SMSC EMC1002-1-ACZT-TR 1â°c dual smbus sensor with resistance error correction Datasheet

EMC1002
1°C Dual SMBus Sensor
with Resistance Error
Correction
PRODUCT FEATURES
Datasheet
General Description
Features
The EMC1002 is an SMBus temperature sensor that
monitors up to two temperature zones and can generate
two system interrupts. With ±1 °C measurement
accuracy, the EMC1002 provides a low-cost solution for
critical temperature monitoring applications. Extended
features include automatic resistance error correction
and programmable ideality factor configuration
eliminating both major sources of temperature
m e a s u r e m e n t e r r o r. 1 T h e 11 - b i t s i g m a d e l t a
temperature-to-digital converter provides superb
linearity, excellent noise immunity and repeatable
temperature readings.
„
The EMC1002 generates two separate interrupts with
programmable thermal trip points. The THERM output
operates as a thermostat with programmable threshold
and hysteresis. The ALERT output can be configured
as a maskable SMBus alert with programmable
window comparator limits, or a second THERM output.
„
The EMC1002 is pin compatible with the ADT7461,
ADM1032, LM99, and the MAX6649.
„
„
„
„
Resistance Error Correction
Ideality Factor Configuration
Select 1 of 4 SMBus addresses with external resistor
Remote Thermal Zones
— ±1°C Accuracy (40°C to 80°C)
— 0.125°C resolution
„
Internal Thermal Zone
„
Maskable Interrupt using ALERT
One-shot Command during standby
Programmable temperature conversion rate
Extended temperature (-64°C to 191°C) available
Over-limit filtering with consecutive counter
Small 8-pin SOIC or MSOP green, lead-free package
— ±3°C Accuracy (0°C to 85°C)
„
„
„
„
Applications
„
„
„
Desktop and Notebook Computers
Smart batteries
Industrial/Automotive
Other Electronic Systems
1.Patents pending.
Simplified Block Diagram
EMC1002
Address Pointer Register
Switching
Current
Internal
Temp Diode
Remote Temp
Register
Internal Temp
Register
Low Limit Registers
THERM Limit Register
THERM Hysteresis Register
Configuration Register
Status Register
Interrupt Masking
SMBus Interface
11-bit
delta-sigma
ADC
High Limit Registers
Digital Mux
DN
Digital Mux
Analog Mux
DP
Limit Comparator
Conversion Rate Register
SMCLK
SMDATA
ALERT
THERM
SMSC EMC1002
DATASHEET
Revision 1.3 (03-24-06)
1°C Dual SMBus Sensor with Resistance Error Correction
Datasheet
ORDER NUMBER(S):
EMC1002-1-ACZT-TR FOR 8 PIN, SOIC GREEN, LEAD-FREE PACKAGE (Fixed Address, Tape and Reel)
EMC1002-2-ACZT-TR FOR 8 PIN, SOIC GREEN, LEAD-FREE PACKAGE (Variable Address, Tape and Reel)
EMC1002-1-ACZL-TR FOR 8 PIN, MSOP GREEN, LEAD-FREE PACKAGE (Fixed Address, Tape and Reel)
EMC1002-2-ACZL-TR FOR 8 PIN, MSOP GREEN, LEAD-FREE PACKAGE (Variable Address, Tape and Reel)
See Table 1.2, “Ordering Information,” on page 3.
Reel size is 4,000 pieces.
Evaluation Board available upon request. (EVB-EMC1002)
80 Arkay Drive
Hauppauge, NY 11788
(631) 435-6000
FAX (631) 273-3123
Copyright © 2006 SMSC or its subsidiaries. All rights reserved.
Circuit diagrams and other information relating to SMSC products are included as a means of illustrating typical applications. Consequently, complete
information sufficient for construction purposes is not necessarily given. Although the information has been checked and is believed to be accurate, no
responsibility is assumed for inaccuracies. SMSC reserves the right to make changes to specifications and product descriptions at any time without
notice. Contact your local SMSC sales office to obtain the latest specifications before placing your product order. The provision of this information does
not convey to the purchaser of the described semiconductor devices any licenses under any patent rights or other intellectual property rights of SMSC
or others. All sales are expressly conditional on your agreement to the terms and conditions of the most recently dated version of SMSC's standard
Terms of Sale Agreement dated before the date of your order (the "Terms of Sale Agreement"). The product may contain design defects or errors
known as anomalies which may cause the product's functions to deviate from published specifications. Anomaly sheets are available upon request.
SMSC products are not designed, intended, authorized or warranted for use in any life support or other application where product failure could cause
or contribute to personal injury or severe property damage. Any and all such uses without prior written approval of an Officer of SMSC and further
testing and/or modification will be fully at the risk of the customer. Copies of this document or other SMSC literature, as well as the Terms of Sale
Agreement, may be obtained by visiting SMSC’s website at http://www.smsc.com. SMSC is a registered trademark of Standard Microsystems
Corporation (“SMSC”). Product names and company names are the trademarks of their respective holders.
SMSC DISCLAIMS AND EXCLUDES ANY AND ALL WARRANTIES, INCLUDING WITHOUT LIMITATION ANY AND ALL IMPLIED WARRANTIES
OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE, TITLE, AND AGAINST INFRINGEMENT AND THE LIKE, AND ANY AND
ALL WARRANTIES ARISING FROM ANY COURSE OF DEALING OR USAGE OF TRADE. IN NO EVENT SHALL SMSC BE LIABLE FOR ANY
DIRECT, INCIDENTAL, INDIRECT, SPECIAL, PUNITIVE, OR CONSEQUENTIAL DAMAGES; OR FOR LOST DATA, PROFITS, SAVINGS OR
REVENUES OF ANY KIND; REGARDLESS OF THE FORM OF ACTION, WHETHER BASED ON CONTRACT; TORT; NEGLIGENCE OF SMSC
OR OTHERS; STRICT LIABILITY; BREACH OF WARRANTY; OR OTHERWISE; WHETHER OR NOT ANY REMEDY OF BUYER IS HELD TO
HAVE FAILED OF ITS ESSENTIAL PURPOSE, AND WHETHER OR NOT SMSC HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH
DAMAGES.
Revision 1.3 (03-24-06)
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DATASHEET
SMSC EMC1002
1°C Dual SMBus Sensor with Resistance Error Correction
Datasheet
Chapter 1 Pin Configuration
VDD
1
DP
2
DN
3
ADDR/THERM
4
EMC1002
TOP VIEW
8
SMCLK
7
SMDATA
6
ALERT/THERM2
5
GND
Figure 1.1 EMC1002 Pin Configuration
Table 1.1 Pin Description
PIN
PIN NO.
DESCRIPTION
VDD
1
Supply Voltage, 3.0V to 3.6V.
DP
2
Anode connection for remote temperature diode.
DN
3
Cathode connection for remote temperature diode.
ADDR/THERM
4
Logic output that can be used to turn on/off a fan or throttle a CPU clock
in the event of an over-temperature condition. This is an open-drain
output. For the EMC1002-2, this pin is sampled following power up and
the value of the pull-up resistor determines the SMBus slave address per
Table 1.2 on page 3. Total capacitance on this pin must not exceed 100
pf, and the pull-up resistor must be connected to the same supply voltage
as VDD.
GND
5
Ground.
ALERT/THERM2
6
Logic output used as interrupt, SMBus alert or as a second THERM
output. This is an open-drain output.
SMDATA
7
SMBus data input/output. This is an open-drain output.
SMCLK
8
SMBus clock input.
Table 1.2 Ordering Information
PART NUMBER
ADDR/THERM
PULL-UP RESISTOR
SMBUS
ADDRESS
EMC1002-1
1kΩ or greater
(If unused, connect to GND)
1001 100b
EMC1002-2
7.5kΩ ±5% Note 1.1 Note 1.2
1001 100b
12kΩ ±5% Note 1.2
1001 101b
20kΩ ±5% Note 1.2
0111 100b
33kΩ ±5% Note 1.2
0111 101b
Note 1.1
This value must be greater than 1kΩ ±5% and less than or equal to 7.5kΩ ±5%.
Note 1.2
The pull-up resistor must be connected to VDD (pin 1), less than 100pf capacitance on pin.
.
SMSC EMC1002
3
DATASHEET
Revision 1.3 (03-24-06)
1°C Dual SMBus Sensor with Resistance Error Correction
Datasheet
Table 1.3 Absolute Maximum Ratings
PARAMETER
RATING
UNIT
Supply Voltage VDD
-0.3 to 5.0
V
Voltage on ALERT/THERM2, SMDATA and SMCLK pins
-0.3 to 5.5
V
-0.3 to VDD+0.3
V
Operating Temperature Range
-40 to +125
°C
Storage Temperature Range
-55 to +150
°C
Voltage on any other pin
Lead Temperature Range
Refer to JEDEC
Spec. J-STD-020
Package Thermal Characteristics for MSOP-8 (TSSOP)
Power Dissipation
TBD
Thermal Resistance (at 0 air flow)
109.6
°C/W
Package Thermal Characteristics for SOIC-8
Power Dissipation
TBD
Thermal Resistance (at 0 air flow)
135.9
°C/W
2000
V
ESD Rating, All Pins (Human Body Model)
Note: Stresses above those listed could cause damage to the device. This is a stress rating only
and functional operation of the device at any other condition above those indicated in the
operation sections of this specification is not implied. When powering this device from
laboratory or system power supplies, it is important that the Absolute Maximum Ratings not be
exceeded or device failure can result. Some power supplies exhibit voltage spikes on their
outputs when the AC power is switched on or off. In addition, voltage transients on the AC
power line may appear on the DC output. If this possibility exists, it is suggested that a clamp
circuit be used.
Revision 1.3 (03-24-06)
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DATASHEET
SMSC EMC1002
1°C Dual SMBus Sensor with Resistance Error Correction
Datasheet
Chapter 2 Electrical Characteristics
Table 2.1 Electrical Characteristics
VDD=3.0V to 3.6V, TA= -40°C to +125°C, Typical values at TA = 27°C unless otherwise noted
PARAMETER
SYMBOL
MIN
TYP
MAX
UNITS
CONDITIONS
Supply Voltage
VDD
3.0
3.3
3.6
V
Average Operating Current
IDD
47
50
μA
0.0625 conversions/s
See Table 4.6,
“Conversion Rates,”
on page 15
IPD
4.8
10
μA
Standby mode
±1
TBD
±3
°C
°C
0°C≤TA≤85°C
-40°C≤TA≤125°C
DC Power
Internal Temperature Monitor
Temperature Accuracy
Temperature Resolution
°C
0.5
External Temperature Monitor
Temperature Accuracy
Remote Diode 40°C to 80°C
Remote Diode 0°C to 125°C
±1
±3
Temperature Resolution
°C
°C
15°C≤TA≤70°C
-40°C≤TA≤125°C
°C
0.125
Voltage Tolerance
Voltage at pin (ADDR/THERM, )
VTOL
-0.3
3.6
V
Voltage at pin (ALERT/THERM2,
SMDATA,SMCLK)
VTOL
-0.3
5.5
V
0.4
V
IOUT=-4mA
1
μA
VOUT=VDD
Digital Outputs (ADDR/THERM, ALERT/THERM2)
Output Low Voltage
VOL
High Level Leakage Current
IOH
0.1
SMBus Interface (SMDATA,SMCLK)
Input High Level
VIH
Input Low Level
VIL
Input High/Low Current
IIH/IIL
2.0
-1
Hysteresis
Input Capacitance
Output Low Sink Current
V
0.8
V
1
μA
500
mV
5
pF
6
mA
SMDATA = 0.6V
SMBus Timing
Clock Frequency
SMSC EMC1002
FSMB
10
5
DATASHEET
400
kHz
Revision 1.3 (03-24-06)
1°C Dual SMBus Sensor with Resistance Error Correction
Datasheet
Table 2.1 Electrical Characteristics (continued)
VDD=3.0V to 3.6V, TA= -40°C to +125°C, Typical values at TA = 27°C unless otherwise noted
PARAMETER
SYMBOL
MIN
TYP
Spike Suppression
MAX
UNITS
50
ns
CONDITIONS
TBUF
1.3
μs
Hold time Start
THD:STA
0.6
μs
Setup time Start
TSU:STA
0.6
μs
Setup time Stop
TSU:STO
0.6
μs
Data Hold Time
THD:DAT
0.3
μs
Data Setup Time
TSU:DAT
100
ns
Clock Low Period
TLOW
1.3
μs
Clock High Period
THIGH
0.6
μs
Clock/Data Fall Time
TF
*
300
ns
*Min = 20+0.1Cb ns
Clock/Data Rise Time
TR
*
300
Note
2.1
ns
*Min = 20+0.1Cb ns
Capacitive Load (each bus line)
Cb
0.6
400
pF
Bus free time Start to Stop
Note 2.1
Revision 1.3 (03-24-06)
300nS rise time max is required for 400kHz bus operation. For lower clock frequencies,
the maximum rise time is (0.1/FSMB)+50nS
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DATASHEET
SMSC EMC1002
1°C Dual SMBus Sensor with Resistance Error Correction
Datasheet
Chapter 3 System Management Bus Interface Protocol
A host controller, such as an SMSC I/O controller, communicates with the EMC1002 via the two wire
serial interface named SMBus. The SMBus interface is used to read and write registers in the
EMC1002, which is a slave-only device. A detailed timing diagram is shown in Figure 3.1.
T LO W
T H IG H
T H D :STA
TR
SM CLK
T SU :S TO
TF
T H D :S TA
T H D :D A T T S U :D AT
T SU :S TA
SM DA TA
TBUF
S
P
S
S - S tart Condition
P - Stop Condition
P
Figure 3.1 System Management Bus Timing Diagram
The EMC1002 implements a subset of the SMBus specification and supports Write Byte, Read Byte,
Send Byte, Receive Byte, and Alert Response Address protocols. as shown. In the tables that describe
the protocol, the “gray” columns indicate that the slave is driving the bus.
3.1
Write Byte
The Write Byte protocol is used to write one byte of data to the registers as shown below:
Table 3.1 SMBus Write Byte Protocol
START
SLAVE ADDRESS
WR
ACK
COMMAND
ACK
DATA
ACK
STOP
1
7
1
1
8
1
8
1
1
3.2
Read Byte
The Read Byte protocol is used to read one byte of data from the registers as shown below:
Table 3.2 SMBus Read Byte Protocol
START
SLAVE ADDRESS
WR
ACK
COMMAND
ACK
START
SLAVE ADDRESS
RD
ACK
DATA
NACK
STOP
1
7
1
1
8
1
1
7
1
1
8
1
1
3.3
Send Byte
The Send Byte protocol is used to set the Internal Address Register to the correct Address. The Send
Byte can be followed by the Receive Byte protocol described below in order to read data from the
register. The send byte protocol cannot be used to write data - if data is to be written to a register then
the write byte protocol must be used as described in subsection above. The send byte protocol is
shown in Table 3.3, "SMBus Send Byte Protocol," on page 7.
Table 3.3 SMBus Send Byte Protocol
FIELD:
START
SLAVE ADDR
WR
ACK
REG. ADDR
ACK
STOP
Bits:
1
7
1
1
8
1
1
SMSC EMC1002
7
DATASHEET
Revision 1.3 (03-24-06)
1°C Dual SMBus Sensor with Resistance Error Correction
Datasheet
3.4
Receive Byte
The Receive Byte protocol is used to read data from a register when the internal register address
pointer is known to be at the right location (e.g. set via Send Byte). This can be used for consecutive
reads of the same register as shown below:
Table 3.4 SMBus Receive Byte Protocol
FIELD:
START
SLAVE ADDR
RD
ACK
REG. DATA
NACK
STOP
Bits:
1
7
1
1
8
1
1
3.5
Alert Response Address
The ALERT/THERM2 output can be used as an SMBALERT# as described in Section 4.5 on page 11.
The Alert Response Address is polled by the Host whenever it detects an SMBALERT#, i.e. when the
ALERT/THERM2 pin is asserted. The EMC1002 will acknowledge the Alert Response Address and
respond with its device address as shown below:
Table 3.5 Modified SMBus Receive Byte Protocol Response to ARA
FIELD:
START
ALERT
RESPONSE
ADDRESS
Bits:
1
7
3.6
RD
ACK
EMC1002 SLAVE
ADDRESS
NACK
STOP
1
1
8
1
1
SMBus Addresses
The EMC1002-2 may be configured to one of four 7-bit slave addresses that are enabled based on
the pull-up resistor on the ADDR/THERM pin. The value of this pull-up resistor determines the slave
address per Table 1.2, “Ordering Information,” on page 3. Attempting to communicate with the
EMC1002 SMBus interface with an invalid slave address or invalid protocol results in no response from
the device and does not affect its register contents. The EMC1002 supports stretching of the SMCLK
signal by other devices on the SMBus but will not perform this operation itself. The EMC1002 has an
SMBus timeout feature. Bit 7 of the Consecutive Alert register enables this function when set to 1 (the
default setting is 0). When this feature is enabled, the SMBus will timeout after approximately 25ms
of inactivity.
Revision 1.3 (03-24-06)
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DATASHEET
SMSC EMC1002
1°C Dual SMBus Sensor with Resistance Error Correction
Datasheet
Chapter 4 Product Description
The EMC1002 is an SMBus sensor that can monitor internal temperature and one remote diode
temperature. The sensor is typically used with an SMBus host such as an SMSC SIO device or an
SMSC fan control chip.
Thermal management is performed in cooperation with the host device. The host reads the
temperature data from the EMC1002 and takes appropriate action such as controlling fan speed or
processor clock frequency. The EMC1002 has programmable temperature limit registers that define
a safe operating window. After the host has configured the temperature limits, the EMC1002 can
perform as a free-running independent watchdog to warn the host of temperature hot spots without
requiring the host to poll the device.
Host
EMC1002
SMCLK
DP
SMDATA
DN
SMBus
Interface
ALERT/THERM2
Internal
Diode
ADDR/THERM
Fan
Driver
Figure 4.1 System Overview
The EMC1002 has two basic modes of operation:
4.1
„
Run Mode: In this mode, the EMC1002 continuously converts temperature data and updates its
registers. The rate of temperature conversion is configured as shown in 4.11, "Conversion Rate
Register," on page 15.
„
Standby Mode: In this mode, the EMC1002 is placed in standby to conserve power as described
in 4.7, "Standby Mode," on page 13.
Temperature Monitors
Thermal diode temperature measurements are based on the change in forward bias voltage (ΔVBE) of
a diode when operated at two different currents:
where:
ΔVBE = VBE _ HIGH − VBE _ LOW =
⎛I
ln⎜⎜ HIGH
q
⎝ I LOW
ηkT
⎞
⎟⎟
⎠
k = Boltzmann’s constant
T = absolute temperature in Kelvin
q = electron charge
η = diode ideality factor
The change in
SMSC EMC1002
ΔVBE voltage is proportional to absolute temperature T.
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DATASHEET
Revision 1.3 (03-24-06)
1°C Dual SMBus Sensor with Resistance Error Correction
Datasheet
VDD
Ihigh
Internal or
Remote Diode
Ilow
Ibias
Bias
Diode
Delta Vbe
Sample
&
Hold
1-bit
DeltaSigma
Modulator
Digital
Averaging
Filter
11-bit Output
Figure 4.2 Detailed Block Diagram
Figure 4.2 shows a detailed block diagram of the temperature measurement circuit. The EMC1002
incorporates switched capacitor technology that integrates the temperature diode ΔVBE from different
bias currents. The negative terminal, DN, for the temperature diode is internally biased with a forward
diode voltage referenced to ground.
The advantages of this architecture over Nyquist rate FLASH or SAR converters are superb linearity
and inherent noise immunity. The linearity can be directly attributed to the delta-sigma ADC single-bit
comparator while the noise immunity is achieved by the ~20ms integration time which translates to
50Hz input noise bandwidth.
4.2
Resistance Error Correction
The EMC1002 includes active resistance error correction implemented in the analog front end of the
chip. Without this automatic feature, voltage developed across the parasitic resistance in the remote
diode path causes the temperature to read higher than the true zone temperature. The error introduced
by parasitic resistance is approximately +0.7°C per ohm. Sources of parasitic resistance include bulk
resistance in the remote temperature transistor junctions along with resistance in the printed circuit
board traces and package leads.
Resistance error correction in the EMC1002 eliminates the need to characterize and compensate for
parasitic resistance in the remote diode path.
4.3
Ideality Factor Configuration
Temperature sensors like the EMC1002 are typically designed for remote diodes with an ideality factor
of 1.008. When the diode does not have this exact factor, an error is introduced in the temperature
measurement. Programmable offset registers are sometimes used to compensate for this error, but
this correction is only perfect at one temperature since the error introduced by ideality factor mismatch
is a function of temperature. The higher the temperature measured, the greater the error introduced.
The EMC1002 provides a 6-bit ideality factor register for the remote diode. The ideality factor of the
remote diode is programmed in a register to eliminate errors across all temperatures. See section 4.16,
"Ideality Factor Register," on page 16 for details on programming this register.
4.4
Temperature Measurement Results and Data
The 11-bit temperature measurement results are stored in temperature value registers. The EMC1002
has two temperature ranges and the default range is from 0 to 127°C. This range uses binary number
format, and the most significant bit is not used. The extended range is from –64°C to +191°C and is
binary offset by 64°C. Table 4.1 shows the two temperature data formats with an LSB equivalent to
0.125°C. The format is selected as described in 4.10, "Configuration Register," on page 14.
Revision 1.3 (03-24-06)
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DATASHEET
SMSC EMC1002
1°C Dual SMBus Sensor with Resistance Error Correction
Datasheet
Table 4.1 Temperature Data Format
ACTUAL TEMP.
(°C)
DEFAULT RANGE
BINARY
EXTENDED RANGE
OFFSET BINARY
-63
0000 0000 000 Note 4.1
0000 0001 000 Note 4.2
-0.125
0000 0000 000 Note 4.1
0011 1111 111
0
0000 0000 000 Note 4.1
0100 0000 000
+0.125
0000 0000 001
0100 0000 001
+0.250
0000 0000 010
0100 0000 010
+1
0000 0001 000
0100 0001 000
+127
0111 1111 000 Note 4.3
1011 1110 000
+128
0111 1111 000 Note 4.3
1011 1111 000
+190
0111 1111 000 Note 4.3
1111 1110 000
+191
0111 1111 000 Note 4.3
1111 1111 000 Note 4.4
Note 4.1
Data in Binary Format reads 0000 0000 000 for all temperatures ≤ 0.00°C.
Note 4.2
Data in Offset Binary Format reads 0000 0000 000 for all temperatures ≤ -64°C.
Note 4.3
Data in Binary Format reads 0111 1111 000 for all temperatures ≥ +127°C.
Note 4.4
Data in Offset Binary Format reads 1111 1111 000 for all temperatures ≥ +191°C.
The 11-bit temperature data is stored with the 8 most significant bits stored in the High Byte register
and the 3 least significant bits in the Low Byte register. The Low Byte register contains the three least
significant bits as outlined in Table 4.2. These bits are stored in the upper three bits of the register,
and the five LSB positions of this register always read zero. In Table 4.2, the upper case “B” shows
the bit position of a 16-bit word created by concatenating the High Byte and Low Byte, and the lower
case “b” shows the bit position in the 11-bit temperature data. The resolution of the internal temperature
is 0.5°C and the b1 and b0 bits of the Internal Temperature Value Low Byte register will always read 0.
Table 4.2 Bit Position of Two Byte Values
HIGH BYTE
B15
b10
4.5
B14
b9
B13
b8
B12
b7
B11
b6
LOW BYTE
B10
b5
B9
b4
B8
b3
B7
b2
B6
b1
B5
b0
B4
0
B3
0
B2
0
B1
0
B0
0
ALERT/THERM2 Output
The ALERT/THERM2 output asserts if an out of limit measurement is detected as described in 4.12,
"Limit Registers," on page 15. The ALERT/THERM2 pin is an open drain output and requires a pull-up
resistor to VDD.The ALERT/THERM2 pin can be used as an SMBALERT#, or may be configured as a
second THERM output.
As described in the SMBus specification, an SMBus slave may inform the SMBus master that it wants
to talk by asserting the SMBALERT# signal. One or more ALERT outputs can be hardwired together
as a wired-or bus to a common input.
SMSC EMC1002
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DATASHEET
Revision 1.3 (03-24-06)
1°C Dual SMBus Sensor with Resistance Error Correction
Datasheet
The ALERT/THERM2 pin de-asserts when the EMC1002 responds to an alert response address
(ARA=0001 100) sent by the host if the out of limit condition no longer exists, but it does not reset if
the error condition remains. The ALERT/THERM2 pin can be masked so that it will not assert in the
event of an out of limit temperature measurement, except when it is configured as a second THERM
pin.
Logic
Level
Temp
Temperature High Limit
SMBus ARA
Temperature Low Limit
Logic High
ALERT/THERM2
Time
Figure 4.3 ALERT/THERM2 Response to Temperature Limits Exceeded
The ALERT/THERM2 pin can be configured as a second THERM pin that asserts when the temperature
measurement exceeds the Temperature High Limit value. In this mode, the output will not de-assert
until the temperature drops below the Temperature High Limit minus the THERM Hysteresis value.
4.6
ADDR/THERM Output
The ADDR/THERM output asserts if the temperature measurement exceeds the programmable THERM
limit. It can be used to drive a fan or other fail-safe devices. The ADDR/THERM pin is open drain and
requires a pull-up resistor to VDD. For the EMC1002-2, the value of this pull-up resistor determines the
slave address per Table 1.2 on page 3. The ADDR/THERM pin cannot be masked. Do not exceed 100pf
capacitance total on this pin.
When the ADDR/THERM pin is asserted, it will not de-assert until the temperature drops below the
THERM limit minus the THERM hysteresis value.
Logic
Level
Temp
THERM
Hysteresis
THERM Limit
THERM Limit - THERM Hysterisis
Logic High
THERM
Time
Figure 4.4 ADDR/THERM Output Response to Temperature Limit Exceeded
Revision 1.3 (03-24-06)
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DATASHEET
SMSC EMC1002
1°C Dual SMBus Sensor with Resistance Error Correction
Datasheet
4.7
Standby Mode
The EMC1002 can be set to standby mode (low power) by setting a bit in the Configuration Register
as described in 4.10, "Configuration Register," on page 14. This shuts down all internal analog
functions while the SMBus remains enabled. When the EMC1002 is in standby mode, a One-Shot
command measurement can be initiated. The user may also write new values to the limit registers
described in 4.12, "Limit Registers," on page 15 while in standby. If the previously stored temperature
is outside any of the new limits, the ALERT/THERM2 output will respond as described in Section 4.5
and the ADDR/THERM output will respond as described in Section 4.6.
4.8
Register Allocation
The registers shown in Table 4.3 are accessible through the SMBus.
Table 4.3 EMC1002 Register Map
READ
ADDRESS
(HEX)
WRITE
ADDRESS
(HEX)
00
01
02
03
04
05
06
07
08
N/A
10
11
12
13
14
19
20
21
22
27
29
FD
N/A
N/A
N/A
09
0A
0B
0C
0D
0E
0F
N/A
11
12
13
14
19
20
21
22
27
N/A
Internal Temperature Value High Byte
Remote Temperature Value High Byte
Status
Configuration
Conversion Rate
Internal Temperature High Limit
Internal Temperature Low Limit
Remote Temperature High Limit High Byte
Remote Temperature Low Limit High Byte
One-Shot
Remote Temperature Value Low Byte
Scratchpad Byte 1
Scratchpad Byte 2
Remote Temperature High Limit Low Byte
Remote Temperature Low Limit Low Byte
Remote THERM Limit
Internal THERM Limit
THERM Hysteresis
Consecutive ALERT
Remote Ideality Factor
Internal Temperature Value Low Byte
Product ID
FE
FF
N/A
N/A
Manufacture ID
Revision Number
Note 4.5
REGISTER NAME
POWER-ON DEFAULT
0000 0000
0000 0000
undefined
0000 0000
0000 1000
0101 0101
0000 0000
0101 0101
0000 0000
0000
0000
0000
0000
0000
0101
0101
0000
0000
0001
0000
0000
0000
0101
0000
(85°C)
(0°C)
(85°C)
(0°C)
0000
0000
0000
0000
0000
0101 (85°C)
0101 (85°C)
1010 (10°C)
0001
0010 (1.008)
0000
0010 - EMC1002-1
0011 - EMC1002-2
1101
0001 Note 4.5
Revision number may change. Please obtain the latest version of this document from the
SMSC web site.
At device power-up, the default values are stored in registers as shown. A power-on-reset is initiated
when power is first applied to the part and the VDD supply exceeds the POR threshold. Reads of
undefined registers will return 00h and writes to undefined registers will be ignored.
The EMC1002 uses an interlock mechanism that locks the low byte value when the high byte register
is read. This prevents updates to the low byte register between high byte and low byte reads. This
SMSC EMC1002
13
DATASHEET
Revision 1.3 (03-24-06)
1°C Dual SMBus Sensor with Resistance Error Correction
Datasheet
interlock mechanism requires that the high byte register always be read prior to reading the low byte
register.
4.9
Status Register
The status register is a read only register that stores the operational status of the part.
Table 4.4 Status Register
STATUS REGISTER
BIT
NAME
FUNCTION
7
Busy
6
LHIGH
1 when Internal Temperature High Limit is exceeded
5
LLOW
1 when Internal Temperature Low Limit is exceeded
4
R1HIGH
1 when Remote Temperature High Limit is exceeded
3
R1LOW
1 when Remote Temperature Low Limit is exceeded
2
FAULT
1 when Remote is open circuit
1
R1THRM
1 when Remote THERM Limit is exceeded
0
LTHRM
1 when Internal THERM Limit is exceeded
1 when ADC is converting
Bit 7 indicates that the ADC is busy converting a value. Bits 6 and 5 indicate that the internal
temperature is above or below its high or low limits respectively. Likewise, bits 4 and 3 indicate that
remote temperature is above or below its limits. See 4.12, "Limit Registers," on page 15 for detail on
the limits are compared. Bit 2 indicates that an open circuit on the remote diode anode connection has
been detected. Bits 1 and 0 indicate that the remote temperature or the internal temperature has
exceeded their respective THERM limits. If bits 1 or 0 go high the ADDR/THERM signal will be asserted.
When the status register is read, bits 2 through 6 will individually clear provided that the error condition
for that bit no longer exists. The ALERT/THERM2 output is latched and will not be reset until the host
has responded to the SMBALERT# with an alert response address. The ALERT/THERM2 signal will not
reset if the status register has not been cleared.
4.10
Configuration Register
The configuration register controls the functionality of the temperature measurements.
Table 4.5 Configuration Register
CONFIGURATION REGISTER
BIT
NAME
FUNCTION
DEFAULT
7
MASK1
0 = ALERT enabled
1 = ALERT disabled
0
6
RUN/STOP
0 = Active mode (continuously running)
1 = Standby mode
0
5
ALERT or THERM2
0 = ALERT
1 = THERM2
0
Revision 1.3 (03-24-06)
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DATASHEET
SMSC EMC1002
1°C Dual SMBus Sensor with Resistance Error Correction
Datasheet
Table 4.5 Configuration Register (continued)
CONFIGURATION REGISTER
BIT
NAME
4–3
2
1-0
FUNCTION
DEFAULT
Reserved
Temperature Range
Select
0
0 = 0°C to 127°C
1 = -64°C to 191°C
0
Reserved
0
Bit 7 is used to mask the ALERT/THERM2 output. When this bit is set to 0, any out of limit condition
will assert ALERT/THERM2. This bit is ignored if the ALERT/THERM2 pin is configured as THERM2 signal
by bit 5.
Bit 6 initiates ADC conversions. When this bit is low, the ADC will convert temperatures in a
continuous mode. When this bit is high, the ADC will be in standby mode, thus reducing supply
current significantly though the SMBus will still be active. If bit 6 is 1 and the one-shot register is
written to, the ADC will execute a temperature measurement and then return to standby mode.
Bit 5 sets the ALERT/THERM2 pin to act as either an SMBALERT# signal or as the THERM2 signal. If
bit 5 is set to 1 the ALERT/THERM2 pin acts as the THERM2 signal and bit 7 is ignored.
Bit 2 selects the range and format of the temperature as shown in Table 4.1, “Temperature Data
Format,” on page 11
4.11
Conversion Rate Register
The conversion rate register determines how many times the temperature value will be updated per
second. The lowest 4 bits configure a programmable delay that waits between consecutive conversion
cycles to obtain the desired conversion rate. Table 4.6 shows the conversion rate and the associated
quiescent current.
Table 4.6 Conversion Rates
CONVERSION RATE
4.12
VALUE
CONVERSIONS/SECOND
TYPICAL QUIESCENT CURRENT (μA)
00h
01h
02h
03h
04h
05h
06h
07h
08h
09h
0Ah
0Bh to FFh
0.0625
0.125
0.25
0.5
1
2
4
8
16
32
64
Reserved
47
50
53
56
68
78
106
165
281
500
550
Limit Registers
The EMC1002 compares the limit registers to the measured temperature. The data format of the
programmed limits for this comparison is the same as the measurement data format determined by
SMSC EMC1002
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DATASHEET
Revision 1.3 (03-24-06)
1°C Dual SMBus Sensor with Resistance Error Correction
Datasheet
the Configuration Register. The user is required to update the limit registers to the new format when
changing between measurement data formats.
The user can configure high and low temperature limits and an independent THERM limit. The
temperature high limit (TH) is an 11-bit value that is set by the Temperature High Limit High Byte
register and the Temperature High Limit Low Byte register. The Temperature High Limit Low Byte
register contains the three least significant bits as shown in Table 4.2 on page 11.
The temperature low limit (TL) is an 11-bit value that is set by the Temperature Low Limit High Byte
register and the Temperature Low Limit Low Byte register as shown in Table 4.2 on page 11.
The limits are automatically compared to the temperature measurement results (TM) and have been
exceeded if (TM ≤ TL or TM > TH). If either limit is exceeded then the appropriate bit is set high in the
status register and the ALERT/THERM2 output will respond as described in Section 4.5 on page 11.
The THERM limit (TTH) is a single byte value set by the THERM Limit register. Exceeding the THERM
limit asserts the ADDR / THERM signal as described in Section 4.6 on page 12. When the
ALERT/THERM2 pin is configured as THERM2, then exceeding the high limit asserts this pin.
4.13
THERM Hysteresis Register
The THERM hysteresis register holds a hysteresis value that impacts the de-assertion of THERM as
shown in Figure 4.4 on page 12. It defaults to 10°C and can be set by the user at any time after power
up. When the ALERT/THERM2 pin is configured as THERM2, then the output will not de-assert until the
temperature drops below the Temperature High Limit minus the THERM Hysteresis value.
4.14
One-Shot Register
Writing to the one-shot register while in standby mode initiates a conversion and comparison cycle.
The EMC1002 will execute a temperature measurement, compare the data to the limit registers and
return to the standby mode. A write to the one-shot register will be ignored if it occurs while the
EMC1002 is in run mode.
4.15
Scratchpad Registers
The scratchpad registers may be used to verify SMBus communications. These registers do not have
any affect on the operation of the device, and may be written and read via the SMBus.
4.16
Ideality Factor Register
The ideality factor registers are used to program the remote diode ideality factor into the EMC1002 so
that this error source can be eliminated. The default ideality factor is 1.008 and has a value of
XX010010b or 12h.
Table 4.7 Diode Ideality Factor Values
DIODE
IDEALITY
FACTOR
VALUE
DIODE
IDEALITY
FACTOR
DIODE
IDEALITY
FACTOR
VALUE
VALUE
DIODE
IDEALITY
FACTOR
VALUE
0.9850
XX00 0000
1.0054
XX01 0000
1.0267
XX10 0000
1.0489
XX11 0000
0.9862
XX00 0001
1.0067
XX01 0001
1.0280
XX10 0001
1.0503
XX11 0001
0.9875
XX00 0010
1.0080
XX01 0010
1.0294
XX10 0010
1.0517
XX11 0010
0.9888
XX00 0011
1.0093
XX01 0011
1.0308
XX10 0011
1.0531
XX11 0011
0.9900
XX00 0100
1.0106
XX01 0100
1.0321
XX10 0100
1.0546
XX11 0100
0.9913
XX00 0101
1.0119
XX01 0101
1.0335
XX10 0101
1.0560
XX11 0101
Revision 1.3 (03-24-06)
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DATASHEET
SMSC EMC1002
1°C Dual SMBus Sensor with Resistance Error Correction
Datasheet
Table 4.7 Diode Ideality Factor Values (continued)
DIODE
IDEALITY
FACTOR
VALUE
DIODE
IDEALITY
FACTOR
DIODE
IDEALITY
FACTOR
VALUE
DIODE
IDEALITY
FACTOR
VALUE
VALUE
0.9925
XX00 0110
1.0133
XX01 0110
1.0349
XX10 0110
1.0574
XX11 0110
0.9938
XX00 0111
1.0146
XX01 0111
1.0363
XX10 0111
1.0589
XX11 0111
0.9951
XX00 1000
1.0159
XX01 1000
1.0377
XX10 1000
1.0603
XX11 1000
0.9964
XX00 1001
1.0173
XX01 1001
1.0391
XX10 1001
1.0618
XX11 1001
0.9976
XX00 1010
1.0186
XX01 1010
1.0404
XX10 1010
1.0632
XX11 1010
0.9989
XX00 1011
1.0199
XX01 1011
1.0418
XX10 1011
1.0647
XX11 1011
1.0002
XX00 1100
1.0213
XX01 1100
1.0432
XX10 1100
1.0661
XX11 1100
1.0015
XX00 1101
1.0226
XX01 1101
1.0446
XX10 1101
1.0676
XX11 1101
1.0028
XX00 1110
1.0240
XX01 1110
1.0460
XX10 1110
1.0690
XX11 1110
1.0041
XX00 1111
1.0253
XX01 1111
1.0475
XX10 1111
1.0705
XX11 1111
4.17
Consecutive ALERT Register
Bit 7 of the Consecutive ALERT register enables the SMBus timeout feature when set to 1 (the default
setting is 0). When enabled, the SMBus will timeout after approximately 25ms of inactivity. Table 4.9
describes how bits 3-1 of the Consecutive ALERT register set how many consecutive error conditions
must occur for each temperature measurement zone before the ALERT/THERM2 signal is asserted.
These error conditions include diode faults and exceeding temperature limits. The default value is one
which means that any out-of-limit measurement or any diode fault will cause the ALERT/THERM2 pin
to be asserted. Any combination of bits 3-1 other than those shown will result in a value of one.
Table 4.8 Consecutive ALERT Register
BIT
7
NAME
SMBTE
6-4
Reserved
3-1
ALERTNUM
0
FUNCTION
DEFAULT
0 = SMBus timeout disabled
1 = SMBus timeout enabled
0
0
See Table 4.9
0
Reserved
0
Table 4.9 Consecutive ALERT Value
VALUE
NUMBER OF EVENTS REQUIRED
b3
b2
b1
1
0
0
0
2
0
0
1
3
0
1
1
4
1
1
1
SMSC EMC1002
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DATASHEET
Revision 1.3 (03-24-06)
1°C Dual SMBus Sensor with Resistance Error Correction
Datasheet
Chapter 5 Application Information
This chapter provides information on maintaining accuracy when using diodes as remote sensors with
SMSC Environmental Monitoring and Control devices. It is assumed that the users have some
familiarity with hardware design and transistor characteristics.
SMSC supplies a family Environmental Monitoring and Control (EMC) devices that are capable of
accurately measuring temperatures. Most devices include an internal temperature sensor along with
the ability to measure one or more external sensors. The characteristics of an appropriate diode for
use as the external sensor are listed in this chapter. Recommendations for the printed circuit board
layout are provided to help reduce error caused by electrical noise or trace resistance.
5.1
Maintaining Accuracy
5.1.1
Physical Factors
Temperature measurement is performed by measuring the change in forward bias voltage of a diode
when different currents are forced through the junction. The circuit board itself can impact the ability
to accurately measure these small changes in voltage.
5.1.1.1
Layout
Apply the following guidelines when designing the printed circuit board:
1. Route the remote diode traces on the top layer.
2. Place a ground guard signal on both sides of the differential pair. This guard band should be
connected to the ground plane at least every 0.25 inches.
3. Place a ground plane on the layer immediately below the diode traces.
4. Keep the diode traces as short as possible.
5. Keep the diode traces parallel, and the length of the two traces identical within 0.3 inches.
6. Use a trace width of 0.01 inches with a 0.01 inch guard band on each side.
7. Keep the diode traces away from sources of high frequency noise such as power supply filtering
or high speed digital signals.
8. When the diode traces must cross high speed digital signals, make them cross at a 90 degree
angle.
9. Avoid joints of copper to solder that can introduce thermocouple effects.
These recommendations are illustrated in Figure 5.1 Routing the Diode Traces on page 18.
.01 GAP MIN.
GND PLANE
.01 WIDE MIN.
.01 WIDE MIN.
.01 GAP MIN.
DP or DN
DP or DN
COPPER TRACE
COPPER TRACE
.01 GAP MIN.
GND PLANE
BOARD MATERIAL
COPPER PLANE (TO SHIELD FROM NOISE)
RECOMMEND VIA STICTCHING AT .25 INCH INTERVALS.
Figure 5.1 Routing the Diode Traces
Revision 1.3 (03-24-06)
18
DATASHEET
SMSC EMC1002
1°C Dual SMBus Sensor with Resistance Error Correction
Datasheet
5.1.1.2
Bypass Capacitors
Accurate temperature measurements require a clean, stable power supply. Locate a 0.1µF capacitor
as close as possible to the power pin with a good ground. A low ESR capacitor (such as a 10µF
ceramic) should be placed across the power source. Add additional power supply filtering in systems
that have a noisy power supply.
A capacitor may be placed across the DP/DN pair at the remote sensor in noisy environments. Do not
exceed a value of 2.2nF if this capacitor is installed.
5.1.1.3
Manufacturing
Circuit board assembly processes may leave a residue on the board. This residue can result in
unexpected leakage currents that may introduce errors if the circuit board is not clean. For example,
processes that use water-soluble soldering fluxes have been known to cause problems if the board is
not kept clean.
5.1.1.4
Thermal Considerations
Keep the sensor in good thermal contact with the component to be measured. The temperature of the
leads of a discrete diode will greatly impact the temperature of the diode junction. Make use of the
printed circuit board to disperse any self-heating that may occur.
5.1.1.5
Remote Sensors Connected by Cables
When connecting remote diodes with a cable (instead of traces on the PCB) use shielded twisted pair
cable. The shield should be attached to ground near the EMC1002, and should be left unconnected
at the sensor end. Belden 8451 cable is a good choice for this application.
5.1.2
Sensor Characteristics
The characteristics of the diode junction used for temperature sensing will affect the accuracy of the
measurement.
5.1.2.1
Selecting a Sensor
A diode connected small signal transistor is recommended. Silicon diodes are not a good choice for
remote sensors. Small signal transistors such as the 2N3904 or the 2N3906 are recommended. Select
a transistor with a constant value of hFE in the range of 2.5 to 220 microamps. The magnitude of hFE
is not critical, and the variation in hFE from one device to another cancels out of the temperature
equations.
5.1.2.2
Compensating for Ideality of the diode
The remote diode may have an ideality factor based on the manufacturing process. Inaccuracy in the
temperature measurement resulting from this ideality factor may be eliminated by configuring the
ideality factor register. The EMC1002 is trimmed to an ideality factor of 1.008.
5.1.2.3
Circuit Connections
The more negative terminal for the remote temperature diode, DN, is internally biased with a forward
diode voltage. Terminal DN is not referenced to ground. Remote temperature diodes can be
constructed as shown in Figure 5.2 Remote Temperature Diode Examples on page 20.
SMSC EMC1002
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DATASHEET
Revision 1.3 (03-24-06)
1°C Dual SMBus Sensor with Resistance Error Correction
Datasheet
To DP
To DP
To DP
To DN
To DN
To DN
Local Ground
Typical Remote Parasitic
Substrate Transistor
e.g. CPU substrate PNP
Typical Remote
Discrete PNP Transistor
e.g 2N3906
Typical Remote
Discrete NPN Transistor
e.g. 2N3904
Figure 5.2 Remote Temperature Diode Examples
Environmental Monitoring and Control (EMC) devices supplied by SMSC are designed to make
accurate temperature measurements. Careful design of the printed circuit board and proper selection
of the remote sensing diode will help to maintain the accuracy.
Revision 1.3 (03-24-06)
20
DATASHEET
SMSC EMC1002
1°C Dual SMBus Sensor with Resistance Error Correction
Datasheet
Chapter 6 Package Outlines
Figure 6.1 8-Pin MSOP and 8-Pin MSOP (Lead-Free) Package Outline - 3x3mm Body 0.65mm Pitch
Table 6.1 8-Pin MSOP and 8-Pin MSOP (Lead-Free) Package Parameters
MIN
NOMINAL
MAX
REMARKS
A
0.80
~
1.10
Overall Package Height
A1
0.05
~
0.15
Standoff
A2
0.75
0.85
0.95
Body Thickness
D
2.80
3.00
3.20
X Body Size
E
4.65
4.90
5.15
Y Span
E1
2.80
~
3.20
Y body Size
H
0.08
~
0.23
Lead Foot Thickness
L
0.40
~
0.80
Lead Foot Length
L1
0.95 REF
e
Lead Length
0.65 BSC
Lead Pitch
θ
0o
W
0.22
~
0.38
Lead Width
ccc
~
~
0.10
Coplanarity
~
8o
Lead Foot Angle
Notes:
1. Controlling Unit: millimeters.
2. Tolerance on the true position of the leads is ± 0.065 mm maximum.
3. Package body dimensions D and E1 do not include mold protrusion or flash. Dimensions D and
E1 to be determined at datum plane H. Maximum mold protrusion or flash is 0.15mm (0.006 inches)
per end, and 0.15mm (0.006 inches) per side.
4. Dimension for foot length L measured at the gauge plane 0.25 mm above the seating plane.
5. Details of pin 1 identifier are optional but must be located within the zone indicated.
SMSC EMC1002
21
DATASHEET
Revision 1.3 (03-24-06)
SEE DETAIL "A"
3
D
A
DESCRIPTION
DATE
RELEASED BY
INITIAL RELEASE
7/07/04
S.K.ILIEV
e
8
3
E1
E
1
2
4
INDEX AREA
(D/2 X E1/2)
2
8X b
c
4
END VIEW
TOP VIEW
C
SEATING PLANE
A
22
DATASHEET
A2
A1
ccc C
SIDE VIEW
3-D VIEW
NOTES:
1. ALL DIMENSIONS ARE IN MILLIMETER.
2. TRUE POSITION SPREAD TOLERANCE IS ± 0.125mm AT MAXIMUM MATERIAL CONDITION.
3. PACKAGE BODY DIMENSION "D" DOES NOT INCLUDE MOLD FLASH, PROTRUSIONS OR
GATE BURRS. MAXIMUM MOLD FLASH, PROTRUSIONS OR GATE BURRS IS 0.15 mm PER
END. DIMENSION "E1" DOES NOT INCLUDE INTERLEAD FLASH OR PROTRUSION.
MAXIMUM INTERLEAD FLASH OR PROTRUSION IS 0.25 mm PER SIDE. "D1" & "E1"
DIMENSIONS ARE DETERMINED AT DATUM PLANE "H".
4. DIMENSIONS "b" & "c" APPLY TO THE FLAT SECTION OF THE LEAD BETWEEN 0.10 TO
0.25 mm FROM THE LEAD TIP.
5. THE CHAMFER FEATURE IS OPTIONAL. IF IT IS NOT PRESENT, THEN A PIN 1 IDENTIFIER
MUST BE LOCATED WITHIN THE INDEX AREA INDICATED.
H
0.25
GAUGE PLANE
L
L1
DETAIL "A"
SCALE: 3/1
0
UNLESS OTHERWISE SPECIFIED
DIMENSIONS ARE IN MILLIMETERS
AND TOLERANCES ARE:
DECIMAL
X.X
±0.1
X.XX ±0.05
X.XXX ±0.025
THIRD ANGLE PROJECTION
80 ARKAY DRIVE
HAUPPAUGE, NY 11788
USA
ANGULAR
±1°
TITLE
NAME
DIM AND TOL PER ASME Y14.5M - 1994
MATERIAL
FINISH
-
PRINT WITH "SCALE TO FIT"
DO NOT SCALE DRAWING
DATE
DRAWN
S.K.ILIEV
7/07/04
CHECKED
S.K.ILIEV
DWG NUMBER
STD COMPLIANCE
SCALE
7/07/04
REV
MO-8-SOIC-4.9x3.9
7/07/04
APPROVED
S.K.ILIEV
PACKAGE OUTLINE
8 PIN SOIC, 3.9mm BODY WIDTH, 1.27mm PITCH
1:1
JEDEC: MS-012 / AA
A
SHEET
1 OF 1
Figure 6.2 8-Pin SOIC and 8-Pin SOIC (Lead-Free) Package Outline and Parameters - 3.9mm Body 1.27 mm Pitch
SMSC EMC1002
5
Revision 1.3 (03-24-06)
REVISION HISTORY
REVISION