AD22105 Datasheet, PDF (1/8 Pages) Analog Devices – Low Voltage, Resistor Programmable Thermostatic Switch

a
FEATURES
User-Programmable Temperature Setpoint
2.0؇C Setpoint Accuracy
4.0؇C Preset Hysteresis
Wide Supply Range (+2.7 V dc to +7.0 V dc)
Wide Temperature Range (–40؇C to +150؇C)
Low Power Dissipation (230 ␮W @ 3.3 V)
APPLICATIONS
Industrial Process Control
Thermal Control Systems
CPU Monitoring (i.e., Pentium)
Computer Thermal Management Circuits
Fan Control
Handheld/Portable Electronic Equipment
Low Voltage, Resistor Programmable
Thermostatic Switch
AD22105
FUNCTIONAL BLOCK DIAGRAM
R_{PULL–UP 1}
OUT 2
GND ₃
NC ₄
AD22105
200kΩ
SET–
POINT
TEMPERATURE
SENSOR
8 NC
7 ^VS
6 ^RSET
5 ^NC
GENERAL DESCRIPTION
The AD22105 is a solid state thermostatic switch. Requiring
only one external programming resistor, the AD22105 can be set
to switch accurately at any temperature in the wide operating
range of –40°C to +150°C. Using a novel circuit architecture,
the AD22105 asserts an open collector output when the ambient
temperature exceeds the user-programmed setpoint temperature.
The AD22105 has approximately 4°C of hysteresis which prevents
rapid thermal on/off cycling.
The AD22105 is designed to operate on a single power supply
voltage from +2.7 V to +7.0 V facilitating operation in battery
powered applications as well as in industrial control systems.
Because of low power dissipation (230 µW @ 3.3 V), self-
heating errors are minimized and battery life is maximized.
An optional internal 200 kΩ pull-up resistor is included to
facilitate driving light loads such as CMOS inputs.
Alternatively, a low power LED indicator may be driven directly.
+2.7V TO +7.0V
8
7
6
5
AD22105
TOP VIEW
R_SET
OUT
1
2
3
4
Figure 1. Typical Application Circuit
REV. 0
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© Analog Devices, Inc., 1996
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