EMC2103 datasheet(63/84 Pages) SMSC

63 / 84 page

RPM-Based Fan Controller with HW Thermal Shutdown

Datasheet

SMSC EMC2103

Revision 0.85 (01-29-08)

DATASHEET

6.32

Look Up Table Configuration Register

The Look Up Table Configuration Register controls the setup information for the temperature to fan

drive look up table.

Bit 7 - USE_DTS_F1 - This bit determines whether the Pushed Temperature 1 Register is using DTS

data.

‘0’ (default) - The Pushed Temperature 1 Register is not using DTS data. The contents of the

Pushed Temperature 1 registers is standard temperature data.

‘1’ - The Pushed Temperature 1 Register is loaded with DTS data. The contents of this register is

automatically subtracted from a fixed value of 100°C before being compared to the Look Up Table

threshold levels.

Bit 6 - USE_DTS_F2 - This bit determines whether the Pushed Temperature 2 Register is using DTS

data.

‘0’ (default) - The Pushed Temperature 2 Register is not using DTS data. The contents of this

‘1’ - The Pushed Temperature 2 Register is loaded with DTS data. The contents of this register is

automatically subtracted from a fixed value of 100°C before being 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 PWM 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 PWM 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 PWM drive setting will be set at whatever

value was last used by the RPM based Fan Speed Control Algorithm or the Look Up Table.

where:

[3]

poles = number of poles of the fan

(typically 2)

n = number of edges measured

(typically 5)

m = the multiplier defined by the

RANGE bits

[4]

COUNT = TACH Reading Register

value (in decimal)

Table 6.48 Look Up Table Configuration Register

ADDR

R/W

DEFAULT

50h

R/W

LUT

Configuration

USE_D

TS_F1

USE_D

TS_F2

LUT_L

OCK

RPM /

PWM

TEMP3

_CFG

TEMP4

_CFG

00h

RPM

poles

()

--------------------

–

()

COUNT

-----

----------------------------------

1,966,080

RPM

3,932,160

COUNT

--------------------------------------

EMC2103 Datasheet(PDF) 63 Page - SMSC Corporation

EMC2103 Datasheet(HTML) 63 Page - SMSC Corporation

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