EMC1422 DATA SHEET (08/10/2012) DOWNLOAD

EMC1422
1°C Temperature Sensor with
Hardware Thermal Shutdown
PRODUCT FEATURES
Datasheet
General Description
Applications
The EMC1422 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.
„
Additionally, the EMC1422 provides a hardware
programmable system shutdown feature that is
programmed at part power-up via two pull-up resistor
values and that cannot be masked or corrupted through
the SMBus.
„
„
„
Notebook Computers
Desktop Computers
Industrial
Embedded applications
Features
„
Hardware Thermal Shutdown
— triggers dedicated SYS_SHDN pin
— hardware configured range 77°C to 112°C in 1°C steps
— cannot be disabled or modified by software
„
Support for diodes requiring the BJT/transistor model
„
Pin compatible with ADM1032, MAX6649, and LM99
Automatically determines external diode type and
optimal settings
Resistance Error Correction
External Temperature Monitors
— supports 45nm, 65nm, and 90nm CPU thermal diodes.
„
Each device provides ±1° accuracy for external diode
temperatures and ±2°C accuracy for the internal diode
temperature. The EMC1422 monitors two temperature
channels (one external and one internal).
„
Resistance Error Correction automatically eliminates 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.
„
Internal Temperature Monitor
„
3.3V Supply Voltage
Programmable temperature limits for ALERT
Available in Small 8-pin MSOP Lead-free RoHS
Compliant Package
SMSC EMC1422
„
— ±1°C Accuracy (60°C < TDIODE < 100°C)
— 0.125°C Resolution
— Supports up to 2.2nF diode filter capacitor
— ±2°C accuracy
„
„
DATASHEET
Revision 2.0 (08-10-12)
1°C Temperature Sensor with Hardware Thermal Shutdown
Datasheet
Ordering Information:
EMC1422-1-ACZL-TR FOR 8-PIN, MSOP LEAD-FREE ROHS COMPLIANT PACKAGE
Note: See Table 1.1, "Part Selection" for SMBus addressing options.
REEL SIZE IS 4,000 PIECES.
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 © 2012 SMSC or its subsidiaries. All rights reserved.
Circuit diagrams and other information relating to SMSC products are included as a means of illustrating typical applications. Consequently, complete information sufficient for
construction purposes is not necessarily given. Although the information has been checked and is believed to be accurate, no responsibility is assumed for inaccuracies. SMSC
reserves the right to make changes to specifications and product descriptions at any time without notice. Contact your local SMSC sales office to obtain the latest specifications
before placing your product order. The provision of this information does not convey to the purchaser of the described semiconductor devices any licenses under any patent
rights or other intellectual property rights of SMSC or others. All sales are expressly conditional on your agreement to the terms and conditions of the most recently dated
version of SMSC's standard Terms of Sale Agreement dated before the date of your order (the "Terms of Sale Agreement"). The product may contain design defects or errors
known as anomalies which may cause the product's functions to deviate from published specifications. Anomaly sheets are available upon request. SMSC products are not
designed, intended, authorized or warranted for use in any life support or other application where product failure could cause or contribute to personal injury or severe property
damage. Any and all such uses without prior written approval of an Officer of SMSC and further testing and/or modification will be fully at the risk of the customer. Copies of
this document or other SMSC literature, as well as the Terms of Sale Agreement, may be obtained by visiting SMSC’s website at http://www.smsc.com. SMSC is a registered
trademark of Standard Microsystems Corporation (“SMSC”). Product names and company names are the trademarks of their respective holders.
SMSC DISCLAIMS AND EXCLUDES ANY AND ALL WARRANTIES, INCLUDING WITHOUT LIMITATION ANY AND ALL IMPLIED WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE, TITLE, AND AGAINST INFRINGEMENT AND THE LIKE, AND ANY AND ALL WARRANTIES ARISING FROM ANY COURSE
OF DEALING OR USAGE OF TRADE. IN NO EVENT SHALL SMSC BE LIABLE FOR ANY DIRECT, INCIDENTAL, INDIRECT, SPECIAL, PUNITIVE, OR CONSEQUENTIAL
DAMAGES; OR FOR LOST DATA, PROFITS, SAVINGS OR REVENUES OF ANY KIND; REGARDLESS OF THE FORM OF ACTION, WHETHER BASED ON CONTRACT;
TORT; NEGLIGENCE OF SMSC OR OTHERS; STRICT LIABILITY; BREACH OF WARRANTY; OR OTHERWISE; WHETHER OR NOT ANY REMEDY OF BUYER IS HELD
TO HAVE FAILED OF ITS ESSENTIAL PURPOSE, AND WHETHER OR NOT SMSC HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGES.
Revision 2.0 (08-10-12)
2
DATASHEET
SMSC EMC1422
1°C Temperature Sensor with Hardware Thermal Shutdown
Datasheet
Table of Contents
Chapter 1 Block Diagram
1.1
...................................................7
Part Selection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
Chapter 2 Pin Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
Chapter 3 Electrical Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
3.1
3.2
3.3
Absolute Maximum Ratings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
Electrical Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
SMBus Electrical Characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
Chapter 4 System Management Bus Interface Protocol . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
4.1
4.2
4.3
4.4
4.5
4.6
4.7
4.8
System Management Bus Interface Protocol . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Write Byte . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Read Byte . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Send Byte . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Receive Byte. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Alert Response Address . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
SMBus Address . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
SMBus Timeout . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
12
12
13
13
13
13
14
14
Chapter 5 Product Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
5.1
5.2
5.3
5.4
5.5
5.6
5.7
5.8
5.9
5.10
5.11
5.12
5.0.1
Conversion Rates . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
5.0.2
Dynamic Averaging . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
SYS_SHDN Output. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Hardware Thermal Shutdown Limit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
ALERT Output . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
5.3.1
ALERT Pin Interrupt Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
5.3.2
ALERT Pin Comparator Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
ALERT and SYS_SHDN Pin Considerations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Beta Compensation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Resistance Error Correction (REC) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Diode Faults . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Consecutive Alerts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Digital Filter. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Temperature Monitors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Temperature Measurement Results and Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
External Diode Connections . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
15
15
16
17
17
18
18
18
19
19
19
19
20
21
22
23
Chapter 6 Register Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
6.1
6.2
6.3
6.4
6.5
6.6
6.7
6.8
6.9
6.10
6.11
Data Read Interlock . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Temperature Data Registers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Status Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Configuration Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Conversion Rate Register. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Limit Registers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Scratchpad Registers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Therm Limit Registers. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
External Diode Fault Register. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Software Thermal Shutdown Configuration Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Hardware Thermal Shutdown Limit Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
SMSC EMC1422
3
DATASHEET
26
26
26
27
28
29
29
30
30
30
31
Revision 2.0 (08-10-12)
1°C Temperature Sensor with Hardware Thermal Shutdown
Datasheet
6.12
6.13
6.14
6.15
6.16
6.17
6.18
6.19
6.20
Channel Mask Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Consecutive ALERT Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
High Limit Status Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Low Limit Status Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
THERM Limit Status Register. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Filter Control Register. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Product ID Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
SMSC ID Register (FEh) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Revision Register (FFh) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
31
32
33
34
34
34
35
35
36
Chapter 7 Typical Operating Curves. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37
Chapter 8 Package Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39
8.1
Package Markings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40
Chapter 9 Datasheet Revision History . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41
Revision 2.0 (08-10-12)
4
DATASHEET
SMSC EMC1422
1°C Temperature Sensor with Hardware Thermal Shutdown
Datasheet
List of Figures
Figure 1.1
Figure 2.1
Figure 4.1
Figure 5.1
Figure 5.2
Figure 5.3
Figure 5.4
Figure 5.5
Figure 5.6
Figure 5.7
Figure 8.1
EMC1422 Block Diagram. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
EMC1422 Pin Diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
SMBus Timing Diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
System Diagram for EMC1422 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
Block Diagram of Hardware Thermal Shutdown . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
Isolating ALERT and SYS_SHDN Pins . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
Temperature Filter Step Response . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
Temperature Filter Impulse Response. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
Block Diagram of Temperature Monitoring Circuit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
Diode Configurations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
8-Pin MSOP / TSSOP Package . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39
SMSC EMC1422
5
DATASHEET
Revision 2.0 (08-10-12)
1°C Temperature Sensor with Hardware Thermal Shutdown
Datasheet
List of Tables
Table 1.1 Part Selection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
Table 2.1 EMC1422 Pin Description. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
Table 3.1 Absolute Maximum Ratings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
Table 3.2 Electrical Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
Table 3.3 SMBus Electrical Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
Table 4.1 Protocol Format . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
Table 4.2 Write Byte Protocol . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
Table 4.3 Read Byte Protocol . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
Table 4.4 Send Byte Protocol . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
Table 4.5 Receive Byte Protocol . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
Table 4.6 Alert Response Address Protocol . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
Table 5.1 Supply Current vs. Conversion Rate for EMC1422 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
Table 5.2 SYS_SHDN Threshold Temperature. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
Table 5.3 Temperature Data Format . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
Table 6.1 Register Set in Hexadecimal Order . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
Table 6.2 Temperature Data Registers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
Table 6.3 Status Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
Table 6.4 Configuration Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
Table 6.5 Conversion Rate Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
Table 6.6 Conversion Rate . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
Table 6.7 Temperature Limit Registers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
Table 6.8 Scratchpad Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
Table 6.9 Therm Limit Registers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
Table 6.10 External Diode Fault Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
Table 6.11 Software Thermal Shutdown Configuration Register. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
Table 6.12 Hardware Thermal Shutdown Limit Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
Table 6.13 Channel Mask Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
Table 6.14 Consecutive ALERT Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
Table 6.15 Consecutive Alert / THERM Settings. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
Table 6.16 High Limit Status Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
Table 6.17 Low Limit Status Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
Table 6.18 THERM Limit Status Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
Table 6.19 Filter Configuration Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
Table 6.20 Filter Settings. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
Table 6.21 Product ID Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
Table 6.22 Manufacturer ID Register. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
Table 6.23 Revision Register. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36
Table 9.1 Customer Revision History . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41
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SMSC EMC1422
1°C Temperature Sensor with Hardware Thermal Shutdown
Datasheet
Chapter 1 Block Diagram
VDD
SYS_SHDN Limit
EMC1422
Switching
Current
Internal
Temperature
Register
DN1
SMBus Interface
DP1
Low Limit Registers
Digital Mux
External
Temperature
Register(s)
ΔΣ ADC
Limit Comparator
Analog
Mux
Digital Mux
Conversion Rate Register
High Limit Registers
Internal
Temp Diode
SMCLK
SMDATA
Configuration Register
Status Registers
Interupt Masking
ALERT
SYS_SHDN
GND
Figure 1.1 EMC1422 Block Diagram
1.1
Part Selection
The EMC1422 device configuration is highlighted below.
Table 1.1 Part Selection
FUNCTIONALITY
PART
NUMBER
SMBUS
ADDRESS
EXTERNAL
DIODES
DIODE 1
DEFAULT
CONFIGURATION
DIODE 2
DEFAULT
CONFIGURATION
OTHER
PRODUCT
ID
Software programmable and maskable High Limit
EMC1422 - 1
1001_100xb
1
Detect Diode w/ REC
enabled
N/A
Software programmable and maskable SYS_SHDN
Limit
22h
Hardware set
SYS_SHDN Limit
on External Diode
1
SMSC EMC1422
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Datasheet
Chapter 2 Pin Description
VDD 1
8
SMCLK
DP1 2
7
SMDATA
DN1 3
6
ALERT
SYS_SHDN 4
5
GND
Figure 2.1 EMC1422 Pin Diagram
Table 2.1 EMC1422 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
SYS_SHDN
Active low System Shutdown output
signal - requires pull-up resistor
which selects the Hardware
Thermal Shutdown Limit
OD (5V)
5
GND
Ground
Power
6
ALERT
Active low digital ALERT 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 pullup resistor
DI (5V)
4
APPLICATION NOTE: For the 5V tolerant pins that have a pull-up resistor (SMCLK, SMDATA, SYS_SHDN, and
ALERT), the voltage difference between VDD and the pull-up voltage must never exceed
3.6V.
The pin types are described below:
Power - these pins are used to supply either VDD or GND to the device.
AIO - Analog Input / Output.
DI - Digital Input.
OD - Open Drain Digital Output.
DIOD - Digital Input / Open Drain Output.
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SMSC EMC1422
1°C Temperature Sensor with Hardware Thermal Shutdown
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
Voltage on 5V tolerant pins (|V5VT_pin - VDD|) (see Note 3.1)
-0.3 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 any other pin to Ground
Lead Temperature Range
Refer to JEDEC Spec. J-STD-020
Package Thermal Characteristics for MSOP-8
Thermal Resistance (θj-a)
ESD Rating, All pins HBM
140.8
°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. When powering this device from
laboratory or system power supplies, it is important that the Absolute Maximum Ratings not be
exceeded or device failure can result. Some power supplies exhibit voltage spikes on their
outputs when the AC power is switched on or off. In addition, voltage transients on the AC
power line may appear on the DC output. If this possibility exists, it is suggested that a clamp
circuit be used.
Note 3.1
SMSC EMC1422
For the 5V tolerant pins that have a pull-up resistor (SMCLK, SMDATA, SYS_SHDN, and
ALERT), the pull-up voltage must not exceed 3.6V when the device is unpowered.
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1°C Temperature Sensor with Hardware Thermal Shutdown
Datasheet
3.2
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
3.0
3.3
3.6
V
430
850
uA
1 conversion / sec, dynamic
averaging disabled
930
1200
uA
4 conversions / sec, dynamic
averaging enabled
uA
> 16 conversions / sec, dynamic
averaging enabled
1120
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
EMC1422, default settings
nF
Connected across external diode
Conversion Time all
Channels
tCONV
190
Capacitive Filter
CFILTER
2.2
2.5
ALERT and SYS_SHDN pins
Output Low Voltage
VOL
Leakage Current
ILEAK
Power up time
Note 3.2
Revision 2.0 (08-10-12)
0.4
V
ISINK = 8mA
±5
uA
ALERT and SYS_SHDN pins
Device powered or unpowered
TA < 85°C
pull-up voltage < 3.6V
15
ms
Temp selection read
Note 3.2
During the power up time, SMBus communication is permitted, however the SYS_SHDN
and ALERT pins must not be pulled low.
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SMSC EMC1422
1°C Temperature Sensor with Hardware Thermal Shutdown
Datasheet
3.3
SMBus Electrical Characteristics
Table 3.3 SMBus 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
Input High/Low Current
IIH / IIL
±5
uA
Powered or unpowered
TA < 85°C
Hysteresis
Input Capacitance
CIN
Output Low Sink Current
IOL
420
mV
5
pF
8.2
15
mA
SMDATA = 0.4V
SMBus Timing
Clock Frequency
fSMB
Spike Suppression
tSP
Bus free time Start to
Stop
tBUF
1.3
us
Hold Time: Start
tHD:STA
0.6
us
Setup Time: Start
tSU:STA
0.6
us
Setup Time: Stop
tSU:STP
0.6
us
Data Hold Time
tHD:DAT
0
us
When transmitting to the master
Data Hold Time
tHD:DAT
0.3
us
When receiving from the master
Data Setup Time
tSU:DAT
100
ns
Clock Low Period
tLOW
1.3
us
Clock High Period
tHIGH
0.6
us
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
SMSC EMC1422
10
400
kHz
50
ns
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1°C Temperature Sensor with Hardware Thermal Shutdown
Datasheet
Chapter 4 System Management Bus Interface Protocol
4.1
System Management Bus Interface Protocol
The EMC1422 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.
.
TLOW
THIGH
THD:STA
TSU:STO
TRISE
SMCLK
THD:STA
TFALL
THD:DAT
TSU:STA
TSU:DAT
SMDTA
TBUF
P
S
S
S - Start Condition
P - Stop Condition P
Figure 4.1 SMBus Timing Diagram
The EMC1422 is SMBus 2.0 compatible and support 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
DATA SENT
TO DEVICE
# of bits sent
DATA SENT TO
THE HOST
# of bits sent
Attempting to communicate with the EMC1422 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
Write Byte
The Write Byte is used to write one byte of data to the registers as shown below Table 4.2:
Table 4.2 Write Byte Protocol
START
SLAVE
ADDRESS
WR
ACK
REGISTER
ADDRESS
ACK
REGISTER
DATA
ACK
STOP
1 -> 0
1001_100
0
0
XXh
0
XXh
0
0 -> 1
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1°C Temperature Sensor with Hardware Thermal Shutdown
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4.3
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
1001_100
0
1
XXh
0
1 -> 0
1001_100
1
1
XX
1
0 -> 1
4.4
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
1001_100
0
0
XXh
0
0 -> 1
4.5
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
1001_100
1
0
XXh
1
0 -> 1
4.6
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
1001_1000
1
0 -> 1
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The EMC1422 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 the Status Register and if the MASK bit is cleared prior to the Status
Register being cleared, the ALERT pin will be reasserted.
4.7
SMBus Address
The EMC1422 responds to hard-wired SMBus slave address as shown in Table 1.1.
Note: Other addresses are available. Contact SMSC for more information.
4.8
SMBus Timeout
The EMC1422 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 6.13).
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1°C Temperature Sensor with Hardware Thermal Shutdown
Datasheet
Chapter 5 Product Description
The EMC1422 is an SMBus temperature sensor with Hardware Thermal Shutdown. The EMC1422
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 EMC1422 and using
that data to control the speed of one or more fans.
The EMC1422 has two levels of monitoring. The first provides a maskable ALERT signal to the host
when measured temperatures meet or exceed user programmable limits. This allows the EMC1422 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 asserts the SYS_SHDN pin when the External Diode temperature
exceeds a hardware specified threshold temperature. Additionally, the internal diodecan be configured
to assert the SYS_SHDN pin when the measured temperature exceeds user programmable limits.
Since the EMC1422 automatically corrects for temperature errors due to series resistance in
temperature diode lines, there is greater flexibility in where external diodes are positioned and better
measurement accuracy than previously available with non-resistance error correcting devices. The
automatic beta detection feature means that there is no need to program the device according to which
type of diode is present. This also includes CPU diodes that require the transistor or BJT model for
monitoring their temperature. Therefore, the EMC1422 can power up ready to operate for any system
configuration.
Figure 5.1 shows a system level block diagram of the EMC1422.
CPU
Thermal
diode
EMC1422
Host
DP1
DN1
Internal
Diode
SMCLK
SMDATA
ALERT
SYS_SHDN
SMBus
Interface
Power Control
Figure 5.1 System Diagram for EMC1422
5.0.1
Conversion Rates
The EMC1422 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.
5.0.2
Dynamic Averaging
Dynamic averaging causes the EMC1422 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). 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)
SMSC EMC1422
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1°C Temperature Sensor with Hardware Thermal Shutdown
Datasheet
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 will affect the average supply current based on the chosen
conversion rate as shown in Table 5.1 for the EMC1422.
Table 5.1 Supply Current vs. Conversion Rate for EMC1422
AVERAGE SUPPLY CURRENT
AVERAGING FACTOR (BASED ON
11-BIT OPERATION)
CONVERSION RATE
ENABLED
(DEFAULT)
DISABLED
ENABLED
(DEFAULT)
DISABLED
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
5.1
SYS_SHDN Output
The SYS_SHDN output is asserted independently of the ALERT output and cannot be masked. If the
External Diode temperature exceeds the Hardware Thermal Shutdown Limit for the programmed
number of consecutive measurements, then the SYS_SHDN pin is asserted.
The Hardware Thermal Shutdown Limit is defined at power-up via the pull-up resistors on the
SYS_SHDN and ALERT pins as shown in Table 5.2. This limit cannot be modified or masked via
software.
In addition to External Diode channel triggering the SYS_SHDN pin when the measured temperature
exceeds to the Hardware Thermal Shutdown Limit, each of the measurement channels can be
configured to assert the SYS_SHDN pin when they exceed the corresponding THERM Limit.
When the SYS_SHDN pin is asserted, it will not release until the External Diode temperature drops
below the Hardware Thermal Shutdown Limit minus 10°C and all other measured temperatures drop
below the THERM Limit minus the THERM Hysteresis value (when linked to SYS_SHDN).
Figure 5.2 shows a block diagram of the interaction between the input channels and the SYS_SHDN
pin.
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1°C Temperature Sensor with Hardware Thermal Shutdown
Datasheet
Hardware Thermal Shutdown
SMBus
Traffic
Internal Diode
Temperature
Conversion
and THERM
Limit
Compare
Software
Shutdown Enable
H/W Thermal
Shutdown Sensor
3.3V
SW_SHDN
Temperature
Conversion
3.3V
SYS_SHDN
HW_SHDN
ALERT
Function
Select
Figure 5.2 Block Diagram of Hardware Thermal Shutdown
5.2
Hardware Thermal Shutdown Limit
The Hardware Thermal Shutdown Limit temperature is determined by pull-up resistors on the
SYS_SHDN and ALERT pins shown in Table 5.2.
Table 5.2 SYS_SHDN Threshold Temperature
SYS_SHD
PULL-UP
4.7K OHM
±10%
ALERT
PULL-UP
6.8K OHM
±10%
10K OHM
±10%
15K OHM
±10%
22K OHM
±10%
33K OHM
±10%
4.7K OHM ±10%
77°C
83°C
89°C
95°C
101°C
107°C
6.8K OHM ±10%
78°C
84°C
90°C
96°C
102°C
108°C
10K OHM ±10%
79°C
85°C
91°C
97°C
103°C
109°C
15K OHM ±10%
80°C
86°C
92°C
98°C
104°C
110°C
22K OHM ±10%
81°C
87°C
93°C
99°C
105°C
111°C
33K OHM ±10%
82°C
88°C
94°C
100°C
106°C
112°C
5.3
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 6.4).
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Datasheet
5.3.1
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 long 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 bit. Once the ALERT pin has been masked, it
will be de-asserted and remain de-asserted until the MASK bit is cleared by the user. Any interrupt
conditions that occur while the ALERT pin is masked will update the Status Register normally.
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.
5.3.2
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 bit will not block the ALERT pin in this mode, however the individual channel masks (see
Section 6.12) will prevent the respective channel from asserting the ALERT pin.
5.4
ALERT and SYS_SHDN Pin Considerations
Because of the decode method used to determine the Hardware Thermal Shutdown Limit, it is
important that the pull-up resistance on both the ALERT and SYS_SHDN pins be within the tolerances
shown in Table 5.2. Additionally, the pull-up resistor on the ALERT and SYS_SHDN pins must be
connected to the same 3.3V supply that drives the VDD pin.
For 15ms after power up, the ALERT and SYS_SHDN pins must not be pulled low or the Hardware
Thermal Shutdown Limit will not be decoded properly. If the system requirements do not permit these
conditions, then the ALERT and SYS_SHDN pins must be isolated from their respective busses during
this time.
One method of isolating this pin is shown in Figure 5.3.
+3.3V
VDD 1
10
SMCLK
DP1 2
9
SMDATA
DN1 3
8
ALERT
7
GND
SYS_SHDN
4
4.7K 33K
+2.5 - 5V
22K
Shared Alert/
Figure 5.3 Isolating ALERT and SYS_SHDN Pins
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1°C Temperature Sensor with Hardware Thermal Shutdown
Datasheet
5.5
Beta Compensation
The EMC1422 is configured to monitor the temperature of basic diodes (e.g. 2N3904), 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
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
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 EMC1422 automatically corrects up to 100 ohms
of series resistance.
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 EMC1422 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 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 pin asserts (unless masked). This condition is indistinguishable from a temperature
measurement of 0.000degC (-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 EMC1422 contains multiple consecutive alert counters. One set of counters applies to the ALERT
pin and the second set of counters applies to the SYS_SHDN pin. Each temperature measurement
channel has a separate consecutive alert counter for each of the ALERT and SYS_SHDN 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 6.13 for more details on the consecutive alert function.
SMSC EMC1422
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1°C Temperature Sensor with Hardware Thermal Shutdown
Datasheet
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. The typical filter performance is shown in Figure 5.4 and Figure 5.5.
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
Revision 2.0 (08-10-12)
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DATASHEET
SMSC EMC1422
1°C Temperature Sensor with Hardware Thermal Shutdown
Datasheet
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
5.10
Temperature Monitors
In general, thermal diode temperature measurements are based on the change in forward bias voltage
of a diode when operated at two different currents. This ΔVBE is proportional to absolute temperature
as shown in the following equation:
where:
Δ V BE =
η kT
q
⎛ I
ln ⎜⎜ HIGH
⎝ I LOW
⎞
⎟⎟
⎠
k = Boltzmann’s constant
T = absolute temperature in Kelvin
[1]
q = electron charge
η = diode ideality factor
Figure 5.6 shows a block diagram of the temperature measurement circuit. The negative terminal for
the remote temperature diode, DN, is internally biased with a forward diode voltage referenced to
ground.
SMSC EMC1422
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1°C Temperature Sensor with Hardware Thermal Shutdown
Datasheet
IHIGH
ILOW
Substrate
PNP
DP
AntiAliasing
Filter
Resistance
Error
Correction
ΔΣ
ADC
DN
Figure 5.6 Block Diagram of Temperature Monitoring Circuit
5.11
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 EMC1422 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 5.3 shows the default and extended range formats.
Table 5.3 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 5.2
-1
000 0000 0000
001 1111 1000
0
000 0000 0000
Note 5.1
010 0000 0000
0.125
000 0000 0001
010 0000 0001
1
000 0000 1000
010 0000 1000
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SMSC EMC1422
1°C Temperature Sensor with Hardware Thermal Shutdown
Datasheet
Table 5.3 Temperature Data Format (continued)
TEMPERATURE (°C)
DEFAULT RANGE 0°C TO 127°C
EXTENDED RANGE -64°C TO 191°C
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
Note 5.3
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
Note 5.4
5.12
Note 5.1
In default mode, all temperatures < 0°C will be reported as 0°C.
Note 5.2
In the extended range, all temperatures < -64°C will be reported as -64°C.
Note 5.3
For the default range, all temperatures > +127.875°C will be reported as +127.875°C.
Note 5.4
For the extended range, all temperatures > +191.875°C will be reported as +191.875°C.
External Diode Connections
The EMC1422 is hard-wired to measure a specific kind of thermal diode and none of the measurement
options can be changed by software. Figure 5.7 shows the different diode configurations.
to
DP
to
DP
to
DP
to
DN
to
DN
to
DN
Local Ground
Typical remote
substrate transistor
i.e. CPU substrate PNP
Typical remote
discrete PNP transistor
i.e. 2N3906
Typical remote
discrete NPN transistor
i.e. 2N3904
Figure 5.7 Diode Configurations
SMSC EMC1422
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Revision 2.0 (08-10-12)
1°C Temperature Sensor with Hardware Thermal Shutdown
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
Status
Stores the status bits for the
Internal Diode and External Diodes
00h
Page 26
03h
R/W
Configuration
Controls the general operation of
the device (mirrored at address
09h)
00h
Page 27
04h
R/W
Conversion Rate
Controls the conversion rate for
updating temperature data
(mirrored at address 0Ah)
06h
(4/sec)
Page 28
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)
PAGE
Page 26
Page 29
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)
00h
(0°C)
09h
R/W
Configuration
Controls the general operation of
the device (mirrored at address
03h)
00h
Page 27
0Ah
R/W
Conversion Rate
Controls the conversion rate for
updating temperature data
(mirrored at address 04h)
06h
(4/sec)
Page 28
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SMSC EMC1422
1°C Temperature Sensor with Hardware Thermal Shutdown
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 29
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)
10h
R
External Diode Data
Low Byte
Stores the fractional data for the
External Diode
00h
Page 26
11h
R/W
Scratchpad
Scratchpad register for software
compatibility
00h
Page 29
12h
R/W
Scratchpad
Scratchpad register for software
compatibility
00h
Page 29
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 30
1Dh
R/W
SYS_SHDN
Configuration
Controls which software channels,
if any, are linked to the
SYS_SHDN pin
00h
Page 30
1Eh
R
Hardware Thermal
Shutdown Limit
When read, returns the selected
Hardware Thermal Shutdown Limit
N/A
Page 31
1Fh
R/W
Channel Mask
Register
Controls the masking of individual
channels
00h
Page 31
20h
R/W
Internal Diode
THERM Limit
Stores the 8-bit critical temperature
limit for the Internal Diode
55h
(85°C)
0Ah
(10°C)
Page 29
Page 30
21h
R/W
THERM Hysteresis
Stores the 8-bit hysteresis value
that applies to all THERM limits
22h
R/W
Consecutive ALERT
Controls the number of out-of-limit
conditions that must occur before
an interrupt is asserted
70h
Page 32
29h
R
Internal Diode Data
Low Byte
Stores the fractional data for the
Internal Diode
00h
Page 26
35h
R-C
High Limit Status
Status bits for the High Limits
00h
Page 33
36h
R-C
Low Limit Status
Status bits for the Low Limits
00h
Page 34
SMSC EMC1422
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DATASHEET
Revision 2.0 (08-10-12)
1°C Temperature Sensor with Hardware Thermal Shutdown
Datasheet
Table 6.1 Register Set in Hexadecimal Order (continued)
REGISTER
ADDRESS
R/W
REGISTER NAME
FUNCTION
DEFAULT
VALUE
PAGE
37h
R
THERM Limit Status
Status bits for the THERM Limits
00h
Page 34
40h
R/W
Filter Control
Controls the digital filter setting for
the External Diode channel
00h
Page 34
FDh
R
Product ID
Stores a fixed value that identifies
each product
Table 6.21
Page 35
FEh
R
SMSC ID
Stores a fixed value that
represents SMSC
5Dh
Page 35
FFh
R
Revision
Stores a fixed value that
represents the revision number
01h or 04h
Page 36
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.
6.3
Status Register
Table 6.3 Status Register
ADDR
R/W
REGISTER
B7
B6
B5
B4
B3
B2
B1
B0
DEFAULT
02h
R
Status
BUSY
-
-
HIGH
LOW
FAULT
THERM
HWSD
00h
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SMSC EMC1422
1°C Temperature Sensor with Hardware Thermal Shutdown
Datasheet
The Status Register reports general error conditions. To identify specific channels, refer to Section 6.9,
Section 6.14, Section 6.15, and Section 6.16. The individual Status Register bits are cleared when the
appropriate High Limit, Low Limit, or THERM Limit register has been read or cleared.
Bit 7 - BUSY - This bit indicates that the ADC is currently converting. This bit does not cause the
ALERT pin to be asserted.
Bit 4 - HIGH - This bit is set when any of the temperature channels exceeds its programmed high limit.
See the High Limit Status Register for specific channel information (Section 6.14). When set, this bit
will assert the ALERT pin.
Bit 3 - LOW - This bit is set when any of the temperature channels drops below its programmed low
limit. See the Low Limit Status Register for specific channel information (Section 6.15). When set, this
bit will assert the ALERT pin.
Bit 2 - FAULT - This bit is asserted when a diode fault is detected on any of the external diode
channels. See the External Diode Fault Register for specific channel information (Section 6.9). When
set, this bit will assert the ALERT pin.
Bit 1 - THERM - This bit is set when the any of the temperature channels exceeds its programmed
THERM limit. See the THERM Limit Status Register for specific channel information (Section 6.16).
Bit 0 - HWSD - This bit is set when the External Diode Temperature exceeds the Hardware Thermal
Shutdown Limit set by the pull-up resistors on the ALERT and SYS_SHDN pins. When set, this bit will
assert the SYS_SHDN pin.
6.4
Configuration Register
Table 6.4 Configuration Register
ADDR
R/W
REGISTER
B7
B6
B5
B4
B3
B2
B1
B0
DEFAULT
R/W
Configuration
MASK_
ALL
-
ALERT/
COMP
-
-
RANGE
DAVG_
DIS
-
00h
03h
09h
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 ALERT 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 to act in comparator mode. The Status Registers will be updated normally.
Bit 5 - ALERT/COMP - Controls the operation of the ALERT pin.
„
‘0’ (default) - The ALERT pin acts as described in Section 5.3.
„
‘1’ - The ALERT pin acts in comparator mode as described in Section 5.3.2. In this mode the
MASK_ALL bit is ignored.
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 5.3).
Bit 1 - DAVG_DIS - Disables the dynamic averaging feature on all temperature channels.
„
SMSC EMC1422
‘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 5.1.
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1°C Temperature Sensor with Hardware Thermal Shutdown
Datasheet
„
6.5
‘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 5.1.
Conversion Rate Register
Table 6.5 Conversion Rate Register
ADDR
R/W
REGISTER
B7
B6
B5
B4
R/W
Conversion
Rate
-
-
-
-
04h
0Ah
B3
B2
B1
B0
DEFAULT
06h
(4/sec)
CONV[3:0]
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.
Table 6.6 Conversion Rate
CONV[3:0]
HEX
3
2
1
0
CONVERSIONS / SECOND
0h
0
0
0
0
1
1h
0
0
0
1
1
2h
0
0
1
0
1
3h
0
0
1
1
1
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
Revision 2.0 (08-10-12)
All others
1
28
DATASHEET
SMSC EMC1422
1°C Temperature Sensor with Hardware Thermal Shutdown
Datasheet
6.6
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
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
05h
0Bh
06h
0Ch
07h
0Dh
13h
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 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.
6.7
Scratchpad Registers
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.
SMSC EMC1422
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DATASHEET
Revision 2.0 (08-10-12)
1°C Temperature Sensor with Hardware Thermal Shutdown
Datasheet
6.8
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)
6.9
External Diode Fault Register
Table 6.10 External Diode Fault Register
ADDR.
R/W
REGISTER
B7
B6
B5
B4
1Bh
R-C
External
Diode Fault
-
-
-
-
B3
B2
-
-
B1
B0
DEFAULT
FLT
-
00h
The External Diode Fault Register indicates which of the external diodes caused the FAULT bit in the
Status Register to be set. This register is cleared when it is read.
Bit 1 - FLT - This bit is set if the External Diode channel reported a diode fault.
6.10
Software Thermal Shutdown Configuration Register
Table 6.11 Software Thermal Shutdown Configuration Register
ADDR.
1Dh
R/W
REGISTER
B7
B6
B5
B4
R/W
Software
Thermal
Shutdown
Configuration
-
-
-
-
B3
B2
-
-
B1
B0
DEFAULT
EXTSYS
INTSYS
00h
The Software Thermal Shutdown Configuration Register controls whether any of the software channels
will assert the SYS_SHDN pin. If a channel is enabled, the temperature is compared against the
corresponding THERM Limit. If the measured temperature exceeds the THERM Limit, then the
SYS_SHDN pin is asserted. This functionality is in addition to the Hardware Shutdown circuitry.
Bit 1 - EXTSYS - configures the External Diode channel to assert the SYS_SHDN pin based on its
THERM Limit.
„
‘0’ (default) - the External Diode channel is not linked to the SYS_SHDN pin. If the temperature
exceeds its THERM Limit, the ETHERM status bit is set but the SYS_SHDN pin is not asserted.
„
‘1’ - the External Diode channel is linked to the SYS_SHDN pin. If the temperature exceeds its
THERM Limit, the ETHERM status bit is set and the SYS_SHDN pin is asserted. It will remain
asserted until the temperature drops below its THERM Limit minus the THERM Hysteresis.
Revision 2.0 (08-10-12)
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SMSC EMC1422
1°C Temperature Sensor with Hardware Thermal Shutdown
Datasheet
Bit 0 - INTSYS - configures the Internal Diode channel to assert the SYS_SHDN pin based on its
THERM Limit.
6.11
„
‘0’ (default) - the Internal Diode channel is not linked to the SYS_SHDN pin. If the temperature
exceeds its THERM Limit, the ITHERM status bit is set but the SYS_SHDN pin is not asserted.
„
‘1’ - the Internal Diode channel is linked to the SYS_SHDN pin. If the temperature exceeds its
THERM Limit, the ITHERM status bit is set and the SYS_SHDN pin is asserted. It will remain
asserted until the temperature drops below its THERM Limit minus the THERM Hysteresis.
Hardware Thermal Shutdown Limit Register
Table 6.12 Hardware Thermal Shutdown Limit Register
ADDR.
R/W
REGISTER
B7
B6
B5
B4
B3
B2
B1
B0
DEFAULT
1Eh
R
Hardware
Thermal
Shutdown Limit
128
64
32
16
8
4
2
1
N/A
This read only register returns the Hardware Thermal Shutdown Limit selected by the value of the pullup resistors on the ALERT and SYS_SHDN pins. The data represents the hardware set temperature
in °C using the active temperature setting set by the RANGE bit in the Configuration Register. See
Table 6.5 for the data format.
When the External Diode Temperature exceeds this limit, the SYS_SHDN pin is asserted and will
remain asserted until the External Diode Temperature drops below this limit minus 10°C.
6.12
Channel Mask Register
Table 6.13 Channel Mask Register
ADDR.
R/W
REGISTER
B7
B6
B5
B4
1Fh
R/W
Channel
Mask
-
-
-
-
B3
B2
B1
B0
DEFAULT
-
-
E
MASK
INT
MASK
00h
The Channel Mask Register controls individual channel masking. When a channel is masked, the
ALERT 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 SYS_SHDN 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.
„
‘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 Internal Diode channel 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.
SMSC EMC1422
31
DATASHEET
Revision 2.0 (08-10-12)
1°C Temperature Sensor with Hardware Thermal Shutdown
Datasheet
6.13
Consecutive ALERT Register
Table 6.14 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 or SYS_SHDN 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 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 asserted, the consecutive alert counter
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 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, the high limits are set at 70°C,
and none of the channels are 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 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 2and 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 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 30ms,
then 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.
If the temperature drops below the THERM limit or Hardware Thermal Shutdown Limit, then the
counter is reset. If the programmed number of consecutive measurements exceed the THERM Limit
Revision 2.0 (08-10-12)
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DATASHEET
SMSC EMC1422
1°C Temperature Sensor with Hardware Thermal Shutdown
Datasheet
or Hardware Thermal Shutdown Limit, and the appropriate channel is linked to the SYS_SHDN pin,
then 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.
The bits are decoded as shown in Table 6.15. 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 pin is asserted. All temperature channels use this value
to set the respective counters. The bits are decoded as shown in Table 6.15. The default setting is 1
consecutive out of limit conversion.
Table 6.15 Consecutive Alert / THERM Settings
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])
APPLICATION NOTE: When measuring a 65nm Intel CPUs, the Ideality Setting should be the default 12h. When
measuring 45nm Intel CPUs, the Ideality Setting should be 15h.
6.14
High Limit Status Register
Table 6.16 High Limit Status Register
ADDR.
R/W
REGISTER
B7
B6
B5
B4
35h
R-C
High Limit
Status
-
-
-
-
B3
B2
-
-
B1
B0
DEFAULT
EHIGH
IHIGH
00h
The High Limit Status Register contains the status bits that are set when a temperature channel high
limit is exceeded. If any of these bits are set, then the HIGH status bit in the Status Register is set.
Reading from the High Limit Status Register will clear all bits if. Reading from the register will also
clear the HIGH status bit in the Status Register.
The ALERT pin will be set if the programmed number of consecutive alert counts have been met and
any of these status bits are set.
The status bits will remain set until read unless the ALERT pin is configured as a comparator output
(see Section 5.3.2).
Bit 1 - EHIGH - This bit is set when the External Diode channel exceeds its programmed high limit.
Bit 0 - IHIGH - This bit is set when the Internal Diode channel exceeds its programmed high limit.
SMSC EMC1422
33
DATASHEET
Revision 2.0 (08-10-12)
1°C Temperature Sensor with Hardware Thermal Shutdown
Datasheet
6.15
Low Limit Status Register
Table 6.17 Low Limit Status Register
ADDR.
R/W
REGISTER
B7
B6
B5
B4
36h
R-C
Low Limit
Status
-
-
-
-
B3
B2
-
-
B1
B0
DEFAULT
ELOW
ILOW
00h
The Low Limit Status Register contains the status bits that are set when a temperature channel drops
below the low limit. If any of these bits are set, then the LOW status bit in the Status Register is set.
Reading from the Low Limit Status Register will clear all bits. Reading from the register will also clear
the LOW status bit in the Status Register.
The ALERT pin will be set if the programmed number of consecutive alert counts have been met and
any of these status bits are set.
The status bits will remain set until read unless the ALERT pin is configured as a comparator output
(see Section 5.3.2).
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.
6.16
THERM Limit Status Register
Table 6.18 THERM Limit Status Register
ADDR.
R/W
REGISTER
B7
B6
B5
B4
37h
R-C
THERM
Limit
Status
-
-
-
-
B3
B2
-
-
B1
B0
DEFAULT
ETHERM
ITHERM
00h
The THERM Limit Status Register contains the status bits that are set when a temperature channel
THERM Limit is exceeded. If any of these bits are set, then the THERM status bit in the Status Register
is set. Reading from the THERM Limit Status Register will not clear the status bits. Once the
temperature drops below the THERM Limit minus the THERM Hysteresis, the corresponding status
bits will be automatically cleared. The THERM bit in the Status Register will be cleared when all
individual channel THERM bits are cleared.
Bit 1 - ETHERM - This bit is set when the External Diode channel exceeds its programmed THERM
limit.
Bit 0- ITHERM - This bit is set when the Internal Diode channel exceeds its programmed THERM limit.
6.17
Filter Control Register
Table 6.19 Filter Configuration Register
ADDR.
R/W
REGISTER
B7
B6
B5
B4
B3
B2
40h
R/W
Filter Control
-
-
-
-
-
-
B1
B0
DEFAULT
FILTER[1:0]
00h
The Filter Configuration Register controls the digital filter on the External Diode channel.
Revision 2.0 (08-10-12)
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DATASHEET
SMSC EMC1422
1°C Temperature Sensor with Hardware Thermal Shutdown
Datasheet
Bits 1-0 - FILTER[1:0] - Control the level of digital filtering that is applied to the External Diode
temperature measurements as shown in Table 6.20. See Figure 5.4and Figure 5.5 for examples on the
filter behavior.
Table 6.20 Filter Settings
FILTER[1:0]
6.18
1
0
AVERAGING
0
0
Disabled (default)
0
1
Level 1
1
0
Level 1
1
1
Level 2
Product ID Register
Table 6.21 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
1
0
22h
EMC1422
The Product ID Register holds a unique value that identifies the device.
6.19
SMSC ID Register (FEh)
Table 6.22 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 EMC1422.
SMSC EMC1422
35
DATASHEET
Revision 2.0 (08-10-12)
1°C Temperature Sensor with Hardware Thermal Shutdown
Datasheet
6.20
Revision Register (FFh)
Table 6.23 Revision Register
ADDR.
R/W
REGISTER
B7
B6
B5
B4
B3
B2
B1
B0
DEFAULT
FFh
R
Revision
0
0
0
0
0
0
0
1
01h
FFh
R
Revision
0
0
0
0
0
1
0
0
04h
The Revision register contains an 8-bit word that identifies the die revision. It can be 01h or 04h.
ENGINEERING NOTE:
Revision 2.0 (08-10-12)
36
DATASHEET
SMSC EMC1422
1°C Temperature Sensor with Hardware Thermal Shutdown
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)
5
Temperature Error (°C)
Temperature Error (°C)
SMSC EMC1422
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)
4
Beta Compensation
Disabled
3
2
1
0
Beta Compensation Enabled
-1
20
110 125
40
60
80
100
120
CPU Temperature (°C)
37
DATASHEET
Revision 2.0 (08-10-12)
1°C Temperature Sensor with Hardware Thermal Shutdown
Datasheet
Supply Current vs. Conversion Rate
0.8
100
80
REC Disabled
0.6
60
0.4
40
0.2
20
REC Enabled
0.0
0
50
100
Series R (Ohm)
150
Supply Current (uA)
120
Temperature Error (°C)
REC Disabled
Temperature Error (°C)
REC Enabled
Temperature Error vs. Series Resistance
1.0
0
200
1200
1100
1000
900
800
700
600
500
400
300
200
Dynamic
Averaging
Enabled
Dynamic
Averaging
Disabled
1
2
4
8
16
32
64
Conversion Rate
Revision 2.0 (08-10-12)
38
DATASHEET
SMSC EMC1422
D
PIN 1 IDENTIFIER
AREA (D/2 X E1/2)
e
3
DESCRIPTION
-
DATE
RELEASED BY
-
-
SEE SPEC FRONT PAGE FOR REVISION HISTORY
5
Revision 2.0 (08-10-12)
REVISION HISTORY
REVISION
3
c
E
E1
SEE DETAIL "A"
2 8X b
TOP VIEW
END VIEW
39
DATASHEET
A2
A
C
SEATING PLANE
A1
ccc C
SIDE VIEW
3-D VIEW
H
C
NOTES:
1. ALL DIMENSIONS ARE IN MILLIMETER.
2. TOLERANCE ON THE TRUE POSITION OF THE LEADS IS ± 0.065mm MAXIMUM.
3. PACKAGE BODY DIMENSIONS "D" AND "E1" DO NOT INCLUDE MOLD PROTRUSIONS OR FLASH.
MAXIMUM MOLD PROTRUSIONS OR FLASH IS 0.15 mm (0.006 INCHES) PER END AND SIDE.
DIMENSIONS "D" AND "E1" ARE DETERMINED AT DATUM PLANE "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 LOCATED WITHIN THE ZONE
INDICATED.
GAUGE PLANE
0.25
SEATING PLANE
0° - 8°
4
L
UNLESS OTHERWISE SPECIFIED
DIMENSIONS ARE IN MILLIMETERS
AND TOLERANCES ARE:
L1
DECIMAL
±0.1
X.X
X.XX ±0.05
X.XXX ±0.025
THIRD ANGLE PROJECTION
80 ARKAY DRIVE
HAUPPAUGE, NY 11788
USA
ANGULAR
±1°
TITLE
DETAIL "A"
NAME
DIM AND TOL PER ASME Y14.5M - 1994
MATERIAL
-
SCALE: 3/1
FINISH
-
DATE
S.K.ILIEV
7/05/04
CHECKED
S.K.ILIEV
S.K.ILIEV
Figure 8.1 8-Pin MSOP / TSSOP Package
REV
DWG NUMBER
MO-8-TSSOP-3x3
7/05/04
APPROVED
PRINT WITH "SCALE TO FIT"
DO NOT SCALE DRAWING
PACKAGE OUTLINE
8 PIN TSSOP, 3x3 MM BODY, 0.65 MM PITCH
DRAWN
SCALE
7/07/04
STD COMPLIANCE
1:1
JEDEC: MO-187 / D
D
SHEET
1 OF 1
SMSC EMC1422
Datasheet
1°C Temperature Sensor with Hardware Thermal Shutdown
Chapter 8 Package Information
1°C Temperature Sensor with Hardware Thermal Shutdown
Datasheet
8.1
Package Markings
All devices will be marked on the first line of the top side with ”1422”. On the second line, they will be
marked with the appropriate -X number (-1, -2, etc), the Functional Revision “B” and Country Code
(CC).
.
Revision 2.0 (08-10-12)
40
DATASHEET
SMSC EMC1422
1°C Temperature Sensor with Hardware Thermal Shutdown
Datasheet
Chapter 9 Datasheet Revision History
Table 9.1 Customer Revision History
REVISION LEVEL & DATE
SECTION/FIGURE/ENTRY
CORRECTION
Rev. 2.0 (08-10-12)
Table 3.3, "SMBus Electrical
Specifications"
Added conditions for tHD:DAT. Data hold time
minimum of 0.3µs is required when receiving from
the master. Data hold time is 0µs min when
transmitting to the master.
Section 6.20, "Revision
Register (FFh)"
Added row to indicate that revision ID can be 04h.
Revision ID may be 04h or 01h.
Table 2.1, "EMC1422 Pin
Description"
In pin description table, added to function column:
“requires pull-up resistor” for SMDATA and SMCLK
pins
Table 2.1, "EMC1422 Pin
Description"
Identified 5V tolerant pins. Added the following
application note below table: “For the 5V tolerant
pins that have a pull-up resistor (SMCLK,
SMDATA, SYS_SHDN, and ALERT), the voltage
difference between VDD and the pull-up voltage
must never exceed 3.6V.”
Table 3.1, "Absolute
Maximum Ratings"
Updated voltage limits for 5V tolerant pins with
pull-up resistors.
Rev. 1.36
(07-02-09)
Added the following note below table: “For the 5V
tolerant pins that have a pull-up resistor (SMCLK,
SMDATA, SYS_SHDN, and ALERT), the pull-up
voltage must not exceed 3.6V when the device is
unpowered.”
Table 3.2, "Electrical
Specifications"
Added leakage current.
Rev. 1.35
(04-17-09)
Table 2.1, "EMC1422 Pin
Description"
“Preliminary” removed from table title
Rev. 1.34
(02-27-09)
Table 5.3, "Temperature
Data Format"
Extended range for -1 updated from 001 1111 1111
to 001 1111 1000
SMSC EMC1422
41
DATASHEET
Revision 2.0 (08-10-12)
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