EMC2104 datasheet(93/101 Pages) SMSC

93 / 101 page

Dual RPM-Based PWM Fan Controller with Hardware Thermal Shutdown

Datasheet

SMSC EMC2104

Revision 1.74 (05-08-08)

DATASHEET

B.2

Example #2

This example uses the RPM based Fan Speed Control Algorithm. The Spin Level (used by the Spin

Up Routine) should be changed to 50% drive for a total Spin Time of 1 second. For all other RPM

configuration settings, the default conditions are used.

For control inputs, it uses the External Diode 1 channel normally, a thermistor input on the External

Diode 2 channel, the internal diode channel, and a Pushed Temperature that represents the MCU

temperature in standard format. The configuration is set as shown in Table B.5 while Table B.6 shows

how the table is loaded.

Note that when using Thermistor data, the VIN2_INV bit should be set. The circuitry will automatically

subtract the measured thermistor voltage from a quantity of FFh (effectively inverting it). Therefore, the

Look Up Table is loaded with ascending voltage thresholds with respect to the drive settings.

Additionally, the reading register will show this same value (subtracted from FFh).

Table B.5 Look Up Table Example #2 Configuration

ADDR

SETTING

22h

Configuration

-VIN4_I

VIN3_E

VIN3_I

VIN2_

VIN2_I

VIN1_

VIN1_I

0Ch

-0

42h

Fan 1

Configuration

EN_

ALGO

RANGE[1:0]

EDGES[1:0]

UPDATE[2:0]

CBh

110

46h

Fan 1 Spin

Configuration

DRIVE_FAIL_CNT

1 [1:0]

NOKICK

SPIN_LVL[2:0]

SPINUP_TIME

[1:0]

0Ah

000

50h

LUT 1

Configuration

USE_D

TS_F1

USE_D

TS_F2

LUT_LO

TACH /

DRIVE

TEMP3_CFG

[1:0]

TEMP4_CFG

[1:0]

28h

001

Table B.6 Fan Speed Control Table Example #2

FAN

SPEED

STEP #

EXTERNAL DIODE

1 TEMPERATURE

(CPU)

THERMISTOR 2

VOLTAGE

READING

PUSHED

TEMPERATURE

SETTING

INTERNAL DIODE

TEMPERATURE

(AMBIENT)

TACH

TARGET

135oC

156.25mV

(45°C)

30oC40oC

3Dh

(1007 RPM)

240oC

178.125mV

(50°C)

35oC45oC

1Eh

(2048 RPM)

350oC

203.125mV

(55°C)

40oC50oC

14h

(3072 RPM)

460oC

228.125mV

(60°C)

45oC55oC

0Fh

(4096 RPM)

570oC

253.125mV

(65°C)

50oC60oC

0Ch

(5120 RPM)

EMC2104 Fiches technique(PDF) 93 Page - SMSC Corporation

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