1°C Triple SMBus Sensor with Resistance Error Correction
Datasheet
Chapter 4 Product Description
The EMC1033 is an SMBus sensor that can monitor internal temperature and one or two remote diode
temperatures. The sensor is typically used with an SMBus host such as an SMSC SIO device or an
SMSC fan control chip.
Thermal management is performed in cooperation with the host device. The host reads the
temperature data from the EMC1033 and takes appropriate action such as controlling fan speed or
processor clock frequency. The EMC1033 has programmable temperature limit registers that define a
safe operating window. After the host has configured the temperature limits, the EMC1033 can perform
as a free-running independent watchdog to warn the host of temperature hot spots without requiring
the host to poll the device.
Host
EMC1033
SMCLK
DP1/DN2
DN1/DP2
SMDATA
SMBus
Interface
ALERT/THERM2
Internal
Diode
ADDR/THERM
Fan
Driver
Figure 4.1 System Overview
Two separate temperature zones are monitored using only two pins on the EMC1033. This is
accomplished using two anti-parallel diodes as shown in Figure 4.1. This technique maintains high
accuracy while minimizing pin count and reducing board routing complexity. The anti-parallel diode
architecture performs very well with diode connected transistors. It is not compatible with substrate
transistors (sometimes called thermal diodes or on-chip sense junctions). See the complete list of
temperature sensor products available from SMSC for devices that can measure two or more remote
zones including substrate transistors. The connections for the two discrete transistors are shown in
Figure 4.2
to DP1/DN2
to DN1/DP2
to DP1/DN2
to DN1/DP2
Typical remote
discrete PNP transistor
i.e. 2N3906
Typical remote
discrete NPN transistor
i.e. 2N3904
Figure 4.2 Anti-parallel Diodes
The EMC1033 has two basic modes of operation:
Run Mode: In this mode, the EMC1033 continuously converts temperature data and updates its
registers. The rate of temperature conversion is configured as shown in Section 4.12, "Conversion
Rate Register," on page 17.
Standby Mode: In this mode, the EMC1033 is placed in standby to conserve power as described
in Section 4.7, "Standby Mode," on page 13.
SMSC EMC1033
9
Revision 1.1 (01-19-07)
DATASHEET
SMSC [ SMSC CORPORATION ]
