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EMC1186-2-AC3-TR

P1-P3P4-P6P7-P9P10-P12P13-P15P16-P18P19-P21P22-P24P25-P27P28-P30P31-P33P34-P36P37-P39P40-P42P43-P43
Dual Channel 1°C Temperature Sensor with Hardware Thermal Shutdown and 1.8V SMBus Communications
Datasheet
Revision 1.0 (07-11-13) 16 SMSC EMC1186
DATASHEET
4.3 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.
The EMC1186 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_ALL bit to clear the ALERT pin.
APPLICATION NOTE: The ARA does not clear the Status Register and if the MASK_ALL bit is cleared prior to the
Status Register being cleared, the ALERT
pin will be reasserted.
Table 4.6 Alert Response Address Protocol
START
ALERT
RESPONSE
ADDRESS RD
ACK
DEVICE
ADDRESS NACK STOP
1 -> 0 0001_100 1 0 YYYY_YYY 1 0 -> 1
Dual Channel 1°C Temperature Sensor with Hardware Thermal Shutdown and 1.8V SMBus Communications
Datasheet
SMSC EMC1186 17 Revision 1.0 (07-11-13)
DATASHEET
Chapter 5 Product Description
The is an SMBus temperature sensor with Hardware Thermal Shutdown. The EMC1186 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 EMC1186 and using
that data to control the speed of one or more fans.
The EMC1186 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 EMC1186 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 1 temperature exceeds a hardware specified threshold temperature. Additionally, the internal
diode can be configured to assert the
SYS_SHDN pin when the measured temperature exceeds user
programmable limits.
Figure 5.1 shows a system level block diagram of the EMC1186.
5.1 Conversion Rates
The EMC1186 may be configured for different conversion rates based on the system requirements.
The conversion rate is configured as described in Section 6.4. The default conversion rate is 4
conversions per second. Other available conversion rates are shown in Table 6.5, "Conversion Rate".
5.2 Dynamic Averaging
Dynamic averaging causes the EMC1186 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 6.3, "Configuration Register 03h / 09h"). 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) 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 applies when a one-shot command is issued. The device will
perform the desired averaging during the one-shot operation according to the selected conversion rate.
Figure 5.1 System Diagram for EMC1186
CPU
EMC1186
DP1
DN1
SMDATA
Thermal
diode
Internal
Diode
SMCLK
SYS_SHDN
ALERT
VDD
VDD = 3.3V
Host
SMBus
Interface
Power
Control
1.8V – 3.3V
Dual Channel 1°C Temperature Sensor with Hardware Thermal Shutdown and 1.8V SMBus Communications
Datasheet
Revision 1.0 (07-11-13) 18 SMSC EMC1186
DATASHEET
When enabled, the dynamic averaging will affect the average supply current based on the chosen
conversion rate as shown in Ta bl e 5.1.
5.3 .SYS_SHDN Output
The SYS_SHDN output is asserted independently of the ALERT output and cannot be masked. If the
External Diode 1 temperature exceeds the Hardware Thermal Shutdown Limit for the programmed
number of consecutive measurements, 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 1 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 1 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.
Table 5.1 Supply Current vs. Conversion Rate for EMC1186
CONVERSION RATE
AVERAGE SUPPLY CURRENT
(TYPICAL)
AVERAGING FACTOR (BASED ON
11-BIT OPERATION)
ENABLED
(DEFAULT) DISABLED
ENABLED
(DEFAULT) DISABLED
1 / 16 sec 210uA 200uA 16x 1x
1 / 8 sec 265uA 200uA 16x 1x
1 / 4 sec 330uA 200uA 16x 1x
1 / 2 sec 395uA 200uA 16x 1x
1 / sec 460uA 215uA 16x 1x
4 / sec (default) 890uA 325uA 8x 1x
8 / sec 1010uA 630uA 4x 1x
16 / sec 1120uA 775uA 2x 1x
32 / sec 1200uA 1050uA 1x 1x
64 / sec 1400uA 1100uA 0.5x 0.5x
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EMC1186-2-AC3-TR

Mfr. #:
Buy EMC1186-2-AC3-TR
Manufacturer:
Microchip Technology
Description:
Board Mount Temperature Sensors 1.8V SMBus Dual Temp Sensor
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