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PDF ADT7408 Data sheet ( Hoja de datos )
| Número de pieza | ADT7408 | |
| Descripción | 12-Bit Digital Temperature Sensor | |
| Fabricantes | Analog Devices | |
| Logotipo |  |
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FEATURES
12-bit temperature-to-digital converter
±2°C accuracy
Operation from −20°C to +125°C
Operation from 3 V to 3.6 V
240 μA typical average supply current
Selectable 1.5°C, 3°C, 6°C hysteresis
SMBus-/I2C®-compatible interface
Dual-purpose event pin: comparator or interrupt
8-lead LFCSP_VD, 3 mm × 3 mm (JEDEC MO-229 VEED-4)
package
Complies with JEDEC standard JC-42.4 memory module
Thermal sensor component specification
APPLICATIONS
Memory module temperature monitoring
Isolated sensors
Environmental control systems
Computer thermal monitoring
Thermal protection
Industrial process control
Power system monitors
GENERAL DESCRIPTION
The ADT7408 is the first digital temperature sensor that complies
with JEDEC standard JC-42.4 for the mobile platform memory
module. The ADT7408 contains a band gap temperature sensor
and a 12-bit ADC to monitor and digitize the temperature to a
resolution of 0.0625°C.
There is an open-drain EVENT# output that is active when the
monitoring temperature exceeds a critical programmable limit or
when the temperature falls above or below an alarm window.
This pin can operate in either comparator or interrupt mode.
There are three slave device address pins that allow up to eight
ADT7408s to be used in a system that monitors temperature of
various components and subsystems.
±2°C Accurate, 12-Bit Digital
Temperature Sensor
ADT7408
FUNCTIONAL BLOCK DIAGRAM
DECIMATOR
TEMPERATURE
SENSOR
VDD
8
12- / 10-Bit
LPF
1-BIT
+
REFERENCE
CLK
AND TIMING
GENERATION
–
∑-∆ 1-BIT
DAC
ADDRESS
POINTER
REGISTER
ADT7408
A0 1
A1 2
A2 3
MANUFACTURER’S
ID REGISTER
FACTORY
RESERVED
REGISTER
SMBus/I²C INTERFACE
4
Vss
Figure 1.
DIGITAL COMPARATOR
– 7 EVENT#
+
CAPABILITY
REGISTER
CONFIGURATION
REGISTER
ALARM TEMP
UPPER
BOUNDARY TRIP
REGISTER
ALARM TEMP
LOWER
BOUNDARY TRIP
REGISTER
CRITICAL TEMP
REGISTER
TEMPERATURE
REGISTER
5 SDA
6 SCL
The ADT7408 is specified for operation at supply voltages from
3.0 V to 3.6 V. Operating at 3.3 V, the average supply current is
less than 240 μA typical. The ADT7408 offers a shutdown mode
that powers down the device and gives a shutdown current of 3 μA
typical. The ADT7408 is rated for operation over the −20°C to
+125°C temperature range. The ADT7408 is available in a lead-
free, 8-lead LFCSP_VD, 3 mm × 3 mm (JEDEC MO-229 VEED-4)
package.
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
©2006 Analog Devices, Inc. All rights reserved.
1 page  
ABSOLUTE MAXIMUM RATINGS
Table 3.
Parameter
Rating
VDD to VSS
SDA Input Voltage to VSS
SDA Output Voltage to VSS
SCL Input Voltage to VSS
EVENT# Output Voltage to VSS
Operating Temperature Range
Storage Temperature Range
Maximum Junction Temperature, TJMAX
Thermal Resistance1
θJA, Junction-to-Ambient (Still Air)
IR Reflow Soldering Profile
–0.3 V to +7 V
–0.3 V to VDD + 0.3 V
–0.3 V to VDD + 0.3 V
–0.3 V to VDD + 0.3 V
–0.3 V to VDD + 0.3 V
–55°C to +150°C
–65°C to +160°C
150°C
85oC/W
Refer to Figure 3
1 Power Dissipation PMAX = (TJMAX − TA)/θJA, where TA is the ambient
temperature. Thermal resistance value relates to the package being used on
a standard 2-layer PCB, which gives a worst-case θJA. Some documents may
publish junction-to-case thermal resistance θJC, but it refers to a component
that is mounted on an ideal heat sink. As a result, junction-to-ambient
thermal resistance is more practical for air-cooled, PCB-mounted
components.
ADT7408
Stresses above those listed under Absolute Maximum Ratings
may cause permanent damage to the device. This is a stress
rating only; functional operation of the device at these or any
other conditions above those indicated in the operational
section of this specification is not implied. Exposure to absolute
maximum rating conditions for extended periods may affect
device reliability.
RAMP UP
3°C/SECOND MAX
217°C
60 – 150 SECONDS
260 – 5/+0°C
150°C – 200°C
RAMP DOWN
6°C/SECOND
MAX.
TIME (Seconds)
60 – 180 SECONDS
480 SECONDS MAX.
20 – 40 SECONDS
Figure 3. LFCSP Pb-Free Reflow Profile Based on JEDEC J-STD-20C
ESD CAUTION
ESD (electrostatic discharge) sensitive device. Electrostatic charges as high as 4000 V readily accumulate on
the human body and test equipment and can discharge without detection. Although this product features
proprietary ESD protection circuitry, permanent damage may occur on devices subjected to high energy
electrostatic discharges. Therefore, proper ESD precautions are recommended to avoid performance degrada-
tion or loss of functionality.
Rev. 0 | Page 5 of 24
5 Page 
ADT7408
CONFIGURATION REGISTER (READ/WRITE)
This 16-bit read/write register stores various configuration modes for the ADT7408, as shown in Table 8 and the following bit map.
Note that RFU means reserved for future use.
MSB
D15 D14 D13 D12 D11 D10 D9 D8 D7
D6
RFU RFU RFU RFU RFU Hysteresis Shut- Critical Alarm
down lock bit lock bit
mode
D5
Clear
event
D4
Event
output
status
D3
Event
output
control
D2
Critical
event
only
D1
Event
polarity
LSB
D0
Event
mode
Table 8. Configuration Mode Description
Bit Description
D0 Event mode
0: Comparator output mode (default)
1: Interrupt mode
When either lock bit (D6 and D7) is set, this bit cannot be altered until unlocked.
D1 Event polarity
0: Active low (default)
1: Active high
When either lock bit (D6 and D7) is set, this bit cannot be altered until unlocked.
D2 Critical event only
0: Event output on alarm or critical temperature event (default)
1: Event only if temperature is above the value in the critical temperature trip register
When either lock bit (D6 and D7) is set, this bit cannot be altered until unlocked.
D3 Event output control
0: Event output disabled (default)
1: Event output enabled
When either lock bit (D6 and D7) is set, this bit cannot be altered until unlocked.
D4 Event output status (read only)
0: Event output condition is not being asserted by this device
1: Event output pin is being asserted by this device due to alarm window or critical trip condition
The actual cause of an event can be determined from the read of the temperature value register. Interrupt events can be cleared
by writing to the clear event bit. Writing to this bit has no effect on the output status because it is a read function only.
D5 Clear event (write only)
0: No effect
1: Clears an active event in interrupt mode
Writing to this register has no effect in comparator mode. When read, this bit always returns 0. Once the DUT temperature
is greater than the critical temperature, an event cannot be cleared (see Figure 12).
D6 Alarm window lock bit
0: Alarm trips are not locked and can be altered (default)
1: Alarm trip register settings cannot be altered
This bit is initially cleared. When set, this bit returns a 1 and remains locked until cleared by internal power on reset. These bits
can be written with a single write and do not require double writes.
D7 Critical trip lock bit
0: Critical trip is not locked and can be altered (default)
1: Critical trip register settings cannot be altered
This bit is initially cleared. When set, this bit returns a 1 and remains locked until cleared by internal power on reset. These bits
can be written with a single write and do not require double writes.
D8 Shutdown mode
0: TS enabled (default)
1: TS shut down
When shut down, the thermal sensing device and ADC are disabled to save power. No events are generated. When either lock bit
is set, this bit cannot be set until unlocked. However, it can be cleared at any time.
Rev. 0 | Page 11 of 24
11 Page | ||
| Páginas | Total 24 Páginas | |
| PDF Descargar | [ Datasheet ADT7408.PDF ] | |
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