emc2105 Standard Microsystems Corp., emc2105 Datasheet - Page 25

• Manufacturer Part Number: emc2105
• Description: Emc2105 Rpm-based High Side Fan Controller With Hardware Thermal Shutdown
• Manufacturer: Standard Microsystems Corp.

RPM-Based High Side Fan Controller with Hardware Thermal Shutdown
Datasheet
SMSC EMC2105
5.2
LOW RANGE
T
TRIP
83
84
85
86
87
88
89
90
91
(°C)
The EMC2105 has four modes of operation for the fan driver. Each mode of operation uses the Ramp
Rate control and Spin Up Routine.
1. Direct Setting Mode- in this mode of operation, the user directly controls the fan drive setting.
2. Fan Speed Control Mode (FSC) - in this mode of operation, the user determines a target
3. Using the Look Up Table with Fan Drive Settings (Direct Setting w/ LUT Mode) - In this mode of
4. Using the Look Up Table with RPM Target Settings (FSC w/ LUT Mode) - In this mode of operation,
Fan Control Modes of Operation
Updating the Fan Driver Setting Register (see
Ramp Rate control is optional and enabled via the EN_RRC bits.
tachometer count 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.
operation, the user programs the Look Up Table with fan drive settings and corresponding
temperature thresholds. The fan drive is set based on the measured temperatures and the
corresponding drive settings. Ramp Rate control is optional and enabled via the EN_RRC bits.
the user programs the Look Up Table with TACH Target values and corresponding temperature
thresholds. The TACH Target will be set based on the measured temperatures and the
corresponding target settings. The fan drive settings will be determined automatically based on the
RPM based Fan Speed Control Algorithm
HIGH RANGE
T
This is the default mode. The Direct Setting Mode is enabled by clearing the LUT_LOCK bit
in the Look Up Table Configuration Register (see
is set to ‘0’.
Whenever the Direct Setting Mode is enabled the current drive will be changed to what was
last written into the Fan Driver Setting Register.
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.
This mode is enabled by programming the Look Up Table then setting the LUT_LOCK bit
while the TACH / DRIVE bit is set to ‘1’.
The TACH / DRIVE bit in the Look Up Table Configuration Register MUST be set to ‘1’ or
the fan drive settings will be incorrectly set. Setting this bit to ‘1’ ensures the settings will be
PWM settings.
This mode is enabled by programming the Look Up Table then setting the LUT_LOCK bit
while the TACH / DRIVE bit is set to ‘0’
TRIP
115
116
117
118
119
120
121
122
123
(°C)
Table 5.2 TRIP_SET Resistor Setting (continued)
RSET (1%)
1020
1100
1150
698
750
787
845
909
953
DATASHEET
25
LOW RANGE
T
TRIP
120
121
122
115
116
117
118
119
60
Section
(°C)
Section
6.18) will instantly update the fan drive.
HIGH RANGE
T
TRIP
6.29) while the TACH / DRIVE bit
147
148
149
150
151
152
153
154
92
(°C)
Revision 1.74 (05-08-08)
RSET (1%)
10700
12700
15800
20500
29400
49900
Open
7870
9090