SMBus Fan Control with 1°C Accurate Temperature Monitoring
Datasheet
6.3
Temperature Data Registers
Table 6.2 Temperature Data Registers
B7 B6 B5 B4 B3
Sign 64 32 16
ADDR.
R/W
REGISTER
B2
B1
B0
DEFAULT
Internal
Temperature
00h
01h
R
8
4
2
1
00h
External Diode
Temperature
High Byte
R
R
Sign
0.5
64
32
16
-
8
-
4
-
2
-
1
-
00h
00h
External Diode
Temperature
Low Byte
10h
0.25
0.125
As shown in Table 6.2, the internal temperature monitor is stored as an 8-bit value while the external
temperature is stored as an 11-bit value.
Please note that the internal temperature monitor is limited to the operating temperature limits of the
part resulting in a guaranteed range of 0ºC to 85ºC.
6.4
Status Register
Table 6.3 Status Register
ADDR
R/W
REGISTER
B7
B6
B5
B4
B3
B2
B1
B0
DEFAULT
INT_
HIGH
EXT_
HIGH
EXT_
LOW
02h
R
Status
BUSY
EEPROM
FAULT
TCRIT
TACH
00h
The Status Register is a read only register and returns the operational status of the part. \
If the ALERT / TACH pin is configured as an ALERT output and any of these bits are set to '1' (except
the BUSY bit and the FAULT bit), then the ALERT / TACH pin is asserted low (if interrupts are not
masked (see Section 6.5).
Reading from the Status Register will cause the MASK bit to be set if any bit (other than BUSY and
FAULT) have been set. Each bit is automatically cleared when the error condition has been removed,
however the internal error condition flags may still be set. The ARA command must be used to clear
the ALERT / TACH pin if there are no bits set in the Status Register. In addition, reading from the
Status Register will clear all bits. If the error condition persists, then the bits will be reset at the end of
the next conversion.
When the device is configured in Comparison Mode (see Section 6.23), reading the Status Register
will not clear any active status bits (except EEPROM and FAULT). These bits are automatically cleared
when the error condition is removed.
Bit 7 - Busy - indicates that the ADC is converting - does not trigger an interrupt.
Bit 6 - INT_HIGH - Internal temperature has met or exceeded the high limit.
Bit 5 - EEPROM - Indicates that the EEPROM could not be found when the device powers up in the
Auto-Program Mode (see Section 5.1). This bit only applies to the EMC2102-R. It will always read ‘0’
for the EMC2101 device.
Bit 4 - EXT_HIGH - External Diode temperature has exceeded the high limit.
Revision 2.53 (03-13-07)
SMSC EMC2101
DATA3S2HEET
SMSC [ SMSC CORPORATION ]
