aSC7531A / aSC7531B
L
OW
-V
OLTAGE
1-W
IRE
D
IGITAL
T
EMPERATURE
S
ENSOR
AND
V
OLTAGE
M
ONITOR
P
RODUCT
S
PECIFICATION
Product Description
The aSC7531 is a high-precision CMOS temperature sensor
and voltage monitor with Simple Serial Transport (SST)
compatible serial digital interface, intended for use in PC
hardware monitor applications.
Communication of device capabilities, temperature and voltage
readings take place over the high-speed bi-directional SST
interface.
The SST temperature sensor provides a means for an analog
signal to travel over a digital bus enabling remote temperature
sensing in areas previously not monitored in the PC. The
temperature sensor supports an internal and external thermal
diode. aSC7531A is used with 2N3904 transistor connected as
a remote diode, aSC7531B is used with CPU substrate diode.
The aSC7531 is available in MSOP-10 surface mount
package.
Pin Configuration
V
DD
GND
D+
D-
12V
1
10
SST
ADD0
2.5V
VCCP
5V
2
9
3
8
aSC7531A/
aSC7531B
4
5
7
6
Features
•
•
On-chip and remote temperature sensors
Accuracy:
o
+/- 3°C over operational range
o
Internal +/- 2°C over 40°C to 70°C
o
Remote +/- 1°C over 50°C to 70°C
Operational Range: -40°C to 125°C
Temperature resolution: 0.125°C
Voltage monitoring of 12V, 5V, 3.3V, 2.5V and Vccp
to +/- 2% accuracy, 7.8mV resolution
1-wire SST serial interface
Negotiable SST signaling rate up to 2-Mbps
Internally corrected for diode non-ideality and series
resistance
3-state address pin sets one of 3 SST bus address
0x48 through 0x4A
10-lead MSOP package
MSL-1 per JEDEC J-STD-020C
Pb-free Matte Sn lead finish & RoHS Compliant
Packages
Applications
Desktop and Notebook Computers
Application Diagram
with aSC7531A
2N3904
3
3.3V
1
•
•
•
•
•
•
•
•
•
•
with aSC7531B
4
5
aSC7531A/
aSC7531B
CPU
ADD0
SST
Interface
SST
9
12V
2.5V
V
CCP
5V
8
7
6
10
2
Ordering Information
Part Number
aSC7531AM10
aSC7531BM10
Package
10-Lead
MSOP
Temp. Range and Operating Voltage
-40°C to 125°C, 3.3V
-40°C to 125°C, 3.3V
Marking
531A
Ayww
531B
Ayww
Supplied In
2500 units Tape &
Reel
2500 units Tape &
Reel
10-Lead
MSOP
Ayww – Assembly site, year, workweek
© Andigilog, Inc. 2006
-1-
www.andigilog.com
December 2006 - 70A05012
aSC7531A / aSC7531B
Absolute Maximum Ratings
1
Parameter
Supply Voltage, V
DD
Voltage on any Digital Input or Output
3
Voltage on 12V Analog Input
3
Voltage on 5V Analog Input
3
Voltage on Other Analog Inputs
Input Current on any pin
Package Input Current
3
Relative Humidity (non-operating)
Maximum Junction Temperature, TJmax
Storage Temperature Range
IR Reflow Peak Temperature
Lead Soldering Temperature (10 sec.)
Human Body Model
ESD
5
3
3
Rating
-0.3, +3.63V
-0.3V to V
DD
+
0.3V
16V
6.5V
V
DD
+ 0.3V
±5mA
±20mA
5% - 85% RH
@ 25°C to 70°C
150°C
-60°C to +150°C
260°C
300°C
2000 V
250 V
>1000 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. For guaranteed specifications and test
conditions, see the Electrical Characteristics. The guaranteed
specifications apply only for the test conditions listed. Some
performance characteristics may degrade when the device is
not operated under the listed test conditions.
All voltages are measured with respect to GND, unless
otherwise specified.
When the input voltage (VIN) at any pin exceeds the power
supplies (VIN< (GND or GNDA) or VIN>V+, except for SST
and analog voltage inputs), the current at that pin should be
limited to 5mA. The 20mA maximum package input current
rating limits to number of pins that can safely exceed the
power supplies with an input current of 5mA to four.
The maximum power dissipation must be de-rated at elevated
temperatures and is dictated by TJmax,
θ
JA
and the ambient
temperature, T
A
. The maximum allowable power dissipation at
any temperature is PD = (TJmax - TA) /
θ
JA
. It must also take
into account self-heating that can adversely affect the
accuracy of internal sensors.
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.
2.
3.
4.
Machine Model
Charged-Device Model
5.
Electrical Characteristics
6
(-40°C
≤
T
A
≤
+125°C, V
D D
= 3 . 3 V unless otherwise noted. Specifications subject to change without notice)
Parameter
Conditions
Min
Typ
Supply Voltage
SST Signal
Local Sensor Accuracy
7, 8
Local Sensor Resolution
Remote Diode Sensor Accuracy
7, 8, 9
Max
3.6
Units
V
V
DD
3.0
3.3
Meets SST Specification Version 1.0
for 1.5V interface
-40°C
≤
T
A
≤
+125°C
40°C
≤
T
A
≤
70°C
0.125
0°C
≤
T
A
≤
70°C,
-40°C≤T
D
≤+125°C
0°C
≤
T
A
≤
70°C,
50°C≤T
D
≤70°C
0.125
t
C
TUE
DNL
PSS
t
C
140
±1
±1
7.8
0.2
≥100
0.2
2
10
±3
±2
°C
°C
°C
±3
±1
°C
°C
°C
Sec
% FS
LSB
%/V
mV
Sec
kΩ
Remote Diode Sensor Resolution
Temperature Monitor Cycle Time
ADC Total Unadjusted Error
11
ADC Differential Nonlinearity
ADC Power Supply Sensitivity
ADC Resolution
ADC Total Monitoring Cycle Time
10
ADC Input Resistance
Notes:
6.
7.
8.
9.
These specifications are guaranteed only for the test conditions listed.
Accuracy (expressed in °C) = Difference between the aSC7531 reported temperature and the device temperature.
The aSC7531 can be read at any time without interrupting the temperature conversion process.
For the aSC7531A, calibration of the remote diode sensor input is set to meet the accuracy limits with a diode-connected 2N3904 that has
a non-ideality factor of 1.0046 with a series resistance of 0.6Ω. For the aSC7531B, calibration of the remote diode sensor input is set to
meet the accuracy limits with a CPU substrate diode that has a non-ideality factor of 1.009 with a series resistance of 4.52Ω.
10. Total monitoring cycle time for all temperature and analog input voltage measurements is 0.2 second.
11. TUE includes Offset, Gain and Linearity errors of the ADC.
-2-
www.andigilog.com
© Andigilog, Inc. 2006
December 2006 - 70A05012
aSC7531A / aSC7531B
Pin Descriptions
Pin #
1
2
3
4
5
6
7
8
9
10
Name
V
DD
(3.3V)
GND
D+
D-
12V
5V
V
CCP
2.5V
ADD0
SST
Direction
Supply
Supply
Current Source
Current Sink
Input
Input
Input
Input
Input
Input
Ground
Remote Diode Anode or Positive Lead
Remote Diode Cathode or Negative Lead
12V PC System Supply Voltage
5V PC System Supply Voltage
CPU Core Voltage (1.2V to 1.5V)
2.5 V PC System Supply Voltage
Device Address Tri-State selector: Ground, Float or V
DD
Digital Input / Output. SST Bi-directional Data Line.
Description
Supply Voltage, 3.3V +/- 10% (measured 3.3V input)
Vccp Voltage
V
CCP
2.5V
3.3V (V
DD
)
5V
12V
2.5V Voltage
3.3V Voltage
5V Voltage
ADC
12V Voltage
On-Chip Temperature
Remote Temperature
DIB Register
D+
D-
Remote Diode
Open / Short
On-Chip
Sensor
Control and SST Interface
VSS
ADD0
SST
Figure 1. Block Diagram
© Andigilog, Inc. 2006
-3-
www.andigilog.com
December 2006 - 70A05012
aSC7531A / aSC7531B
SST Sensors
The SST voltage and temperature sensor provides a means for
an analog signal to travel over a single-wire digital bus
enabling remote voltage and temperature sensing in areas
previously not monitored in the PC. The temperature sensor
supports an internal temperature sensor and external thermal
diodes.
This section outlines general requirements for Simple Serial
Transport (SST) sensors intended for use in PC desktop
applications that conform to SST Version 1.0 specification.
The aSC7531 is a Combination Voltage and Temperature
Sensor. It reports external temperature sensed by a remote
diode-connected transistor and an internal temperature
measurement. It also has five voltage measurements: 2.5V,
3.3V, 5V, 12V, and V
CCP
.
Device Power-on Timing
Following a power-on reset, such as a system transitioning
from S3-S5 to S0, the aSC7531 will be able to participate in
the address and message timing negotiation and respond to
required SST bus commands such as respond to a GetDIB()
command within 10ms of the device’s V
DD
rail reaching 90%.
The aSC7531 has an internal power on reset and will be fully
functional within 50ms of power on.
The aSC7531 does not employ any device power
management.
Voltage and Temperature Sensor Data
Little Endian Format
The bit level transfer is defined in the SST specification. The 2-
byte data values are returned in little Endian format, in other
words, the LSB is sent first followed by MSB.
For multi-function devices that allow access to multiple
sensors, the data is returned LSB followed by the MSB for the
first sensor, LSB followed by the MSB for the second sensor,
and so on. The specific order is explicitly specified in the
command description.
Addressing
The aSC7531 complies with the address range set aside for
fixed-address, discoverable devices as defined in the SST
Specification Version 1.0. Combination voltage and
temperature sensors use fixed addresses in the range of 0x48
to 0x4A. The aSC7531 may be programmed to any of these
addresses via the address select pin AD0.
Atomic Readings
The aSC7531 ensures that every value returned is derived
from a single analog to digital conversion and is not skewed
(e.g. the MSB and the LSB come from two different
conversions).
Frame Check Sequence (FCS)
Each message requires a frame check sequence byte to
ensure reliable data exchange between host and client. The
message originator and client both make an FCS calculation.
One FCS byte must be returned from the message target to
the originator after all bytes including the header and the data
block are written. If data is read from the target, a second FCS
byte must follow the data block read.
The FCS byte is the result of an 8-bit cyclic redundancy check
(CRC) of the each data block preceding the FCS up to the
most recent, earlier FCS byte. The first FCS in the message
does not include the two address timing negotiation ‘0’ bits that
precede the address byte or the message timing negotiation bit
after the address byte. The first FCS does include the address
byte in its computation. The FCS is initialized at 0x00 and is
calculated in a way that conforms to a CRC-8 represented by
8
2
the CRC polynomial, C(x) = x + x + x + 1.
Conversion Time
The maximum refresh time for all voltage and temperature
values is 200ms. The aSC7531 provides the logic to ensure all
readings meet the conversion time requirements.
There are 7 channels (5 voltage and 2 temperature) channels
which must be measured every 250ms.
Temperature Data
Data Precision, Accuracy and Resolution
The temperature data meets the following minimum
requirements:
•
Operational Range: -40°C to +125°C
•
Internal Sensor Accuracy:
o
+/- 3°C over operational range
o
+/- 2°C over 40°C to 70°C
•
Remote Sensor Accuracy (when TA is from 0°C to
70°C):
o
+/- 3°C over operational range
o
+/- 1°C over 50°C to 70°C
•
Resolution: 0.125°C
Bus Voltage
All SST sensor devices used for PC applications must be
capable of operating the SST interface portion of the sensor
device at 1.5 volts as defined in 1.5 Volt Static (DC)
Characteristics section of the SST Version 1.0 specification
.
Bus Timing
All SST sensor devices must be able to negotiate timing and
operate at a maximum bus transfer rate of 2-Mbps. If the bus
address timing is negotiated at a lower rate due to the
performance limitations of other devices on the bus, the sensor
device will operate at that lower rate.
Temperature Data Format
The data format is capable of reporting temperature values in
the range of +/-512°C. The temperature sensor data is
returned as a 2’s complement 16-bit binary value. It represents
the number of 1/64°C increments in the actual reading. This
allows temperatures to be represented with approximately a
0.016°C resolution.
© Andigilog, Inc. 2006
-4-
www.andigilog.com
December
2006 - 70A05012
aSC7531A / aSC7531B
Values that would represent temperatures below -273.15°C (0
K or absolute zero) are reserved and are not be returned
except as specifically noted.
For the aSC7531 the required resolution is 0.125°C. Bits [2:0]
will be defined but they are beyond the required resolution.
The sign bit will indicate a negative temperature except when
reporting an error condition (see
Sensor Error Condition).
Temperature
80°C
79.875°C
1°C
0°C
-1°C
-5°C
2’s complement representation
0001 0100 0000 0000
0001 0011 1111 1000
0000 0000 0100 0000
0000 0000 0000 0000
1111 1111 1100 0000
1111 1110 1100 0000
Table 1. Temperature Representation
Sign
15
14
13
Integer Temperature 0°C to 512°C
12
11
10
9
8
7
6
●
Fractional
Temperature
LSB 0.125°C
5
4
3
Always Zero
2
1
0
Figure 2. Temperature Reading
The aSC7531 will write one of the values from the table
below to appropriate memory locations for GetIntTemp()
and/or GetExtTemp().
The aSC7531 uses the OEM defined values of 0x8102
(open) and 0x8103 (short) rather than the generic errors
defined for codes 0x8000 to 0x8003.
A to D Converter Resolution and Mapping
The mapping of the A-D converter bit values is a two’s
complement representation with the binary point between bits
5 and 6 of the 16-bit data word. Bit 15 is the sign, bits 14
through 6 are integer temperature in degrees, bits 5 down to
3 are the fractional part with 0.125°C as the LSB. The lowest
3 bits are set to zero.
Temperature Inputs
The aSC7531A has an internal thermal sensor plus an
external sensor using a remote diode. The remote sensor is
calibrated for a 2N3904 NPN transistor that has a non-
ideality (η) factor of approximately 1.0046. Use of the remote
diode is discussed in the Applications Information section.
The aSC7531B also has an internal thermal sensor plus an
external sensor using a remote diode however the remote
sensor is calibrated for an Intel CPU (Pentium 4, 65nM) that
has a non-ideality (η) factor of approximately 1.009. Use of
the remote diode is discussed in the Applications Information
section.
It is recommended that the actual transistor type and
manufacturers chosen for the remote sensor be
characterized for non-ideality as part of system qualification.
Error Code
0x8000 to 0x80FF
0x8102
0x8103
0x8100-0x81FF
Description
Reserved
Remote Diode Open
Remote Diode Short
Reserved
Table 2. Error Codes
Voltage Data
Accuracy and Resolution
The aSC7531 measures the following voltages:
•
Measured voltages:
o
12V
o
5V
o
3.3V
o
2.5V
o
V
CCP
Measurement Error: +/- 2% of full scale
Resolution: 7.8 mV
Sensor Error Condition
The aSC7531 has the capability to detect and report open or
shorted external diode inputs per Sensor Error Condition.
When an error or failure condition is detected, the sensor
device must return a large negative value in response to
either the GetIntTemp() or GetExtTemp() command. In this
manner software is provided with a means to determine
whether or not the sensor is working normally and that the
data returned is good.
•
•
Voltage Data Format
The data format used to report voltage allows values in the
range of +/-32V. The voltage sensor data is returned as a 16-
bit 2’s complement binary value. It represents the number of
1/1024 volts in the reading if extended the full 16-bits. This
allows voltages to be represented with approximately a 1mV
resolution.
December
2006 - 70A05012
© Andigilog, Inc. 2006
-5-
www.andigilog.com
京公网安备 11010802033920号
Copyright © 2005-2026 EEWORLD.com.cn, Inc. All rights reserved
电子工程世界
