EMC2113 datasheet(26/88 Pages) MICROCHIP

26 / 88 page

RPM-Based Fan Controller with Multiple Temperature Zones & Hardware Thermal Shutdown

Datasheet

DS20005251A-page 26

 2013 Microchip Technology Inc.

6.2

Fan Control Modes of Operation

The EMC2113 has four modes of operation for the fan driver. Each mode uses Ramp Rate control and

the Spin Up Routine.

1. PWM Setting Mode - in this mode of operation, the user directly controls the PWM duty cycle

setting. Updating the Fan Driver Setting Register (see Section 7.22, "Fan Setting Registers") will

instantly update the fan drive. The driver uses the Spin Up Routine and has user definable ramp

rate controls.



This is the default mode. The PWM Setting Mode is enabled by clearing both the EN_ALGO

bit in the Fan Configuration Register (see Section 7.24) and the LUT_LOCK bit in the Look

Up Table Configuration Register (see Section 7.34).



Whenever the PWM Setting Mode is enabled, the current drive will be changed to what was

last written into the Fan Driver Setting Register.



The Ramp Rate is controlled by the settings of the Max Step register (see Section 7.28) and

Update Period controls (Section 7.24) and must be enabled via the EN_RRC bit (see

Section 7.25).

2. Fan Speed Control Mode (FSC) - in this mode of operation, the user determines a fan speed and

the drive setting is automatically updated to achieve this target speed. The algorithm uses the Spin

Up Routine and has user definable ramp rate controls.



This mode is enabled by clearing the LUT_LOCK bit in the Look Up Table (LUT)

Configuration Register and setting the EN_ALGO bit in the Fan Configuration Register.

3. Using the Look Up Table with Fan Drive Settings (PWM Setting w/ LUT Mode) - In this mode of

operation, the user programs the Look Up Table with PWM duty cycle settings and corresponding

temperature thresholds. The fan drive is set based on the measured temperatures and the

corresponding drive settings. The fan driver uses the Spin Up Routine and has user definable ramp

rate controls.



This mode is enabled by programming the Look Up Table then setting the LUT_LOCK bit

while the EN_ALGO bit is set to ‘0’.



The RPM / PWM bit in the Look Up Table Configuration Register MUST be set to ‘1’ or the

PWM drive settings will be incorrectly set.

4. Using the Look Up Table with Fan Speed Control algorithm (FSC w/ LUT Mode)- In this mode of

operation, the user programs the Look Up Table with fan speed target values and corresponding

temperature thresholds. The TACH Target Register will be set based on the measured

temperatures and the corresponding target settings. The PWM drive settings will be determined

automatically based on the RPM-based Fan Speed Control Algorithm. PWM drive settings will be

determined automatically based on the RPM-based Fan Speed Control Algorithm



This mode is enabled by programming the Look Up Table then setting the LUT_LOCK bit

while the EN_ALGO bit is set to ‘1’.



The RPM / PWM bit in the Look Up Table Configuration Register MUST be set to ‘0’ or the

TACH Target values will be incorrectly set.

APPLICATION NOTE: It is important that the TACH Target settings are in the proper format when using the RPM-

based Fan Speed Control Algorithm.

1020

126

29400

1100

127

49900

1150

Open

Table 6.2 TRIP_SET Resistor Setting (continued)

TTRIP (°C)

RSET (1%)

TTRIP (°C)

RSET (1%)

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