Analog Devices AD596AR, AD596AH Datasheet
FUNCTIONAL BLOCK DIAGRAM
REV. B
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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.
a
Thermocouple Conditioner and
Setpoint Controller
AD596*/AD597*
FEATURES
Low Cost
Operates with Type J (AD596) or Type K (AD597)
Thermocouples
Built-In Ice Point Compensation
Temperature Proportional Operation – 10 mV/8C
Temperature Setpoint Operation – ON/OFF
Programmable Switching Hysteresis
High Impedance Differential Input
GENERAL DESCRIPTION
The AD596/AD597 is a monolithic temperature setpoint controller that has been optimized for use at elevated temperatures
such as those found in oven control applications. The device
cold junction compensates and amplifies a type J or K thermocouple input to derive an internal signal proportional to temperature. The internal signal is then compared with an externally
applied setpoint voltage to yield a low impedance switched output
voltage. Dead-Band or switching hysteresis can be programmed
using a single external resistor. Alternately, the AD596/AD597 can
be configured to provide a voltage output (10 mV/°C) directly from
a type J or K thermocouple signal. It can also be used as a standalone voltage output temperature sensor.
The AD596/AD597 can be powered with a single supply from
+5 V to +30 V, or dual supplies up to a total span of 36 V.
Typical quiescent supply current is 160 µA, which minimizes
self-heating errors.
The AD596/AD597 H package option includes a thermocouple
failure alarm that indicates an open thermocouple lead when
operated in the temperature proportional measurement mode.
The alarm output has a flexible format which can be used to
drive relays, LEDs or TTL logic.
The device is packaged in a reliability qualified, cost effective
10-pin metal can or SOIC and is trimmed to operate over an
ambient temperature range from +25°C to +100°C. Operation
over an extended ambient temperature range is possible with
slightly reduced accuracy. The AD596 will amplify thermocouple signals covering the entire –200°C to +760°C temperature range recommended for type J thermocouples while the
AD597 can accommodate –200°C to +1250°C type K inputs.
The AD596/AD597 has a calibration accuracy of ±4°C at an
ambient temperature of 60°C and an ambient temperature
stability specification of 0.05°C/°C from +25°C to +100°C. If
higher accuracy, or a lower ambient operating temperature is
required, either the AD594 (J thermocouple) or AD595 (K
thermocouple) should be considered.
*Protected by U.S. Patent No. 4,029,974.
PRODUCT HIGHLIGHTS
1. The AD596/AD597 provides cold junction compensation
and a high gain amplifier which can be used as a setpoint
comparator.
2. The input stage of the AD596/AD597 is a high quality instrumentation amplifier that allows the thermocouple to float
over most of the supply voltage range.
3. Linearization not required for thermocouple temperatures
close to 175°C (+100°C to +540°C for AD596).
4. Cold junction compensation is optimized for ambient temperatures ranging from +25°C to +100°C.
5. In the stand-alone mode, the AD596/AD597 produces an
output voltage that indicates its own temperature.
One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.
Tel: 781/329-4700 World Wide Web Site: http://www.analog.com
Fax: 781/326-8703 © Analog Devices, Inc., 1998
TO-100
+
–
G
FB
V
OUT
+ALM
+IN
V–
V+
A
+
ICE
POINT
COMP
+
AD596/
AD597
–ALM
–IN
HYS
GND
+
–
G
SOIC
+IN
–IN
TOP VIEW
(Not to Scale)
AD597
G
–
+
+
G
–
+
A
+
ICE POINT
COMP
HYS
V+
GND
V
OUT
V–
FB
1
2
3
45
6
7
8
AD596/AD597–SPECIFICA TIONS
(@ +608C and VS = 10 V, Type J (AD596), Type K (AD597) Thermocouple,
unless otherwise noted)
REV. B
–2–
Model AD596AH AD597AH AD597AR
Min Typ Max Min Typ Max Min Typ Max Units
ABSOLUTE MAXIMUM RATINGS
+VS to –V
S
36 36 36 Volts
Common-Mode Input Voltage (–VS – 0.15) +V
S
(–VS – 0.15) +V
S
(–VS – 0.15) +V
S
Volts
Differential Input Voltage –V
S
+V
S
–V
S
+V
S
–V
S
+V
S
Volts
Alarm Voltages
+ALM –V
S
(–VS +36) –V
S
(–VS +36) –V
S
(–VS +36) Volts
–ALM –V
S
+V
S
–V
S
+V
S
–V
S
+V
S
Volts
Operating Temperature Range –55 +125 –55 +125 –40 +125 °C
Output Short Circuit to Common Indefinite Indefinite Indefinite
TEMPERATURE MEASUREMENT
(Specified Temperature Range
+25°C to +100°C)
Calibration Error
1
–4 +4 –4 +4 –4 +4 °C
Stability vs. Temperature
2
± 0.02 ± 0.05 ± 0.02 ± 0.05 ± 0.02 ± 0.05 °C/°C
Gain Error –1.5 +1.5 –1.5 +1.5 –1.5 +1.5 %
Nominal Transfer Function 10 10 10 mV/°C
AMPLIFIER CHARACTERISTICS
Closed Loop Gain
3
180.6 245.5 245.5 V/V
Input Offset Voltage °C × 53.21 + 235 °C × 41.27 – 37 °C × 41.27 – 37 µV
Input Bias Current 0.1 0.1 0.1 µA
Differential Input Range –10 +50 –10 +50 –10 +50 mV
Common-Mode Range (–VS – 0.15) (+VS – 4) (+VS – 0.15) (+VS – 4) (–VS – 0.15) (+VS – 4) Volts
Common-Mode Sensitivity–RTO 10 10 10 mV/V
Power Supply Sensitivity–RTO 1 10 1 10 1 10 mV/V
Output Voltage Range
Dual Supplies (–VS + 2.5) (+VS – 2) (–VS + 2.5) (+VS – 2) (–VS + 2.5) (+VS – 2) Volts
Single Supply 0 (+VS – 2) 0 (+VS – 2) 0 (+VS – 2) Volts
Usable Output Current
4
± 5 ± 5 ± 5mA
3 dB Bandwidth 15 15 15 kHz
ALARM CHARACTERISTICS
5
Alarm Function Not Pinned Out
V
CE(SAT)
at 2 mA 0.3 0.3 Volts
Leakage Current 61 61 µA
Operating Voltage at – ALM (+VS – 4) (+VS – 4) Volts
Short Circuit Current 20 20 mA
POWER REQUIREMENTS
Operating (+VS to –VS) ≤ 30 (+VS to –VS) ≤ 30 (+VS to –VS) ≤ 30 Volts
Quiescent Current
+V
S
160 300 160 300 160 300 µA
–V
S
100 200 100 200 100 200 µA
NOTES
1
This is a measure of the deviation from ideal with a measuring thermocouple junction of 175°C and a chip temperature of 60°C. The ideal transfer function is given by:
AD596: V
OUT
= 180.57 × (Vm – Va + (ambient in °C) × 53.21 µV/°C + 235 µV)
AD597: V
OUT
= 245.46 × (Vm – Va + (ambient in °C) × 41.27 µV/°C – 37 µV)
where V
m
, and Va represent the measuring and ambient temperatures and are taken from the appropriate J or K thermocouple table. The ideal transfer function minimizes the
error over the ambient temperature range of 25°C to 100°C with a thermocouple temperature of approximately 175°C.
2
Defined as the slope of the line connecting the AD596/AD597 CJC errors measured at 25°C and 100°C ambient temperature.
3
Pin 6 shorted to Pin 7.
4
Current Sink Capability in single supply configuration is limited to current drawn to ground through a 50 kΩ resistor at output voltages below 2.5 V.
5
Alarm function available on H package option only.
Specifications subject to change without notice.
Specifications shown in boldface are tested on all production units at final electrical test. Results from those tests are used to calculate outgoing quality levels. All min and max
specifications are guaranteed, although only those shown in boldface
are tested on all production units.
ORDERING GUIDE
Model Package Description Package Options
AD596AH TO-100 H-10A
AD597AH TO-100 H-10A
AD597AR* Plastic SOIC SO-8
*Consult factory for availability.
AD596/AD597
REV. B –3–
Table I. Output Voltage vs. Thermocouple Temperature (Ambient +608C, VS = –5 V, +15 V)
Thermocouple Type J AD596 Type K AD597
Temperature Voltage Output Voltage Output
8C mVmVmVmV
–200 –7.890 –1370 –5.891 –1446
–180 –7.402 –1282 –5.550 –1362
–160 –6.821 –1177 –5.141 –1262
–140 –6.159 –1058 –4.669 –1146
–120 –5.426 –925 –4.138 –1016
–100 –4.632 –782 –3.553 –872
–80 –3.785 –629 –2.920 –717
–60 –2.892 –468 –2.243 –551
–40 –1.960 –299 –1.527 –375
–20 –.995 –125 –.777 –191
–10 –.501 –36 –.392 –96
005400
10 .507 146 .397 97
20 1.019 238 .798 196
25 1.277 285 1.000 245
30 1.536 332 1.203 295
40 2.058 426 1.611 395
50 2.585 521 2.022 496
60 3.115 617 2.436 598
80 4.186 810 3.266 802
100 5.268 1006 4.095 1005
120 6.359 1203 4.919 1207
140 7.457 1401 5.733 1407
160 8.560 1600 6.539 1605
180 9.667 1800 7.338 1801
200 10.777 2000 8.137 1997
220 11.887 2201 8.938 2194
240 12.998 2401 9.745 2392
260 14.108 2602 10.560 2592
280 15.217 2802 11.381 2794
300 16.325 3002 12.207 2996
320 17.432 3202 13.039 3201
340 18.537 3402 13.874 3406
360 19.640 3601 14.712 3611
380 20.743 3800 15.552 3817
400 21.846 3999 16.395 4024
420 22.949 4198 17.241 4232
440 24.054 4398 18.088 4440
460 25.161 4598 18.938 4649
480 26.272 4798 19.788 4857
Thermocouple Type J AD596 Type K AD597
Temperature Voltage Output Voltage Output
8CmVmVmVmV
500 27.388 5000 20.640 5066
520 28.511 5203 21.493 5276
540 29.642 5407 22.346 5485
560 30.782 5613 23.198 5694
580 31.933 5821 24.050 5903
600 33.096 6031 24.902 6112
620 34.273 6243 25.751 6321
640 35.464 6458 26.599 6529
660 36.671 6676 27.445 6737
680 37.893 6897 28.288 6944
700 39.130 7120 29.128 7150
720 40.382 7346 29.965 7355
740 41.647 7575 30.799 7560
750 42.283 7689 31.214 7662
760 – – 31.629 7764
780 – – 32.455 7966
800 – – 33.277 8168
820 – – 34.095 8369
840 – – 34.909 8569
860 – – 35.718 8767
880 – – 36.524 8965
900 – – 37.325 9162
920 – – 38.122 9357
940 – – 38.915 9552
960 – – 39.703 9745
980 – – 40.488 9938
1000 – – 41.269 10130
1020 – – 42.045 10320
1040 – – 42.817 10510
1060 – – 43.585 10698
1080 – – 44.439 10908
1100 – – 45.108 11072
1120 – – 45.863 11258
1140 – – 46.612 11441
1160 – – 47.356 11624
1180 – – 48.095 11805
1200 – – 48.828 11985
1220 – – 49.555 12164
1240 – – 50.276 12341
1250 – – 50.633 12428
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