鈥?/div>
G
+
+
+A
V+
GENERAL DESCRIPTION
The AD596/AD597 is a monolithic temperature setpoint con-
troller 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 thermo-
couple input to derive an internal signal proportional to tem-
perature. 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/擄C) directly from
a type J or K thermocouple signal. It can also be used as a stand-
alone 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
碌A(chǔ),
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擄C to +100擄C. Operation
over an extended ambient temperature range is possible with
slightly reduced accuracy. The AD596 will amplify thermo-
couple signals covering the entire 鈥?00擄C to +760擄C tempera-
ture range recommended for type J thermocouples while the
AD597 can accommodate 鈥?00擄C to +1250擄C type K inputs.
The AD596/AD597 has a calibration accuracy of
鹵4擄C
at an
ambient temperature of 60擄C and an ambient temperature
stability specification of 0.05擄C/擄C from +25擄C to +100擄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.
HYS
AD596/
AD597
V
OUT
GND
V鈥?/div>
FB
SOIC
AD597
+IN 1
+
G
HYS 2
+
G
鈥?/div>
+A
7 V+
鈥?/div>
8 鈥揑N
GND 3
+
6 V
OUT
V鈥?4
ICE POINT
COMP
TOP VIEW
(Not to Scale)
5 FB
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 in-
strumentation amplifier that allows the thermocouple to float
over most of the supply voltage range.
3. Linearization not required for thermocouple temperatures
close to 175擄C (+100擄C to +540擄C for AD596).
4. Cold junction compensation is optimized for ambient tem-
peratures ranging from +25擄C to +100擄C.
5. In the stand-alone mode, the AD596/AD597 produces an
output voltage that indicates its own temperature.
REV. B
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.
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
漏 Analog Devices, Inc., 1998
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