SMBus Fan Control with 1°C Accurate Temperature Monitoring
Datasheet
Chapter 6 Register Set
The following registers are accessible through the SMBus Interface. The registers are described in
functional order. Registers with multiple addresses are included for software compatibility. Writing or
reading from either address will point to the same internal register.
Table 6.1 Register Set in Hexadecimal Order
DEFAULT
REGISTER
ADDRESS
R/W
REGISTER NAME
FUNCTION
VALUE
PAGE
00h
01h
02h
R
R
R
Internal Temperature
Stores the Internal
Temperature
00h
Page 32
External Diode Temperature
High Byte
Stores the External
Temperature High Byte
00h
00h
00h
Page 32
Page 32
Page 33
Status
Reports internal, external,
and TCRIT alarms
03h and 09h R/W
Configuration
Alert Mask, STANDBY,
TCRIT override, Alert Fault
Queue
04h and 0Ah R/W
05h and 0Bh R/W
Conversion Rate
Sets conversion rate
08h
Page 34
Page 35
(16 / sec)
Internal Temp Limit
ALERT / TACH asserted if
measured temp above this
value
46h
(70°C)
07h and
0Dh
R/W
External Temp High Limit
High Byte
ALERT / TACH asserted if
measured temp above this
value
46h
Page 35
Page 35
Page 35
(70°C)
08h and 0Eh R/W
External Temp Low Limit
High Byte
ALERT / TACH asserted if
measured temp below this
value
00h
(0°C)
0Ch
R/W
External Temperature Force
One Shot
Force the temperature for
determining the next fan
speed used in the Fan
Control Look-Up Table
00h
0Fh
10h
11h
R/W
R
When written, performs a
one-shot conversion.
00h
00h
00h
Page 36
Page 32
Page 36
External Diode Temperature
Low Byte
Stores the External
Temperature Low Byte
R/W
Scratchpad
Scratchpad - This register
is read/write but does
nothing
12h
R/W
Scratchpad
Scratchpad - This register
is read/write but does
nothing
00h
Page 36
13h
14h
16h
R/W
R/W
R/W
External Diode High Limit
Low Byte
Fractional data of High
Limit
00h
00h
A4h
Page 35
Page 35
Page 36
External Diode Low Limit
Low Byte
Fractional data of Low
Limit
Alert Mask
Disables alarms
SMSC EMC2101
Revision 2.53 (03-13-07)
DATA2S9HEET
SMSC [ SMSC CORPORATION ]
