Dual RPM-Based PWM Fan Controller with Hardware Thermal Shutdown
Datasheet
6.32
Look Up Table Configuration Registers
Table 6.47 Look Up Table Configuration Registers
ADDR
R/W
REGISTER
B7
B6
B5
B4
B3
B2
B1
B0
DEFAULT
LUT 1
Configuration
USE_D
TS_F1
USE_D
TS_F2
LUT_L
OCK
TACH /
DRIVE
TEMP3_CFG
[1:0]
TEMP4_CFG
[1:0]
50h
R/W
00h
LUT2
Configuration
USE_D
TS_F3
USE_D
TS_F4
LUT_L
OCK
TACH /
DRIVE
TEMP3_CFG
[1:0]
TEMP4_CFG
[1:0]
90h
R/W
00h
The Look Up Table Configuration Register holds the setup information for the two temperature to fan
drive look up tables.
Bit 7 - USE_DTS_F1 or USE_DTS_F3 - This bit determines whether the Pushed Temperature 1 or
Pushed Temperature 3 registers are using DTS data.
‘0’ (default) - The Pushed Temperature 1 or Pushed Temperature 3 registers are not using DTS
data. The contents of these registers are standard 2’s complement temperature data.
‘1’ - The Pushed Temperature 1 or Pushed Temperature 3 registers are loaded with DTS data. The
contents of these registers are automatically subtracted from a fixed value of 100°C before they
are compared to the Look Up Table threshold levels.
Bit 6 - USE_DTS_F2 or USE_DTS_F4 - This bit determines whether the Pushed Temperature 2 or
Pushed Temperature 4 Registers are using DTS data.
‘0’ (default) - The Pushed Temperature 2 or Pushed Temperature 4 registers are not using DTS
data. The contents of these registers are standard 2’s complement temperature data.
‘1’ - The Pushed Temperature 2 or Pushed Temperature 4 registers are loaded with DTS data. The
contents of these registers are automatically subtracted from a fixed value of 100°C before they
are compared to the Look Up Table threshold levels.
Bit 5 - LUT_LOCK - This bit locks updating the Look Up Table entries and determines whether the look
up table is being used.
‘0’ (default) - The Look Up Table entries can be updated normally. The Look Up Table will not be
used while the Look Up Table entries are unlocked. During this condition, the fan drive output will
not change states regardless of temperature or tachometer variation.
‘1’ - The Look Up Table entries are locked and cannot be updated. The Look Up Table is fully active
and will be used based on the loaded values. The fan drive output will be updated depending on
the temperature and / or TACH variations.
APPLICATION NOTE: When the LUT_LOCK bit is set at a logic ‘0’, the fan drive setting will be set at whatever
value was last used by the RPM based Fan Speed Control Algorithm or the Look Up Table.
Bit 4 - TACH / DRIVEx - This bit selects the data format for the LUT drive settings.
‘0’ (default) - The Look Up Table drive settings are RPM TACH count values for use by the RPM
based Fan Speed Control Algorithm. The Look Up Table drive settings should be loaded highest
value to lowest value (to coincide with the inversion between TACH counts and actual RPM).
‘1’ - The Look Up Table drive settings are fan drive setting values and are used directly. The drive
settings should be loaded lowest value to highest value.
APPLICATION NOTE: The TACH / DRIVE bit should be set prior to the LUT_LOCK bit being set so that, if the fan
driver is disabled, the output drive is in the proper state.
Bits 3-2 - TEMP3_CFG[1:0] - These bits determine the temperature channel that is used for the
Temperature 3 inputs to the Look Up Table as shown in Table 6.48.
SMSC EMC2104
Revision 1.74 (05-08-08)
DATA7S5HEET
SMSC [ SMSC CORPORATION ]
