8. 器件修正空= 无修正字母指示项A-Z9. 封装D, DW -- 小型集成电路(SOIC)DB, DL -- 紧缩小型封装(SSOP)DBB, DGV -- 薄型超小外形封装(TVSOP)DBQ -- 四分之一小型封装(QSOP)DBV, DCK -- 小型晶体管封装(SOT)DGG, PW -- 薄型紧缩小型封装(TSSOP)FK -- 陶瓷无引线芯片载体(LCCC)FN -- 塑料引线芯片载体(PLCC)GB -- 陶瓷针型栅阵列(CPGA)GKE, GKF -- MicroS tar™ BGA 低截面球栅阵列封装(LFBGA)GQL, GQN -- MicroStar Junior BGA 超微细球栅阵列(VFBGA)HFP, HS, HT, HV -- 陶瓷四方扁平封装(CQFP)J, JT -- 陶瓷双列直插式封装(CDIP)N, NP, NT -- 塑料双列直插式封装(PDIP)NS, PS -- 小型封装(SOP)PAG, PAH, PCA, PCB, PM, PN, PZ -- 超薄四方扁平封装(TQFP)PH, PQ, RC -- 四方扁平封装(QFP)W, WA, WD -- 陶瓷扁平封装(CFP)10. 卷带封装DB 和PW 封装类型中的所有新增器件或更换器件的名称包括为卷带产品指定的R。
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压/频频/压转换器
ADVFC32
一、产品说明
行业标准ADVFC32是低成本的V / F转换F / V转换器,具有很好的线性度(最大误差在10千赫时为%),最高转换频率为。
在V/F转换模式下只需要外接很少的器件就可以把输入的正、负电压或电流转换为与之成比例的频率。
频率电压转换的模式所用的器件与电压频率转换的相同,只是要有一个简单的逻辑偏压或网络组合来保证输入逻辑电平有较大的范围。
在V/F模式下用一个开放的输出频率收集器可以实现TTL和CMOS兼容。
上拉电阻可以接到30V、15V的电压,或者5V标准CMOS和TTL逻辑电平。
应选取这个电阻值限制输出集电极的电流不超过8毫安。
低输入电压失调漂移,仅有满度的3ppm/℃。
ADVFC32芯片可以广泛运用与工业和商业,有很大的温度适应范围。
商品级的为塑封的14管脚双列直插式芯片,有更高的温度范围的芯片灌装在密封的10管脚的金属罐里。
ADVFC32具有以下的一些优点:
1、ADVFC32采用的是电荷平衡电路技术,这使得它的电压频率转换具有很高的精度。
它的工作频率的范围仅仅由一个精密电阻和电容决定,其它的元件对频率范围影响不大。
所以可以采用比较便宜的,精度±20%的电阻和电容,这样并不会影响线性和温度漂移。
2、ADVFC32可以很容易满足系统工作范围要求。
选择不同的输入电阻可以实现不同的输入电压缩放比。
输入电阻还可以在最大的输入电压时使输入电流达到。
3、频率电压转换的模式所用的器件与电压频率转换的相同,只是要有一个简单的逻辑偏置、网络相加和重新组合即可。
4、ADVFC32和其它公司生产的VFC32具有引脚的兼容性。
5、ADVFC32与军用标准MIL_STD_883兼容。
二、封装结构
ADVFC32有两种封装方式:一种是14管脚的双列直插式,另一种是10管脚的金属罐式。
图1(A)给出的是ADVFC32的14脚封装结构及引脚排布,图1(B)给出的是ADVFC32的10脚封装结构及引脚排布。
(A):14引脚封装结构
(B):10引脚封装结构
图1:ADVFC32的两种封装结构
三、工作原理及应用设计
ADVFC32应用广泛,除了用于电压频率转换和频率电压转换,还可以用于微处理器控制的A/D转换及其他的电路。
下面介绍一些它的应用电路设计。
1、单极输入的电压频率转换
(1)输入为正电压
当作为电压频率转换器使用时,电压到频率的转换是基于输入信号和内部1mA的电
流源比较实现的。
当输入的电压为正时,连接的电路图为图2。
在一个周期开始时,和输入
电压成比例的电流通过3R 和1R 对电容2C 充电。
随着电容上电荷的积累,输入放大器的输出电压降低。
当输入放大器的输出电压达到零时,比较器反转一次,时间由电容1C 决定。
反转时间的精确值为:。
在这个过程中有1mA -IN I 的电流流过电容2C ,
在一个周期内电容上损耗的电荷为(1mA -IN I )⨯os
t 。
在一个周期的其余时间电容2C 上继续充电,积分器的电压达到原来的值。
因为每个周期内2C 的充电量和放电量相等。
(1)IN os mA I t -⨯os t =1
()IN os OUT I t F ⨯-,整理得OUT F =IN os
I 1mA t ⨯ 用IN IN V R 取代其中的IN I ,并把os t 用1C 表示得到ADVFC32的输出频率公式为:
OUT F =11(44) 6.7IN
IN V R mA C pF K ⨯+⨯Ω 用下面的公式计算元件的参数使输入电压和输出频率的范围优化。
2C =410sec OUTFS
Farads F -(最小1000pF );IN R =0.25INFS V mA ;2R ≥8LOGIC V mA + 表1中给出了建议使用的IN R 、2C 和1C 的值。
输入电阻IN R 由固定电阻3R 和可变电阻1R 组成,可以进行对内部增益的失调进行补偿。
为了满足所有的可能情况,3R 应该为输入电阻的20%,1R 应为输入电阻的90%。
这就允许有±10%的增益调节来补偿ADVFC32的全范围误差和1C 的误差。
如果需要更精确的内部偏置,则可以加入4R 和5R 组成的电路。
5R 的阻值可以在10K Ω和100K Ω之间,4R 应大约为10M Ω。
纠正零漂所需的电流相对很小,因此这两个电阻的温度系数不做要求。
如果加上这个电路后会产生大的偏移,则两个电阻的温漂就都非常重要了。
图2:正电压输入的电压频率转换电路
表1:建议使用的IN R 、2C 和1C 的值
(2) 输入为负电压
图3给出的是输入电压为负的V/F 转换的连接电路。
在这种结构中,最大的输出频 率对应最大的输入负电压,输出频率为零时对应输入电压也为零。
因为它只驱动积分器的输入,所以输入的信号源可以有很高的阻抗。
末端的典型输入阻抗值为250M Ω或更高。
对于正电压的V/F 转换来说,信号发生器必须可以提供 mA 来驱动ADVFC32,但对于负电压V/F 转换 mA 的电流是从地经3R 和1R 得到的。
负电压的电路工作原理和正电压的非常相似,上面已经给出了元件选择的公式,这里就不做进一步介绍了。
图3:输入为负电压的V/F 转换
2、双极输入V/F 转换
在脚1(对于10脚的是脚2)接一个稳定的正电压,ADVFC32就可以工作在双极电压输入状态。
例如,把80K Ω的电阻接到10V 的电压上得到一个外加的电流进入放大器。
这样一来即使在负电压输入时流入积分器的电流也是正的。
在最大的负电压输入时有的电流从IN V 流入积分器,从偏置电阻流出,输出的频率为零;当输入为最大的正电压时,两个电流的总和为,输出为最大频率。
3、 频率电压转换
图4给出了在输入幅值为TTL 逻辑电平上的F/V 转换连接图。
图中的电阻3R 主要
起增益调节的作用,使输出电压的幅值达到设计要求。
每次输入信号超过比较器极限时,产生一个单稳触发脉冲,开关闭合一次,1mA 的电流源接到比较器的输入端,持续时间由C1决定。
当频率增加时,积分电容上积累的电荷随之成比例增加。
当电容上的电荷达到稳定,经过3R 和1R 的漏电流和开关接入积分器的平均电流相等。
这两种作用的代数和为输出电压的均值,这个值是和输入频率成比例的。
如上面V/F 转换一样,选取合适的元件值可以使转换达最优。
图4:频率电压转换电路
4、高噪声抑制、高共模抑制比电路的设计
在许多应用中,信号可能在一个距离接受器很远的地方,在传到接受地点进行处理
的过程中会携带很大的噪声。
在现代医学中,远程医疗越来越为人们重视和看好,但在这种情况下,即使使用屏蔽电缆也不能把信号和噪声完全隔离。
图5给出了这种高噪声、高共模抑制比电路在心电信号传输中的应用。
用两个ADVFC32将模拟电压信号转换成与之成比例的数字信号,然后经过光电隔离后,再利用ADVFC32的频率/电压转换功能把数字信号转换为成比例的模拟信号。
这种连接方法可以很好的去除噪声和共模干扰。
采集到并经过放大处理的心电信号输入第一个ADVFC32,它把输入模拟心电信号调制为成比例的频率信号,一个输入电阻Ω和一个偏置电阻100KΩ确定转换比例。
这样0V的电压转换为50KHz,10V的输入对应最大的输出频率500KHz。
一个高频的光电隔离器把除去共模干扰后的信号送到第二个ADVFC32,这个ADVFC32负责把数字信号解调成成比例的模拟信号。
对于心电信号的传输我们采用光纤代替HCPL2630作为光电隔离器件,这样可以消除高达几十兆伏特的共模干扰,并可完全滤除电噪声。
光电隔离器的输出和第二个ADVFC32连接起来。
由于在10脚的重建信号中会有相当数量载波。
所以对于50KHz和500KHz之间的任何频率要求滤除效果都很好。
F/V转换器的响应频率只有3KHz,因此一个二阶截止频率为3KHz的滤波器并不会对带宽有限制作用。
用图5的单极滤波电路,输入到输出的3分贝衰减点大约在2KHz,输出的噪声小于15mV。
如果需要有较低的输出阻抗,则推荐使用双极的滤波器。
图5:高噪声、高共模抑制比电路。