Datasheet > AB-066

AB-066

更新时间： 2024-11-18 23:26:55

品牌	Logo	应用领域
其他 - ETC		转换器
页数	文件大小	规格书
4页	46K
描述
AB-066 - VOLTAGE-TO FREQUENCY CONVERTERS OFFER USEFUL OPTIONS IN A/D CONVERSION

阅读下载

中文翻译

获取价格

数据手册

如果您发现信息不准确，欢迎纠错

AB-066 数据手册

AP P LICATION BULLETIN

Mailing Address: PO Box 11400 • Tucson, AZ 85734 • Street Address: 6730 S. Tucson Blvd. • Tucson, AZ 85706

Tel: (602) 746-1111 • Twx: 910-952-111 • Telex: 066-6491 • FAX (602) 889-1510 • Immediate Product Info: (800) 548-6132

VOLTAGE-TO FREQUENCY CONVERTERS

OFFER USEFUL OPTIONS IN A/D CONVERSION

Specialized Counting Techniques Achieve Improved Speed and Resolution

Voltage-to-frequency converters (VFCs) provide unique

characteristics when used as analog-to-digital (A/D) con-

verters. Their excellent accuracy, linearity, and integrating

input characteristics often provide performance attributes

unattainable with other converter types. By using efficient

frequency counting techniques, familiar speed/accuracy

tradeoffs can be averted.

When system requirements suggest the VFC as an appropri-

ate choice, a frequency measurement technique must also be

chosen which meets the conversion speed requirements.

While it is clearly not a “fast” converter, conversion speed

of a VFC system can be optimized by using efficient

counting techniques.

The frequency counting scheme shown in Figure 1 is the

most commonly used technique for converting the output of

a VFC to a numerical quantity. A gate time is created by

dividing a reference frequency down to a suitable period, T.

The output pulses of the VFC are simply accumulated

during the time the gate signal is high. If T is equal to one

second, for instance, the output count M is equal to the VFC

frequency. Other gate periods (often 0.1 seconds, 10 sec-

onds, etc.) are conveniently scaled by a decimal point shift

or a simple multiplying factor. The reset circuitry which

must be used to clear the counter before the next gate period

occurs is not shown in this simplified diagram.

Since an analog quantity represented as a frequency is

inherently a serial data stream, it is easily handled in large

multichannel systems. Frequency information can be trans-

mitted over long lines with excellent noise immunity using

low cost digital line transmitters and receivers. Voltage

isolation can be accomplished with low cost optical couplers

or transformers without loss in accuracy. Many channels of

frequency data can be efficiently steered to one counter

circuit using simple digital gating, avoiding expensive ana-

log multiplexing circuitry.

9 1

Like a dual-slope A/D converter, the VFC possesses a true

integrating input. While a successive approximation A/D

converter takes a “snapshot” in time, making it susceptible

to noise peaks, the VFC’s input is constantly integrating,

smoothing the effects of noise or varying input signals.

Since the gate period is not synchronized to the VFC output

pulses, there is a potential counting inaccuracy of plus or

minus one count on M. This is easily seen by imagining a

sliding window of width T along the VFC output waveform.

V_IN

VFC

Counter M

M = 3

M ± 1

f =

3 ± 1

f =

f_r

Reference

Oscillator

f_r

M = 3

M = 2

FIGURE 1. This Simplified Diagram of the Standard Counting Method Shows the Potential Inaccuracies That Can Occur.

Although the first gate counts three rising edges of the VFC output frequency, f, the second gate period counts only

two.

AB-066

Printed in U.S.A.May, 1994

12 3 4

中文翻译

下载PDF

与AB-066相关器件

型号	品牌	获取价格	描述	数据表
AB-067	ETC	获取价格	AB-067 - Single-Supply Operation of Operational Amplifiers
AB-068	ETC	获取价格	AB-068 - Using DSP101 with Multiplexed Analog Inputs
AB-069	ETC	获取价格	AB-069 - Interleaving Analog-to-Digital Converters
AB-07.9990MHZ-10-7X-Q45	ABRACON	获取价格	Parallel - Fundamental Quartz Crystal,
AB-07.9990MHZ-10-A3G-I	ABRACON	获取价格	Parallel - Fundamental Quartz Crystal,
AB-07.9990MHZ-10-B1W	ABRACON	获取价格	Parallel - Fundamental Quartz Crystal,
AB-07.9990MHZ-10-B2-Q15	ABRACON	获取价格	Parallel - Fundamental Quartz Crystal,
AB-07.9990MHZ-10-B4Y	ABRACON	获取价格	Parallel - Fundamental Quartz Crystal,
AB-07.9990MHZ-2H-Q115	ABRACON	获取价格	Parallel - Fundamental Quartz Crystal,
AB-07.9990MHZ-A7H-I	ABRACON	获取价格	Parallel - Fundamental Quartz Crystal,

与AB-066相关文章

解析光耦仿真器：升级光耦合器技术的必要性
2024-11-18

23
英伟达新一代Blackwell GPU过热问题致交付延迟
2024-11-18

15
国产厂商思特威CMOS图像传感器芯片单月出货超1亿颗，技术创新引领行业发展
2024-11-14

45
台积电5nm和3nm产能利用率达100%，半导体行业景气度持续攀升
2024-11-14

44

产品中心

服务支持

精选活动

关于我们

帮助中心

AB-066

AB-066 数据手册

与AB-066相关器件

与AB-066相关文章

您还可以找

产品中心

服务支持

精选活动

关于我们

帮助中心

AB-066

AB-066 数据手册

与AB-066相关器件

与AB-066相关文章

您还可以找

您在本页遇到什么问题？