ADT70GN Analog Devices Inc, ADT70GN Datasheet

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ADT70GN

Manufacturer Part Number
ADT70GN
Description
Manufacturer
Analog Devices Inc
Datasheet

Specifications of ADT70GN

Operating Temperature (min)
-40C
Operating Temperature (max)
125C
Operating Temperature Classification
Automotive
Mounting
Through Hole
Pin Count
20
Package Type
PDIP
Lead Free Status / RoHS Status
Not Compliant
a
GENERAL DESCRIPTION
The ADT70 provides excitation and signal conditioning for
resistance-temperature devices (RTDs). It is ideally suited for
1 k Platinum RTDs (PRTDs), allowing a very wide range of
temperature measurement. It can also easily interface to 100
PRTDs. Using a remote, low cost thin-film PRTD, the ADT70
can measure temperature in the range of –50 C to +500 C.
With high performance platinum elements, the temperature
change can be extended to 1000 C. Accuracy of the ADT70
and PRTD system over a –200 C to +1000 C temperature
range heavily depends on the quality of the PRTD. Typically
the ADT70 will introduce an error of only 1 C over the
transducer's temperature range, and the error may be trimmed
to zero at a single calibration point.
The ADT70 consists of two matched 1 mA (nominal) current
sources for transducer and reference resistor excitation, a preci-
sion rail-to-rail output instrumentation amplifier, a 2.5 V refer-
ence and an uncommitted rail-to-rail output op amp. The
ADT70 includes a shutdown function for battery powered
equipment, which reduces the quiescent current from 4 mA to
less than 10 A. The ADT70 operates from either single +5 V
or 5 V supplies. Gain or full-scale range for the PRTD and
ADT70 system is set by a precision external resistor connected
to the instrumentation amplifier. The uncommitted op amp may
be used for scaling the internal voltage reference, providing a
“PRTD open” signal or “over-temperature” warning, a heater
switching signal, or other external conditioning determined by
the user.
The ADT70 is specified for operation from 40 C to 125 C
and is available in 20-lead DIP and SO packages.
*
REV. 0
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
which may result from its use. No license is granted by implication or
otherwise under any patent or patent rights of Analog Devices.
Patent pending.
FEATURES
PRTD Temperature Measurement Range
Typical IC Measurement Error
Includes Two Matched Current Sources
Rail-to-Rail Output Instrumentation Amp
Uncommitted, Rail-to-Rail Output Op Amp
On-Board
Temperature Coefficient
Supply Current 4 mA Max
10 A Max in Shutdown
APPLICATIONS
Temperature Controllers
Portable Instrumentation
Temperature Acquisition Cards
5 V or
5 V Operation
2.5 V Reference
25 ppm/ C
1 C
One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.
Tel: 781/329-4700
Fax: 781/326-8703
I
I
+IN
OUTA
OUTB
IN
IA
IA
NULLA
and Temperature Controller
RGA RGB
INST
AMP
PRTD Conditioning Circuit
FUNCTIONAL BLOCK DIAGRAM
SOURCES
MATCHED
CURRENT
NULLB
V
V
REFOUT
NULLA
NULLB
REFOUT
NULLA
NULLB
AGND
AGND
GND
SENSE
I
I
I
I
BIAS
OUTA
OUTB
–IN
+IN
BIAS
OUTA
OUTB
PIN CONFIGURATIONS
–V
IN
IN
–V
IA
IA
IA
IA
S
S
World Wide Web Site: http://www.analog.com
10
10
BIAS 2.5V
1
2
3
4
5
6
7
1
2
3
4
5
6
7
8
9
8
9
20-Lead P-DIP
20-Lead SOIC
(Not to Scale)
(Not to Scale)
TOP VIEW
OUT
TOP VIEW
(N Suffix)
(R Suffix)
ADT70
ADT70
a
a
IA
REFOUT
AGND
2.5V
REF
20
19
18
16
15
14
13
12
20
19
18
16
15
14
13
12
17
11
17
11
+V
V
–IN
+IN
SHUTDOWN
DGND
V
GND SENSE
RGB
RGA
+V
V
–IN
+IN
SHUTDOWN
DGND
V
GND SENSE
RGB
RGA
© Analog Devices, Inc., 1998
V
OUT OA
OUT IA
OUT OA
OUT IA
S
S
S
OA
OA
OA
OA
ADT70
DOWN
DGND
SHUT-
ADT70*
+V
OUT
+IN
SHUTDOWN
IN
S
OA
OA
OA

Related parts for ADT70GN

ADT70GN Summary of contents

Page 1

FEATURES PRTD Temperature Measurement Range Typical IC Measurement Error Includes Two Matched Current Sources Rail-to-Rail Output Instrumentation Amp Uncommitted, Rail-to-Rail Output Op Amp On-Board 2.5 V Reference Temperature Coefficient 25 ppm Operation Supply ...

Page 2

ADT70–SPECIFICATIONS Parameter SYSTEM CONFIGURATION Gain Line Regulation CURRENT SOURCES Output Current Output Current Mismatch Voltage Compliance INSTRUMENTATION AMP Input Offset Voltage Output Offset Voltage Input Bias Current Input Offset Current Common-Mode Rejection Output Voltage Swing Power Supply Rejection Ratio VOLTAGE ...

Page 3

... Although the ADT70 features proprietary ESD protection circuitry, permanent damage may occur on devices subjected to high energy electrostatic discharges. Therefore, proper ESD precautions are recommended to avoid performance degradation or loss of functionality. REV Model 150 C ADT70GR 125 C ADT70GN 125 C 300 C Units JC 24 C/W 31 C/W – ...

Page 4

ADT70 5 4 +5V, NO LOAD S 4 3.5 3 2.5 2 1 TEMPERATURE – C Figure 1. Supply Current vs. Temperature 1 +5V, NO LOAD S 1.35 1.3 1.25 ...

Page 5

V = +5V, NO LOAD S 300 200 100 0 100 200 300 400 500 25 25 TEMPERATURE – C Figure 7. Instrumentation Amplifier Input Offset Current vs. Temperature 1 +5V, NO LOAD S 1.55 1.5 ...

Page 6

ADT70 1000 + SOURCING 100 CURRENT 100 LOAD CURRENT – A Figure 13. Op Amp Output Voltage from Rails vs. Load Current 2.52 ...

Page 7

PSRR 100 1k 10k FREQUENCY – Hz Figure 19. In Amp PSRR vs. Frequency – A 140 120 100 PSRR 100 1k 10k ...

Page 8

ADT70 AMP = 300mV OUT SINGLE SUPPLY CC 40 TURNING LOW TO HIGH V SHUTDOWN 20 TURNING OFF = HIGH TO LOW 10 V SHUTDOWN ...

Page 9

RTD and the reference resistor. Thus, an error in reading the ac- tual temperature could occur. Table I. Copper Wire Gauge Size to Resistance Table. Lead-wire AWG Ohms/foot at +25ºC ...

Page 10

ADT70 1k REF RESISTOR NODE C NODE D NODE A 1k PRTD NODE B Figure 28. 4-Wire Lead-Wire Resistance Cancellation Circuit If PRTD has a tempco resistance of 0.00385 / / C or sensi- tivity of 3. the ...

Page 11

V. Therefore, to achieve full scale operation the output of ADT70 should be shifted allow for opera- tion in the 0 V ...

Page 12

ADT70 because the input voltage range of the on-board op amp only ex- tends to about 1 V above the negative rail. If the application re- quires the inputs of either the on-board amp or instrumentation amplifier to operate within ...

Page 13

American PRTD Application Circuit The majority of PRTD sensors use a scale factor of 0.00385 / / C. This type of sensor is known as the European PRTD and is the most common PRTD sensor. However, there is also an ...

Page 14

ADT70 0.210 (5.33) MAX 0.160 (4.06) 0.115 (2.93) 0.0118 (0.30) 0.0040 (0.10) OUTLINE DIMENSIONS Dimensions shown in inches and (mm). 20-Lead Plastic DIP (P-Suffix) 1.060 (26.90) 0.925 (23.50 0.280 (7.11) 0.240 (6.10 0.060 (1.52) PIN 1 ...

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