aSC7511
L
OW
-V
OLTAGE
2-W
IRE
D
IGITAL
T
EMPERATURE
S
ENSOR
W
ITH
T
HERMAL
A
LARM
Fully Released Specification
Product Description
The aSC7511 is a high-precision CMOS temperature
sensor with SMBus compatible serial digital interface,
intended for use in PC thermal management applications.
The aSC7511 can measure temperature of a remote
thermal diode to an accuracy of ±1°C. Internal temperature
can be measured to ±3°C.
Communication of configuration, temperature and alarm
status takes place over the PC standard System
Management Bus (SMBus).
The aSC7511 features thermal alarm functions with a user-
programmable trip and turn-off temperatures. The
THERM
output comparator can be set to control a fan while
P
RODUCT
S
PECIFICATION
Pin Configuration
SOP-8 and MSOP-8
V
DD
D+
D-
1
8
SCL
SDA
ALERT
/
2
7
aSC7511
3
6
THERM2
THERM
4
5
GND
ALERT
signals that the remote or local temperature is
outside of a range of temperatures.
ALERT
pin may be
optionally configured as a second
THERM
output,
THERM2
, controlling a second fan.
The aSC7511 is available in SOP-8 and MSOP-8 surface
mount packages.
Application Diagram
3.3V
1
2
3
Features
•
•
•
•
•
•
•
•
•
Local and remote temperature sensors
0.25°C resolution, ±1°C accuracy on remote diode
1°C resolution, ±3°C accuracy on local sensor
Extended temperature measurement range 0°C to
+127°C (default) or –55°C to +150°C
2-wire SMBus serial interface with SMBus alert
Programmable over / under temperature limits
Offset registers for system calibration
One or two over-temperature fail-safe
THERM
outputs
8-lead, Pb-free, SOIC (SOP) or MSOP package
CPU
aSC7511
SMBus
Interface
SDA
SCL
7
8
4
THERM
ALERT
/
THERM2
6
Applications
Desktop Computers – Motherboards and Graphics Cards
Laptop Computers
Ordering Information
Part Number
aSC7511D8
aSC7511M8
Package
8-Lead SOP
8-Lead MSOP
Temperature Range
and Operating Voltage
-40°C to +125°C, 3.3V
-40°C to +125°C, 3.3V
Marking
aSC7511
Ayww
7511
Ayww
How Supplied
2500 units Tape & Reel
2500 units Tape & Reel
Ayww – Assembly site, year, workweek
© Andigilog, Inc. 2006
-1-
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August 2006 - 70A04010
aSC7511
Absolute Maximum Ratings
1
Parameter
Supply Voltage, V
D D
, 3.3V nom.
Output Voltage
D+
D- to GND
SDA, SCL,
ALERT
,
THERM
I/O Current, SCL, SDA,
Rating
-0.3, +3.6V
V
D D
+ 0.5V
-0.3V to V
D D
+
0.5V
-0.3V to 0.6V
-0.3V to 5.5V
-1mA
±1mA
10mA
-60°C to +150°C
260°C
300°C
> 2000 V
> 250 V
> 2000 V
Notes:
1. Absolute maximum ratings are limits beyond which
operation may cause permanent damage to the device.
These are stress ratings only; functional operation at or
above these limits is not implied.
2. Human Body Model: 100pF capacitor discharged through
a 1.5kΩ resistor into each pin. Machine Model: 200pF
capacitor discharged directly into each pin. Charged
Device Model is per JESD22-C101C.
3. These specifications are guaranteed only for the test
conditions listed.
4. Accuracy (expressed in °C) = Difference between the
aSC7511 reported output temperature and the
temperature being measured.
5. Guaranteed by characterization but not production tested.
6. The accuracy of the aSC7511 is guaranteed when using
the thermal diode of a processor or any thermal diode with
a non-ideality of 1.008 and internal series resistance of
3.52Ω. When using a 2N3904 type transistor as a thermal
diode the error band will be typically shifted depending on
transistor characteristics.
7. The aSC7511 can be read at any time without interrupting
the temperature conversion process.
ALERT
,
THERM
Input Current, D-
Continuous Current,
any other terminal
Storage Temperature Range
IR Reflow Peak Temperature
Lead Soldering
Temperature (10 sec.)
ESD
2
Human Body Model
Machine Model
Charged Device Model
Electrical Characteristics
3
(-40°C
≤
T
A
≤
+125°C, V
D D
= 3 . 3 V unless otherwise noted. Specifications subject to change without notice)
Parameter
Supply Voltage
Operating Supply Current
Local Sensor Accuracy
4
Conditions
V
DD
0.0625 Conversions-per-second rate
I
DD
Standby Mode, -40°C
≤
T
A
< +85°C
Standby Mode, +85°C
≤
T
A
≤
+120°C
-40°C
≤
T
A
≤
+100°C, 3V≤ V
D D
≤
3.6V
+60°C
≤
T
A
≤
+100°C,
-55°C≤T
D
≤+150°C,
3V≤V
DD
≤3.6V
-40°C
≤
T
A
≤
+120°C,
-55°C≤T
D
≤+150°C,
3V≤V
DD
≤3.6V
Min
3.0
Typ
3.3
170
6
6
±1
1
±1
Max
3.6
215
10
20
±3
Units
V
µA
µA
µA
°C
°C
Local Sensor Resolution
Remote Sensor Accuracy
4,5,6
±2
±3
°C
°C
°C
Remote Sensor Resolution
Temperature Conversion Time
7
Temperature Conversion Time
7
From Stop Bit to Conversion
Complete, One-Shot Mode, 2
Sensors, Averaging On
One-Shot Mode, Averaging Off
0.25
115
30
ms
ms
© Andigilog, Inc. 2006
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August 2006 - 70A04010
aSC7511
Logic Electrical Characteristics
(T
A
= 25 °C, V
DD
= 3.3V unless otherwise noted)
Parameter
Input Voltage Logic High
Input Voltage Logic Low
Output Voltage Logic Low
(
ALERT
and
THERM
)
Output Low Sink Current
(
ALERT
and
THERM
)
Input Leakage Current
SMBus Output Sink Current
SMBus Logic Input Current
Output Leakage Current
Output Transition Time
Input Capacitance
Symbol
V
IH
V
IL
V
OL
I
OL
I
IN
I
OL
I
IH,
I
IL
I
OH
t
F
C
IN
V
OH
= V
DD
= 3.6V
C
L
= 400pF, I
OL
= -3mA
All Digital Inputs
Conditions
3V≤ V
D D
≤
3.6V
3V≤ V
D D
≤
3.6V
V
DD
=3.6V, I
OL
= -6mA
Min
2.1
0.8
0.4
1
±1.0
6
-1
0.1
+1
1
250
5
Typ
Max
Units
V
V
V
mA
µA
mA
µA
µA
ns
pF
ALERT
or
THERM
forced to 0.4V
V
IN
= 0V or 5.5V,
-40°C
≤
T
A
≤
+125°C
T
A
= 25 °C, V
OL
= 0.6V
Serial Port Timing
(T
A
= 25 °C, V
DD
= 3.3V unless otherwise noted, Guaranteed by design, not production tested)
Parameter
SCL Operating Frequency
SCL Clock Transition Time
SCL Clock Low Period
SCL Clock High Period
Bus free time between a Stop and a new Start Condition
Data in Set-Up to SCL High
Data Out Stable after SCL Low
SCL Low Set-up to SDA Low (Repeated Start Condition)
SCL High Hold after SDA Low (Start Condition)
SDA High after SCL High (Stop Condition)
Time in which aSC7511 must be operational after a power-on reset
Symbol
f
SCL
t
T:LH
, t
T:HL
t
LOW
t
HIGH
t
BUF
t
SU:DAT
t
HD:DAT
t
SU:STA
t
HD:STA
t
SU:STO
t
POR
1.3
0.6
1.3
100
300
600
600
600
500
50
Min
Typ
Max
400
300
Units
kHz
ns
μs
μs
μs
ns
ns
ns
ns
ns
ms
SCL
t
HD:STA
t
SU:DAT
t
SU:STA
t
SU:STO
t
BUF
t
LOW
t
HIGH
t
T:LH
90
10
t
T:HL
90
10
SCL
SDA
Data Out
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t
HD:DAT
August 2006 - 70A04010
© Andigilog, Inc. 2006
aSC7511
Pin Descriptions
Pin #
1
2
3
4
5
6
Name
V
DD
D+
D-
Direction
Supply
Current
Source
Current Sink
Output
Supply
Output
Supply Voltage
Remote Diode Anode or Positive Lead
Remote Diode Cathode or Negative Lead
Open-drain logic output that may be used to control a fan or throttle CPU
when programmed temperature limit is exceeded.
Ground
Open-drain logic output used as a mask-able interrupt or SMBus alert.
Description
THERM
GND
Configurable as second
THERM
output.
7
SDA
Input/Output
Serial Data—Open drain I/0-data pin for two-wire serial interface.
8
SCL
Input
Serial Clock—Clock for two-wire serial interface.
Note: Open-drain pins require a pull-up resistor.
ALERT
/
THERM2
Conversion Rate
Local
Sensor
Local Temp.
Address Pointer
Remote Low Limit
Remote High Limit
D+
D-
2
3
ADC
Remote Temp.
Com
-
parator
Remote
THERM
Limit
Local Low Limit
Local High Limit
Local
THERM
Limit
Remote Offset
Busy
Remote Diode Open
Status
Configuration
SMBus Interface
Mask
1
5
7
8
4
6
VDD VSS
SDA
SCL
THERM
ALERT
/
THERM2
Figure 1. Block Diagram
© Andigilog, Inc. 2006
-4-
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August 2006 - 70A04010
aSC7511
Basic Operation Overview
The aSC7511 temperature sensing circuitry continuously
monitors two thermal diode base-emitter voltages, one on-
chip, called “local” and one remotely located, connected to
the D+ and D- pins. At regular intervals the aSC7511
converts both analog voltages to digital values, which are
placed into the temperature registers.
The aSC7511 has an SMBus-compatible serial interface
that allows the user to access the data in the temperature
registers at any time. In addition, the serial interface gives
the user easy access to all other aSC7511 registers to
customize operation of the device.
The aSC7511 temperature-to-digital converter has two
temperature formats, 0°C to +127°C binary and extended-
range, -55°C to +150°C, offset-binary. The local sensor
resolution is 8-bits, with an LSB of 1°C. The remote or
remote diode sensor resolution is 10-bits with an LSB of
0.25°C. The temperature range of the local and remote
sensors are controlled by bit 2 of the configuration register,
default value is 0, 0°C to 127°C.
Table 1 gives examples of the relationship between the
output digital data and the measured temperature for the
default range. Table 2 gives examples for the extended
range. All output values are offset by +64°C when in this
mode.
The aSC7511 has a Shutdown Mode that reduces the
operating current to < 20µA. This mode is controlled by
RUN / STOP, bit 6 in the configuration register.
Comparisons to limits and diode open test are suspended
until the next measurement has taken place.
Digital Output (Binary)
Temperature
Local Sensor
Remote Sensor
>127°C
+127°C
+125°C
+100°C
+50°C
+25°C
+10°C
+1.75°C
+0.25°C
0°C
< 0°C
High Byte
Low Byte
Digital Output (Offset Binary)
Temperature
Local Sensor
Remote Sensor
+150°C
+127°C
+125°C
+100°C
+50°C
+25°C
+10°C
+1.75°C
+0.25°C
0°C
-55°C
High Byte
Low Byte
Always Zero
8-Bit Resolution
1101
1011
1011
1010
0111
0101
0100
0100
0100
0100
0000
0110
1111
1101
0100
0010
1001
1010
0001
0000
0000
1001
00
00
00
00
00
00
00
00
11
01
00
00
00
00
00
00
00
00
00
00
00
00
00
00
00
0000
0000
0000
0000
0000
0000
0000
0000
0000
0000
0000
0000
0000
10-Bit Resolution
Table 2. Relationship Between Temperature and Digital
Output, Extended Range, -55°C to +150°C
Power-Up Default Conditions
The aSC7511 always powers-up in the following default
state:
• Configuration Register: 00h (i.e.,
ALERT
enabled, Run
Mode,
ALERT
pin selected, normal range)
• Conversion Rate: 16 per second, 08h
• All Temperature and Offset Registers: 00h
• Consecutive
ALERT
: 1 fault (i.e., 01h in the register)
• Local and Remote Low Limit: 0°C
• Local and Remote
THERM
Limit: 85°C
•
THERM
Hysteresis: 10°C
• Register Address Pointer: Undefined, must be set by
first write sequence.
• Normal / Extended Range: Normal
After power-up, these conditions can be reprogrammed via
the serial interface. Refer to the Serial Data Bus Operation
section to for aSC7511 programming instructions.
Always Zero
8-Bit Resolution
00
00
00
00
00
00
00
00
11
01
00
00
00
00
00
00
00
00
00
00
00
00
00
00
00
0000
0000
0000
0000
0000
0000
0000
0000
0000
0000
0000
0000
0000
10-Bit Resolution
0111
0111
0111
0110
0011
0001
0000
0000
0000
0000
0000
1111
1111
1101
0100
0010
1001
1010
0001
0000
0000
0000
Table 1. Relationship Between Temperature and Digital
Output, Default Range, 0°C to +127°C
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August 2006 - 70A04010
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