emc1428 Standard Microsystems Corp., emc1428 Datasheet - Page 15

• Manufacturer Part Number: emc1428
• Description: 1 Degree C Multiple Temperature Sensor With Hw Thermal Shutdown
• Manufacturer: Standard Microsystems Corp.

1°C Multiple Temperature Sensor with HW Thermal Shutdown & Hottest of Thermal Zones
Datasheet
Chapter 4 Product Description
.
SMSC EMC1428
Optional
Optional
Optional
APD
APD
APD
CPU
The EMC1428 is an SMBus temperature sensor with Hardware Critical / Thermal Shutdown support.
The EMC1428 monitors up to seven (7) external diodes and one internal 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 EMC1428 and using
that data to control the speed of one or more fans.
The EMC1428 device 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
EMC1428 to be used as an independent thermal watchdog to warn the host of temperature hot spots
without constant monitoring by the host.
The second level of monitoring asserts the SYS_SHDN pin when the External Diode 1 temperature
meets or exceeds a hardware specified threshold temperature. Additionally, any of the external diode
channels can be configured to assert the SYS_SHDN pin when the measured temperature meets or
exceeds user programmable limits.
Because the EMC1428 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 devices without resistance error correction. As well,
the automatic beta detection feature means that there is no need to program the device according to
which type of diode is present. Therefore, the device can power up ready to operate for any system
configuration including those diodes that require the BJT or transistor model.
Figure 4.1
shows a system level block diagram of the EMC1428.
DP1
DN1
DP2 / DN3
DN2 / DP3
DP4 / DN5
DN4 / DP5
DP6 / DN7
DN6 / DP7
Figure 4.1 System Diagram for EMC1428
EMC1428
DATASHEET
Precision
SYS_SHDN
TRIP_SET
SMDATA
R
SMCLK
15
ALERT
N/C
VDD
VDD
1% RSET
SMBus
Interface
Host
Revision 0.68 (07-08-08)