ADT7461A
+15C
Temperature Monitor
with Series Resistance
Cancellation
The ADT7461A is a dual-channel digital thermometer and
undertemperature/overtemperature alarm, intended for use in PCs and
thermal management systems. It is pin- and register-compatible with the
ADM1032 and ADT7461. A feature of the ADT7461A is series
resistance cancellation, where up to 1.5 kW (typical) of resistance in
series with the temperature monitoring diode can be automatically
cancelled from the temperature result, allowing noise filtering. The
ADT7461A has a configurable ALERT output and an extended,
switchable temperature measurement range.
The ADT7461A can measure the temperature of a remote thermal
diode accurate to
±1°C
and the ambient temperature accurate to
±3°C.
The temperature measurement range defaults to 0°C to +127°C,
compatible with the ADM1032, but it can be switched to a wider
measurement range of
−64°C
to +191°C.
The ADT7461A communicates over a 2-wire serial interface,
compatible with system management bus (SMBus) standards. The
default SMBus address of the ADT7461A is 0x4C. An ADT7461A−2 is
available with an SMBus address of 0x4D. This is useful if more than one
ADT7461A is used on the same SMBus.
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.
Features
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MSOP−8
CASE 846AB
PIN ASSIGNMENT
V
DD
D+
D−
THERM
1
2
3
4
8
7
6
5
SCLK
SDATA
ALERT/THERM2
GND
(Top View)
MARKING DIAGRAM
8
T1x
AYWG
G
1
T1x
A
Y
W
G
= Refer to Ordering Information Table
= Assembly Location
= Year
= Work Week
= Pb-Free Package
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
On-Chip and Remote Temperature Sensor
0.25°C Resolution/1°C Accuracy on Remote Channel
1°C Resolution/1°C Accuracy on Local Channel
Automatically Cancels Up to 1.5 kW (Typ) of Resistance in Series
with Remote Diode to Allow Noise Filtering
Extended, Switchable Temperature Measurement Range
0°C to +127°C (Default) or –64°C to +191°C
Pin- and Register-Compatible with ADM1032 and ADT7461
2-wire SMBus Serial Interface with SMBus Alert Support
Programmable Over/Undertemperature Limits
Offset Registers for System Calibration
Up to Two Overtemperature Fail-Safe THERM Outputs
Small 8-lead MSOP
240
mA
Operating Current, 5
mA
Standby Current
These are Pb-Free Devices*
Desktop and Notebook Computers
Industrial Controllers
Smart Batteries
Automotive
(Note: Microdot may be in either location)
ORDERING INFORMATION
See detailed ordering and shipping information in the package
dimensions section on page 18 of this data sheet.
Applications
•
Embedded Systems
•
Burn-In Applications
•
Instrumentation
* For additional information on our Pb-Free strategy and soldering details, please download the ON Semiconductor Soldering and Mounting
Techniques Reference Manual, SOLDERRM/D.
©
Semiconductor Components Industries, LLC, 2013
April, 2013
−
Rev. 8
1
Publication Order Number:
ADT7461A/D
ADT7461A
ON-CHIP
TEMPERATURE
SENSOR
CONVERSION RATE
REGISTER
LOCAL TEMPERATURE
VALUE REGISTER
A-TO-D
CONVERTER
ADDRESS POINTER
REGISTER
LOCAL TEMPERATURE
LOW-LIMIT REGISTER
LOCAL TEMPERATURE
HIGH-LIMIT REGISTER
DIGITAL MUX
REMOTE TEMPERATURE
LOW-LIMIT REGISTER
REMOTE TEMPERATURE
HIGH-LIMIT REGISTER
LOCAL THERM LIMIT
REGISTER
D+
D−
2
3
ANALOG
MUX
DIGITAL MUX
LIMIT
COMPARATOR
BUSY
RUN/STANDBY
REMOTE TEMPERATURE
VALUE REGISTER
REMOTE OFFSET
REGISTER
EXTERNAL THERM LIMIT
REGISTER
CONFIGURATION
REGISTER
EXTERNAL DIODE OPEN-CIRCUIT
STATUS REGISTER
SMBUS INTERFACE
INTERRUPT
MASKING
6
4
ALERT/
THERM2
THERM
ADT7461A
1
V
DD
5
GND
7
SDATA
8
SCLK
Figure 1. Functional Block Diagram
Table 1. ABSOLUTE MAXIMUM RATINGS
Parameter
Positive Supply Voltage (V
DD
) to GND
D+
D− to GND
SCLK, SDATA, ALERT, THERM
Input Current, SDATA, THERM
Input Current, D−
ESD Rating, All Pins (Human Body Model)
Maximum Junction Temperature (T
J
Max)
Storage Temperature Range
Rating
−0.3,
+3.6
−0.3
to V
DD
+ 0.3
−0.3
to +0.6
−0.3
to +3.6
−1,
+50
±1
1500
150
−65
to +150
Unit
V
V
V
V
mA
mA
V
°C
°C
Stresses exceeding Maximum Ratings may damage the device. Maximum Ratings are stress ratings only. Functional operation above the
Recommended Operating Conditions is not implied. Extended exposure to stresses above the Recommended Operating Conditions may affect
device reliability.
NOTE: This device is ESD sensitive. Use standard ESD precautions when handling.
Table 2. THERMAL CHARACTERISTICS
Package Type
8-Lead MSOP
q
JA
142
q
JC
43.74
Unit
°C/W
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ADT7461A
Table 3. PIN ASSIGNMENT
Pin No.
1
2
3
4
5
6
7
Mnemonic
V
DD
D+
D−
THERM
GND
ALERT/THERM2
SDATA
SCLK
Positive Supply, 3.0 V to 3.6 V.
Positive Connection to Remote Temperature Sensor.
Negative Connection to Remote Temperature Sensor.
Open-Drain Output. Can be used to turn a fan on/off or throttle a CPU clock in the event of an
overtemperature condition. Requires pullup resistor.
Supply Ground Connection.
Open-Drain Logic Output Used as Interrupt or SMBus ALERT. This can also be configured as a
second THERM output. Requires pullup resistor.
Logic Input/Output, SMBus Serial Data. Open-Drain Output. Requires pullup resistor.
Logic Input, SMBus Serial Clock. Requires pullup resistor.
Description
8
Table 4. SMBus TIMING SPECIFICATIONS
(Note 1)
Parameter
f
SCLK
t
LOW
t
HIGH
t
R
t
F
t
SU; STA
t
HD; STA
(Note 2)
t
SU; DAT
(Note 3)
t
SU; STO
(Note 4)
t
BUF
1.
2.
3.
4.
Limit at T
MIN
and T
MAX
400
1.3
0.6
300
300
600
600
100
600
1.3
Unit
kHz max
ms
min
ms
min
ns max
ns max
ns min
ns min
ns min
ns min
ms
min
−
Clock Low Period, between 10% Points
Clock High Period, between 90% Points
Clock/Data Rise Time
Clock/Data Fall Time
Start Condition Setup Time
Start Condition Hold Time
Data Setup Time
Stop Condition Setup Time
Bus Free Time between Stop and Start Conditions
Description
Guaranteed by design, but not production tested.
Time from 10% of SDATA to 90% of SCLK.
Time for 10% or 90% of SDATA to 10% of SCLK.
Time for 90% of SCLK to 10% of SDATA.
t
LOW
SCLK
t
F
t
R
t
HD; STA
t
HD; STA
t
HD; DAT
t
HIGH
t
SU; DAT
t
SU; STA
t
SU; STO
SDATA
t
BUF
STOP START
START
STOP
Figure 2. Serial Bus Timing
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ADT7461A
Table 5. ELECTRICAL CHARACTERISTICS
(T
A
=
−40°C
to +125°C, V
DD
= 3.0 V to 3.6 V, unless otherwise noted.)
Parameter
Power Supply
Supply Voltage, V
DD
Average Operating Supply Current, I
DD
Undervoltage Lockout Threshold
Power-On-Reset Threshold
Temperature-To-Digital Converter
Local Sensor Accuracy
0°C
≤
T
A
≤
+70°C
0°C
≤
T
A
≤
+85°C
−40°C
≤
T
A
≤
+100°C
−
−
−
−
0°C
≤
T
A
≤
+70°C,
−55°C
≤
T
D
(Note 2)
≤
+150°C
0°C
≤
T
A
≤
+85°C,
−55°C
≤
T
D
(Note 2)
≤
+150°C
−40°C
≤
T
A
≤
+100°C,
−55°C
≤
T
D
(Note 2)
≤
+150°C
−
−
−
−
High Level (Note 3)
Middle Level (Note 3)
Low Level (Note 3)
From Stop Bit to Conversion Complete, One-shot
Mode with Averaging Switched On
One-shot Mode with Averaging Off (That Is,
Conversion Rate = 16-, 32-, or 64-conversions per
Second)
Maximum Series Resistance Cancelled
Resistance Split Evenly on Both the D+ and D–
Inputs
−
−
−
−
−
−
−
−
1.0
−
−
−
0.25
220
82
13.5
40
6.0
±1.0
±1.5
±2.5
−
±1.0
±1.5
±2.5
−
−
−
−
52
8.0
°C
0.0625 Conversions/Sec Rate (Note 1)
Standby Mode
V
DD
Input, Disables ADC, Rising Edge
3.0
−
−
−
1.0
3.30
240
5.0
2.55
−
3.6
350
30
−
2.5
V
mA
V
V
Conditions
Min
Typ
Max
Unit
Resolution
Remote Diode Sensor Accuracy
°C
°C
Resolution
Remote Sensor Source Current
°C
mA
Conversion Time
ms
ms
−
1.5
−
kW
Open-Drain Digital Outputs (THERM, ALERT/THERM2)
Output Low Voltage, V
OL
High Level Output Leakage Current, I
OH
SMBus Interface
(Note 3 and 4)
Logic Input High Voltage, V
IH
SCLK, SDATA
Logic Input Low Voltage, V
IL
SCLK, SDATA
Hysteresis
SDA Output Low Voltage, V
OL
Logic Input Current, I
IH
, I
IL
SMBus Input Capacitance, SCLK, SDATA
SMBus Clock Frequency
SMBus Timeout (Note 5)
SCLK Falling Edge to SDATA Valid Time
1.
2.
3.
4.
5.
User Programmable
Master Clocking in Data
3.0 V
≤
V
DD
≤
3.6 V
3.0 V
≤
V
DD
≤
3.6 V
2.1
−
−
−
−1.0
−
−
−
−
−
−
500
−
−
5.0
−
25
−
−
0.8
−
0.4
+1.0
−
400
64
1.0
V
V
mV
mA
mA
pF
kHz
ms
ms
I
OUT
=
−6.0
mA
V
OUT
= V
DD
−
−
−
0.1
0.4
1.0
V
mA
See Table 10 for information on other conversion rates.
Guaranteed by characterization, but not production tested.
Guaranteed by design, but not production tested.
See SMBus Timing Specifications section for more information.
Disabled by default. Detailed procedures to enable it are in the Serial Bus Interface section of the datasheet.
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ADT7461A
TYPICAL PERFORMANCE CHARACTERISTICS
3.5
TEMPERATURE ERROR (°C)
TEMPERATURE ERROR (°C)
3.0
2.5
2.0
1.5
1.0
0.5
0
−0.5
−1.0
−50
0
50
TEMPERATURE (°C)
100
150
DEV 1
DEV 2
DEV 3
DEV 4
DEV 5
DEV 6
DEV 7
DEV 8
DEV 9
DEV 10
DEV 11
DEV 12
DEV 13
DEV 14
DEV 15
DEV 16
MEAN
HIGH 4S
LOW 4S
3.5
3.0
2.5
2.0
1.5
1.0
0.5
0
−0.5
−1.0
−50
0
50
TEMPERATURE (°C)
100
150
DEV 1
DEV 2
DEV 3
DEV 4
DEV 5
DEV 6
DEV 7
DEV 8
DEV 9
DEV 10
DEV 11
DEV 12
DEV 13
DEV 14
DEV 15
DEV 16
HIGH 4S
LOW 4S
Figure 3. Local Temperature Error vs. Temperature
Figure 4. Remote Temperature Error vs. Actual
Temperature
0
10
TEMPERATURE ERROR (°C)
D+ To GND
TEMPERATURE ERROR (°C)
5
0
−5
−10
−15
−20
−25
1
10
LEAKAGE RESISTANCE (MW)
100
D+ To V
CC
−2
−4
−6
−8
−10
−12
−14
−16
−18
0
5
10
DEV 2
DEV 4
15
20
25
DEV 3
CAPACITANCE (nF)
Figure 5. Temperature Error vs. D+/D− Leakage
Resistance
1000
900
800
700
I
DD
(mA)
500
400
300
200
100
0
0.01
0.1
1
10
100
600
DEV 4BC
DEV 3BC
Figure 6. Temperature Error vs. D+/D− Capacitance
DEV 2BC
422
420
418
I
DD
(mA)
416
414
412
410
408
3.0
3.1
3.2
3.3
V
DD
(V)
3.4
3.5
3.6
DEV 3BC
DEV 4BC
DEV 2BC
CONVERSION RATE (Hz)
Figure 7. Operating Supply Current vs.
Conversion Rate
Figure 8. Operating Supply Current vs. Voltage
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