EMC1072 Datasheet, PDF (15/36 Pages) SMSC Corporation – 1°C Temperature Sensor with Selectable Address

1°C Temperature Sensor with Selectable Address
Datasheet
Chapter 5 Product Description
The EMC1072 is an SMBus temperature sensor. The EMC1072 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 EMC1072 and using
that data to control the speed of one or more fans.
The EMC1072 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 EMC1072 to be
used as an independent thermal watchdog to warn the host of temperature hot spots without direct
control by the host. The second level of monitoring provides a non maskable interrupt on the THERM
pin if the measured temperatures meet or exceed a second programmable limit.
Figure 5.1 shows a system level block diagram of the EMC1072.
CPU
Thermal
diode
EMC1072
DP
DN
Internal
Diode
SMCLK
SMDATA
ALERT
Host
SMBus
Interface
THERM
Power Control
5.1
5.1.1
Figure 5.1 System Diagram for EMC1072
Modes of Operation
The EMC1072 has two modes of operation.
„ Active (Run) - In this mode of operation, the ADC is converting on all temperature channels at the
programmed conversion rate. The temperature data is updated at the end of every conversion and
the limits are checked. In Active mode, writing to the one-shot register will do nothing.
„ Standby (Stop) - In this mode of operation, the majority of circuitry is powered down to reduce
supply current. The temperature data is not updated and the limits are not checked. In this mode
of operation, the SMBus is fully active and the part will return requested data. Writing to the one-
shot register will enable the device to update all temperature channels. Once all the channels are
updated, the device will return to the Standby mode.
Conversion Rates
The EMC1072 may be configured for different conversion rates based on the system requirements.
The conversion rate is configured as described in Section 6.5, "Conversion Rate Register". The default
conversion rate is 4 conversions per second. Other available conversion rates are shown in Table 6.6,
"Conversion Rate".
SMSC EMC1072
15
DATASHEET
Revision 1.39 (10-11-10)