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PDF ADT6401 Data sheet ( Hoja de datos )
| Número de pieza | ADT6401 | |
| Descripción | (ADT6401 / ADT6402) Pin-Selectable Temperature Switches | |
| Fabricantes | Analog Devices | |
| Logotipo |  |
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Low Cost, 2.7 V to 5.5 V, Pin-Selectable
Temperature Switches in SOT-23
ADT6401/ADT6402
FEATURES
±0.5°C (typical) threshold accuracy
Pin-selectable trip points from
−45°C to +5°C in 10°C increments (undertemperature)
45°C to 115°C in 10°C increments (overtemperature)
Maximum operating temperature of 125°C
Open-drain output (ADT6401)
Push-pull output (ADT6402)
Pin-selectable hysteresis of 2°C and 10°C
Supply current of 30 μA (typical)
Space-saving, 6-lead SOT-23 package
APPLICATIONS
Medical equipment
Automotive
Cell phones
Hard disk drives
Personal computers
Electronic test equipment
Domestic appliances
Process control
GENERAL DESCRIPTION
The ADT6401/ADT6402 are trip point temperature switches
available in a 6-lead SOT-23 package. Each part contains an
internal band gap temperature sensor for local temperature
sensing. When the temperature crosses the trip point setting,
the logic output is activated. The ADT6401 logic output is
active low and open-drain. The ADT6402 logic output is active
high and push-pull. The temperature is digitized to a resolution
of 0.125°C (11-bit). The pin-selectable trip point settings are
10°C apart starting from −45°C to +5°C for undertemperature
switching, and from 45°C to 115°C for overtemperature
switching.
These devices typically consume 30 μA of supply current. Hystere-
sis is pin selectable at 2°C and 10°C. The temperature switch is
specified to operate over the supply range of 2.7 V to 5.5 V.
When the ADT6401/ADT6402 are used for monitoring tempera-
tures from 45°C to 115°C, the logic output pin becomes active
when the temperature goes higher than the selected trip point
temperature.
FUNCTIONAL BLOCK DIAGRAM
VCC GND
45
Σ-Δ
TEMPERATURE-TO-
DIGITAL CONVERTER
ADT6401
COMPARATOR
6 TOVER/TUNDER
S2 1
S1 2
S0 3
TRIP POINT AND
HYSTERESIS
DECODING
2ºC/10ºC
Figure 1.
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When the ADT6401/ADT6402 are used for monitoring tempera-
tures from −45°C to +5°C, the logic output pin becomes active
when the temperature goes lower than the selected trip point
temperature.
PRODUCT HIGHLIGHTS
1. Σ-Δ based temperature measurement gives high accuracy
and noise immunity.
2. Wide operating temperature range from −55°C to +125°C.
3. ±0.5°C typical accuracy from −45°C to +115°C.
4. Pin-selectable threshold settings from −45°C to +115°C in
10°C increments.
5. Supply voltage is 2.7 V to 5.5 V.
6. Supply current of 30 μA.
7. Space-saving, 6-lead SOT-23 package.
8. Pin-selectable temperature hysteresis of 2°C or 10°C.
9. Temperature resolution of 0.125°C.
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 that may result from its use. Specifications subject to change without notice. No
license is granted by implication or otherwise under any patent or patent rights of Analog Devices.
Trademarksandregisteredtrademarksarethepropertyoftheirrespectiveowners.
One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.
Tel: 781.329.4700
www.analog.com
Fax: 781.461.3113
©2008 Analog Devices, Inc. All rights reserved.
Datasheet pdf - http://www.DataSheet4U.co.kr/
1 page  
PIN CONFIGURATIONS AND FUNCTION DESCRIPTIONS
ADT6401/ADT6402
S2 1
S1 2
ADT6401
TOP VIEW
(Not to Scale)
6 TOVER/TUNDER
5 GND
S0 3
4 VCC
Figure 3. ADT6401 Pin Configuration
S2 1
S1 2
ADT6402
TOP VIEW
(Not to Scale)
6 TOVER/TUNDER
5 GND
S0 3
4 VCC
Figure 4. ADT6402 Pin Configuration
Table 3. Pin Function Descriptions
Pin Number
ADT6401
ADT6402
Mnemonic
11
S2
22
S1
33
S0
44
VCC
55
GND
6 N/A TOVER/TUNDER
N/A 6
TOVER/TUNDER
Description
Select Pin for Trip Point and Hysteresis Values.
Select Pin for Trip Point and Hysteresis Values.
Select Pin for Trip Point and Hysteresis Values.
Supply Input (2.7 V to 5.5 V).
Ground.
Open-Drain, Active Low Output. Pull-up resistor required. This pin goes low when
the temperature of the part exceeds the pin-selectable threshold.
Push-Pull, Active High Output. This pin goes high when the temperature of the part
exceeds the pin-selectable threshold.
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Rev. 0 | Page 5 of 12
Datasheet pdf - http://www.DataSheet4U.co.kr/
5 Page 
ADT6401/ADT6402
APPLICATIONS INFORMATION
THERMAL RESPONSE TIME
The time required for a temperature sensor to settle to a specified
accuracy is a function of the thermal mass of the sensor and
the thermal conductivity between the sensor and the object
being sensed. Thermal mass is often considered equivalent to
capacitance. Thermal conductivity is commonly specified using
the symbol Q and can be thought of as thermal resistance. It is
commonly specified in units of degrees per watt of power
transferred across the thermal joint. Thus, the time required for
the ADT6401/ADT6402 to settle to the desired accuracy is
dependent on the characteristics of the SOT-23 package, the
thermal contact established in that particular application, and
the equivalent power of the heat source. In most applications,
the settling time is best determined empirically.
SELF-HEATING EFFECTS
The temperature measurement accuracy of the ADT6401/
ADT6402 can be degraded in some applications due to self-
heating. Errors can be introduced from the quiescent dissipation
and power dissipated when converting. The magnitude of these
temperature errors depends on the thermal conductivity of the
ADT6401/ADT6402 package, the mounting technique, and the
effects of airflow. At 25°C, static dissipation in the ADT6401/
ADT6402 is typically 99 μW operating at 3.3 V. In the 6-lead
SOT-23 package mounted in free air, this accounts for a tempera-
ture increase due to self-heating of
ΔT = PDISS × θJA = 99 μW × 240°C/W = 0.024°C
It is recommended that current dissipated through the device be
kept to a minimum because it has a proportional effect on the
temperature error.
SUPPLY DECOUPLING
The ADT6401/ADT6402 should be decoupled with a 0.1 μF
ceramic capacitor between VCC and GND. This is particularly
important when the ADT6401/ADT6402 are mounted remotely
from the power supply. Precision analog products such as the
ADT6401/ADT6402 require well-filtered power sources.
Because the ADT6401/ADT6402 operate from a single supply,
it may seem convenient to tap into the digital logic power supply.
Unfortunately, the logic supply is often a switch-mode design,
which generates noise in the 20 kHz to 1 MHz range. In addition,
fast logic gates can generate glitches that are hundreds of millivolts
in amplitude due to wiring resistance and inductance.
If possible, the ADT6401/ADT6402 should be powered directly
from the system power supply. This arrangement, shown in
Figure 22, isolates the analog section from the logic-switching
transients. Even if a separate power supply trace is not available,
generous supply bypassing reduces supply line induced errors.
Local supply bypassing consisting of a 0.1 μF ceramic capacitor
is advisable to achieve the temperature accuracy specifications.
This decoupling capacitor must be placed as close as possible to
the ADT6401/ADT6402 VCC pin.
TTL/CMOS
LOGIC
CIRCUITS
0.1µF
ADT6401/
ADT6402
POWER
SUPPLY
Figure 22. Separate Traces Used to Reduce Power Supply Noise
TEMPERATURE MONITORING
The ADT6401/ADT6402 are ideal for monitoring the thermal
environment within electronic equipment. For example, the
surface-mount package accurately reflects the exact thermal
conditions that affect nearby integrated circuits.
The ADT6401/ADT6402 measure and convert the temperature
www.DataSheet.net/ at the surface of its own semiconductor chip. When the ADT6401/
ADT6402 are used to measure the temperature of a nearby heat
source, the thermal impedance between the heat source and the
ADT6401/ADT6402 must be as low as possible.
As much as 60% of the heat transferred from the heat source to
the thermal sensor on the ADT6401/ADT6402 die is discharged
via the copper tracks, package pins, and bond pads. Of the pins
on the ADT6401/ADT6402, the GND pin transfers most of the
heat. Therefore, to monitor the temperature of a heat source, it is
recommended that the thermal resistance between the ADT6401/
ADT6402 GND pin and the GND of the heat source be reduced
as much as possible.
For example, the unique properties of the ADT6401/ADT6402
can be used to monitor a high power dissipation microproces-
sor. The ADT6401/ADT6402 device in its SOT-23 package is
mounted directly beneath the pin grid array (PGA) package of
the microprocessor. The ADT6401/ADT6402 require no external
characterization.
Rev. 0 | Page 11 of 12
Datasheet pdf - http://www.DataSheet4U.co.kr/
11 Page | ||
| Páginas | Total 12 Páginas | |
| PDF Descargar | [ Datasheet ADT6401.PDF ] | |
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