AD637KD Analog Devices Inc, AD637KD Datasheet

AD637KD

Manufacturer Part Number

AD637KD

Description

RMS TO DC CONVERTER IC

Manufacturer

Analog Devices Inc

Datasheet

1.AD637JRZ.pdf (20 pages)

Specifications of AD637KD

Rohs Status

RoHS non-compliant

Current - Supply

2.2mA

Voltage - Supply

±3.0V ~ 18V

Mounting Type

Through Hole

Package / Case

14-CDIP (0.300", 7.62mm)

Bandwidth

8MHz

Supply Current

2.2mA

Power Dissipation Pd

108mW

Supply Voltage Range

Â± 3V To Â± 18V

Digital Ic Case Style

DIP

No. Of Pins

Operating Temperature Range

0Â°C To +70Â°C

For Use With

AD637-EVALZ - BOARD EVALUATION FOR AD637

Lead Free Status / RoHS Status

Available stocks

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Part Number

Manufacturer

Quantity

Price

Company:

BOSTOCK HK LIMITED

Part Number:

AD637KD

Manufacturer:

ADI

Quantity:

485

Company:

BOSTOCK HK LIMITED

Part Number:

AD637KDZ

Manufacturer:

ADI

Quantity:

485

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FEATURES

High accuracy

Wide bandwidth

Computes

dB output (60 dB range)

Chip select/power-down feature allows

14-lead SBDIP, 14-lead low cost CERDIP, and 16-lead SOIC_W

GENERAL DESCRIPTION

The AD637 is a complete, high accuracy, monolithic rms-to-dc

converter that computes the true rms value of any complex

waveform. It offers performance that is unprecedented in

integrated circuit rms-to-dc converters and comparable to

discrete and modular techniques in accuracy, bandwidth, and

dynamic range. A crest factor compensation scheme in the

AD637 permits measurements of signals with crest factors of

up to 10 with less than 1% additional error. The wide band-

width of the AD637 permits the measurement of signals up to

600 kHz with inputs of 200 mV rms and up to 8 MHz when the

input levels are above 1 V rms.

As with previous monolithic rms converters from Analog

Devices, Inc., the AD637 has an auxiliary dB output available to

users. The logarithm of the rms output signal is brought out to a

separate pin, allowing direct dB measurement with a useful

range of 60 dB. An externally programmed reference current

allows the user to select the 0 dB reference voltage to correspond to

any level between 0.1 V and 2.0 V rms.

A chip select connection on the AD637 permits the user to

decrease the supply current from 2.2 mA to 350 μA during periods

when the rms function is not in use. This feature facilitates the

addition of precision rms measurement to remote or handheld

applications where minimum power consumption is critical. In

addition, when the AD637 is powered down, the output goes to a

high impedance state. This allows several AD637s to be tied

together to form a wideband true rms multiplexer.

Rev. K

Information furnished by Analog Devices is believed to be accurate and reliable. However, no

responsibility is assumed by Analog Devices for its use, nor for any infringements of patents or other

rights of third parties that may result from its use. Specifications subject to change without notice. No

license is granted by implication or otherwise under any patent or patent rights of Analog Devices.

Trademarks and registered trademarks are the property of their respective owners.

0.02% maximum nonlinearity, 0 V to 2 V rms input

0.10% additional error to crest factor of 3

8 MHz at 2 V rms input

600 kHz at 100 mV rms

True rms

Square

Mean square

Absolute value

Analog three-state operation

Quiescent current reduction from 2.2 mA to 350 μA

One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.

Tel: 781.329.4700

Fax: 781.461.3113

DEN INPUT

The input circuitry of the AD637 is protected from overload

voltages in excess of the supply levels. The inputs are not

damaged by input signals if the supply voltages are lost.

The AD637 is available in accuracy Grade J and Grade K for

commercial temperature range (0°C to 70°C) applications, accuracy

Grade A and Grade B for industrial range (−40°C to +85°C) appli-

cations, and accuracy Grade S rated over the −55°C to +125°C

temperature range. All versions are available in hermetically sealed,

14-lead SBDIP, 14-lead CERDIP, and 16-lead SOIC_W packages.

The AD637 computes the true root mean square, mean square,

or absolute value of any complex ac (or ac plus dc) input

waveform and gives an equivalent dc output voltage. The true

rms value of a waveform is more useful than an average

rectified signal because it relates directly to the power of the

signal. The rms value of a statistical signal is also related to the

standard deviation of the signal.

The AD637 is laser wafer trimmed to achieve rated performance

without external trimming. The only external component

required is a capacitor that sets the averaging time period. The

value of this capacitor also determines low frequency accuracy,

ripple level, and settling time.

The on-chip buffer amplifier can be used either as an input

buffer or in an active filter configuration. The filter can be used

to reduce the amount of ac ripple, thereby increasing accuracy.

COMMON

OUTPUT

BUFF IN

OFFSET

High Precision, Wideband

FUNCTIONAL BLOCK DIAGRAM

25kΩ

ABSOLUTE

VALUE

RMS-to-DC Converter

SQUARER/

DIVIDER

BIAS

Figure 1.

25kΩ

AD637

www.analog.com

AD637

BUFF

OUT

RMS OUT

dB OUTPUT

Related parts for AD637KD

AD637KD Summary of contents

Page 1

FEATURES High accuracy 0.02% maximum nonlinearity rms input 0.10% additional error to crest factor of 3 Wide bandwidth 8 MHz rms input 600 kHz at 100 mV rms Computes True rms Square ...

AD637 TABLE OF CONTENTS Features .............................................................................................. 1 Functional Block Diagram .............................................................. 1 General Description ......................................................................... 1 Revision History ............................................................................... 2 Specifications..................................................................................... 3 Absolute Maximum Ratings............................................................ 5 ESD Caution.................................................................................. 5 Pin Configurations and Function Descriptions ........................... 6 Functional Description .................................................................... 7 ...

Page 3

SPECIFICATIONS At 25°C and ±15 V dc, unless otherwise noted. Table 1. AD637J/AD637A Parameter Min Typ TRANSFER FUNCTION V = OUT CONVERSION ACCURACY 2 Total Error, Internal Trim Figure MIN MAX vs. Supply 30 ...

Page 4

AD637 AD637J/AD637A Parameter Min Typ OUTPUT CHARACTERISTICS Offset Voltage vs. Temperature ±0.05 Voltage Swing, 13 12.0 ±15 V Supply, 2 kΩ Load Voltage Swing, 2 ±3 V Supply, 2 kΩ Load Output Current 6 Short-Circuit ...

Page 5

ABSOLUTE MAXIMUM RATINGS Table 2. Parameter ESD Rating Supply Voltage Internal Quiescent Power Dissipation Output Short-Circuit Duration Storage Temperature Range Lead Temperature (Soldering 10 sec) Rated Operating Temperature Range AD637J, AD637K AD637A, AD637B AD637S, 5962-8963701CA Stresses above those listed under ...

Page 6

AD637 PIN CONFIGURATIONS AND FUNCTION DESCRIPTIONS BUFF AD637 COMMON 3 OUTPUT OFFSET TOP VIEW 4 (Not to Scale DEN INPUT 6 dB OUTPUT CONNECT Figure 2. 14-Lead SBDIP/CERDIP Pin Configuration ...

Page 7

FUNCTIONAL DESCRIPTION BUFF OUT 14 1 BUFF IN 24kΩ ABSOLUTE VALUE VOLTAGE TO CURRENT CONVERTER 6kΩ 12kΩ The AD637 embodies an implicit solution of the rms equation that overcomes the inherent limitations of straightforward rms computation. ...

Page 8

AD637 STANDARD CONNECTION The AD637 is simple to connect for a majority of rms measurements. In the standard rms connection shown in Figure 5, only a single external capacitor is required to set the averaging time constant. In this configuration, ...

Page 9

AD637K MAX 2.5 0 EXTERNAL TRIM –2.5 AD637K: 0.5mV ± 0.2% 0.25mV ± 0.05% EXTERNAL –5.0 0 0.5 1.0 INPUT LEVEL (V) Figure 7. Maximum Total Error vs. Input Level AD637K Internal and External Trims AD637 1 BUFF IN ...

Page 10

AD637 AD637 1 BUFF ABSOLUTE VALUE 3 COMMON SQUARER/ OUTPUT DIVIDER 4 OFFSET BIAS +V 4.7kΩ 25kΩ DEN 25kΩ 6 INPUT 7 dB OUTPUT RX 24kΩ Figure 11. 2-Pole Sallen-Key Filter Figure ...

Page 11

Table 5. Practical Values of C and C2 for Various Input Waveforms AV Absolute Value Input Waveform Circuit Waveform and Period and Period T 1/ Symmetrical Sine Wave Sine Wave with dc Offset T ...

Page 12

AD637 AC MEASUREMENT ACCURACY AND CREST FACTOR Crest factor is often overlooked in determining the accuracy measurement. Crest factor is defined as the ratio of the peak signal amplitude to the rms value of the signal (CF ...

Page 13

CALIBRATION Refer to Figure 20: • Set 1.00 V rms IN • Adjust R1 for 0 dB out = 0.00 V • Set 0.10 V rms IN ...

Page 14

AD637 OUTPUT 1MΩ 4 OFFSET 50kΩ ADJUST + –V S 4.7kΩ NOTES 1. VALUES CHOSEN TO GIVE 0.1% AVERAGING ERROR @ 1Hz CONNECT. LOW FREQUENCY MEASUREMENTS If ...

Page 15

EXPANDABLE BUFFER AD637 IC1 BUFF IN 1 ABSOLUTE 2 NC VALUE 3 COMMON BIAS OUTPUT SECTION 4 OFFSET SQUARER/DIVIDER + 4.7kΩ 25kΩ 6 DEN INPUT FILTER 7 dB OUTPUT BUFFER AD637 IC2 BUFF ...

Page 16

AD637 EVALUATION BOARD Figure 23 shows a digital image of the AD637-EVALZ, an evaluation board specially designed for the AD637 available at www.analog.com and is fully tested and ready for bench testing after connecting power and signal I/O. ...

Page 17

Figure 24. AD637-EVALZ Assembly Figure 25. Component Side Silkscreen Figure 26. Evaluation Board—Component Side Copper Figure 27. Evaluation Board—Secondary Side Copper Figure 28. Evaluation Board—Internal Power Plane Figure 29. Evaluation Board—Internal Ground Plane Rev Page ...

Page 18

AD637 GND1 GND2 GND3 GND4 + 50kΩ +V – CF2 47µF 25V POWER SUPPLY – 10µF 10µF 25V 25V + – FILTER BUF_IN 4 OUT 1 2 ...

Page 19

OUTLINE DIMENSIONS 0.005 (0.13) MIN 0.080 (2.03) MAX 14 8 0.310 (7.87) 0.220 (5.59 PIN 1 0.100 (2.54) BSC 0.765 (19.43) MAX 0.060 (1.52) 0.200 (5.08) MAX 0.015 (0.38) 0.150 (3.81) 0.200 (5.08) MIN 0.125 (3.18) SEATING 0.070 ...

Page 20

... AD637BR AD637BRZ AD637JD AD637JDZ AD637JQ AD637JR AD637JR-REEL AD637JR-REEL7 AD637JRZ AD637JRZ-RL AD637JRZ-R7 AD637KD AD637KDZ AD637KQ AD637KRZ AD637SD AD637SD/883B AD637SQ/883B AD637-EVALZ RoHS Compliant Part standard microcircuit drawing is available. ©2007–2011 Analog Devices, Inc. All rights reserved. Trademarks and registered trademarks are the property of their respective owners. ...

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