EMC1182 Data Sheet

EMC1182
Dual Channel 1°C Temperature Sensor with Beta
Compensation and 1.8V SMBus Communications
PRODUCT FEATURES
Datasheet
General Description
Applications
The EMC1182 is a high accuracy, low cost, 1.8V System
Management Bus (SMBus) compatible temperature sensor.
Advanced features such as Resistance Error Correction (REC),
Beta Compensation (to support CPU diodes requiring the
BJT/transistor model including 65nm and lower geometry
processors) and automatic diode type detection combine to
provide a robust solution for complex environmental monitoring
applications. The ability to communicate at 1.8V SMBus levels
provides compatible I/O for the advanced processors found in
today’s tablet and smartphone applications.



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Notebook Computers
Desktop Computers
Industrial
Embedded applications
Features

Support for diodes requiring the BJT/transistor model
— Supports 65nm and lower geometry CPU thermal
diodes


The EMC1182 monitors two temperature channels (one
external and one internal), providing ±1°C accuracy for both
external and internal diode temperatures.


REC automatically eliminates the temperature error caused by
series resistance allowing greater flexibility in routing thermal
diodes. Frequency hopping* and analog filters ensure remote
diode traces can be as far as eight (8) inches without degrading
the signal. Beta Compensation eliminates temperature errors
caused by low, variable beta transistors common in today's fine
geometry processors. The automatic beta detection feature
monitors the external diode/transistor and determines the
optimum sensor settings for accurate temperature
measurements regardless of processor technology. This frees
the user from providing unique sensor configurations for each
temperature monitoring application. These advanced features
plus ±1°C measurement accuracy provide a low-cost, highly
flexible and accurate solution for critical temperature monitoring
applications.


Pin and register compatible with EMC1412
Automatically determines external diode type and
optimal settings
Resistance Error Correction
Frequency hops the remote sample frequency to reject
DC converter and other coherent noise sources*
Consecutive Alert queue to further reduce false Alerts
Up to 1 External Temperature Monitor
— 25°C typ, ±1°C max accuracy (20°C < TDIODE < 110°C)
— 0.125°C resolution
— Supports up to 2.2nF diode filter capacitor

Internal Temperature Monitor
— ±1°C accuracy
— 0.125°C resolution
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3.3V Supply Voltage
1.8V SMBus operation
Programmable temperature limits for ALERT/THERM2
(85°C default high limit and 0°C default low limit) and
THERM (85°C default)
Available in small 8-pin 2mm x 3mm TDFN RoHS
compliant package
Available in small 8-pin 3mm x 3mm DFN RoHS
compliant package
VDD = 3.3V
1.8V
1.8V – 3.3V
VDD
VDD
EMC1182
DP
Internal
Temp Diode
ALERT / THERM2
Interupt Masking
THERM / ADDR
SMBus Address Decode
External
Temperature
Register(s)
Internal
Temperature
Register
High Limit Registers
THERM Limit Register
THERM Hysteresis
Register
SMBus Interface
ΔΣADC
Digital Mux
Analog
Mux
Digital Mux
Low Limit Registers
Limit Comparator
DP
1
D
N1
Host
CPU / GPU
Conversion Rate Register
Switching
Current
SMCLK
Thermal
Junction
SMCLK
DN
SMDATA
EMC1182
SMDATA
SMBus
Interface
ALERT / THERM2
Configuration Register
THERM / ADDR
GND
Status Registers
Power Control
GND
* Technology covered under the US patent 7,193,543.
SMSC EMC1182
Revision 1.0 (07-11-13)
DATASHEET
Dual Channel 1°C Temperature Sensor with Beta Compensation and 1.8V SMBus Communications
Datasheet
Ordering Information:
ORDERING NUMBER
PACKAGE
FEATURES
SMBUS
ADDRESS
EMC1182-A-AC3-TR
8-pin TDFN 2mm x 3mm
(RoHS compliant)
Two temperature sensors, ALERT/THERM2
and THERM pins, fixed SMBus address
Selectable via
THERM pull-up
EMC1182-1-AIA-TR
8-pin DFN 3mm x 3mm
(RoHS compliant)
Two temperature sensors, ALERT/THERM2
and THERM pins, fixed SMBus address
1001_100(r/w)
EMC1182-1-AC3-TR
8-pin TDFN 2mm x 3mm
(RoHS compliant)
Two temperature sensors, ALERT/THERM2
and THERM pins, fixed SMBus address
1001_100(r/w)
EMC1182-2-AIA-TR
8-pin DFN 3mm x 3mm
(RoHS compliant)
Two temperature sensors, ALERT/THERM2
and THERM pins, fixed SMBus address
1001_101(r/w)
EMC1182-2-AC3-TR
8-pin TDFN 2mm x 3mm
(RoHS compliant)
Two temperature sensors, ALERT/THERM2
and THERM pins, fixed SMBus address
1001_101(r/w)
This product meets the halogen maximum concentration values per IEC61249-2-21
For RoHS compliance and environmental information, please visit www.smsc.com/rohs
Please contact your SMSC sales representative for additional documentation related to this product
such as application notes, anomaly sheets, and design guidelines.
Copyright © 2013 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.
The Microchip name and logo, and the Microchip logo are registered trademarks of Microchip Technology Incorporated in the U.S.A. and other countries.
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 1.0 (07-11-13)
2
DATASHEET
SMSC EMC1182
Dual Channel 1°C Temperature Sensor with Beta Compensation and 1.8V SMBus Communications
Datasheet
Table of Contents
Chapter 1 Block Diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
Chapter 2 Pin Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
Chapter 3 Electrical Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
3.1 Absolute Maximum Ratings. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
3.2 Electrical Specifications. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
3.3 SMBus Electrical Characteristics. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
Chapter 4 System Management Bus Interface Protocol . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
4.1 Communications Protocol . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
4.1.1 SMBus Start Bit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
4.1.2 SMBus Address and RD / WR Bit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
4.1.3 THERM Pin Considerations. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
4.1.5 SMBus Data Bytes. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
4.1.6 SMBus ACK and NACK Bits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
4.1.7 SMBus Stop Bit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
4.1.8 SMBus Timeout . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
4.1.9 SMBus and I2C Compatibility . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
4.2 SMBus Protocols . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
4.2.1 Write Byte . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
4.2.2 Read Byte . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
4.2.3 Send Byte . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
4.2.4 Receive Byte . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
4.3 Alert Response Address . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
13
13
13
14
14
14
15
15
15
15
16
16
16
16
17
Chapter 5 Product Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
5.1 Modes of Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
5.2 Conversion Rates . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
5.3 Dynamic Averaging . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
5.4 THERM Output . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
5.4.1 THERM Pin Considerations. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
5.5 ALERT / THERM2 Output . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
5.5.1 ALERT / THERM2 Pin InterruptALERT Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
5.5.2 ALERT / THERM2 Pin ComparatorTHERM Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
5.6 Temperature Measurement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
5.6.1 Beta Compensation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
5.6.2 Resistance Error Correction (REC) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
5.6.3 Programmable External Diode Ideality Factor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
5.7 Diode Faults . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
5.8 Consecutive Alerts. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
5.9 Digital Filter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
5.10 Temperature Measurement Results and Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
18
19
19
19
20
20
20
20
21
21
21
21
22
22
22
24
Chapter 6 Register Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
6.1 Data Read Interlock. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
6.2 Temperature Data Registers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
6.3 Status Register 02h . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
SMSC EMC1182
3
DATASHEET
Revision 1.0 (07-11-13)
Dual Channel 1°C Temperature Sensor with Beta Compensation and 1.8V SMBus Communications
Datasheet
6.4 Configuration Register 03h / 09h. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
6.5 Conversion Rate Register 04h / 0Ah . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
6.6 Limit Registers. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
6.7 Scratchpad Registers 11h and 12h . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
6.8 One Shot Register 0Fh . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
6.9 Therm Limit Registers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
6.10 Channel Mask Register 1Fh . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
6.11 Consecutive ALERT Register 22h. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
6.12 Beta Configuration Register 25h . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
6.13 External Diode Ideality Factor Register 27h . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
6.14 Filter Control Register 40h. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
6.15 Product ID Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
6.16 SMSC ID Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
6.17 Revision Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
28
29
30
31
31
32
32
33
34
35
37
37
37
38
Chapter 7 Typical Operating Curves . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39
Chapter 8 Package Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40
8.1 Package Markings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45
Chapter 9 Datasheet Revision History . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48
Revision 1.0 (07-11-13)
4
DATASHEET
SMSC EMC1182
Dual Channel 1°C Temperature Sensor with Beta Compensation and 1.8V SMBus Communications
Datasheet
List of Figures
Figure 1.1
Figure 2.1
Figure 4.1
Figure 4.4
Figure 5.1
Figure 5.2
Figure 5.3
Figure 5.4
Figure 5.5
Figure 8.1
Figure 8.3
Figure 8.2
Figure 8.4
Figure 8.5
Figure 8.6
Figure 8.7
Figure 8.8
Figure 8.9
Figure 8.10
Figure 8.11
EMC1182 Block Diagram. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
EMC1182 Pin Diagram, TDFN-8 2mm x 3mm / DFN-8 3mm x 3mm . . . . . . . . . . . . . . . . . . . 8
SMBus Timing Diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
Isolating the THERM pin . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
System Diagram for EMC1182 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
Isolating THERM Pin . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
Isolating ALERT and SYS_SHDN Pin . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
Temperature Filter Step Response . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
Temperature Filter Impulse Response. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
2mm x 3mm TDFN Package Drawing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40
2mm x 3mm TDFN Package PCB Land Pattern . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41
2mm x 3mm TDFN Package Dimensions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41
3mm x 3mm DFN Package Drawing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42
3mm x 3mm DFN Package Dimensions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43
8 Pin DFN PCB Footprint . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44
EMC1182-1 8-Pin TDFN Package Markings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45
EMC1182-2 8-Pin TDFN Package Markings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45
EMC1182-A 8-Pin TDFN Package Markings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46
EMC1182-1 8-Pin DFN Package Markings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46
EMC1182-2 8-Pin DFN Package Markings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47
SMSC EMC1182
5
DATASHEET
Revision 1.0 (07-11-13)
Dual Channel 1°C Temperature Sensor with Beta Compensation and 1.8V SMBus Communications
Datasheet
List of Tables
Table 2.1 EMC1182 Pin Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
Table 2.2 Pin Types. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
Table 3.1 Absolute Maximum Ratings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
Table 3.2 Electrical Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
Table 3.3 SMBus Electrical Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
Table 4.1 SMBus Address Decode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
Table 4.1 Protocol Format . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
Table 4.2 Write Byte Protocol . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
Table 4.3 Read Byte Protocol . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
Table 4.4 Send Byte Protocol . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
Table 4.5 Receive Byte Protocol . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
Table 4.6 Alert Response Address Protocol . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
Table 5.1 Supply Current vs. Conversion Rate for EMC1182 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
Table 5.2 Temperature Data Format . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
Table 6.1 Register Set in Hexadecimal Order . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
Table 6.2 Temperature Data Registers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
Table 6.3 Status Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
Table 6.4 Configuration Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
Table 6.5 Conversion Rate Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
Table 6.6 Conversion Rate . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
Table 6.7 Temperature Limit Registers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
Table 6.8 Scratchpad Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
Table 6.9 Therm Limit Registers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
Table 6.10 Channel Mask Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
Table 6.11 Consecutive ALERT Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
Table 6.12 Consecutive Alert / Therm Settings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
Table 6.13 Beta Configuration Register. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
Table 6.14 Ideality Configuration Registers. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
Table 6.15 Ideality Factor Look-Up Table (Diode Model) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
Table 6.16 Substrate Diode Ideality Factor Look-Up Table (BJT Model) . . . . . . . . . . . . . . . . . . . . . . . . . 36
Table 6.17 Filter Configuration Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37
Table 6.18 FILTER Decode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37
Table 6.19 Product ID Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37
Table 6.20 Manufacturer ID Register. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37
Table 6.21 Revision Register. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38
Table 9.1 Customer Revision History . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48
Revision 1.0 (07-11-13)
6
DATASHEET
SMSC EMC1182
Dual Channel 1°C Temperature Sensor with Beta Compensation and 1.8V SMBus Communications
Datasheet
Chapter 1 Block Diagram
VDD
EMC1182
Conversion Rate Register
Switching
Current
Low Limit Registers
ALERT
THERM / ADDR
THERM Limit Register
THERM Hysteresis Register
SMBus Interface
Internal Temp
Diode
External Temperature
Register(s)
High Limit Registers
Digital Mux
ΔΣ ADC
DN
Digital Mux
Analog
Mux
Limit Comparator
SMCLK
DP
SMDATA
Internal
Temperature Register
Interupt Masking
Configuration Register
SMBus Address Decode
Status Registers
GND
Figure 1.1 EMC1182 Block Diagram
SMSC EMC1182
7
DATASHEET
Revision 1.0 (07-11-13)
Dual Channel 1°C Temperature Sensor with Beta Compensation and 1.8V SMBus Communications
Datasheet
Chapter 2 Pin Description
EMC1182
VDD
1
8
SMCLK
DP
2
7
SMDATA
Exposed pad
DN
3
6
ALERT / THERM2
THERM / ADDR
4
5
GND
Figure 2.1 EMC1182 Pin Diagram, TDFN-8 2mm x 3mm / DFN-8 3mm x 3mm
Table 2.1 EMC1182 Pin Description
PIN NUMBER
NAME
1
VDD
2
DP
External diode positive (anode) connection
AIO
3
DN
External diode negative (cathode) connection
AIO
4
FUNCTION
Power supply
TYPE
Power
THERM - Active low Critical THERM output
signal - requires pull-up resistor
OD (5V)
ADDR - Selects SMBus address based on pullup resistor
OD (5V)
THERM / ADDR
5
GND
6
ALERT / THERM2
Active low digital ALERT / THERM2 output
signal - requires pull-up resistor
OD (5V)
7
SMDATA
SMBus Data input/output - requires pull-up
resistor
DIOD (5V)
8
SMCLK
SMBus Clock input - requires pull-up resistor
Bottom Pad
Exposed Pad
Revision 1.0 (07-11-13)
Ground
Power
Not internally connected, but recommend
grounding.
8
DATASHEET
DI (5V)
-
SMSC EMC1182
Dual Channel 1°C Temperature Sensor with Beta Compensation and 1.8V SMBus Communications
Datasheet
The pin types are described Table 2.2.
Table 2.2 Pin Types
PIN TYPE
Power
AIO
DI
DESCRIPTION
This pin is used to supply power or ground to the device.
Analog Input / Output -This pin is used as an I/O for analog signals.
Digital Input - This pin is used as a digital input. This pin is 5V tolerant.
DIOD
Digital Input / Open Drain Output - This pin is used as a digital I/O. When it is used as
an output, it is open drain and requires a pull-up resistor. This pin is 5V tolerant.
OD
Open Drain Digital Output - This pin is used as a digital output. It is open drain and
requires a pull-up resistor. This pin is 5V tolerant.
SMSC EMC1182
9
DATASHEET
Revision 1.0 (07-11-13)
Dual Channel 1°C Temperature Sensor with Beta Compensation and 1.8V SMBus Communications
Datasheet
Chapter 3 Electrical Specifications
3.1
Absolute Maximum Ratings
Table 3.1 Absolute Maximum Ratings
DESCRIPTION
RATING
UNIT
Supply Voltage (VDD)
-0.3 to 4.0
V
Voltage on 5V tolerant pins (V5VT_pin)
-0.3 to 5.5
V
0 to 3.6
V
-0.3 to VDD +0.3
V
Operating Temperature Range
-40 to +125
°C
Storage Temperature Range
-55 to +150
°C
Voltage on 5V tolerant pins (|V5VT_pin - VDD|) (see Note 3.1)
Voltage on any other pin to Ground
Lead Temperature Range
Refer to JEDEC Spec. J-STD-020
Package Thermal Characteristics for TDFN-8
Thermal Resistance (θj-a)
ESD Rating, All pins HBM
89
°C/W
2000
V
Note: Stresses at or above those listed could cause permanent 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.
Note 3.1
3.2
For the 5V tolerant pins that have a pull-up resistor (SMCLK, SMDATA, THERM, and
ALERT / THERM2), the pull-up voltage must not exceed 3.6V when the device is
unpowered.
Electrical Specifications
Table 3.2 Electrical Specifications
VDD = 3.0V to 3.6V, TA = -40°C to 125°C, all typical values at TA = 27°C unless otherwise noted.
CHARACTERISTIC
SYMBOL
MIN
TYP
MAX
UNITS
CONDITIONS
DC Power
Supply Voltage
VDD
Supply Current
IDD
Revision 1.0 (07-11-13)
3.0
3.3
3.6
V
200
410
µA
0.0625 conversion / sec, dynamic
averaging disabled
215
425
µA
1 conversion / sec, dynamic
averaging disabled
10
DATASHEET
SMSC EMC1182
Dual Channel 1°C Temperature Sensor with Beta Compensation and 1.8V SMBus Communications
Datasheet
Table 3.2 Electrical Specifications (continued)
VDD = 3.0V to 3.6V, TA = -40°C to 125°C, all typical values at TA = 27°C unless otherwise noted.
CHARACTERISTIC
SYMBOL
MIN
TYP
MAX
IDD
CONDITIONS
325
465
µA
4 conversions / sec, dynamic
averaging disabled
890
1050
µA
4 conversions / sec, dynamic
averaging enabled
µA
> 16 conversions / sec, dynamic
averaging enabled
µA
Device in Standby mode, no SMBus
communications, ALERT and
THERM pins not asserted.
1120
Standby Supply Current
UNITS
170
230
Internal Temperature Monitor
Temperature Accuracy
±0.25
Temperature Resolution
±1
°C
-5°C < TA < 100°C
±2
°C
-40°C < TA < 125°C
0.125
°C
External Temperature Monitor
Temperature Accuracy
Temperature Resolution
±0.25
±1
°C
+20°C < TDIODE < +110°C
0°C < TA < 100°C
±0.5
±2
°C
-40°C < TDIODE < 127°C
0.125
°C
ms
default settings
nF
Connected across external diode
Conversion Time all
Channels
tCONV
190
Capacitive Filter
CFILTER
2.2
2.7
ALERT / THERM2 and THERM pins
Output Low Voltage
VOL
Leakage Current
ILEAK
SMSC EMC1182
0.4
±5
11
DATASHEET
V
ISINK = 8mA
µA
ALERT / THERM2 and SYS_SHDN
pins
Device powered or unpowered
TA < 85°C
pull-up voltage < 3.6V
Revision 1.0 (07-11-13)
Dual Channel 1°C Temperature Sensor with Beta Compensation and 1.8V SMBus Communications
Datasheet
3.3
SMBus Electrical Characteristics
Table 3.3 SMBus Electrical Specifications
VDD = 3.0 to 3.6V, TA = -40°C to 125°C, all typical values are at TA = 27°C unless otherwise noted.
CHARACTERISTIC
SYMBOL
MIN
TYP
MAX
UNITS
CONDITIONS
SMBus Interface
Input High Voltage
VIH
1.4
VDD
V
5V Tolerant. Voltage threshold
based on 1.8V operation
Input Low Voltage
VIL
-0.3
0.8
V
5V Tolerant. Voltage threshold
based on 1.8V operation
Leakage Current
ILEAK
±5
µA
Powered or unpowered
TA < 85°C
Hysteresis
50
Input Capacitance
CIN
Output Low Sink Current
IOL
mV
5
pF
8.2
15
mA
SMDATA = 0.4V
SMBus Timing
Clock Frequency
fSMB
Spike Suppression
tSP
Bus Free Time Stop to
Start
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
µs
When transmitting to the master
Data Hold Time
tHD:DAT
0.3
µs
When receiving from the master
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
tFALL
300
ns
Min = 20+0.1CLOAD ns
Clock/Data Rise time
tRISE
300
ns
Min = 20+0.1CLOAD ns
Capacitive Load
CLOAD
400
pF
per bus line
Timeout
tTIMEOUT
35
ms
Disabled by default
Revision 1.0 (07-11-13)
10
25
400
kHz
50
ns
12
DATASHEET
SMSC EMC1182
Dual Channel 1°C Temperature Sensor with Beta Compensation and 1.8V SMBus Communications
Datasheet
Chapter 4 System Management Bus Interface Protocol
4.1
Communications Protocol
The EMC1182 communicates with a host controller, such as an SMSC SIO, through the SMBus. The
SMBus is a two-wire serial communication protocol between a computer host and its peripheral
devices. A detailed timing diagram is shown in Figure 4.1.
For the first 15ms after power-up the device may not respond to SMBus communications.
.
T LOW
T HD:STA
T HIGH
T SU:STO
T FALL
SMCLK
T RISE
T HD:STA
T HD:DAT
T SU:DAT
T SU:STA
SMDATA
TBUF
S
P
S
S - Start Condition
P - Stop Condition
P
Figure 4.1 SMBus Timing Diagram
4.1.1
SMBus Start Bit
The SMBus Start bit is defined as a transition of the SMBus Data line from a logic ‘1’ state to a logic
‘0’ state while the SMBus Clock line is in a logic ‘1’ state.
4.1.2
SMBus Address and RD / WR Bit
The SMBus Address Byte consists of the 7-bit client address followed by the RD / WR indicator bit. If
this RD / WR bit is a logic ‘0’, the SMBus Host is writing data to the client device. If this RD / WR bit
is a logic ‘1’, the SMBus Host is reading data from the client device.
The EMC1182-A SMBus slave address is determined by the pull-up resistor on the THERM pin as
shown in Table 4.1, "SMBus Address Decode".
The Address decode is performed by pulling known currents from VDD through the external resistor
causing the pin voltage to drop based on the respective current / resistor relationship. This pin voltage
is compared against a threshold that determines the value of the pull-up resistor.
Table 4.1 SMBus Address Decode
SMSC EMC1182
PULL UP RESISTOR ON
THERM PIN (±5%)
SMBUS ADDRESS
4.7k
1111_100(r/w)b
6.8k
1011_100(r/w)b
13
DATASHEET
Revision 1.0 (07-11-13)
Dual Channel 1°C Temperature Sensor with Beta Compensation and 1.8V SMBus Communications
Datasheet
Table 4.1 SMBus Address Decode (continued)
PULL UP RESISTOR ON
THERM PIN (±5%)
SMBUS ADDRESS
10k
1001_100(r/w)b
15k
1101_100(r/w)b
22k
0011_100(r/w)b
33k
0111_100(r/w)b
The EMC1182-1 SMBus address is hard coded to 1001_100(r/w).
The EMC1182-2 SMBus address is hard coded to 1001_101(r/w).
4.1.3
THERM Pin Considerations
Because of the decode method used to determine the SMBus Address, it is important that the pull-up
resistance on the THERM pin be within the tolerances shown in Table 4.1. Additionally, the pull-up
resistor on the THERM pin must be connected to the same 3.3V supply that drives the VDD pin.
For 15ms after power up, the THERM pin must not be pulled low or the SMBus address will not be
decoded properly. If the system requirements do not permit these conditions, the THERM pin must be
isolated from its hard-wired OR’d bus during this time.
One method of isolating this pin is shown in Figure 4.4, "Isolating the THERM pin".
+3.3V
+2.5 - 5V
4.7K -
22K
33K
VDD
1
DP
2
8
SMCLK
7
SMDATA
EMC1182
DN
3
6
ALERT / ADDR
THERM
4
5
GND
Shared THERM
Figure 4.4 Isolating the THERM pin
4.1.5
SMBus Data Bytes
All SMBus Data bytes are sent most significant bit first and composed of 8-bits of information.
4.1.6
SMBus ACK and NACK Bits
The SMBus client will acknowledge all data bytes that it receives. This is done by the client device
pulling the SMBus data line low after the 8th bit of each byte that is transmitted. This applies to the
Write Byte protocol.
The Host will NACK (not acknowledge) the last data byte to be received from the client by holding the
SMBus data line high after the 8th data bit has been sent.
Revision 1.0 (07-11-13)
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DATASHEET
SMSC EMC1182
Dual Channel 1°C Temperature Sensor with Beta Compensation and 1.8V SMBus Communications
Datasheet
4.1.7
SMBus Stop Bit
The SMBus Stop bit is defined as a transition of the SMBus Data line from a logic ‘0’ state to a logic
‘1’ state while the SMBus clock line is in a logic ‘1’ state. When the device detects an SMBus Stop bit
and it has been communicating with the SMBus protocol, it will reset its client interface and prepare
to receive further communications.
4.1.8
SMBus Timeout
The EMC1182 supports SMBus Timeout. If the clock line is held low for longer than tTIMEOUT, the
device will reset its SMBus protocol. This function can be enabled by setting the TIMEOUT bit (see
Section 6.11, "Consecutive ALERT Register 22h").
4.1.9
SMBus and I2C Compatibility
The EMC1182 is compatible with SMBus and I2C. The major differences between SMBus and I2C
devices are highlighted here. For more information, refer to the SMBus 2.0 and I2C specifications. For
information on using the EMC1182 in an I2C system, refer to SMSC AN 14.0 SMSC Dedicated Slave
Devices in I2C Systems.
1. EMC1182 supports I2C fast mode at 400kHz. This covers the SMBus max time of 100kHz.
2. Minimum frequency for SMBus communications is 10kHz.
3. The SMBus client protocol will reset if the clock is held at a logic ‘0’ for longer than 30ms. This
timeout functionality is disabled by default in the EMC1182 and can be enabled by writing to the
TIMEOUT bit. I2C does not have a timeout.
4. I2C devices do not support the Alert Response Address functionality (which is optional for SMBus).
Attempting to communicate with the EMC1182 SMBus interface with an invalid slave address or invalid
protocol will result in no response from the device and will not affect its register contents. Stretching
of the SMCLK signal is supported, provided other devices on the SMBus control the timing.
4.2
SMBus Protocols
The device supports Send Byte, Read Byte, Write Byte, Receive Byte, and the Alert Response Address
as valid protocols as shown below.
All of the below protocols use the convention in Table 4.1.
Table 4.1 Protocol Format
SMSC EMC1182
DATA SENT
TO DEVICE
DATA SENT TO
THE HOST
# of bits sent
# of bits sent
15
DATASHEET
Revision 1.0 (07-11-13)
Dual Channel 1°C Temperature Sensor with Beta Compensation and 1.8V SMBus Communications
Datasheet
4.2.1
Write Byte
The Write Byte is used to write one byte of data to the registers, as shown in Table 4.2.
Table 4.2 Write Byte Protocol
START
SLAVE
ADDRESS
WR
ACK
REGISTER
ADDRESS
ACK
REGISTER
DATA
ACK
STOP
1 -> 0
YYYY_YYY
0
0
XXh
0
XXh
0
0 -> 1
4.2.2
Read Byte
The Read Byte protocol is used to read one byte of data from the registers as shown in Table 4.3.
Table 4.3 Read Byte Protocol
START
SLAVE
ADDRESS
WR
ACK
REGISTER
ADDRESS
ACK
START
SLAVE
ADDRESS
RD
ACK
REGISTER
DATA
NACK
STOP
1 -> 0
YYYY_
YYY
0
0
XXh
0
1 -> 0
YYYY_
YYY
1
0
XX
1
0 -> 1
4.2.3
Send Byte
The Send Byte protocol is used to set the internal address register pointer to the correct address
location. No data is transferred during the Send Byte protocol as shown in Table 4.4.
Table 4.4 Send Byte Protocol
START
SLAVE
ADDRESS
WR
ACK
REGISTER
ADDRESS
ACK
STOP
1 -> 0
YYYY_YYY
0
0
XXh
0
0 -> 1
4.2.4
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 is used for consecutive reads
of the same register as shown in Table 4.5.
Table 4.5 Receive Byte Protocol
START
SLAVE
ADDRESS
RD
ACK
REGISTER DATA
NACK
STOP
1 -> 0
YYYY_YYY
1
0
XXh
1
0 -> 1
Revision 1.0 (07-11-13)
16
DATASHEET
SMSC EMC1182
Dual Channel 1°C Temperature Sensor with Beta Compensation and 1.8V SMBus Communications
Datasheet
4.3
Alert Response Address
The ALERT output can be used as a processor interrupt or as an SMBus Alert.
When it detects that the ALERT pin is asserted, the host will send the Alert Response Address (ARA)
to the general address of 0001_100xb. All devices with active interrupts will respond with their client
address as shown in Table 4.6.
Table 4.6 Alert Response Address Protocol
START
ALERT
RESPONSE
ADDRESS
RD
ACK
DEVICE
ADDRESS
NACK
STOP
1 -> 0
0001_100
1
0
YYYY_YYY
1
0 -> 1
The EMC1182 will respond to the ARA in the following way:
1. Send Slave Address and verify that full slave address was sent (i.e. the SMBus communication
from the device was not prematurely stopped due to a bus contention event).
2. Set the MASK_ALL bit to clear the ALERT pin.
APPLICATION NOTE: The ARA does not clear the Status Register and if the MASK_ALL bit is cleared prior to the
Status Register being cleared, the ALERT pin will be reasserted.
SMSC EMC1182
17
DATASHEET
Revision 1.0 (07-11-13)
Dual Channel 1°C Temperature Sensor with Beta Compensation and 1.8V SMBus Communications
Datasheet
Chapter 5 Product Description
The is an SMBus temperature sensor. The EMC1182 monitors one internal diode and one externally
connected temperature diode.
Thermal management is performed in cooperation with a host device. This consists of the host reading
the temperature data of both the external and internal temperature diodes of the EMC1182 and using
that data to control the speed of one or more fans.
The EMC1182 has two levels of monitoring. The first provides a maskable ALERT / THERM2 signal
to the host when the measured temperatures exceeds user programmable limits. This allows the
EMC1182 to be used as an independent thermal watchdog to warn the host of temperature hot spots
without direct control by the host. The second level of monitoring provides a non-maskable interrupt
on the THERM pin if the measured temperatures meet or exceed a second programmable limit.
Figure 5.1 shows a system level block diagram of the EMC1182.
VDD = 3.3V
1.8V
1.8V – 3.3V
VDD
CPU / GPU
Host
DP
Thermal
Junction
DN
SMCLK
EMC1182
SMDATA
ALERT / THERM2
SMBus
Interface
THERM / ADDR
GND
Power
Control
Figure 5.1 System Diagram for EMC1182
5.1
Modes of Operation
The EMC1182 has two modes of operation.

Active (Run) - In this mode of operation, the ADC is converting on all temperature channels at the
programmed conversion rate. The temperature data is updated at the end of every conversion and
the limits are checked. In Active mode, writing to the one-shot register will do nothing.

Standby (Stop) - In this mode of operation, the majority of circuitry is powered down to reduce
supply current. The temperature data is not updated and the limits are not checked. In this mode
of operation, the SMBus is fully active and the part will return requested data. Writing to the oneshot register will enable the device to update all temperature channels. Once all the channels are
updated, the device will return to the Standby mode.
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Dual Channel 1°C Temperature Sensor with Beta Compensation and 1.8V SMBus Communications
Datasheet
5.2
Conversion Rates
The EMC1182 may be configured for different conversion rates based on the system requirements.
The conversion rate is configured as described in Section 6.5. The default conversion rate is 4
conversions per second. Other available conversion rates are shown in Table 6.6, "Conversion Rate".
5.3
Dynamic Averaging
Dynamic averaging causes the EMC1182 to measure the external diode channels for an extended time
based on the selected conversion rate. This functionality can be disabled for increased power savings
at the lower conversion rates (see Section 6.4, "Configuration Register 03h / 09h"). When dynamic
averaging is enabled, the device will automatically adjust the sampling and measurement time for the
external diode channels. This allows the device to average 2x or 16x longer than the normal 11 bit
operation (nominally 21ms per channel) while still maintaining the selected conversion rate. The
benefits of dynamic averaging are improved noise rejection due to the longer integration time as well
as less random variation of the temperature measurement.
When enabled, the dynamic averaging applies when a one-shot command is issued. The device will
perform the desired averaging during the one-shot operation according to the selected conversion rate.
When enabled, the dynamic averaging will affect the average supply current based on the chosen
conversion rate as shown in Table 5.1.
Table 5.1 Supply Current vs. Conversion Rate for EMC1182
AVERAGE SUPPLY CURRENT
(TYPICAL)
AVERAGING FACTOR (BASED ON
11-BIT OPERATION)
CONVERSION RATE
ENABLED
(DEFAULT)
DISABLED
ENABLED
(DEFAULT)
DISABLED
1 / 16 sec
210uA
200uA
16x
1x
1 / 8 sec
265uA
200uA
16x
1x
1 / 4 sec
330uA
200uA
16x
1x
1 / 2 sec
395uA
200uA
16x
1x
1 / sec
460uA
215uA
16x
1x
4 / sec (default)
890uA
325uA
8x
1x
8 / sec
1010uA
630uA
4x
1x
16 / sec
1120uA
775uA
2x
1x
32 / sec
1200uA
1050uA
1x
1x
64 / sec
1400uA
1100uA
0.5x
0.5x
5.4
THERM Output
The THERM output is asserted independently of the ALERT output and cannot be masked. Whenever
any of the measured temperatures exceed the user programmed Therm Limit values for the
programmed number of consecutive measurements, the THERM output is asserted. Once it has been
asserted, it will remain asserted until all measured temperatures drop below the Therm Limit minus
the Therm Hysteresis (also programmable).
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When the THERM pin is asserted, the THERM status bits will likewise be set. Reading these bits will
not clear them until the THERM pin is deasserted. Once the THERM pin is deasserted, the THERM
status bits will be automatically cleared.
5.4.1
THERM Pin Considerations
Because of the decode method used to determine the SMBus Address, it is important that the pull-up
resistance on THERM pin be within ±10% tolerance. Additionally, the pull-up resistor on the THERM
pin must be connected to the same 3.3V supply that drives the VDD pin.
For 15ms after power up, the THERM pin must not be pulled low or the SMBus Address will not be
decoded properly. If the system requirements do not permit these conditions, the THERM pin must be
isolated from the bus during this time. One method of isolating this pin is shown in Figure 5.2.
.
+3.3V
+2.5 - 5V
22
K
4.7K 33
K
VDD
1
DP
2
DN
THERM /
ADDR
Shared THERM
3
EMC1182
4
8
SMCLK
7
SMDATA
6
ALERT
5
GND
Figure 5.2 Isolating THERM Pin
5.5
ALERT / THERM2 Output
The ALERT / THERM2 pin is an open drain output and requires a pull-up resistor to VDD and has two
modes of operation: interrupt mode and comparator mode. The mode of the ALERT / THERM2 output
is selected via the ALERT / COMPALERT/THERM bit in the Configuration Register (see Section 6.4).
5.5.1
ALERT / THERM2 Pin InterruptALERT Mode
When configured to operate in interrupt mode, the ALERT / THERM2 pin asserts low when an out of
limit measurement (> high limit or < low limit) is detected on any diode or when a diode fault is
detected, functioning as any standard ALERT in on the SMBus. The ALERT / THERM2 pin will remain
asserted as long as an out-of-limit condition remains. Once the out-of-limit condition has been
removed, the ALERT / THERM2 pin will remain asserted until the appropriate status bits are cleared.
The ALERT/ THERM2 pin can be masked by setting the MASK_ALL bit. Once the ALERT / THERM2
pin has been masked, it will be de-asserted and remain de-asserted until the MASK_ALL bit is cleared
by the user. Any interrupt conditions that occur while the ALERT / THERM2 pin is masked will update
the Status Register normally. There are also individual channel masks (see Section 6.10).
The ALERT / THERM2 pin is used as an interrupt signal or as an SMBus Alert signal that allows an
SMBus slave to communicate an error condition to the master. One or more ALERT / THERM2 outputs
can be hard-wired together.
5.5.2
ALERT / THERM2 Pin ComparatorTHERM Mode
When the ALERT / THERM2 pin is configured to operate in comparator mode, it will be asserted if any
of the measured temperatures exceeds the respective high limit, acting as a second THERM function
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Dual Channel 1°C Temperature Sensor with Beta Compensation and 1.8V SMBus Communications
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in. The ALERT / THERM2 pin will remain asserted until all temperatures drop below the corresponding
high limit minus the Therm Hysteresis value.
When the ALERT / THERM2 pin is asserted in comparator mode, the corresponding high limit status
bits will be set. Reading these bits will not clear them until the ALERT / THERM2 pin is deasserted.
Once the ALERT pin is deasserted, the status bits will be automatically cleared.
The MASK_ALL bit will not block the ALERT / THERM2 pin in this mode; however, the individual
channel masks (see Section 6.10) will prevent the respective channel from asserting the ALERT/
THERM2 pin.
5.6
Temperature Measurement
The EMC1182 can monitor the temperature of one externally connected diode.
The device contains programmable High, Low, and Therm limits for all measured temperature
channels. If the measured temperature goes below the Low limit or above the High limit, the ALERT
pin can be asserted (based on user settings). If the measured temperature meets or exceeds the
Therm Limit, the THERM pin is asserted unconditionally, providing two tiers of temperature detection.
5.6.1
Beta Compensation
The EMC1182 is configured to monitor the temperature of basic diodes (e.g., 2N3904) or CPU thermal
diodes. For External Diode 1, it automatically detects the type of external diode (CPU diode or diode
connected transistor) and determines the optimal setting to reduce temperature errors introduced by
beta variation. Compensating for this error is also known as implementing the transistor or BJT model
for temperature measurement.
For discrete transistors configured with the collector and base shorted together, the beta is generally
sufficiently high such that the percent change in beta variation is very small. For example, a 10%
variation in beta for two forced emitter currents with a transistor whose ideal beta is 50 would contribute
approximately 0.25°C error at 100°C. However for substrate transistors where the base-emitter junction
is used for temperature measurement and the collector is tied to the substrate, the proportional beta
variation will cause large error. For example, a 10% variation in beta for two forced emitter currents
with a transistor whose ideal beta is 0.5 would contribute approximately 8.25°C error at 100°C.
5.6.2
Resistance Error Correction (REC)
Parasitic resistance in series with the external diodes will limit the accuracy obtainable from
temperature measurement devices. The voltage developed across this resistance by the switching
diode currents cause the temperature measurement to read higher than the true temperature.
Contributors to series resistance are PCB trace resistance, on die (i.e. on the processor) metal
resistance, bulk resistance in the base and emitter of the temperature transistor. Typically, the error
caused by series resistance is +0.7°C per ohm. The EMC1182 automatically corrects up to 100 ohms
of series resistance.
5.6.3
Programmable External Diode Ideality Factor
The EMC1182 is designed for external diodes with an ideality factor of 1.008. Not all external diodes,
processor or discrete, will have this exact value. This variation of the ideality factor introduces error in
the temperature measurement which must be corrected for. This correction is typically done using
programmable offset registers. Since an ideality factor mismatch introduces an error that is a function
of temperature, this correction is only accurate within a small range of temperatures. To provide
maximum flexibility to the user, the EMC1182 provides a 6-bit register for each external diode where
the ideality factor of the diode used is programmed to eliminate errors across all temperatures.
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APPLICATION NOTE: When monitoring a substrate transistor or CPU diode and beta compensation is enabled, the
Ideality Factor should not be adjusted. Beta Compensation automatically corrects for most
ideality errors.
5.7
Diode Faults
The EMC1182 detects an open on the DP and DN pins, and a short across the DP and DN pins. For
each temperature measurement made, the device checks for a diode fault on the external diode
channel(s). When a diode fault is detected, the ALERT / THERM2 pin asserts (unless masked, see
Section 5.8) and the temperature data reads 00h in the MSB and LSB registers (note: the low limit will
not be checked). A diode fault is defined as one of the following: an open between DP and DN, a short
from VDD to DP, or a short from VDD to DN.
If a short occurs across DP and DN or a short occurs from DP to GND, the low limit status bit is set
and the ALERT / THERM2 pin asserts (unless masked). This condition is indistinguishable from a
temperature measurement of 0.000°C (-64°C in extended range) resulting in temperature data of 00h
in the MSB and LSB registers.
If a short from DN to GND occurs (with a diode connected), temperature measurements will continue
as normal with no alerts.
5.8
Consecutive Alerts
The EMC1182 contains multiple consecutive alert counters. One set of counters applies to the ALERT
/ THERM2 pin and the second set of counters applies to the THERM pin. Each temperature
measurement channel has a separate consecutive alert counter for each of the ALERT / THERM2 and
THERM pins. All counters are user programmable and determine the number of consecutive
measurements that a temperature channel(s) must be out-of-limit or reporting a diode fault before the
corresponding pin is asserted.
See Section 6.11, "Consecutive ALERT Register 22h" for more details on the consecutive alert
function.
5.9
Digital Filter
To reduce the effect of noise and temperature spikes on the reported temperature, the External Diode
channel uses a programmable digital filter. This filter can be configured as Level 1, Level 2, or Disabled
(default) (see Section 6.14). The typical filter performance is shown in Figure 5.4 and Figure 5.5.
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Dual Channel 1°C Temperature Sensor with Beta Compensation and 1.8V SMBus Communications
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Filter Step Response
Temperature (C)
90
Disabled
80
70
Level1
Level2
60
50
40
30
20
10
0
0
2
4
6
8
10
12
14
Samples
Figure 5.4 Temperature Filter Step Response
Filter Impulse Response
90
Temperature (C)
80
Disabled
70
60
50
Level1
40
Level2
30
20
10
0
0
2
4
6
8
10
12
14
Samples
Figure 5.5 Temperature Filter Impulse Response
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5.10
Temperature Measurement Results and Data
The temperature measurement results are stored in the internal and external temperature registers.
These are then compared with the values stored in the high and low limit registers. Both external and
internal temperature measurements are stored in 11-bit format with the eight (8) most significant bits
stored in a high byte register and the three (3) least significant bits stored in the three (3) MSB
positions of the low byte register. All other bits of the low byte register are set to zero.
The EMC1182 has two selectable temperature ranges. The default range is from 0°C to +127°C and
the temperature is represented as binary number able to report a temperature from 0°C to +127.875°C
in 0.125°C steps.
The extended range is an extended temperature range from -64°C to +191°C. The data format is a
binary number offset by 64°C. The extended range is used to measure temperature diodes with a large
known offset (such as AMD processor diodes) where the diode temperature plus the offset would be
equivalent to a temperature higher than +127°C.
Table 5.2 shows the default and extended range formats.
Table 5.2 Temperature Data Format
TEMPERATURE (°C)
DEFAULT RANGE 0°C TO 127°C
EXTENDED RANGE -64°C TO 191°C
Diode Fault
000 0000 0000
000 0000 0000
-64
000 0000 0000
000 0000 0000
-1
000 0000 0000
001 1111 1000
0
000 0000 0000
010 0000 0000
0.125
000 0000 0001
010 0000 0001
1
000 0000 1000
010 0000 1000
64
010 0000 0000
100 0000 0000
65
010 0000 1000
100 0000 1000
127
011 1111 1000
101 1111 1000
127.875
011 1111 1111
101 1111 1111
128
011 1111 1111
110 0000 0000
190
011 1111 1111
111 1111 0000
191
011 1111 1111
111 1111 1000
>= 191.875
011 1111 1111
111 1111 1111
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Dual Channel 1°C Temperature Sensor with Beta Compensation and 1.8V SMBus Communications
Datasheet
Chapter 6 Register Description
The registers shown in Table 6.1 are accessible through the SMBus. An entry of ‘-’ indicates that the
bit is not used and will always read ‘0’.
Table 6.1 Register Set in Hexadecimal Order
REGISTER
ADDRESS
R/W
REGISTER NAME
FUNCTION
DEFAULT
VALUE
00h
R
Internal Diode Data
High Byte
Stores the integer data for the
Internal Diode
00h
01h
R
External Diode Data
High Byte
Stores the integer data for the
External Diode
00h
02h
R-C
Status
Stores status bits for the Internal
Diode and External Diode
00h
Page 28
03h
R/W
Configuration
Controls the general operation of
the device (mirrored at address
09h)
00h
Page 28
04h
R/W
Conversion Rate
Controls the conversion rate for
updating temperature data
(mirrored at address 0Ah)
06h
(4/sec)
Page 29
05h
R/W
Internal Diode High
Limit
Stores the 8-bit high limit for the
Internal Diode (mirrored at address
0Bh)
55h
(85°C)
06h
R/W
Internal Diode Low
Limit
Stores the 8-bit low limit for the
Internal Diode (mirrored at address
0Ch)
00h
(0°C)
55h
(85°C)
00h
(0°C)
PAGE
Page 27
Page 30
07h
R/W
External Diode High
Limit High Byte
Stores the integer portion of the
high limit for the External Diode
(mirrored at register 0Dh)
08h
R/W
External Diode Low
Limit High Byte
Stores the integer portion of the
low limit for the External Diode
(mirrored at register 0Eh)
09h
R/W
Configuration
Controls the general operation of
the device (mirrored at address
03h)
0Ah
R/W
Conversion Rate
Controls the conversion rate for
updating temperature data
(mirrored at address 04h)
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00h
06h
(4/sec)
Page 28
Page 29
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Datasheet
Table 6.1 Register Set in Hexadecimal Order (continued)
REGISTER
ADDRESS
R/W
REGISTER NAME
FUNCTION
DEFAULT
VALUE
0Bh
R/W
Internal Diode High
Limit
Stores the 8-bit high limit for the
Internal Diode (mirrored at address
05h)
55h
(85°C)
0Ch
R/W
Internal Diode Low
Limit
Stores the 8-bit low limit for the
Internal Diode (mirrored at address
06h)
00h
(0°C)
55h
(85°C)
PAGE
Page 30
0Dh
R/W
External Diode High
Limit High Byte
Stores the integer portion of the
high limit for the External Diode
(mirrored at register 07h)
0Eh
R/W
External Diode Low
Limit High Byte
Stores the integer portion of the
low limit for the External Diode
(mirrored at register 08h)
00h
(0°C)
0Fh
W
One Shot
A write to this register initiates a
one shot update.
00h
Page 31
10h
R
External Diode Data
Low Byte
Stores the fractional data for the
External Diode
00h
Page 27
11h
R/W
Scratchpad
Scratchpad register for software
compatibility
00h
Page 31
12h
R/W
Scratchpad
Scratchpad register for software
compatibility
00h
Page 31
13h
R/W
External Diode High
Limit Low Byte
Stores the fractional portion of the
high limit for the External Diode
00h
14h
R/W
External Diode Low
Limit Low Byte
Stores the fractional portion of the
low limit for the External Diode
00h
19h
R/W
External Diode
Therm Limit
Stores the 8-bit critical temperature
limit for the External Diode
55h
(85°C)
Page 32
1Fh
R/W
Channel Mask
Register
Controls the masking of individual
channels
00h
Page 32
20h
R/W
Internal Diode Therm
Limit
Stores the 8-bit critical temperature
limit for the Internal Diode
55h
(85°C
21h
R/W
Therm Hysteresis
Stores the 8-bit hysteresis value
that applies to all Therm limits
0Ah
(10°C)
22h
R/W
Consecutive ALERT
Controls the number of out-of-limit
conditions that must occur before
an interrupt is asserted
70h
Page 33
25h
R/W
External Diode1 Beta
Configuration
Stores the Beta Compensation
circuitry settings for External
Diode1
08h
Page 35
27h
R/W
External Diode
Ideality Factor
Stores the ideality factor for the
External Diode
12h
(1.008)
Page 35
Page 30
Page 32
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Dual Channel 1°C Temperature Sensor with Beta Compensation and 1.8V SMBus Communications
Datasheet
Table 6.1 Register Set in Hexadecimal Order (continued)
REGISTER
ADDRESS
R/W
REGISTER NAME
FUNCTION
DEFAULT
VALUE
PAGE
29h
R
Internal Diode Data
Low Byte
Stores the fractional data for the
Internal Diode
00h
Page 27
40h
R/W
Filter Control
Controls the digital filter setting for
the External Diode channel
00h
Page 37
FDh
R
Product ID
Stores a fixed value that identifies
the device
20h
Page 37
FEh
R
Manufacturer ID
Stores a fixed value that
represents SMSC
5Dh
Page 37
FFh
R
Revision
Stores a fixed value that
represents the revision number
07h
Page 38
6.1
Data Read Interlock
When any temperature channel high byte register is read, the corresponding low byte is copied into
an internal ‘shadow’ register. The user is free to read the low byte at any time and be guaranteed that
it will correspond to the previously read high byte. Regardless if the low byte is read or not, reading
from the same high byte register again will automatically refresh this stored low byte data.
6.2
Temperature Data Registers
Table 6.2 Temperature Data Registers
ADDR
R/W
REGISTER
B7
B6
B5
B4
B3
B2
B1
B0
DEFAULT
00h
R
Internal Diode
High Byte
128
64
32
16
8
4
2
1
00h
29h
R
Internal Diode
Low Byte
0.5
0.25
0.125
-
-
-
-
-
00h
01h
R
External Diode
High Byte
128
64
32
16
8
4
2
1
00h
10h
R
External Diode
Low Byte
0.5
0.25
0.125
-
-
-
-
-
00h
As shown in Table 6.2, all temperatures are stored as an 11-bit value with the high byte representing
the integer value and the low byte representing the fractional value left justified to occupy the MSBits.
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Datasheet
6.3
Status Register 02h
Table 6.3 Status Register
ADDR
R/W
REGISTER
B7
B6
B5
B4
B3
B2
B1
B0
DEFAULT
02h
R-C
Status
BUSY
IHIGH
ILOW
EHIGH
ELOW
FAULT
ETHERM
ITHERM
00h
The Status Register reports the operating status of the Internal Diode and External Diode channels.
When any of the bits are set (excluding the BUSY bit) either the ALERT / THERM2 or THERM pin is
being asserted.
The ALERT / THERM2 and THERM pins are controlled by the respective consecutive alert counters
(see Section 6.11) and will not be asserted until the programmed consecutive alert count has been
reached. The status bits (except ETHERM and ITHERM) will remain set until read unless the ALERT
pin is configured as a second THERM output (see Section 5.4).
Bit 7 - BUSY - This bit indicates that the ADC is currently converting. This bit does not cause either
the ALERT / THERM2 or THERM pin to be asserted.
Bit 6 - IHIGH - This bit is set when the Internal Diode channel exceeds its programmed high limit.
When set, this bit will assert the ALERT / THERM2 pin.
Bit 5 - ILOW - This bit is set when the Internal Diode channel drops below its programmed low limit.
When set, this bit will assert the ALERT / THERM2 pin.
Bit 4 - EHIGH - This bit is set when the External Diode channel exceeds its programmed high limit.
When set, this bit will assert the ALERT / THERM2 pin.
Bit 3 - ELOW - This bit is set when the External Diode channel drops below its programmed low limit.
When set, this bit will assert the ALERT / THERM2 pin.
Bit 2 - FAULT - This bit is asserted when a diode fault is detected. When set, this bit will assert the
ALERT / THERM2 pin.
Bit 1 - ETHERM - This bit is set when the External Diode channel exceeds the programmed Therm
Limit. When set, this bit will assert the THERM pin. This bit will remain set until the THERM pin is
released at which point it will be automatically cleared.
Bit 0 - ITHERM - This bit is set when the Internal Diode channel exceeds the programmed Therm Limit.
When set, this bit will assert the THERM pin. This bit will remain set until the THERM pin is released
at which point it will be automatically cleared.
6.4
Configuration Register 03h / 09h
Table 6.4 Configuration Register
ADDR
R/W
REGISTER
B7
B6
R/W
Configuration
MASK_
ALL
RUN/
STOP
03h
09h
B5
B4
B3
B2
B1
B0
DEFAULT
ALERT/
THERM2
RECD
-
RANGE
DAVG_
DIS
-
00h
The Configuration Register controls the basic operation of the device. This register is fully accessible
at either address.
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Datasheet
Bit 7 - MASK_ALL - Masks the ALERT / THERM2 pin from asserting.

‘0’ - (default) - The ALERT / THERM2 pin is not masked. If any of the appropriate status bits are
set the ALERT / THERM2 pin will be asserted.

‘1’ - The ALERT/ THERM2 pin is masked. It will not be asserted for any interrupt condition unless
it is configured in comparator mode. The Status Registers will be updated normally.
Bit 6 - RUN / STOP - Controls Active/Standby modes.

‘0’ (default) - The device is in Active mode and converting on all channels.

‘1’ - The device is in Standby mode and not converting.
Bit 5 - ALERT/THERM2 - Controls the operation of the ALERT / THERM2 pin.

‘0’ (default) - The ALERT / THERM2 acts as an Alert pin and has interrupt behavior as described
in Section 5.5.1.

‘1’ - The ALERT / THERM2 acts as a THERM pin and has comparator behavior as described in
Section 5.5.2. In this mode the MASK_ALL bit is ignored.
Bit 4 - RECD - Disables the Resistance Error Correction (REC) for the External Diode.

‘0’ (default) - REC is enabled for the External Diode.

‘1’ - REC is disabled for the External Diode.
Bit 2 - RANGE - Configures the measurement range and data format of the temperature channels.

‘0’ (default) - The temperature measurement range is 0°C to +127.875°C and the data format is
binary.

‘1’ -The temperature measurement range is -64°C to +191.875°C and the data format is offset
binary (see Table 5.2).
Bit 1 - DAVG_DIS - Disables the dynamic averaging feature on all temperature channels.
6.5

‘0’ (default) - The dynamic averaging feature is enabled. All temperature channels will be converted
with an averaging factor that is based on the conversion rate as shown in Table 6.6.

‘1’ - The dynamic averaging feature is disabled. All temperature channels will be converted with a
maximum averaging factor of 1x (equivalent to 11-bit conversion). For higher conversion rates, this
averaging factor will be reduced as shown in Table 6.6.
Conversion Rate Register 04h / 0Ah
Table 6.5 Conversion Rate Register
ADDR
R/W
REGISTER
B7
B6
B5
B4
R/W
Conversion
Rate
-
-
-
-
04h
0Ah
B3
B2
B1
CONV[3:0]
B0
DEFAULT
06h
(4/sec)
The Conversion Rate Register controls how often the temperature measurement channels are updated
and compared against the limits. This register is fully accessible at either address.
Bits 3-0 - CONV[3:0] - Determines the conversion rate as shown in Table 6.6.
SMSC EMC1182
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Dual Channel 1°C Temperature Sensor with Beta Compensation and 1.8V SMBus Communications
Datasheet
Table 6.6 Conversion Rate
CONV[3:0]
HEX
3
2
1
0
CONVERSIONS / SECOND
0h
0
0
0
0
/ 16
1h
0
0
0
1
1/8
2h
0
0
1
0
1/4
3h
0
0
1
1
1 / 21
4h
0
1
0
0
1
5h
0
1
0
1
2
6h
0
1
1
0
4 (default)
7h
0
1
1
1
8
8h
1
0
0
0
16
9h
1
0
0
1
32
Ah
1
0
1
0
64
Bh - Fh
6.6
All others
1
Limit Registers
Table 6.7 Temperature Limit Registers
ADDR.
R/W
REGISTER
B7
B6
B5
B4
B3
B2
B1
B0
DEFAULT
R/W
Internal Diode
High Limit
128
64
32
16
8
4
2
1
55h
(85°C)
R/W
Internal Diode
Low Limit
128
64
32
16
8
4
2
1
00h
(0°C)
R/W
External
Diode High
Limit High
Byte
128
64
32
16
8
4
2
1
55h
(85°C)
R/W
External
Diode High
Limit Low
Byte
0.5
0.25
0.125
-
-
-
-
-
00h
05h
0Bh
06h
0Ch
07h
0Dh
13h
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Dual Channel 1°C Temperature Sensor with Beta Compensation and 1.8V SMBus Communications
Datasheet
Table 6.7 Temperature Limit Registers (continued)
ADDR.
R/W
REGISTER
B7
B6
B5
B4
B3
B2
B1
B0
DEFAULT
R/W
External
Diode Low
Limit High
Byte
128
64
32
16
8
4
2
1
00h
(0°C)
R/W
External
Diode Low
Limit Low
Byte
0.5
0.25
0.125
-
-
-
-
-
00h
08h
0Eh
14h
The device contains both high and low limits for all temperature channels. If the measured temperature
exceeds the high limit, then the corresponding status bit is set and the ALERT / THERM2 pin is
asserted. Likewise, if the measured temperature is less than or equal to the low limit, the
corresponding status bit is set and the ALERT / THERM2 pin is asserted.
The data format for the limits must match the selected data format for the temperature so that if the
extended temperature range is used, the limits must be programmed in the extended data format.
The limit registers with multiple addresses are fully accessible at either address.
When the device is in Standby mode, updating the limit registers will have no effect until the next
conversion cycle occurs. This can be initiated via a write to the One Shot Register (see Section 6.8,
"One Shot Register 0Fh") or by clearing the RUN / STOP bit (see Section 6.4, "Configuration Register
03h / 09h").
6.7
Scratchpad Registers 11h and 12h
Table 6.8 Scratchpad Register
ADDR
R/W
REGISTER
B7
B6
B5
B4
B3
B2
B1
B0
DEFAULT
11h
R/W
Scratchpad
7
6
5
4
3
2
1
0
00h
12h
R/W
Scratchpad
7
6
5
4
3
2
1
0
00h
The Scratchpad Registers are Read / Write registers that are used for place holders to be software
compatible with legacy programs. Reading from the registers will return what is written to them.
6.8
One Shot Register 0Fh
The One Shot Register is used to initiate a one shot command. Writing to the one shot register when
the device is in Standby mode and BUSY bit (in Status Register) is ‘0’, will immediately cause the ADC
to update all temperature measurements. Writing to the One Shot Register while the device is in Active
mode will have no effect.
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Dual Channel 1°C Temperature Sensor with Beta Compensation and 1.8V SMBus Communications
Datasheet
6.9
Therm Limit Registers
Table 6.9 Therm Limit Registers
ADDR.
R/W
REGISTER
B7
B6
B5
B4
B3
B2
B1
B0
DEFAULT
19h
R/W
External
Diode Therm
Limit
128
64
32
16
8
4
2
1
55h
(85°C)
20h
R/W
Internal Diode
Therm Limit
128
64
32
16
8
4
2
1
55h
(85°C)
21h
R/W
Therm
Hysteresis
128
64
32
16
8
4
2
1
0Ah
(10°C)
The Therm Limit Registers are used to determine whether a critical thermal event has occurred. If the
measured temperature exceeds the Therm Limit, the THERM pin is asserted. The limit setting must
match the chosen data format of the temperature reading registers.
Unlike the ALERT / THERM2 pin, the THERM pin cannot be masked. Additionally, the THERM pin will
be released once the temperature drops below the corresponding threshold minus the Therm
Hysteresis.
6.10
Channel Mask Register 1Fh
Table 6.10 Channel Mask Register
ADDR.
R/W
REGISTER
B7
B6
B5
B4
B3
B2
B1
B0
DEFAULT
1Fh
R/W
Channel
Mask
-
-
-
-
-
-
EXT
MASK
INT
MASK
00h
The Channel Mask Register controls individual channel masking. When a channel is masked, the
ALERT / THERM2 pin will not be asserted when the masked channel reads a diode fault or out of limit
error. The channel mask does not mask the THERM pin.
Bit 1 - EXTMASK - Masks the ALERT / THERM2 pin from asserting when the External Diode channel
is out of limit or reports a diode fault.

‘0’ (default) - The External Diode channel will cause the ALERT / THERM2 pin to be asserted if it
is out of limit or reports a diode fault.

‘1’ - The External Diode channel will not cause the ALERT / THERM2 pin to be asserted if it is out
of limit or reports a diode fault.
Bit 0 - INTMASK - Masks the ALERT / THERM2 pin from asserting when the Internal Diode
temperature is out of limit.

‘0’ (default) - The Internal Diode channel will cause the ALERT / THERM2 pin to be asserted if it
is out of limit.

‘1’ - The Internal Diode channel will not cause the ALERT / THERM2 pin to be asserted if it is out
of limit.
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Dual Channel 1°C Temperature Sensor with Beta Compensation and 1.8V SMBus Communications
Datasheet
6.11
Consecutive ALERT Register 22h
Table 6.11 Consecutive ALERT Register
ADDR.
R/W
REGISTER
B7
22h
R/W
Consecutive
ALERT
TIME
OUT
B6
B5
B4
CTHRM[2:0]
B3
B2
B1
CALRT[2:0]
B0
DEFAULT
-
70h
The Consecutive ALERT Register determines how many times an out-of-limit error or diode fault must
be detected in consecutive measurements before the ALERT / THERM2 or THERM pin is asserted.
Additionally, the Consecutive ALERT Register controls the SMBus Timeout functionality.
An out-of-limit condition (i.e. HIGH, LOW, or FAULT) occurring on the same temperature channel in
consecutive measurements will increment the consecutive alert counter. The counters will also be reset
if no out-of-limit condition or diode fault condition occurs in a consecutive reading.
When the ALERT / THERM2 pin is configured as an interrupt, when the consecutive alert counter
reaches its programmed value, the following will occur: the STATUS bit(s) for that channel and the last
error condition(s) (i.e. EHIGH) will be set to ‘1’, the ALERT / THERM2 pin will be asserted, the
consecutive alert counter will be cleared, and measurements will continue.
When the ALERT / THERM2 pin is configured as a comparator, the consecutive alert counter will
ignore diode fault and low limit errors and only increment if the measured temperature exceeds the
High Limit. Additionally, once the consecutive alert counter reaches the programmed limit, the ALERT/
THERM2 pin will be asserted, but the counter will not be reset. It will remain set until the temperature
drops below the High Limit minus the Therm Hysteresis value.
For example, if the CALRT[2:0] bits are set for 4 consecutive alerts on an EMC1182 device, the high
limits are set at 70°C, and none of the channels are masked, the ALERT / THERM2 pin will be
asserted after the following four measurements:
1. Internal Diode reads 71°C and the external diode reads 69°C. Consecutive alert counter for INT is
incremented to 1.
2. Both the Internal Diode and the External Diode read 71°C. Consecutive alert counter for INT is
incremented to 2 and for EXT is set to 1.
3. The External Diode reads 71°C and the Internal Diode reads 69°C. Consecutive alert counter for
INT is cleared and EXT is incremented to 2.
4. The Internal Diode reads 71°C and the external diode reads 71°C. Consecutive alert counter for
INT is set to 1 and EXT is incremented to 3.
5. The Internal Diode reads 71°C and the external diode reads 71°C. Consecutive alert counter for
INT is incremented to 2 and EXT is incremented to 4. The appropriate status bits are set for EXT
and the ALERT / THERM2 pin is asserted. EXT counter is reset to 0 and all other counters hold
the last value until the next temperature measurement.
Bit 7 - TIMEOUT - Determines whether the SMBus Timeout function is enabled.

‘0’ (default) - The SMBus Timeout feature is disabled. The SMCLK line can be held low indefinitely
without the device resetting its SMBus protocol.

‘1’ - The SMBus Timeout feature is enabled. If the SMCLK line is held low for more than tTIMEOUT,
the device will reset the SMBus protocol.
Bits 6-4 CTHRM[2:0] - Determines the number of consecutive measurements that must exceed the
corresponding Therm Limit and Hardware Thermal Shutdown Limit before the SYS_SHDN pin is
asserted. All temperature channels use this value to set the respective counters. The consecutive
THERM counter is incremented whenever any of the measurements exceed the corresponding Therm
Limit or if the External Diode measurement exceeds the Hardware Thermal Shutdown Limit.
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Datasheet
If the temperature drops below the Therm Limit or Hardware Thermal Shutdown Limit, the counter is
reset. If the programmed number of consecutive measurements exceed the Therm Limit or Hardware
Thermal Shutdown Limit, and the appropriate channel is linked to the SYS_SHDN pin, the SYS_SHDN
pin will be asserted low.
Once the SYS_SHDN pin is asserted, the consecutive Therm counter will not reset until the
corresponding temperature drops below the appropriate limit minus the corresponding hysteresis.
Bits 6-4 - CTHRM[2:0] - Determines the number of consecutive measurements that must exceed the
corresponding Therm Limit before the THERM pin is asserted. All temperature channels use this value
to set the respective counters. The consecutive Therm counter is incremented whenever any
measurement exceed the corresponding Therm Limit.
If the temperature drops below the Therm Limit, the counter is reset. If a number of consecutive
measurements above the Therm Limit occurs, the THERM pin is asserted low.
Once the THERM pin has been asserted, the consecutive therm counter will not reset until the
corresponding temperature drops below the Therm Limit minus the Therm Hysteresis value.
The bits are decoded as shown in Table 6.12. The default setting is 4 consecutive out of limit
conversions.
Bits 3-1 - CALRT[2:0] - Determine the number of consecutive measurements that must have an out of
limit condition or diode fault before the ALERT / THERM2 pin is asserted. Both temperature channels
use this value to set the respective counters. The bits are decoded as shown in Table 6.12. The default
setting is 1 consecutive out of limit conversion.
Table 6.12 Consecutive Alert / Therm Settings
6.12
NUMBER OF CONSECUTIVE OUT OF LIMIT
MEASUREMENTS
2
1
0
0
0
0
1
(default for CALRT[2:0])
0
0
1
2
0
1
1
3
1
1
1
4
(default for CTHRM[2:0])
Beta Configuration Register 25h
Table 6.13 Beta Configuration Register
ADDR.
R/W
REGISTER
B7
B6
B5
B4
B3
25h
R/W
External
Diode Beta
Configuration
-
-
-
-
ENABLE
B2
B1
BETA[2:0]
B0
DEFAULT
08h
This register is used to set the Beta Compensation factor that is used for the external diode channel.

‘0’ - The Beta Compensation Factor auto-detection circuitry is disabled.
‘1’ (default) - The Beta Compensation factor auto-detection circuitry is enabled. At the beginning of
every conversion, the optimal Beta Compensation factor setting will be determined and applied.
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Dual Channel 1°C Temperature Sensor with Beta Compensation and 1.8V SMBus Communications
Datasheet
6.13
External Diode Ideality Factor Register 27h
Table 6.14 Ideality Configuration Registers
ADDR.
27h
R/W
REGISTER
B7
B6
R/W
External
Diode
Ideality
Factor
-
-
B5
B4
B3
B2
B1
IDEALITY[5:0]
B0
DEFAULT
12h
This register stores the ideality factors that are applied to the external diode. Table 6.15 defines each
setting and the corresponding ideality factor. Beta Compensation and Resistance Error Correction
automatically correct for most diode ideality errors; therefore, it is not recommended that these settings
be updated without consulting SMSC.
Table 6.15 Ideality Factor Look-Up Table (Diode Model)
SETTING
FACTOR
SETTING
FACTOR
SETTING
FACTOR
08h
0.9949
18h
1.0159
28h
1.0371
09h
0.9962
19h
1.0172
29h
1.0384
0Ah
0.9975
1Ah
1.0185
2Ah
1.0397
0Bh
0.9988
1Bh
1.0200
2Bh
1.0410
0Ch
1.0001
1Ch
1.0212
2Ch
1.0423
0Dh
1.0014
1Dh
1.0226
2Dh
1.0436
0Eh
1.0027
1Eh
1.0239
2Eh
1.0449
0Fh
1.0040
1Fh
1.0253
2Fh
1.0462
10h
1.0053
20h
1.0267
30h
1.0475
11h
1.0066
21h
1.0280
31h
1.0488
12h
1.0080
22h
1.0293
32h
1.0501
13h
1.0093
23h
1.0306
33h
1.0514
14h
1.0106
24h
1.0319
34h
1.0527
15h
1.0119
25h
1.0332
35h
1.0540
16h
1.0133
26h
1.0345
36h
1.0553
17h
1.0146
27h
1.0358
37h
1.0566
For CPU substrate transistors that require the BJT transistor model, the ideality factor behaves slightly
differently than for discrete diode-connected transistors. Refer to Table 6.16 when using a CPU
substrate transistor.
SMSC EMC1182
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Dual Channel 1°C Temperature Sensor with Beta Compensation and 1.8V SMBus Communications
Datasheet
Table 6.16 Substrate Diode Ideality Factor Look-Up Table (BJT Model)
SETTING
FACTOR
SETTING
FACTOR
SETTING
FACTOR
08h
0.9869
18h
1.0079
28h
1.0291
09h
0.9882
19h
1.0092
29h
1.0304
0Ah
0.9895
1Ah
1.0105
2Ah
1.0317
0Bh
0.9908
1Bh
1.0120
2Bh
1.0330
0Ch
0.9921
1Ch
1.0132
2Ch
1.0343
0Dh
0.9934
1Dh
1.0146
2Dh
1.0356
0Eh
0.9947
1Eh
1.0159
2Eh
1.0369
0Fh
0.9960
1Fh
1.0173
2Fh
1.0382
10h
0.9973
20h
1.0187
30h
1.0395
11h
0.9986
21h
1.0200
31h
1.0408
12h
1.0000
22h
1.0213
32h
1.0421
13h
1.0013
23h
1.0226
33h
1.0434
14h
1.0026
24h
1.0239
34h
1.0447
15h
1.0039
25h
1.0252
35h
1.0460
16h
1.0053
26h
1.0265
36h
1.0473
17h
1.0066
27h
1.0278
37h
1.0486
APPLICATION NOTE: When measuring a 65nm Intel CPU, the Ideality Setting should be the default 12h. When
measuring a 45nm Intel CPU, the Ideality Setting should be 15h.
Bit 1 - E1HIGH - This bit is set when the External Diode 1 channel exceeds its programmed high limit.
Bit 0 - IHIGH - This bit is set when the Internal Diode channel exceeds its programmed high limit.
Bit 1 - ELOW - This bit is set when the External Diode channel drops below its programmed low limit.
Bit 0 - ILOW - This bit is set when the Internal Diode channel drops below its programmed low limit.
Bit 1 - ETHERM - This bit is set when the External Diode channel exceeds its programmed Therm
Limit. When set, this bit will assert the THERM pin.
Bit 0- ITHERM - This bit is set when the Internal Diode channel exceeds its programmed Therm Limit.
When set, this bit will assert the THERM pin.
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Dual Channel 1°C Temperature Sensor with Beta Compensation and 1.8V SMBus Communications
Datasheet
6.14
Filter Control Register 40h
Table 6.17 Filter Configuration Register
ADDR.
R/W
REGISTER
B7
B6
B5
B4
B3
B2
40h
R/W
Filter Control
-
-
-
-
-
-
B1
B0
FILTER[1:0]
DEFAULT
00h
The Filter Configuration Register controls the digital filter on the External Diode channel.
Bits 1-0 - FILTER[1:0] - Control the level of digital filtering that is applied to the External Diode
temperature measurement as shown in Table 6.18. See Figure 5.4 and Figure 5.5 for examples on the
filter behavior.
Table 6.18 FILTER Decode
FILTER[1:0]
6.15
1
0
AVERAGING
0
0
Disabled (default)
0
1
Level 1
1
0
Level 1
1
1
Level 2
Product ID Register
Table 6.19 Product ID Register
ADDR
R/W
REGISTER
B7
B6
B5
B4
B3
B2
B1
B0
DEFAULT
FDh
R
Product ID
0
0
1
0
0
0
0
0
20h
The Product ID Register holds a unique value that identifies the device.
6.16
SMSC ID Register
Table 6.20 Manufacturer ID Register
ADDR.
R/W
REGISTER
B7
B6
B5
B4
B3
B2
B1
B0
DEFAULT
FEh
R
SMSC ID
0
1
0
1
1
1
0
1
5Dh
The Manufacturer ID register contains an 8-bit word that identifies the SMSC as the manufacturer of
the EMC1182.
SMSC EMC1182
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Revision 1.0 (07-11-13)
Dual Channel 1°C Temperature Sensor with Beta Compensation and 1.8V SMBus Communications
Datasheet
6.17
Revision Register
Table 6.21 Revision Register
ADDR.
R/W
REGISTER
B7
B6
B5
B4
B3
B2
B1
B0
DEFAULT
FFh
R
Revision
0
0
0
0
0
1
1
1
07h
The Revision register contains an 8-bit word that identifies the die revision.
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SMSC EMC1182
Dual Channel 1°C Temperature Sensor with Beta Compensation and 1.8V SMBus Communications
Datasheet
Chapter 7 Typical Operating Curves
Tem perature Error vs. Am bient Tem perature
(2N3904, TDIODE = 42.5°C, VDD = 3.3V)
1.0
1.0
0.8
0.8
0.6
Temperature Error (°C)
Temperature Error (°C)
Tem perature Error vs. Filter Capacitor
(2N3904, TA = 27°C, TDIODE = 27°C, VDD = 3.3V)
0.5
0.3
0.0
-0.3
-0.5
-0.8
-1.0
0
1000
2000
3000
0.4
0.2
0.0
-0.2
-0.4
-0.6
-0.8
4000
-1.0
-40 -25 -10
Filter Capacitor (pF)
Temperature Error (°C)
Temperature Error (°C)
SMSC EMC1182
5
4
Beta Compensation
Disabled
3
2
1
0
Beta Compensation Enabled
-1
20
110 125
95 110 125
Temperature Error vs. CPU Temperature
Typical 65nm CPU from major vendor
(TA = 27°C, VDD = 3.3V, BETA = 011, CFILTER = 470pF)
Tem perature Error vs. External Diode Tem perature
(2N3904, TA = 42.5°C, VDD = 3.3V)
1.0
0.8
0.6
0.4
0.2
0.0
-0.2
-0.4
-0.6
-0.8
-1.0
-40 -25 -10 5
20 35 50 65 80 95
External Diode Tem perature (°C)
5
20 35 50 65 80
Am bient Tem perature (°C)
40
60
80
100
120
CPU Temperature (°C)
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DATASHEET
Revision 1.0 (07-11-13)
Dual Channel 1°C Temperature Sensor with Beta Compensation and 1.8V SMBus Communications
Datasheet
Chapter 8 Package Information
Figure 8.1 2mm x 3mm TDFN Package Drawing
Revision 1.0 (07-11-13)
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DATASHEET
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Dual Channel 1°C Temperature Sensor with Beta Compensation and 1.8V SMBus Communications
Datasheet
Figure 8.2 2mm x 3mm TDFN Package Dimensions
Figure 8.3 2mm x 3mm TDFN Package PCB Land Pattern
SMSC EMC1182
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DATASHEET
Revision 1.0 (07-11-13)
Dual Channel 1°C Temperature Sensor with Beta Compensation and 1.8V SMBus Communications
Datasheet
Figure 8.4 3mm x 3mm DFN Package Drawing
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DATASHEET
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Dual Channel 1°C Temperature Sensor with Beta Compensation and 1.8V SMBus Communications
Datasheet
Figure 8.5 3mm x 3mm DFN Package Dimensions
SMSC EMC1182
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DATASHEET
Revision 1.0 (07-11-13)
Dual Channel 1°C Temperature Sensor with Beta Compensation and 1.8V SMBus Communications
Datasheet
Figure 8.6 8 Pin DFN PCB Footprint
Revision 1.0 (07-11-13)
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DATASHEET
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Dual Channel 1°C Temperature Sensor with Beta Compensation and 1.8V SMBus Communications
Datasheet
8.1
Package Markings
The EMC1182 devices will be marked as shown in Figure 8.7, Figure 8.8., Figure 8.9, Figure 8.10 and
Figure 8.11.
TOP
LINE 1: Preface, First digit of Device Code
E 3
LINE 2: Second digit of Device Code, Revision
C R
PIN 1
BOTTOM
BOTTOM MARKING IS NOT ALLOWED
Figure 8.7 EMC1182-1 8-Pin TDFN Package Markings
TOP
LINE 1: Preface, First digit of Device Code
E 3
LINE 2: Second digit of Device Code, Revision
D R
PIN 1
BOTTOM
BOTTOM MARKING IS NOT ALLOWED
Figure 8.8 EMC1182-2 8-Pin TDFN Package Markings
SMSC EMC1182
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DATASHEET
Revision 1.0 (07-11-13)
Dual Channel 1°C Temperature Sensor with Beta Compensation and 1.8V SMBus Communications
Datasheet
TOP
LINE 1: Preface, First digit of Device Code
E 3
LINE 2: Second digit of Device Code, Revision
A R
PIN 1
BOTTOM
BOTTOM MARKING IS NOT ALLOWED
Figure 8.9 EMC1182-A 8-Pin TDFN Package Markings
TOP
LINE 1: Device Code, First two digits of 6
digits of lot number
4 4 L L
LINE 2: Last 4 digits of lot number
L L L L
PIN 1
BOTTOM
BOTTOM MARKING IS NOT ALLOWED
Figure 8.10 EMC1182-1 8-Pin DFN Package Markings
Revision 1.0 (07-11-13)
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SMSC EMC1182
Dual Channel 1°C Temperature Sensor with Beta Compensation and 1.8V SMBus Communications
Datasheet
TOP
LINE 1: Device Code, First two digits of 6
digits of lot number
4 4 L L
LINE 2: Last 4 digits of lot number
L L L L
PIN 1
BOTTOM
BOTTOM MARKING IS NOT ALLOWED
Figure 8.11 EMC1182-2 8-Pin DFN Package Markings
SMSC EMC1182
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DATASHEET
Revision 1.0 (07-11-13)
Dual Channel 1°C Temperature Sensor with Beta Compensation and 1.8V SMBus Communications
Datasheet
Chapter 9 Datasheet Revision History
Table 9.1 Customer Revision History
REVISION LEVEL & DATE
Rev. 1.0 (07-11-13)
Revision 1.0 (07-11-13)
SECTION/FIGURE/ENTRY
CORRECTION
Formal document release
48
DATASHEET
SMSC EMC1182
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