SMSC EMC1412 DATASHEET Revision 1.41 (02-23-12)
Datasheet
PRODUCT FEATURES
EMC1412
Multiple Channel 1°C
Temperature Sensor with
Beta Compensation
General Description
The EMC1412 is a high accuracy, low cost, System
Management Bus (SMBus) temperature sensor.
Advanced features such as Resistance Error Correction
(REC), Beta Compensation (to support CPU diodes
requiring the BJT/transistor model including 45nm,
65nm and 90nm processors) and automatic diode type
detection combine to provide a robust solution for
complex environmental monitoring applications.
The EMC1412 monitors two temperature channels (one
external and one internal). It p rovides ±1°C accuracy for
both external and internal diode temperatures.
Resistance Error Correction automatically elimina tes the
temperature error caused by series resistance allowing
greater flexibility in routing thermal diodes. 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.
Applications
Notebook Computers
Desktop Computers
Industrial
Embedded applications
Features
Programmable SMBus address
Support for diodes requiring the BJT/transistor model
— supports 45nm, 65nm, and 90nm CPU thermal diodes
Automatically determines external diode type and
optimal settings
Resistance Error Correction
External Temperature Monitor
— ±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
3.3V Supply Voltage
Programmable temperature limits for ALERT and
THERM
Available in small 8-pin 2mm x 3mm TDFN lead-free
RoHS compliant package
Available in small 8-pin MSOP lead-free RoHS
compliant package
REEL SIZE IS 4,000 PIECES FOR THE MSOP
REEL SIZE IS 5,000 PIECES FOR THE TDFN
This product meets the halogen maximum concentration values per IEC61249-2-21
For RoHS compliance and environmental information, please visit www.smsc.com/rohs
ORDERING NUMBER PACKAGE FEATURES SMBUS
ADDRESS
EMC1412-A-ACZL-TR 8-pin MSOP
(lead-free RoHS compliant Two temperature sensors, ALERT and
THERM pins, programmable SMBus address Selectable via
THERM pull-up
EMC1412-A-AC3-TR 8-pin TDFN 2mm x 3mm
(lead-free RoHS compliant Two temperature sensors, ALERT and
THERM pins, fixed SMBus address Selectable via
THERM pull-up
EMC1412-1-ACZL-TR 8-pin MSOP
(lead-free RoHS compliant Two temperature sensors, ALERT and
THERM pins, fixed SMBus address 1001_100(r/w)
EMC1412-1-AC3-TR 8-pin TDFN 2mm x 3mm
(lead-free RoHS compliant Two temperature sensors, ALERT and
THERM pins, fixed SMBus address 1001_100(r/w)
EMC1412-2-ACZL-TR 8-pin MSOP
(lead-free RoHS compliant Two temperature sensors, ALERT and
THERM pins, fixed SMBus address 1001_101(r/w)
Multiple Channel 1°C Temperature Sensor with Beta Compensation
Datasheet
Revision 1.41 (02-23-12) 2 SMSC EMC1412
DATASHEET
80 ARKAY DRIVE, HAUPPAUGE, NY 11788 (631) 435-6000 or 1 (800) 443-SEMI
Copyright © 2012 SMSC or its subsidi aries. All rights reserve d.
Circuit diagrams and other information relating to SMSC products are included as a means of illustrating typical applications. Co nsequently, complete informa tion 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 semicond uctor 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 desi gn 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 use s without prior written approval of an Officer of SMSC and further te sting and/or modification will be fully at the risk of the customer. Copies of
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Ordering Information:
Multiple Channel 1°C Temperature Sensor with Beta Compensation
Datasheet
SMSC EMC1412 3 Revision 1.41 (02-23-12)
DATASHEET
Table of Contents
Chapter 1 Block Diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
Chapter 2 Delta . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
2.1 Functional Delta from EMC1412 rev A to rev B . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
Chapter 3 Pin Description. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
Chapter 4 Electrical Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
4.1 Absolute Maximum Ratings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
4.2 Electrical Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
4.3 SMBus Electrical Characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
Chapter 5 System Management Bus Interface Protocol . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
5.1 Communications Protocol. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
5.1.1 SMBus Start Bit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
5.1.2 SMBus Address and RD / WR Bit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
5.1.3 THERM Pin Considerations. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
5.1.4 SMBus Data Bytes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
5.1.5 SMBus ACK and NACK Bits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
5.1.6 SMBus Stop Bit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
5.1.7 SMBus Timeout. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
5.1.8 SMBus and I2C Compatibility . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
5.2 SMBus Protocols . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
5.2.1 Write Byte . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
5.2.2 Read Byte . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
5.2.3 Send Byte . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
5.2.4 Receive Byte . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
5.3 Alert Response Address. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
Chapter 6 Product Description. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
6.1 Modes of Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
6.1.1 Conversion Rates . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
6.1.2 Dynamic Averaging . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
6.2 THERM Output . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
6.3 ALERT Output . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
6.3.1 ALERT Pin Interrupt Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
6.3.2 ALERT Pin Comparator Mode. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
6.4 Temperature Measurement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
6.4.1 Beta Compensation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
6.4.2 Resistance Error Correction (REC) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
6.4.3 Programmable External Diode Ideality Factor. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
6.5 Diode Faults . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
6.6 Consecutive Alerts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
6.7 Digital Filter. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
6.8 Temperature Measurement Results and Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
6.9 External Diode Connections . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
Chapter 7 Register Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
7.1 Data Read Interlock . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
7.2 Temperature Data Registers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
Multiple Channel 1°C Temperature Sensor with Beta Compensation
Datasheet
Revision 1.41 (02-23-12) 4 SMSC EMC1412
DATASHEET
7.3 Status Register. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
7.4 Configuration Register. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
7.5 Conversion Rate Register. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
7.6 Limit Registers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
7.7 Scratchpa d Re gist er s . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
7.8 One Shot Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
7.9 Therm Limit Registers. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
7.10 Channel Mask Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
7.11 Consecutive ALERT Register. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
7.12 Beta Configuration Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
7.13 External Diode Ideality Factor Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
7.14 Filter Control Register. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36
7.15 Product ID Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36
7.16 SMSC ID Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36
7.17 Revision Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37
Chapter 8 Typical Operating Curves. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38
Chapter 9 Package Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40
9.1 Package Markings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43
Chapter 10 Document Revision History . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46
Multiple Channel 1°C Temperature Sensor with Beta Compensation
Datasheet
SMSC EMC1412 5 Revision 1.41 (02-23-12)
DATASHEET
List of Figures
Figure 1.1 EMC1412 Block Diagram. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
Figure 3.1 EMC1412 Pin Diagram, MSOP-8. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
Figure 3.2 EMC1412 Pin Diagram, TDFN-8 2mm x 3mm. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
Figure 5.1 SMBus Timing Diagram. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
Figure 5.2 Isolating THERM Pin . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
Figure 6.1 System Diagram for EMC1412 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
Figure 6.2 Temperature Filter Step Response . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
Figure 6.3 Temperature Filter Impulse Response. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
Figure 6.4 Diode Configurations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
Figure 9.1 EMC1412 2mm x 3mm TDFN Package Drawing. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40
Figure 9.2 EMC1412 2mm x 3mm TDFN Package Dimensions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41
Figure 9.3 EMC1412 2mm x 3mm TDFN Package PCB Land Pattern. . . . . . . . . . . . . . . . . . . . . . . . . . 41
Figure 9.4 8-Pin MSOP / TSSOP Package. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42
Figure 9.5 EMC1412-1 8-Pin TDFN Package Markings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43
Figure 9.6 EMC1412-A 8-Pin TDFN Package Markings. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44
Figure 9.7 EMC1412 8-Pin MSOP Package Markings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45
Multiple Channel 1°C Temperature Sensor with Beta Compensation
Datasheet
Revision 1.41 (02-23-12) 6 SMSC EMC1412
DATASHEET
List of Tables
Table 3.1 EMC1412 Pin Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
Table 3.2 Pin Types. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
Table 4.1 Absolute Maximum Ratings. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
Table 4.2 Electrical Specifications. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
Table 4.3 SMBus Electrical Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
Table 5.1 SMBus Address Decode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
Table 5.2 Protocol Format. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
Table 5.3 Write Byte Protocol . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
Table 5.4 Read Byte Protocol . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
Table 5.5 Send Byte Protocol . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
Table 5.6 Receive Byte Protocol . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
Table 5.7 Alert Response Address Protocol . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
Table 6.1 Supply Curren t vs. Co nve r sion Rat e for EMC14 12 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
Table 6.2 Temperature Data Format. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
Table 7.1 Register Set in Hexadecimal Order . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
Table 7.2 Temperature Data Registers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
Table 7.3 Status Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
Table 7.4 Configuration Register. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
Table 7.5 Conversion Rate Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
Table 7.6 Conversion Rate . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
Table 7.7 Temperature Limit Registers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
Table 7.8 Scratchpad Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
Table 7.9 One Shot Register. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
Table 7.10 Th er m Lim i t Re gis ter s . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
Table 7.11 Channel Mask Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
Table 7.12 Consecutive ALERT Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
Table 7.13 Consecutive Alert / Therm Settings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
Table 7.14 Beta Configuration Register. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
Table 7.15 CPU Beta Values. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
Table 7.16 Ideality Configuration Registers. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
Table 7.17 Ideality Factor Look-Up Table (Diode Model) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
Table 7.18 Substrate Diode Ideality Factor Look-Up Table (BJT Model) . . . . . . . . . . . . . . . . . . . . . . . . . 35
Table 7.19 Filter Configuration Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36
Table 7.20 FILTER Decode. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36
Table 7.21 Product ID Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36
Table 7.22 Manufacturer ID Register. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36
Table 7.23 Revision Register. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37
Table 10.1 Customer Revision History . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46
Intern al Temp
Diode
Switching
Current
Analog
Mux
Internal
Temperature Register
Digital Mux
Digital Mux
Limit Comparator
Low Limit Registers
High Limit Registers
Conversion Rate Register
Interupt Ma s k in g
Status Registers
Configuration Register
SMBus Inter fa ce
SMCLK
SMDATA
DP
DN
VDD
GND
External Temperature
Register(s)
ΔΣ ADC THERM Limit Register
THERM Hysteresis Register
SMBu s A ddress De co de
ALERT
EMC1412
THERM / ADD R
Multiple Channel 1°C Temperature Sensor with Beta Compensation
Datasheet
SMSC EMC1412 7 Revision 1.41 (02-23-12)
DATASHEET
Chapter 1 Block Diagram
Figure 1.1 EMC1412 Block Diagram
Chapter 2 Delta
2.1 Functional Delta from EMC1412 rev A to rev B
1. Updated revision number to 04h.
8
7
6
5
SMDATA
SMCLK
1
2
3
4
ALERT
VDD
DP
DN
THERM / ADDR GND
Multiple Channel 1°C Temperature Sensor with Beta Compensation
Datasheet
Revision 1.41 (02-23-12) 8 SMSC EMC1412
DATASHEET
Chapter 3 Pin Description
SMDATA
SMCLK
1
2
3
4
ALERT
DN
THERM / ADDR GND
Exposed pad
DP
VDD 8
7
6
5
Figure 3.1 EMC1412 Pin Diagram, MSOP-8
Figure 3.2 EMC1412 Pin Diagram, TDFN-8 2mm x 3mm
Table 3.1 EMC1412 Pin Description
PIN NUMBER NAME FUNCTION TYPE
1 VDD Power supply Power
2 DP External diode positive (anode) connection AIO
3 DN External diode negative (cathode) connection AIO
4 THERM / ADDR
THERM - Active low Critical THERM output
signal - requires pull-up resistor OD (5V)
ADDR - Selects SMBus address based on pull-
up resistor OD (5V)
5 GND Ground Power
6ALERT
Active low digital ALERT output signal -
requires pull-up resistor OD (5V)
Multiple Channel 1°C Temperature Sensor with Beta Compensation
Datasheet
SMSC EMC1412 9 Revision 1.41 (02-23-12)
DATASHEET
APPLICATION NOTE: For the 5V tolerant pins that have a pull-up resistor (SMCLK, SMDATA, THERM, and
ALERT), the voltage difference between VDD and the pull-up voltage must never exceed
3.6V.
The pin types are described Table 3.2.
7SMDATA
SMBus Data input/output - requires pull-up
resistor DIOD (5V)
8 SMCLK SMBus Clock input - requires pull-up resistor DI (5V)
Bottom Pad Exposed Pad Not internally connected, but recommend
grounding. -
Table 3.2 Pin Types
PIN TYPE DESCRIPTION
Power This pin is used to supply power or ground to the device.
AIO Analog Input / Output -This pin is used as an I/O for analog signals.
DI 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.
Table 3.1 EMC1412 Pin Description
PIN NUMBER NAME FUNCTION TYPE
Multiple Channel 1°C Temperature Sensor with Beta Compensation
Datasheet
Revision 1.41 (02-23-12) 10 SMSC EMC1412
DATASHEET
Chapter 4 Electrical Specifications
4.1 Absolute Maximum Ratings
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 4.1 For the 5V tolerant pins that have a pull-up resistor (SMCLK, SMDATA, THERM, and
ALERT), the pull-up voltage must not exceed 3.6V when the device is unpowered.
Table 4.1 Absolute Maximu m Ratin gs
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
Voltage on 5V tolerant pins (|V 5VT_pin - VDD|) (see Note 4.1)0 to 3.6 V
Voltage on any other pin to Ground -0.3 to VDD +0.3 V
Operating Temperature Range -40 to +125 °C
Storage Temperature Range -55 to +150 °C
Lead Temperature Range Refer to JEDEC Spec. J-STD-020
Package Thermal Characteristics for MSOP-8
Thermal Resistance (θj-a) 140.8 °C/W
Package Thermal Characteristics for TDFN-8
Thermal Resistance (θj-a)89°C/W
ESD Rating, All pins HBM 2000 V
Multiple Channel 1°C Temperature Sensor with Beta Compensation
Datasheet
SMSC EMC1412 11 Revision 1.41 (02-23-12)
DATASHEET
4.2 Electrical Specifications
Table 4.2 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 3.0 3.3 3.6 V
Supply Current IDD 430 850 µA 1 conversion / sec, dynamic
averaging disabled
930 1200 µA 4 conversions / sec, dynamic
averaging enabled
1120 µA > 16 conversions / sec, dynamic
averaging enabled
Standby Supply Current IDD 170 230 µA Device in Standby mode, no SMBus
communications, ALERT and
THERM pins not asserted.
Internal Temperature Monitor
Temperature Accuracy ±0.25 ±1 °C -5°C < TA < 100°C
±2 °C -40°C < TA < 125°C
Temperature Resolution 0.125 °C
External Temperature Monitor
Temperature Accuracy ±0.25 ±1 °C +20°C < TDIODE < +110°C
0°C < TA < 100°C
±0.5 ±2 °C -40°C < TDIODE < 127°C
Temperature Resolution 0.125 °C
Conversion Time all
Channels tCONV 190 ms default settings
Capacitive Filter CFILTER 2.2 2.7 nF Connected across external diode
ALERT and THERM pins
Output Low Voltage VOL 0.4 V ISINK = 8mA
Leakage Current ILEAK ±5 µA ALERT and THERM pins
Device powered or unpowered
TA < 85°C
pull-up voltage < 3.6V
Multiple Channel 1°C Temperature Sensor with Beta Compensation
Datasheet
Revision 1.41 (02-23-12) 12 SMSC EMC1412
DATASHEET
4.3 SMBus Electrical Characteristics
Table 4.3 SMBu s Electrical Specifications
VDD = 3.0V 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 2.0 VDD V 5V Tolerant
Input Low Voltage VIL -0.3 0.8 V 5V Tolerant
Leakage Current ILEAK ±5 µA Powered or unpowered
TA < 85°C
Hysteresis 420 mV
Input Capacitance CIN 5pF
Output Low Sink Current IOL 8.2 15 mA SMDATA = 0.4V
SMBus Timing
Clock Frequency fSMB 10 400 kHz
Spike Suppression tSP 50 ns
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
Multiple Channel 1°C Temperature Sensor with Beta Compensation
Datasheet
SMSC EMC1412 13 Revision 1.41 (02-23-12)
DATASHEET
Chapter 5 System Management Bus Interface Protocol
5.1 Communications Protocol
The EMC1412 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 5.1.
For the first 15ms after power-up the device may not respond to SMBus communications.
.
5.1.1 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.
5.1.2 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 EMC1412-A SMBus slave address is determined by the pull-up resistor on the THERM pin as
shown in Table 5.1, "SMBus Address Decode".
The Address decode is performed by pulling known currents from VDD through the external resistor
causing the pin voltage to dro p based on the respective cu rrent / resistor relationship. Thi s pin voltage
is compared against a threshold that determines the value of the pull-up resistor.
Figure 5.1 SMBus Timing Diagram
Table 5.1 SMBus Address Decode
PULL UP RESISTOR ON
THERM PIN (±5%) SMBUS ADDRESS
4.7k 1111_100(r/w)b
6.8k 1011_100(r/w)b
10k 1001_100(r/w)b
SMDATA
SMCLK
TBUF
PS S - Start Condition P - Stop Condition PS
THIGH
TLOW THD:STA TSU:STO
THD:STA THD:DAT TSU:DAT TSU:STA
TFALL
TRISE
Multiple Channel 1°C Temperature Sensor with Beta Compensation
Datasheet
Revision 1.41 (02-23-12) 14 SMSC EMC1412
DATASHEET
The EMC1412-1 SMBus address is hard coded to 1001_100(r/w).
The EMC1412-2 SMBus address is hard coded to 1001_101(r/w).
5.1.3 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 5.1. 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 require ments do no t 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 5.2.
5.1.4 SMBus Data Bytes
All SMBus Data bytes are sent most significant bit first and composed of 8-bits of information.
5.1.5 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.
15k 1101_100(r/w)b
22k 0011_100(r/w)b
33k 0111_100(r/w)b
Figure 5.2 Isolating THERM Pin
Table 5.1 SMBus Address Decode (continued)
PULL UP RESISTOR ON
THERM PIN (±5%) SMBUS ADDRESS
EMC1412
8
7
6
5
SMDATA
SMCLK
1
2
3
4
ALERT
VDD
DP
DN
THERM / ADDR GND
+3.3V
22K 4.7K – 33k
+2.5 - 5V
Shared THERM
Multiple Channel 1°C Temperature Sensor with Beta Compensation
Datasheet
SMSC EMC1412 15 Revision 1.41 (02-23-12)
DATASHEET
5.1.6 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.
5.1.7 SMBus Timeout
The EMC1412 supports SMBus Timeout. If the clock line is held low for longer than 30ms, the device
will reset its SMBus protocol. This function can be enabled by setting the TIMEOUT bit in the
Consecutive Alert Register (see Section 7.11).
5.1.8 SMBus and I2C Compatibility
The EMC1412 is compatible with SMBus and I2C. The major differences between SMBus and I2C
devices are highlighted he re. For more information, refer to the SMBus 2.0 and I 2C specifications. For
information on using the EMC1412 in an I2C system, refer to SMSC AN 14.0 SMSC Dedicated Slave
Devices in I2C Systems.
1. EMC1412 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 EMC1412 and can be enabled by writing to the
TIMEOUT bit. I2C does not have a timeout.
4. I2C devices do not suppo rt the Ale rt Respon se Addre ss functionality (wh ich is op ti onal for SMBus).
Attempting to communicate with the EMC1412 SMBu s interface with an in valid slave ad dress 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.
5.2 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 5.2.
5.2.1 Write Byte
The Write Byte is used to write one byte of data to the registers, as shown in Table 5.3.
Table 5.2 Protocol Format
DATA SENT
TO DEVICE DAT A SENT TO
THE HOST
# of bits sent # of bits sent
Table 5.3 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
Multiple Channel 1°C Temperature Sensor with Beta Compensation
Datasheet
Revision 1.41 (02-23-12) 16 SMSC EMC1412
DATASHEET
5.2.2 Read Byte
The Read Byte protocol is used to read one byte of data from the registers as shown in Table 5.4.
5.2.3 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 5.5.
5.2.4 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 con secutive reads
of the same register as shown in Table 5.6.
5.3 Alert Response Address
The ALERT output can be used as a processor interrupt or as an SMBus Alert.
When it detects that the ALERT p in 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 5.7.
Table 5.4 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 10 XX 10 -> 1
Table 5.5 Send Byte Protocol
START SLAVE
ADDRESS WR ACK REGISTER
ADDRESS ACK STOP
1 -> 0 YYYY_YYY 0 0 XXh 0 0 -> 1
Table 5.6 Receive Byte Protocol
START SLAVE
ADDRESS RD ACK REGISTER DATA NACK STOP
1 -> 0 YYYY_YYY 1 0 XXh 1 0 -> 1
Table 5.7 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
Multiple Channel 1°C Temperature Sensor with Beta Compensation
Datasheet
SMSC EMC1412 17 Revision 1.41 (02-23-12)
DATASHEET
The EMC1412 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 bit to clear the ALERT pin.
APPLICATION NOTE: The ARA does not clear th e Status Register and if the MASK bit is cleared prior to th e Status
Register being cleared, the ALERT pin will be reasserted.
Multiple Channel 1°C Temperature Sensor with Beta Compensation
Datasheet
Revision 1.41 (02-23-12) 18 SMSC EMC1412
DATASHEET
Chapter 6 Product Description
The EMC1412 is an SMBus temperature sensor. The EMC1412 monitors one internal diode and one
externally connected temperature diode.
Thermal management is performed in cooperation with a host de vice. This consists of the host reading
the temperature data of both the external and internal temperature diodes of the EMC1412 and using
that data to control the speed of one or more fans.
The EMC1412 has two levels of monitoring. The first provides a maskable ALERT signal to the host
when the measured temperatures exceeds user programmable limits. This allows the EMC1412 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 6.1 shows a system level block diagram of the EMC1412.
6.1 Modes of Operation
The EMC1412 has two modes of operation.
Active (Run) - In this mode of operatio n, the ADC is converting on all tempe rature channels at the
programmed conversion rate. The tempera ture data is updated at the e nd of every conversion an d
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 one-
shot register will e nable the device to update a ll temperature channels. Once all the channels are
updated, the device will return to the Standby mode.
6.1.1 Conversion Rates
The EMC1412 may be configured for different conversion rates based on the system requirements.
The conversion rate is configured as described in Section 7.5. The default conversion rate is 4
conversions per second. Other avail able conversion rates are shown in Table 7.6, "Conversion Rate".
Figure 6.1 System Diagram for EMC1412
CPU / GPU
EMC1412
Host
DP
DN
SMDATA
Thermal
Junction SMCLK
SMBus
Interface
THERM / ADDR
ALERT
Power Control
VDD
GND
VDD = 3.3V
3.3V – 5V
Multiple Channel 1°C Temperature Sensor with Beta Compensation
Datasheet
SMSC EMC1412 19 Revision 1.41 (02-23-12)
DATASHEET
6.1.2 Dynamic Averaging
Dynamic averaging causes the EMC1412 to measure the external dio de channels for an extended time
based on the selected conversion rate. This functional ity can be disabled for increased power savings
at the lower conversion rates (see Section 7.4, "Configuration Register"). When dynamic averaging is
enabled, the de vice will a uto matically a djust the samplin g and mea surement 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 6.1.
6.2 THERM Output
The THERM output is a sserted independently of the ALERT output and cannot be masked. When ever
any of the measured temperatures exceed the user programmed Therm Limit values for the
programmed number of cons ecutive 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).
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.
Table 6.1 Supply Current vs. Conversion Rate for EMC1412
CONVERSION RATE
AVERAGE SUPPLY CURRENT AVERAGING FACTOR (BASED ON
11-BIT OPERATION)
ENABLED
(DEFAULT) DISABLED ENABLED
(DEFAULT) DISABLED
1 / 16 sec 660uA 430uA 16x 1x
1 / 8 sec 660uA 430uA 16x 1x
1 / 4 sec 660uA 430uA 16x 1x
1 / 2 sec 660uA 430uA 16x 1x
1 / sec 660uA 430uA 16x 1x
2 / sec 930uA 475uA 16x 1x
4 / sec (default) 950uA 510uA 8x 1x
8 / sec 1010uA 630uA 4x 1x
16 / sec 1020uA 775uA 2x 1x
32 / sec 1050uA 1050uA 1x 1x
64 / sec 1100uA 1100uA 0.5x 0.5x
Multiple Channel 1°C Temperature Sensor with Beta Compensation
Datasheet
Revision 1.41 (02-23-12) 20 SMSC EMC1412
DATASHEET
6.3 ALERT Output
The ALERT 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 output is selected via the
ALERT / COMP bit in the Configuration Register (see Section 7.4).
6.3.1 ALERT Pin Interrupt Mode
When configured to operate in interrupt mode, the ALERT 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.
The ALERT pin will remain asserted as lon g as an out-of-limit condition remains. Once the out-of-limit
condition has been removed, the ALERT pin will remain asserted until the appropriate status bits are
cleared.
The ALERT pin can be masked by setting the MASK_ALL bit. Once the ALERT 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 conditi ons that occur while the ALERT pin is masked will update the Status Register normally.
There are also individual channel masks (see Section 7.10).
The ALERT 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 outputs can be hard-wired
together.
6.3.2 ALERT Pin Comparator Mode
When the ALERT pin is configured to operate in comparator mode, it will be asserted if any of the
measured temperatures exceeds the respective high limit. The ALERT pin will remain asserted until
all temperatures drop below the corresponding high limit minus the Therm Hysteresis value.
When the ALERT 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 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 pin in this mode; however, the individual channel masks
(see Section 7.10) will prevent the respective channel from asserting the ALERT pin.
6.4 Temperature Measurement
The EMC1412 can monitor the temperature of one externally connected diode. The external diode
channel is configured with R esistance Error Correction and Beta Compensation ba sed on user settings
and system requirements.
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.
6.4.1 Beta Compensation
The EMC1412 is configured to monitor the tempera ture of basic diodes (e.g., 2 N3904) or CPU thermal
diodes. 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 temp erature
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 tran sistor whose ideal beta is 50 would contribute
approximately 0.25°C error at 100°C. However for substrate transistors where the base-emitte r juncti on
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.
Multiple Channel 1°C Temperature Sensor with Beta Compensation
Datasheet
SMSC EMC1412 21 Revision 1.41 (02-23-12)
DATASHEET
6.4.2 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 EMC1412 automatically corrects up to 100 ohms
of series resistance.
6.4.3 Programmable External Diode Ideality Factor
The EMC1412 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 EMC1412 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.
APPLICATION NOTE: When monitorin g a substrate transisto r or CP U diode an d beta compensation is enable d, the
Ideality Factor should not be adjusted. Beta Compensation automatically corrects for most
ideality errors.
6.5 Diode Faults
The EMC1412 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 pin asserts (unless masked, see Section 6.6)
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 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.
6.6 Consecutive Alerts
The EMC1412 contain multiple consecutive alert counters. One set of counters applies to the ALERT
pin and the second set of cou nters applies to the THERM pin. Each temperature measurement ch annel
has a separate consecutive alert counter for each of the ALERT 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 7.11, "Consecutive ALERT Register" for more details on the consecutive alert function.
6.7 Digital Filter
To reduce the effect of noise and te mperature spikes on the reported temperature, the External Dio de
channel uses a programmable dig ital filter. This filter ca n be co nfigure d as Level 1 , Level 2 , or D isabled
(default) (see Section 7.14). The typical filter performance is shown in Figure 6.2 and Figure 6.3.
Multiple Channel 1°C Temperature Sensor with Beta Compensation
Datasheet
Revision 1.41 (02-23-12) 22 SMSC EMC1412
DATASHEET
Figure 6.2 Temperature Filter Step Response
Figure 6.3 Temperature Filter Impulse Response
Filter Step Response
0
10
20
30
40
50
60
70
80
90
02468101214
Samples
Temperat ure (C)
Disabled Level1 Level2
Filter Impulse Response
0
10
20
30
40
50
60
70
80
90
0 2 4 6 8 10 12 14
Samples
T emp er ature (C)
Disabled
Level1
Level2
Multiple Channel 1°C Temperature Sensor with Beta Compensation
Datasheet
SMSC EMC1412 23 Revision 1.41 (02-23-12)
DATASHEET
6.8 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 EMC1412 has two selectable temperature ranges. The default range is from 0°C to +127°C and
the temperature i s represented as binary n umber able to report a tempe rature 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 measu re tempe ratu re diod es w ith a la rge
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 6.2 shows the default and extended range formats.
Note 6.1 In default mode, all temperatures < 0°C will be reported as 0°C.
Note 6.2 In the extended range, all temperatures < -64°C will be reported as -64°C.
Note 6.3 For the default range, all temperatures > +127.875°C will be reported as +127.875°C.
Note 6.4 For the extended range, all temperatures > +191.875°C will be reported as +191.875°C.
Table 6.2 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
Note 6.2
-1 000 0000 0000 001 1111 1000
0 000 0000 0000
Note 6.1 010 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
1 2 7 .8 7 5 0 11 1111 1111 10 1 1111 1111
1 2 8 0 11 1111 1111
Note 6.3 110 0000 0000
190 011 1111 1111 111 1111 0000
191 011 1111 1111 111 1111 1000
> = 1 91 . 8 7 5 0 11 1111 1111 111 1111 1111
Note 6.4
Multiple Channel 1°C Temperature Sensor with Beta Compensation
Datasheet
Revision 1.41 (02-23-12) 24 SMSC EMC1412
DATASHEET
6.9 External Diode Connections
The EMC1412 can be configured to measure a CPU substrate transistor, a discrete 2N3904 thermal
diode, or an AMD processor diode. The diodes can be connected as indicated in Figure 6.4.
Figure 6.4 Diode Configurations
Local
Ground
to
DP1
Typical remote
substrate transistor
e.g. CPU substrate
PNP
Typical remote
discrete NPN transistor
e.g. 2N3904
to
DN1
to
DP1
to
DN1
Multiple Channel 1°C Temperature Sensor with Beta Compensation
Datasheet
SMSC EMC1412 25 Revision 1.41 (02-23-12)
DATASHEET
Chapter 7 Register Description
The registers shown in Table 7.1 are accessible through the SMBus. An entry of ‘-’ indicates that the
bit is not used and will always read ‘0’.
Table 7.1 Register Set in Hexadecimal Order
REGISTER
ADDRESS R/W REGISTER NAME FUNCTION DEFAULT
VALUE PAGE
00h R Internal Diode Data
High Byte Stores the integer data for the
Internal Diode 00h Page 27
01h R External Di ode 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 27
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)
Page 30
06h R/W Internal Diode Low
Limit Stores the 8-bit low limit for the
Internal Diode (mirrored at address
0Ch) 00h
(0°C)
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) 55h
(85°C)
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) 00h
(0°C)
09h R/W Configuration Controls the general operation of
the device (mirrored at address
03h) 00h Page 28
0Ah R/W Conversion Rate Controls the conversion rate for
updating temperature data
(mirrored at address 04h) 06h
(4/sec) Page 29
Multiple Channel 1°C Temperature Sensor with Beta Compensation
Datasheet
Revision 1.41 (02-23-12) 26 SMSC EMC1412
DATASHEET
0Bh R/W Internal Diode High
Limit Stores the 8-bit high limit for the
Internal Diode (mirrored at address
05h) 55h
(85°C)
Page 30
0Ch R/W Internal Diode Low
Limit Stores the 8-bit low limit for the
Internal Diode (mirrored at address
06h) 00h
(0°C)
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) 55h
(85°C)
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 Di ode 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 30
12h R/W Scratchpad Scratchpad register for software
compatibility 00h Page 30
13h R/W External Diode High
Limit Low Byte Stores the fractional portion of the
high limit for the External Diode 00h Page 30
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 S tores the 8-bit critical temperature
limit for the External Diode 55h
(85°C) Page 31
1Fh R/W Channel Mask
Register Controls the masking of individual
channels 00h Page 31
20h R/W Internal Diode Therm
Limit S tores the 8-bit critical temperature
limit for the Internal Diode 55h
(85°C) Page 31
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 ou t-of-limit
conditions that must occur before
an interrupt is asserted 70h Page 32
25h R/W External Diode Beta
Configuration Stores the Beta Compensation
circuitry settings for External Diode 08h Page 33
27h R/W External Diode
Ideality Factor Stores the ideality factor for the
External Diode 12h
(1.008) Page 34
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 36
Table 7.1 Register Set in Hexadecimal Order (continue d)
REGISTER
ADDRESS R/W REGISTER NAME FUNCTION DEFAULT
VALUE PAGE
Multiple Channel 1°C Temperature Sensor with Beta Compensation
Datasheet
SMSC EMC1412 27 Revision 1.41 (02-23-12)
DATASHEET
7.1 Data Read Interlock
When any temperature channel high byte register is read, the corresponding low byte is copied into
an internal ‘shadow’ register. T he user is free to read the l ow 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.
7.2 Temperature Data Registers
As shown in Table 7.2, 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.
7.3 Status Register
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 or THERM pin is being
asserted.
The ALERT and THERM pins are controlled by the respective consecutive alert counters (see
Section 7.11) and will not be asserted until the progra mmed consecutive alert count has been reached.
FDh R Product ID Stores a fixed value that identifies
the device 20h Page 36
FEh R Manufacturer ID Stores a fixed value that
represents SMSC 5Dh Page 36
FFh R Revision Stores a fixed value that
represents the revision number 04h Page 37
Table 7.2 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
Tab le 7.3 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
Table 7.1 Register Set in Hexadecimal Order (continue d)
REGISTER
ADDRESS R/W REGISTER NAME FUNCTION DEFAULT
VALUE PAGE
Multiple Channel 1°C Temperature Sensor with Beta Compensation
Datasheet
Revision 1.41 (02-23-12) 28 SMSC EMC1412
DATASHEET
The status bits (except E1THERM and ITHERM) will remain set until read unless the ALERT pin is
configured as a second THERM output (see Section 6.3.2).
Bit 7 - BUSY - This bit indicates that the ADC is currently converting. This bit does not cause either
the ALERT or THERM pins 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 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 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 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 pin.
Bit 2 - FAULT - This bit is asserted when a diode fault is detected. When set, this bit will assert the
ALERT 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 channe l exceeds th e programmed The rm L imit.
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.
7.4 Configuration Register
The Configuration Register controls the basic operation of the device. This register is fully accessible
at either address.
Bit 7 - MASK_ALL - Masks the ALERT pin from asserting.
‘0’ - (default) - The ALER T pin is not masked. If any of the appropriate status bits are set the ALERT
pin will be asserted.
‘1’ - - The ALERT pin is masked. It will not be asserted for any interrupt condition unless it is
configured in comparator mode. The Status Register 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/COMP - Controls the operation of the ALERT pin.
‘0’ (default) - The ALERT pin acts as described in Section 6.3.
‘1’ - The ALERT pin acts in comparator mode as described in Section 6.3.2. 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.
Table 7.4 Configuration Register
ADDR R/W REGISTER B7 B6 B5 B4 B3 B2 B1 B0 DEFAULT
03h R/W Configuration MASK_
ALL RUN/
STOP ALERT/
COMP RECD - RANGE DAVG_
DIS - 00h
09h
Multiple Channel 1°C Temperature Sensor with Beta Compensation
Datasheet
SMSC EMC1412 29 Revision 1.41 (02-23-12)
DATASHEET
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 6.2).
Bit 1 - DAVG_DIS - Disables the dynamic averaging feature on all temperature channels.
‘0’ (defau l t) - The dy n a m i c av e raging feature is enabled. All temperature channels will be converted
with an averaging factor that is based on the conversion rate as shown in Table 6.1.
‘1’ - The dynamic averagin g feature is disabled. All temperature channels will be converted with a
maximum averaging facto r of 1x (equivalent to 11-bit conversion). For h igher conversion rate s, this
averaging factor will be reduced as shown in Table 6.1.
7.5 Conversion Rate Register
The Conversion Rate Regi ster controls how o ften the temperatu re measurement cha nnels 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 7.6.
Table 7.5 Conversion Rate Register
ADDR R/W REGISTER B7 B6 B5 B4 B3 B2 B1 B0 DEFAULT
04h R/W Conversion
Rate - - - - CONV[3:0] 06h
(4/sec)
0Ah
Table 7.6 Con version Rate
CONV[3:0]
CONVERSIONS / SECONDHEX 3 2 1 0
0h 0 0 0 0 1 / 16
1h 0 0 0 1 1 / 8
2h 0 0 1 0 1 / 4
3h 0 0 1 1 1 / 2
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 All others 1
Multiple Channel 1°C Temperature Sensor with Beta Compensation
Datasheet
Revision 1.41 (02-23-12) 30 SMSC EMC1412
DATASHEET
7.6 Limit Registers
The device contains both high and low limi ts for all temperature channels. If the measured temp erature
exceeds the high limit, then the corresponding status bit is set and the ALERT 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 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 or by clearing the
RUN / STOP bit in the Configuration Register (see Section 7.4).
7.7 Scratchpad Registers
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.
Tab le 7.7 Temperature Limit Registers
ADDR. R/W REGISTER B7 B6 B5 B4 B3 B2 B1 B0 DEFAULT
05h R/W Internal Diode
High Limit 128643216 8 42 1 55h
(85°C)
0Bh
06h R/W Internal Diode
Low Limit 128643216 8 421 00h
(0°C)
0Ch
07h R/W External
Diode High
Limit High
Byte 128643216 8 421 55h
(85°C)
0Dh
13h R/W External
Diode High
Limit Low
Byte 0.5 0.25 0.125 - - - - - 00h
08h R/W External
Diode Low
Limit High
Byte 128643216 8 421 00h
(0°C)
0Eh
14h R/W External
Diode Low
Limit Low
Byte 0.5 0.25 0.125 - - - - - 00h
Table 7.8 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
Multiple Channel 1°C Temperature Sensor with Beta Compensation
Datasheet
SMSC EMC1412 31 Revision 1.41 (02-23-12)
DATASHEET
7.8 One Shot Register
The One Shot Register is used to initiate a one shot command. Writing to the one shot register when
the device is i n standby mode and BUSY b it (in Status Register) is ‘0’ , will immediately cause the ADC
to update all temperature me asurements. Writing to the One Shot Register while the de vice is in active
mode will have no effect.
7.9 Therm Limit Registers
The Therm Limit Registe rs 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 pin, the THERM pin cannot be masked. Additiona lly, the THERM pin will be released
once the temperature drops below the corresponding threshold minus the Therm Hysteresis.
7.10 Channel Mask Register
The Channel Mask Register controls individual channel masking. When a channel is masked, the
ALERT pin will not be asserted whe n the masked channel reads a diode fault or out of limit error. The
channel mask does not mask the THERM pin.
Bit 1 - EMASK - Masks the ALERT 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 pin to be asserted if it is out of
limit or reports a diode fault.
Table 7.9 One Shot Register
ADDR. R/W REGISTER B7 B6 B5 B4 B3 B2 B1 B0 DEFAULT
0Fh W One Shot Writing to this register initiates a single conversion cycle. Data
is not stored and always reads 00h 00h
Table 7.10 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)
Table 7.11 Channel Mask Reg ister
ADDR. R/W REGISTER B7 B6 B5 B4 B3 B2 B1 B0 DEFAULT
1Fh R/W Channel
Mask ---- - - E
MASK INT
MASK 00h
Multiple Channel 1°C Temperature Sensor with Beta Compensation
Datasheet
Revision 1.41 (02-23-12) 32 SMSC EMC1412
DATASHEET
‘1’ - The External Diode channel will not cause the ALERT pin to be asserted if it is out of limit or
reports a diode fault.
Bit 0 - INTMASK - Masks the ALERT pin from asserting when the Internal Diode temperature is out
of limit.
‘0’ (default) - The Inte rnal Diode chann el will cause the ALERT pin to be asserted if it is out of limit.
‘1’ - The Internal Diode channel will not cause the ALERT pin to be asserted if it is out of limit.
7.11 Consecutive ALERT Register
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 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 increm ent the con secutive al ert 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 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 pin will be asserte d, th e consec utive alert co unter
will be cleared, and measurements will continue.
When the ALERT 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 pin will be
asserted, but the counte r will not be reset. It will rema in set until the temp erature 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 EMC1412 device, the high
limits are set at 70°C, and none of the channels a re masked, then the ALERT pin will be asserted after
the following four measurements:
1. Internal Diode reads 71°C and the external diode reads 69°C. Consecutive a lert 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 read 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 pin is asserted. EXT counter is reset to 0 and all oth er 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 SMCL K line ca n be held low indefinitely
without the device resetting its SMBus protocol.
Table 7.12 Consecutive ALERT Register
ADDR. R/W REGISTER B7 B6 B5 B4 B3 B2 B1 B0 DEFAULT
22h R/W Consecutive
ALERT TIME
OUT CTHRM[2:0] CALRT[2:0] - 70h
Multiple Channel 1°C Temperature Sensor with Beta Compensation
Datasheet
SMSC EMC1412 33 Revision 1.41 (02-23-12)
DATASHEET
‘1’ - The SMBus Timeout feature is enabled. If the SMCLK line is held low for more than 30ms,
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 before the THERM pin is asserted. All temper ature channels use th is 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 7.13. 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 be fore the ALERT pin is asserted. All temperature chann els use this value
to set the respective counters. The bits are decoded as shown in Table 7.13. The default setting is 1
consecutive out of limit conversion.
7.12 Beta Configuration Register
This register is used to set the Beta Compensation factor that is used for the external diode channel.
Bit 3 - ENABLE - Enables the Beta Compensation factor auto-detection function.
‘0’ - The Beta Compensation Factor auto-detection circuitry is disabled.
‘1’ (default) - The Beta Compensation factor au to-detection circu itry is enabled. At the b eginning of
every conversion, the optimal Beta Compensation factor setting will be determined and applied.
The BETA[2:0] bits will be automatically updated to indicate the current setting.
Bit 2-0 - BETA[2:0] - These bi ts always reflect the current beta configuration settings. If auto-detection
circuitry is enabled, these bits will be updated automati cally and writing to these bits will have no effect.
If the auto-detection circuitry is disabled, these bits will determine the beta configuration setting.
Care should be taken when setting the BETA[2:0] bits when the auto-detection circuitry is disabled. If
the Beta Compensation factor is set at a beta value that is higher than the transistor beta, the circuit
Table 7.13 Conse cutive Alert / Therm Settings
210
NUMBER OF CONSECUTIVE OUT OF LIMIT
MEASUREMENTS
000 1
(default for CALRT[2:0])
001 2
011 3
111 4
(default for CTHRM[2:0])
Table 7.14 Beta Configuration Register
ADDR. R/W REGISTER B7 B6 B5 B4 B3 B2 B1 B0 DEFAULT
25h R/W External
Diode Beta
Configuration - - - - ENABLE BETA[2:0] 08h
Multiple Channel 1°C Temperature Sensor with Beta Compensation
Datasheet
Revision 1.41 (02-23-12) 34 SMSC EMC1412
DATASHEET
may introduce measurement errors. When measuring a discrete thermal diode (such as 2N3904) or a
CPU diode that functions like a discrete thermal diode (such as an AMD processor diode), the
BETA[2:0] bits should be set to ‘111b’.
7.13 External Diode Ideality Factor Register
This register stores the ideality factors that are applied to the external diode. Table 7.17 defines each
setting and the corresponding ideality factor. Beta Compensation and Resistance Error Correction
automatically correct for most diode idea lity errors; therefore, it is not recommended that these setti ngs
be updated without consulting SMSC.
Table 7.15 CPU Beta Values
HEX ENABLEX
BETA[2:0]
MINIMUM BETA21 0
0h 0 0 0 0 0.11
1h 0 0 0 1 0.18
2h 0 0 1 0 0.25
3h 0 0 1 1 0.33
4h 0 1 0 0 0.43
5h 0 1 0 1 1.00
6h 0 1 1 0 2.33
7h 0 1 1 1 Disabled
8h - Fh 1 X X X Auto-detection
Table 7.16 Ideality Configuration Registers
ADDR. R/W REGISTER B7 B6 B5 B4 B3 B2 B1 B0 DEFAULT
27h R/W External
Diode
Ideality
Factor - - IDEALITY[5:0] 12h
Table 7.17 Ideality Factor Lo ok -Up Table (Diode Mode l)
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
Multiple Channel 1°C Temperature Sensor with Beta Compensation
Datasheet
SMSC EMC1412 35 Revision 1.41 (02-23-12)
DATASHEET
For CPU substrate transistors that re quire the BJT transistor model , the ideality factor behaves slightly
differently than for discrete diode-connected transistors. Refer to Table 7.18 when using a CPU
substrate transistor.
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
Table 7.18 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
Table 7.17 Ideality Facto r Look-Up Table (Diode Model) (continued)
SETTING FACTOR SETTING FACTOR SETTING FACTOR
Multiple Channel 1°C Temperature Sensor with Beta Compensation
Datasheet
Revision 1.41 (02-23-12) 36 SMSC EMC1412
DATASHEET
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.
7.14 Filter Control Register
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 sh own in Table 7.20. See Figure 6.2 and Figure 6.3 for examples on the
filter behavior.
7.15 Product ID Register
The Product ID Register holds a unique value that identifies the device.
7.16 SMSC ID Register
The Manufacturer ID register contains an 8-bit word that identifies the SMSC as the manufacturer of
the EMC1412.
Table 7.19 Filter Configuration Register
ADDR. R/W REGISTER B7 B6 B5 B4 B3 B2 B1 B0 DEFAULT
40h R/W Filter Control - - - - - - FILTER[1:0] 00h
Table 7.20 FILTER Decode
FILTER[1:0]
AVERAGING10
0 0 Disabled (default)
0 1 Level 1
1 0 Level 1
1 1 Level 2
Table 7.21 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
Table 7.22 Ma nufacturer ID Register
ADDR.R/WREGISTERB7B6B5B4B3B2B1B0DEFAULT
FEh RSMSC ID01011101 5Dh
Multiple Channel 1°C Temperature Sensor with Beta Compensation
Datasheet
SMSC EMC1412 37 Revision 1.41 (02-23-12)
DATASHEET
7.17 Revision Register
The Revision register contains an 8-bit word that identifies the die revision.
Table 7.23 Revision Register
ADDR. R/W REGISTER B7 B6 B5 B4 B3 B2 B1 B0 DEFAULT
FFh R Revision00000100 04h
Multiple Channel 1°C Temperature Sensor with Beta Compensation
Datasheet
Revision 1.41 (02-23-12) 38 SMSC EMC1412
DATASHEET
Chapter 8 Typical Operating Curves
Temperature Error vs. Filter Capacitor
(2N3904, TA = 27°C, TDIODE = 27°C, VDD = 3.3V)
-1.0
-0.8
-0.5
-0.3
0.0
0.3
0.5
0.8
1.0
0 1000 2000 3000 4000
Filter Capacitor (pF)
Temperature Error (°C)
Temperature Error vs. Ambient Temperature
(2N3904, TDIODE = 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 95 110 125
Ambient Temperature (°C)
Temperature Error (°C)
Temperature Error vs. External Diode Temperature
(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 95 110 125
External Diode Temperature (°C)
Temperature Error (°C)
Tempera ture Error vs. C PU Tempera ture
Typic a l 65 nm CP U from major vendor
(TA = 27°C, VDD = 3.3V, BETA = 011, CFILTER = 470pF)
-1
0
1
2
3
4
5
20 40 60 80 100 120
CPU Temperature (°C)
Temperature Error (°C)
Beta Compensation
Disabled
Beta Compensation Enabled
Multiple Channel 1°C Temperature Sensor with Beta Compensation
Datasheet
SMSC EMC1412 39 Revision 1.41 (02-23-12)
DATASHEET
T e m p erature Error v s . Seri es Re sis tan ce
0.0
0.2
0.4
0.6
0.8
1.0
0 50 100 150 2000
20
40
60
80
100
120
REC Enabled
RE C D isabled
Series R (Ohm )
Temperature Error (°C)
REC Enabled
Temperature Error (°C)
REC Disabled
Temperature Error vs. Ambient Temperature
(2N3904, TDIODE = 27°C, VDD = 3.3V)
-2.0
-1.5
-1.0
-0.5
0.0
0.5
1.0
1.5
2.0
-40 -25 -10 5 20 35 50 65 80 95 110 125
Ambient Temperature (°C)
Temperature Error (°C)
EXT2 - APD
EXT3 - APD
Supply Current vs. Conve rsion Ra te
200
300
400
500
600
700
800
900
1000
1100
1200
1248 163264
Conve rsion Rate
Supply Current (u
A
Dynamic
Averaging
Enabled
Dynamic
Averaging
Disabled
Multiple Channel 1°C Temperature Sensor with Beta Compensation
Datasheet
Revision 1.41 (02-23-12) 40 SMSC EMC1412
DATASHEET
Chapter 9 Package Information
Figure 9.1 EMC1412 2mm x 3mm TDFN Package Drawing
Multiple Channel 1°C Temperature Sensor with Beta Compensation
Datasheet
SMSC EMC1412 41 Revision 1.41 (02-23-12)
DATASHEET
Figure 9.2 EMC1412 2mm x 3mm TDFN Package Dimensions
Figure 9.3 EMC1412 2mm x 3mm TDFN Package PCB Land Pattern
-SEE SPEC FRONT PAGE FOR REVISION HISTORY --
c
SEE DET AIL "A"
e
D
E1 E
PIN 1 IDENTIFIER
AREA (D/2 X E1/2)
8X b
L
L1
0.25
0° - 8°
DIM AND TOL PER ASME Y14.5M - 1994
FINISH
MATERIAL
DECIMAL
X.X
X.XX
X.XXX
80 ARKAY DRIVE
HAUPPAUGE, NY 11788
USA
ANGULAR
PRINT WITH "SCALE TO FIT"
DO N OT SCAL E DRAW ING
CHECKED
APPROVED
NAME
DRAWN
DWG NUM B ER
SCALE
TITLE
DATE
STD COMPLIANCE
UNLESS OTHERWISE SPECIFIED
DIMENSIONS ARE IN MILLIMETERS
AND TOLERANCES ARE:
THI RD ANGLE PROJEC T I O N
REV
SHEET
REVISION DESCRIPTION
REVISI ON HISTORY
RELEASED BYDATE
PACK AGE OUTL I NE
8 PIN TSSOP, 3x3 MM BODY, 0.65 MM PITCH
±1°
-
-
±0.1
±0.05
±0.025
S.K.ILIEV
S.K.ILIEV
S.K.ILIEV
7/07/04
7/05/04
1:1
7/05/04
MO-8-TSSOP-3x3
JEDEC: MO -187 / D 1 OF 1
D
C
SEATING PLA N E
A
A2
A1
SEATING PLANE
SIDE VIEW
ccc C
GAUGE PLANE
H
3-D V IEW
TOP VIEW
C
3
2
END VIEW
4
3
5
DETAI L "A "
SCALE: 3/1
NOTES:
1. ALL DIMENSIO NS ARE IN MILLIMETER.
2. TOLERANCE ON THE TRUE POSITION OF THE LEADS IS ± 0.065mm MAXI MUM.
3. PACKAG E BO DY DIMENSION S "D" AND "E1" DO NOT INCLUDE MO LD PROTRUSIONS OR FLASH.
MAXIMUM MOLD PROTRUSIONS OR FLASH IS 0.15 mm (0.00 6 INCHES) PER END AND SID E.
DIMENS IO NS "D" AND "E1" AR E DETERMINED AT DATUM PLAN E "H".
4. DIMENSION FOR FOOT LENGTH "L" IS MEASURED AT THE GAUGE PLANE 0. 25mm ABOVE THE
SEATING PLANE.
5. DETAILS OF PIN 1 IDENTIFIER ARE OPTIONAL, BUT MUST BE LOC ATED WITHIN T HE ZONE
INDICA TED.
Multiple Channel 1°C Temperature Sensor with Beta Compensation
Datasheet
Revision 1.41 (02-23-12) 42 SMSC EMC1412
DATASHEET
Figure 9.4 8-Pin MSOP / TSSOP Package
Multiple Channel 1°C Temperature Sensor with Beta Compensation
Datasheet
SMSC EMC1412 43 Revision 1.41 (02-23-12)
DATASHEET
9.1 Package Markings
The devices will be marked as shown in Figure 9.5, Figure 9.6 and Figure 9.7.
BOTTOM
LINE 1: Preface, First digit of Device Co de
LINE 2: Second digit of Device Cod e, Re vision
LINES 1 & 2: CENTER
HORIZONTAL ALIGNMEN T
2x 0.6
TOP
PIN 1
E1
LINE 3: AS SHOWN
BOTTOM MARKING IS NOT ALLOWED
5R
Figure 9.5 EMC1412-1 8-Pin TDFN Package Markings
BOTTOM
LINE 1: Preface, First digit of Device Co de
LINE 2: Second digit of Device Cod e, Re vision
LINES 1 & 2: CENTER
HORIZONTAL ALIG NMENT
2x 0.6
TOP
PIN 1
E3
LINE 3: AS SHOWN
BOTTOM MA RKING IS NOT ALLOWED
4R
Multiple Channel 1°C Temperature Sensor with Beta Compensation
Datasheet
Revision 1.41 (02-23-12) 44 SMSC EMC1412
DATASHEET
Figure 9.6 EMC1412-A 8-Pin TDFN Package Markings
BOTTOM
LINE: 1-T – Device Number
LINE: 2-T Version, Revision, Country Code (VRCC)
ALL TOP LINES CENTER
HORIZONTAL ALIGNMENT
PB-FREE/GREEN SYMBOL
(Matte Sn)
2x 1.5pt
TOP
e3
PIN 1
LINE: 1-B – Date Code (YYWW)
LINE: 2-B – First 3 Digits of Lot Number
3x 1.5pt
PIN 1
LINE: 3-B – Last 4 Digits of Lot Number
14 12
VR CC
YYWW
123
456a
Multiple Channel 1°C Temperature Sensor with Beta Compensation
Datasheet
SMSC EMC1412 45 Revision 1.41 (02-23-12)
DATASHEET
Figure 9.7 EMC1412 8-Pin MSOP Package Markings
Multiple Channel 1°C Temperature Sensor with Beta Compensation
Datasheet
Revision 1.41 (02-23-12) 46 SMSC EMC1412
DATASHEET
Chapter 10 Document Revision History
Table 10.1 Cu stomer Revision History
REVISION LEVEL & DATE SECTION/FIGURE/ENTRY CORRECTION
Rev. 1.41 (02-23-12) Chapter 3, Pin Description Labeled exposed pad in pinout figure and added
row in pin description table. Recommendation is to
ground the exposed pad.
Rev. 1.40 (01-05-12) Table 4.3, "SMBus Electrical
Specifications" Added conditions for tHD:DAT. Data hold time
minimum of 0.3µs is required when receiving from
the master.
Section 5.1.8, "SMBus and
I2C Compatibility" Renamed from “SMBus and I2C Compliance.” First
paragraph, added first sentence: “The EMC1412 is
compatible with SMBus and I2C.”
And added last sentence: “For information on
using the EMC1412 in an I2C system, refer to
SMSC AN 14.0 SMSC Dedicated Slave Devices in
I2C Systems.”
Rev. 1.38 (09-30-10) Table 4.2, "Electrical
Specifications" Filter MAX changed from “2.5nF” to “2.7nF”.
Section 7.17, "Revision
Register" Set revision ID to 04h.
Chapter 5, System
Management Bus Interface
Protocol
Updated error on ACK bit settings and reorganized
chapter information and moved ALERT pin
considerations.
Chapter 6, Product
Description Reorganized information for temperature
monitoring and ALERT pin considerations.
Rev. 1.37 (12-23-09) Section 7.17, "Revision
Register" Changed default from 01h to 03h to match the
actual value.
Rev. 1.36 (09-19-09) Ordering Information Added EMC1412-1-AC3-TR in an 8-pin TDFN
package.
Section 4.1, "Absolute
Maximum Ratings" Updated voltage on 5V tolerant pins with pull up
from -0.3 to 3.6 to 0 to 3.6. Added thermal
characteristics for TDFN package.
Chapter 9, Package
Information Added package information for the TDFN.
Section 9.1, "Package
Markings" Added package marking information for the TDFN.
Rev. 1.35 (05-06-09) Pin Table Identified 5V tolerant pins. Added the following
application note below table: “For the 5V tolerant
pins that have a pull-up resistor (SMCLK,
SMDATA, THERM, ALERT), the voltage diff erence
between VDD and the pull-up voltage must never
exceed 3.6V.”
Multiple Channel 1°C Temperature Sensor with Beta Compensation
Datasheet
SMSC EMC1412 47 Revision 1.41 (02-23-12)
DATASHEET
Table 4.1, "Absolute
Maximum Ratings" Updated voltage limits for 5V tolerant pins with
pull-up resistors.
Added the following note below table: “For the 5V
tolerant pins that have a pull-up resistor (SMCLK,
SMDATA, THERM, ALERT), the pull-up voltage
must not exceed 3.6V when the device is
unpowered.”
Table 4.2, "Electrical
Specifications" Added leakage current
Rev. 1.34 (12-02-08) Initial document creation
Table 10.1 Customer Revision History (continued)
REVISION LEVEL & DATE SECTION/FIGURE/ENTRY CORRECTION
