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ADT7461AR-REEL7

P1-P3P4-P6P7-P9P10-P12P13-P15P16-P18P19-P21P22-P23
±1°C Temperature Monitor with
Series Resistance Cancellation
ADT7461
©2007 SCILLC. All rights reserved. Publication Order Number:
December 2007 – Rev. 3 ADT7461/D
FEATURES
On-chip and remote temperature sensor
0.25°C resolution/1°C accuracy on remote channel
1°C resolution/3°C accuracy on local channel
Automatically cancels up to 3 kΩ (typ) of resistance in series
with remote diode to allow noise filtering
Extended, switchable temperature measurement range
0°C to +127°C (default) or –55°C to +150°C
Pin- and register-compatible with the ADM1032
2-wire SMBus serial interface with SMBus alert support
Two SMBus address versions available:
ADT7461 SMBus address is 0x4C
ADT7461-2 SMBus address is 0x4D
Programmable over/under temperature limits
Offset registers for system calibration
Up to two over temperature fail-safe
THERM
outputs
Small 8-lead SOIC or8-lead MSOP packages
170 μA operating current, 5.5 μA standby current
APPLICATIONS
Desktop and notebook computers
Industrial controllers
Smart batteries
Embedded systems
Instrumentation
GENERAL DESCRIPTION
The ADT7461
1
is a dual-channel digital thermometer and
under/over temperature alarm intended for use in PCs and
thermal management systems. It is pin- and register-compatible
with the ADM1032. The ADT7461 has three additional
features: series resistance cancellation (where up to 3 kΩ
(typical) of resistance in series with the temperature monitoring
diode may be automatically cancelled from the temperature
result, allowing noise filtering); configurable
ALERT
output;
and an extended, switchable temperature measurement range.
The ADT7461 can accurately measure the temperature of a
remote thermal diode to ±1°C and the ambient temperature to
±3°C. The temperature measurement range defaults to 0°C to
+127°C, compatible with the ADM1032, but can be switched to
a wider measurement range of −55°C to +150°C. The ADT7461
communicates over a 2-wire serial interface compatible with
system management bus (SMBus) standards. An
ALERT
output
signals when the on-chip or remote temperature is out of range.
The
THERM
output is a comparator output that allows on/off
control of a cooling fan. The
ALERT
output can be reconfigured
as a second
THERM
output, if required.
The SMBus address of the ADT7461 is 0x4C. An ADT7461-2
is also available, which uses SMBus Address 0x4D.
1
Protected by U.S. Patents 5,195,827; 5,867,012; 5,982,221; 6,097,239;
6,133,753; 6,169,442; other patents pending.
04110-0-012
DIGITAL MUX
DIGITAL MUX
SCLKSDATAGNDV
DD
6
4
ADDRESS POINTER
REGISTER
LOCAL TEMPERATURE
LOW LIMIT REGISTER
LOCAL TEMPERATURE
HIGH LIMIT REGISTER
REMOTE TEMPERATURE
LOW LIMIT REGISTER
REMOTE TEMPERATURE
HIGH LIMIT REGISTER
LIMIT
COMPARATOR
LOCAL TEMPERATURE
VALUE REGISTER
REMOTE TEMPERATURE
VALUE REGISTER
ADC
ANALOG
MUX
ON-CHIP
TEMPERATURE
SENSOR
RUN/STANDBYBUSY
REMOTE OFFSET
REGISTER
EXTERNAL DIODE OPEN CIRCUIT
ADT7461
STATUS REGISTER
SMBus INTERFACE
LOCAL THERM LIMIT
REGISTER
EXTERNAL THERM LIMIT
REGISTER
CONFIGURATION
REGISTER
INTERRUPT
MASKING
751 8
THERM ALERT/
THERM2
D+
D–
SRC
BLOCK
2
3
CONVERSION RATE
REGISTER
Figure 1. Functional Block Diagram
ADT7461
Rev. 3 | Page 2 of 23 | www.onsemi.com
TABLE OF CONTENTS
Specifications .....................................................................................3
SMBus Timing Specifications..........................................................4
Absolute Maximum Ratings ............................................................5
Thermal Characteristics...............................................................5
ESD Caution ..................................................................................5
Pin Configuration and Function Descriptions .............................6
Typical Performance Characteristics..............................................7
Functional Description.....................................................................9
Series Resistance Cancellation ....................................................9
Temperature Measurement Method...........................................9
Temperature Measurement Results ..........................................10
Temperature Measurement Range............................................10
Temperature Data Format..........................................................10
ADT7461 Registers.....................................................................11
Serial Bus Interface .....................................................................15
Addressing the Device................................................................15
ALERT
Output ............................................................................17
Low Power Standby Mode .........................................................17
Sensor Fault Detection...............................................................17
The ADT7461 Interrupt System ...............................................17
Application Information ............................................................19
Thermal Inertia and Self-Heating ............................................19
Layout Considerations ...............................................................20
Application Circuit .....................................................................21
Outline Dimensions........................................................................22
Ordering Guide ...........................................................................23
REVISION HISTORY
12/07- Rev 1: Conversion to ON Semiconductor
7/05—Rev. A to Rev. B
Changes to Features Section .............................................................1
Changes to Applications Section......................................................1
Changes to General Description Section........................................1
Changes to Addressing the Device Section ...................................14
Updated Outline Dimensions..........................................................21
Changes to the Ordering Guide ......................................................22
10/04—Rev. 0 to Rev. A
Change to SMBus Specifications.....................................................4
Changes to Figure 6 and Figure 10 .................................................7
Added Figure 9 and Figure 13 .........................................................7
Changes to Temperature Measurement Section .........................10
Changes to Figure 19 and Figure 25 .............................................16
Changes to Serial Bus Interface Section.......................................23
10/03—Revision 0: Initial Version
ADT7461
Rev. 3 | Page 3 of 23 | www.onsemi.com
SPECIFICATIONS
T
A
= −40°C to +120°C, V
DD
= 3 V to 5.5 V, unless otherwise noted.
Table 1.
Parameter Min Typ Max Unit Test Conditions
POWER SUPPLY
Supply Voltage, V
DD
3.0 3.30 5.5 V
Average Operating Supply Current, I
DD
170 215 μA 0.0625 conversions/sec rate
1
5.5 10 μA Standby mode, –40°C ≤ T
A
≤ +85°C
5.5 20 μA Standby mode, +85°C ≤ T
A
≤ +120°C
Undervoltage Lockout Threshold 2.2 2.55 2.8 V V
DD
input, disables ADC, rising edge
Power-On-Reset Threshold 1 2.5 V
TEMPERATURE-TO-DIGITAL CONVERTER
Local Sensor Accuracy ±1 ±3 °C −40°C ≤ T
A
≤ +100°C, 3 V ≤ V
DD
≤ 3.6 V
Resolution 1 °C
Remote Diode Sensor Accuracy ±1 °C +60°C ≤ T
A
≤ +100°C, −55°C ≤ T
D
2
≤ +150°C, 3 V ≤ V
DD
≤ 3.6 V
±3 °C −40°C ≤ T
A
≤ +120°C, −55°C ≤ T
D
2
≤ +150°C, 3 V ≤ V
DD
≤ 5.5 V
Resolution 0.25 °C
Remote Sensor Source Current 96 μA High level
3
36 μA Middle level
3
6 μA Low level
3
Conversion Time 32.13 114.6 ms From stop bit to conversion complete (both channels),
one-shot mode with averaging switched on
3.2 12.56 ms One-shot mode with averaging off (that is,
conversion rate = 16, 32, or 64 conversions per second)
Maximum Series Resistance Cancelled 3 kΩ Resistance split evenly on both the D+ and D– inputs
OPEN-DRAIN DIGITAL OUTPUTS
(
THERM
,
ALERT
/
THERM2
)
Output Low Voltage, V
OL
0.4 V I
OUT
= −6.0 mA
3
High Level Output Leakage Current, I
OH
0.1 1 μA V
OUT
= V
DD
3
ALERT
Output Low Sink Current
1 mA
ALERT
forced to 0.4 V
SMBus INTERFACE
3,
4
Logic Input High Voltage, V
IH
2.1 V 3 V ≤ V
DD
≤ 3.6 V
SCLK, SDATA
Logic Input Low Voltage, V
IL
0.8 V 3 V ≤ V
DD
≤ 3.6 V
SCLK, SDATA
Hysteresis 500 mV
SMBus Output Low Sink Current 6 mA SDATA forced to 0.6 V
Logic Input Current, I
IH
, I
IL
−1 +1 μA
SMBus Input Capacitance, SCLK, SDATA 5 pF
SMBus Clock Frequency 400 kHz
SMBus Timeout
5
25 64 ms User programmable
SCLK Falling Edge to SDATA Valid Time 1 μs Master clocking in data
1
See Table 8 for information on other conversion rates.
2
Guaranteed by characterization, but not production tested.
3
Guaranteed by design, but not production tested.
4
See the SMBUS Timing Specifications section for more information.
5
Disabled by default; see the Serial Bus Interface section for details on enabling it.
P1-P3P4-P6P7-P9P10-P12P13-P15P16-P18P19-P21P22-P23

ADT7461AR-REEL7

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Buy ADT7461AR-REEL7
Manufacturer:
ON Semiconductor
Description:
SENSOR DIGITAL -40C-120C 8SOIC
Lifecycle:
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