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PDF ADT45 Data sheet ( Hoja de datos )
| Número de pieza | ADT45 | |
| Descripción | (ADT45 / ADT50) Temperature Sensors | |
| Fabricantes | Analog Devices | |
| Logotipo |  |
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Hay una vista previa y un enlace de descarga de ADT45 (archivo pdf) en la parte inferior de esta página. Total 12 Páginas | ||
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a
FEATURES
Low Voltage Operation (2.7 V to 12 V)
Calibrated Directly in ؇C
10 mV/؇C Scale Factor
؎2؇C Accuracy Over Temperature (typ)
؎0.5؇C Linearity (typ)
Stable with Large Capacitive Loads
Specified –40؇C to +125؇C, Operation to +150؇C
Less than 60 mA Quiescent Current
Low Self-Heating
APPLICATIONS
Environmental Control Systems
Thermal Protection
Industrial Process Control
Fire Alarms
Power System Monitors
CPU Thermal Management
GENERAL DESCRIPTION
The ADT45 and ADT50 are low voltage, precision centigrade
temperature sensors. They provide a voltage output that is lin-
early proportional to the Celsius (Centigrade) temperature. The
ADT45/ADT50 do not require any external calibration to pro-
vide typical accuracies of ± 1°C at +25°C and ± 2°C over the
–40°C to +125°C temperature range. The low output imped-
ance of the ADT45/ADT50, linear output and precise calibra-
tion simplify interfacing to temperature control circuitry and
A/D converters. All three devices are intended for single supply
operation from 2.7 V to 12 V maximum. Supply current runs
well below 60 µA providing very low self-heating—less than
0.1°C in still air. The ADT45/ADT50 are functionally and pin
compatible with LM45/LM50 respectively. The ADT45 pro-
vides a 250 mV output at +25°C and reads temperature from
0°C to +100°C. The ADT50 is specified from –40°C to +125°C,
provides a 750 mV output at +25°C and operates to +125°C
from a single 2.7 V supply. Both the ADT45 and ADT50 have
an output scale factor of +10 mV/°C. Operation extends to
+150°C with reduced accuracy for all devices when operating
from a 12 V supply.
The ADT45/ADT50 are available in the low cost 3-lead
SOT-23 surface mount package.
Low Voltage SOT-23
Temperature Sensors
ADT45/ADT50
FUNCTIONAL BLOCK DIAGRAM
+Vs (2.7V to 12V)
ADT45
ADT50
VOUT
PACKAGE TYPES AVAILABLE
SOT-23
+VS 1
TOP VIEW 3 GND
(Not to Scale)
VOUT 2
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.
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., 1997
Free Datasheet http://www.Datasheet4U.com
1 page  
60
a. V؉ = 5V
b. V؉ = 3V
50
NO LOAD
40
a
30
20
b
10
؊50
؊25
0 25 50 75
TEMPERATURE – ؇C
100 125
Figure 8. Supply Current vs. Temperature
50
TA = ؉25؇C, NO LOAD
40
30
20
10
0
01
23
45
67
8
SUPPLY VOLTAGE – Volts
Figure 9. Supply Current vs. Supply Voltage
400
300
= V؉ PIN HIGH-TO-LOW ( 3V TO 0V )
200
= V؉ PIN LOW-TO-HIGH ( 0V TO 3V )
VOUT SETTLES WITHIN ±1؇C
100
0
؊50
؊25
0 25 50 75
TEMPERATURE – ؇C
100 125
Figure 10. VOUT Response Time for V+ Power-Up/Power-
Down vs. Temperature
ADT45/ADT50
1.0
TA = 25؇C
V؉ SIGNAL =
0.8
0.6
0.4
0.2
0
؊50 0
50 100 150 200 250 300 350 400 450
TIME – s
Figure 11. VOUT Response Time to Power-On vs. Time
120
100
80
60
SOT-23 SOLDERED TO 0.338" ؋ 0.307" Cu PCB
V؉ = 2.7V TO 5V, NO LOAD
40
20
0
0 50 100 150 200 250 300
TIME – Sec
Figure 12. Thermal Response Time in Still Air
35
30
V؉ = 2.7V TO 5V, NO LOAD
25
SOT-23 SOLDERED TO 0.338" ؋ 0.307" Cu PCB
20
15
10
5
0
0 100 200 300 400 500 600 700
AIR VELOCITY – FPM
Figure 13. Thermal Response Time in Forced Air
REV. 0
–5–
Free Datasheet http://www.Datasheet4U.com
5 Page 
10F/0.1F
+5V
0.1F
VS
VOUT
ADT45/50
GND
CT
AD654
RPU
5k⍀
fOUT
R1
RT
+5V
P1
NB: ATTA (min), fOUT = 0Hz
P2
100k⍀
ROFF1
470⍀
fOUT
OFFSET
ROFF2
10⍀
ADT45/ADT50
Driving Long Cables or Heavy Capacitive Loads
Although the ADT45/ADT50 temperature sensors are capable
of driving capacitive loads up to 10,000 pF without oscillation,
output voltage transient response times can be improved with
the use of a small resistor in series with the output of the tem-
perature sensor, as shown in Figure 26. As an added benefit,
this resistor forms a low-pass filter with the cable’s capacitance,
which helps to reduce bandwidth noise. Furthermore, since the
temperature sensor is likely to be used in environments where
the ambient noise level can be very high, this resistor helps to
prevent rectification by the devices of the high frequency noise.
The combination of this resistor and the supply bypass capacitor
offers the best protection.
+VS
SENSOR
ADT45
ADT50
RT(R1+P1)
11.8k⍀ + 500⍀
16.2k⍀ + 500⍀
CT
1.7nF
1.8nF
Figure 24. A Temperature-to-Frequency Converter
An offset trim network (fOUT OFFSET) is included with this
circuit to set fOUT at 0 Hz when the temperature sensor’s mini-
mum output voltage is reached. Potentiometer P1 is required to
calibrate the absolute accuracy of the AD654. The table in the
figure illustrates the circuit element values for each of the three
sensors. The nominal offset voltage required for 0 Hz output
from the ADT45 is 50 mV; for the ADT50, the offset voltage
required is 100 mV. In all cases for the circuit values shown, the
output frequency transfer characteristic of the circuit was set at
50 Hz/°C. At the receiving end, a frequency-to-voltage converter
(FVC) can be used to convert the frequency back to a dc voltage
for further processing. One such FVC is the AD650.
For complete information on the AD650 and AD654, please
consult the individual data sheets for those devices.
0.1F
VOUT 750⍀
ADT45/50
LONG CABLE OR
HEAVY CAPACTIVE LOADS
GND
Figure 26. Driving Long Cables or Heavy Capacitive Loads
Commentary on Long-Term Stability
The concept of long-term stability has been used for many years
to describe by what amount an IC’s parameter would shift dur-
ing its lifetime. This is a concept that has been typically applied
to both voltage references and monolithic temperature sensors.
Unfortunately, integrated circuits cannot be evaluated at room
temperature (+25°C) for 10 years or so to determine this shift.
As a result, manufacturers very typically perform accelerated
lifetime testing of integrated circuits by operating ICs at
elevated temperatures (between +125°C and +150°C) over a
shorter period of time (typically, between 500 and 1000 hours).
R2*
P2*
4mA
VS ADJUST
ADT45/50
GND
R1*
VOUT
P1*
20mA
ADJUST
R3*
D1
+3V
REF193
+
1F
OP193
R3*
R6
100k⍀
R5
100k⍀
Q1
2N1711
*SEE TEXT
FOR VALUES
D1: HP5082–2810
R7
100⍀
IL
Figure 25. A Temperature to 4 mA-to-20 mA Loop Transmitter
VLOOP
+9V TO +18V
VOUT
RL
250⍀
REV. 0
–11–
Free Datasheet http://www.Datasheet4U.com
11 Page | ||
| Páginas | Total 12 Páginas | |
| PDF Descargar | [ Datasheet ADT45.PDF ] | |
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