AD736BR Analog Devices Inc, AD736BR Datasheet

IC TRUE RMS/DC CONV LP 8-SOIC

AD736BR

Manufacturer Part Number
AD736BR
Description
IC TRUE RMS/DC CONV LP 8-SOIC
Manufacturer
Analog Devices Inc
Datasheet

Specifications of AD736BR

Rohs Status
RoHS non-compliant
Current - Supply
160µA
Voltage - Supply
±5.0V
Mounting Type
Surface Mount
Package / Case
8-SOIC (3.9mm Width)
For Use With
AD736-EVALZ - BOARD EVALUATION FOR AD736

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FEATURES
Computes
Provides
AD737—an unbuffered voltage output version with
GENERAL DESCRIPTION
The AD736 is a low power, precision, monolithic true rms-to-
dc converter. It is laser trimmed to provide a maximum error of
±0.3 mV ± 0.3% of reading with sine wave inputs. Furthermore,
it maintains high accuracy while measuring a wide range of
input waveforms, including variable duty-cycle pulses and triac
(phase)-controlled sine waves. The low cost and small size of
this converter make it suitable for upgrading the performance
of non-rms precision rectifiers in many applications. Compared
to these circuits, the AD736 offers higher accuracy at an equal
or lower cost.
The AD736 can compute the rms value of both ac and dc input
voltages. It can also be operated as an ac-coupled device by
adding one external capacitor. In this mode, the AD736 can
resolve input signal levels of 100 μV rms or less, despite variations
in temperature or supply voltage. High accuracy is also maintained
for input waveforms with crest factors of 1 to 3. In addition,
crest factors as high as 5 can be measured (introducing only 2.5%
additional error) at the 200 mV full-scale input level.
The AD736 has its own output buffer amplifier, thereby pro-
viding a great deal of design flexibility. Requiring only 200 μA
of power supply current, the AD736 is optimized for use in
portable multimeters and other battery-powered applications.
Rev. H
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.
chip power-down also available
True rms value
Average rectified value
Absolute value
200 mV full-scale input range (larger inputs with input
High input impedance: 10
Low input bias current: 25 pA maximum
High accuracy: ±0.3 mV ± 0.3% of reading
RMS conversion with signal crest factors up to 5
Wide power supply range: +2.8 V, −3.2 V to ±16.5 V
Low power: 200 mA maximum supply current
Buffered voltage output
No external trims needed for specified accuracy
attenuator)
12
Ω
One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.
Tel: 781.329.4700
Fax: 781.461.3113
The AD736 allows the choice of two signal input terminals: a
high impedance FET input (10
High-Z input attenuators and a low impedance input (8 kΩ) that
allows the measurement of 300 mV input levels while operating
from the minimum power supply voltage of +2.8 V, −3.2 V. The
two inputs can be used either single ended or differentially.
The AD736 has a 1% reading error bandwidth that exceeds
10 kHz for the input amplitudes from 20 mV rms to 200 mV rms
while consuming only 1 mW.
The AD736 is available in four performance grades. The
AD736J and AD736K grades are rated over the 0°C to +70°C
and −20°C to +85°C commercial temperature ranges. The
AD736A and AD736B grades are rated over the −40°C to +85°C
industrial temperature range. The AD736 is available in three
low cost, 8-lead packages: PDIP, SOIC, and CERDIP.
PRODUCT HIGHLIGHTS
1. The AD736 is capable of computing the average rectified
2. Only one external component, an averaging capacitor, is
3. The low power consumption of 1 mW makes the AD736
4. A high input impedance of 10
5. A low impedance input is available for those applications that
value, absolute value, or true rms value of various input signals.
required for the AD736 to perform true rms measurement.
suitable for many battery-powered applications.
external buffer when interfacing with input attenuators.
require an input signal up to 300 mV rms operating from low
power supply voltages.
–V
V
C
C
IN
True RMS-to-DC Converter
C
F
S
1
2
3
4
8kΩ
FUNCTIONAL BLOCK DIAGRAM
SECTION
BIAS
AMPLIFIER
Low Cost, Low Power,
INPUT
©2007 Analog Devices, Inc. All rights reserved.
rms CORE
RECTIFIER
WAVE
FULL
Figure 1.
12
12
Ω) that directly interfaces with
Ω eliminates the need for an
AD736
AMPLIFIER
8kΩ
OUTPUT
www.analog.com
8
7
6
5
AD736
COM
OUTPUT
+V
C
AV
S

Related parts for AD736BR

AD736BR Summary of contents

Page 1

FEATURES Computes True rms value Average rectified value Absolute value Provides 200 mV full-scale input range (larger inputs with input attenuator) 12 High input impedance: 10 Ω Low input bias current maximum High accuracy: ±0.3 mV ± 0.3% ...

Page 2

AD736 TABLE OF CONTENTS Features .............................................................................................. 1 General Description ......................................................................... 1 Functional Block Diagram .............................................................. 1 Product Highlights ........................................................................... 1 Revision History ............................................................................... 2 Specifications..................................................................................... 3 Absolute Maximum Ratings............................................................ 5 ESD Caution.................................................................................. 5 Pin Configuration and Function Descriptions............................. 6 Typical ...

Page 3

SPECIFICATIONS At 25°C ± supplies, ac-coupled with 1 kHz sine wave input applied, unless otherwise noted. Specifications in bold are tested on all production units at final electrical test. Results from those tests are used to calculate outgoing ...

Page 4

... AD736JN, AD736JR AD736KN, AD736KR AD736AQ, AD736AR AD736BQ, AD736BR . C /V rms. PEAK Rev Page Max Unit ±0.3 mV ±0 μV/°C μV/V 130 μV Ω kHz ...

Page 5

ABSOLUTE MAXIMUM RATINGS Table 2. Parameter Supply Voltage 1 Internal Power Dissipation Input Voltage Output Short-Circuit Duration Differential Input Voltage Storage Temperature Range (Q) Storage Temperature Range (N, R) Lead Temperature (Soldering, 60 sec) ESD Rating 1 8-Lead PDIP: θ ...

Page 6

AD736 PIN CONFIGURATION AND FUNCTION DESCRIPTIONS Table 3. Pin Function Descriptions Pin No. Mnemonic Description 1 C Coupling Capacitor coupling is desired at Pin 2, connect a coupling capacitor to this pin. If the coupling at C Pin ...

Page 7

TYPICAL PERFORMANCE CHARACTERISTICS 0 200mV rms IN 1kHz SINE WAVE 0 100µ 22µF F 0.3 0.1 0 –0.1 –0.3 –0 SUPPLY VOLTAGE (±V) Figure 3. Additional Error ...

Page 8

AD736 0 200mV rms IN 1kHz SINE WAVE 0 100mF 22mF F 0 ±5V S 0.2 0 –0.2 –0.4 –0.6 –0.8 –60 –40 – TEMPERATURE (°C) Figure ...

Page 9

SUPPLY VOLTAGE (±V) Figure 15. Pin 2 Input Bias Current vs. Supply Voltage 1V 100mV C = 10µF AV 10mV C = 33µF AV 1mV 100µV 1ms ...

Page 10

AD736 THEORY OF OPERATION – shown by Figure 18, the AD736 has five functional subsections: the input amplifier, full-wave rectifier (FWR), rms core, output amplifier, and bias section. The FET input amplifier ...

Page 11

Mathematically, the rms value of a voltage is defined (using a simplified equation rms Avg V This involves squaring the signal, taking the average, and then obtaining the square root. True rms converters are ...

Page 12

AD736 RAPID SETTLING TIMES VIA THE AVERAGE RESPONDING CONNECTION Because the average responding connection shown in Figure 19 does not use the C averaging capacitor, its settling time does AV not vary with the input signal level determined ...

Page 13

APPLICATIONS CONNECTING THE INPUT The inputs of the AD736 resemble an op amp, with noninverting and inverting inputs. The input stages are JFETs accessible at Pin 1 and Pin 2. Designated as the high impedance input, Pin 2 is connected ...

Page 14

AD736 SELECTING PRACTICAL VALUES FOR INPUT COUPLING (C ), AVERAGING ( CAPACITORS F Table 5 provides practical values common applications. The input coupling capacitor conjunction with the C 8 kΩ internal ...

Page 15

C AD711 10µF C –IN 8kΩ +IN 2 INPUT 12 INPUT IMPEDANCE: 10 Ω||10pF AMPLIFIER C F BIAS 3 SECTION –V S – 1µF Figure 26. Differential Input Connection ...

Page 16

AD736 EVALUATION BOARD An evaluation board, AD736-EVALZ, is available for experimentation or becoming familiar with rms-to-dc converters. Figure photograph of the board, and Figure 30 is the top silkscreen showing the component locations. Figure 31, Figure 32, ...

Page 17

GND1 W1 DC COUP VIN CIN J1 0.1µ Table 6. Evaluation Board Bill of Materials Qty Name Description 1 Test loop Red 1 Test loop Green 2 Capacitors Tantalum 10 μ Capacitors 0.1 μF, 16 ...

Page 18

AD736 OUTLINE DIMENSIONS 0.210 (5.33) MAX 0.150 (3.81) 0.130 (3.30) 0.115 (2.92) 0.022 (0.56) 0.018 (0.46) 0.014 (0.36) CONTROLLING DIMENSIONS ARE IN INCHES; MILLIMETER DIMENSIONS (IN PARENTHESES) ARE ROUNDED-OFF INCH EQUIVALENTS FOR REFERENCE ONLY AND ARE NOT APPROPRIATE FOR USE ...

Page 19

... AD736BR –40°C to +85°C AD736BR-REEL –40°C to +85°C AD736BR-REEL7 –40°C to +85°C 1 AD736BRZ –40°C to +85°C 1 AD736BRZ-R7 –40°C to +85°C 1 AD736BRZ-RL –40°C to +85°C AD736JN 0°C to +70°C 1 AD736JNZ 0°C to +70°C AD736KN 0° ...

Page 20

AD736 NOTES ©2007 Analog Devices, Inc. All rights reserved. Trademarks and registered trademarks are the property of their respective owners. C00834-0-2/07(H) Rev Page ...

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