SMBus Fan Control with 1°C Accurate Temperature Monitoring
Datasheet
The External Diode Force Register is used to force the Fan Control Look-Up Table to a specific fan-
speed setting. When this function is enabled (see Section 6.16), the contents of this register are
compared against the temperature thresholds in the Fan Control Look-Up Table to determine the fan
setting to use.
The contents of this register represent temperature data in the same format as the data registers and
can be updated at any time.
The External Diode Temperature Registers are updated normally with the measured temperature and
compared against the THIGH and TCRIT limits normally but not used to determine the fan speed.
APPLICATION NOTE: This mode is used if the host or system requires temperature data from a source other than
the EMC2101 External Diode to be used for fan control.
6.9
One Shot Register
Table 6.9 One Shot Register
B7 B6 B5 B4 B3
ADDR.
0Fh
R/W
REGISTER
B2
B1
B0
DEFAULT
Writing to this register initiates a one shot update of the
temperature data. Data is not relevant and is not stored.
W
One Shot
00h
The One Shot Register initiates an update of the temperature measurements. This register can be
written at any time, however will only perform a one-shot conversion when the temperature monitoring
is in standby mode. When the one shot temperature conversion is complete the temperature data
registers are updated and the fan setting is updated if necessary. This register is self-clearing.
6.10
Scratchpad Registers
Table 6.10 Scratchpad Registers
ADDR.
R/W
REGISTER
B7
B6
B5
B4
B3
B2
B1
B0
DEFAULT
11h
12h
R/W
R/W
Scratchpad
Scratchpad
B7
B7
B6
B6
B5
B5
B4
B4
B3
B3
B2
B2
B1
B1
B0
B0
00h
00h
The Scratchpad Registers are R/W registers that perform no function. They are included for software
compatibility.
6.11
Alert Mask Register
Table 6.11 Alert Mask Register
ADDR.
R/W
REGISTER
B7
B6
B5
B4
B3
B2
B1
B0
DEFAULT
INT_
MSK
HIGH
MSK
LOW_
MSK
TCRIT_ TACH_
MSK MSK
16h
R/W
Alert Mask
1
1
1
A4h
The Alert Mask Register enables interrupts from the temperature monitors and limits. Regardless of
the condition of the individual mask bits, the Status Register will be updated normally.
Revision 2.53 (03-13-07)
SMSC EMC2101
DATA3S6HEET
SMSC [ SMSC CORPORATION ]
