EMC2104 datasheet(75/101 Pages) SMSC

75 / 101 page

Dual RPM-Based PWM Fan Controller with Hardware Thermal Shutdown

Datasheet

SMSC EMC2104

Revision 1.74 (05-08-08)

DATASHEET

6.32

Look Up Table Configuration Registers

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.

Table 6.47 Look Up Table Configuration Registers

ADDR

R/W

DEFAULT

50h

R/W

LUT 1

Configuration

USE_D

TS_F1

USE_D

TS_F2

LUT_L

OCK

TACH /

DRIVE

TEMP3_CFG

[1:0]

TEMP4_CFG

[1:0]

00h

90h

R/W

LUT2

Configuration

USE_D

TS_F3

USE_D

TS_F4

LUT_L

OCK

TACH /

DRIVE

TEMP3_CFG

[1:0]

TEMP4_CFG

[1:0]

00h

EMC2104 Datasheet(PDF) 75 Page - SMSC Corporation

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