EMC2103 datasheet(27/85 Pages) MICROCHIP

27 / 85 page

RPM-Based Fan Controller with Hardware Thermal Shutdown

Datasheet

DS0005250A-page 27

 2013 Microchip Technology Inc.

5.3

PWM Fan Driver

The EMC2103 supports a high or low frequency PWM driver. The output can be configured as either

push-pull or open drain and the frequency ranges from 9.5Hz to 26kHz in four programmable

frequency bands.

5.4

Fan Control Look-Up Table

The EMC2103 uses a look-up table to apply a user-programmable fan control profile based on

measured temperature to the fan driver. In this look-up table, each temperature channel is allowed to

control the fan drive output independently (or jointly) by programming up to eight pairs of temperature

and drive setting entries.

The user programs the look-up table based on the desired operation. If the RPM based Fan Speed

Control Algorithm is to be used (see Section 5.5), then the user must program a fan speed target for

each temperature setting of interest. Alternately, if the RPM based Fan Speed Control Algorithm is not

to be used, then the user must program a PWM setting for each temperature setting of interest.

If the measured temperature on the External Diode channel meets or exceeds any of the temperature

thresholds for any of the channels, the fan output will be automatically set to the desired setting

corresponding to the exceeded temperature. In cases where multiple temperature channel thresholds

are exceeded, the highest fan drive setting will take precedence. Figure 5.3 shows an example of this

behavior using a single channel.

When the measured temperature drops to a point below a lower threshold minus the hysteresis value,

the fan output will be set to the corresponding lower set point.

LEVEL

(Spin Up Configuration)

LEVEL

(Spin Up Configuration)

LEVEL

(Spin Up Configuration)

LEVEL

(Spin Up Configuration)

SPINUP_TIME[1:0]

(Spin Up Configuration)

SPINUP_TIME[1:0]

(Spin Up Configuration)

SPINUP_TIME[1:0]

(Spin Up Configuration)

SPINUP_TIME[1:0]

(Spin Up Configuration)

Fan Step

Fan Minimum Drive

Valid TACH Count

TACH Target (read /

write)

TACH Target (read only)

TACH Reading

Look Up Table Drive /

Temperature Settings (read

only)

Look up Table Drive /

Temperature Settings

(read only)

DRIVE_FAIL_CNT [1:0]

(Spin Up Configuration) +

Fan Drive Fail Band

DRIVE_FAIL_CNT [1:0]

(Spin Up Configuration)

+ Fan Drive Fail Band

Table 5.3 Fan Controls Active for Operating Mode (continued)

DIRECT PWM

SETTING MODE

FSC MODE

DIRECT PWM SETTING W/

LUT MODE

FSC W/ LUT MODE

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