Dual Channel 1°C Temperature Sensor with Beta Compensation and 1.8V SMBus Communications
Datasheet
Chapter 5 Product Description
The is an SMBus temperature sensor. The EMC1182 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 EMC1182 and using
that data to control the speed of one or more fans.
The EMC1182 has two levels of monitoring. The first provides a maskable ALERT / THERM2 signal
to the host when the measured temperatures exceeds user programmable limits. This allows the
EMC1182 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 EMC1182.
1.8V 1.8V – 3.3V
VDD = 3.3V
VDD
Host
CPU / GPU
DP
DN
Thermal
Junction
SMCLK
SMDATA
EMC1182
SMBus
Interface
ALERT / THERM2
THERM / ADDR
Power
Control
GND
Figure 5.1 System Diagram for EMC1182
5.1
Modes of Operation
The EMC1182 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.
Revision 1.0 (07-11-13)
18
SMSC EMC1182
DATASHEET
SMSC [ SMSC CORPORATION ]
