Dual RPM-Based PWM Fan Controller with Hardware Thermal Shutdown
Datasheet
The TACH / DRIVE bit in the Look Up Table Configuration Register MUST be set to ‘0’ or
the TACH Target values will be incorrectly set. Setting this bit to ‘0’ ensures that the settings
will be RPM settings (Tachometer counts).
APPLICATION NOTE: It is important that the TACH Target settings are in the proper format when using the RPM
based Fan Speed Control Algorithm.
Table 5.3 Fan Controls Active for Operating Mode
DIRECT SETTING
MODE
DIRECT SETTING W/ LUT
MODE
FSC MODE
FSC W/ LUT MODE
Fan Driver Setting
(read / write)
Fan Driver Setting (read
only)
Fan Driver Setting (read
only)
Fan Driver Setting (read
only)
EDGES[1:0]
EDGES[1:0]
(Fan Configuration)
EDGES[1:0]
EDGES[1:0]
-
RANGE[1:0]
(Fan Configuration)
-
RANGE[1:0]
(Fan Configuration)
UPDATE[2:0]
(Fan Configuration)
UPDATE[2:0]
(Fan Configuration)
UPDATE[2:0]
(Fan Configuration)
UPDATE[2:0]
(Fan Configuration)
LEVEL
LEVEL
(Spin Up Configuration)
LEVEL
(Spin Up Configuration)
LEVEL
(Spin Up Configuration)
(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 Step
Fan Step
Fan Step
-
Fan Minimum Drive
Valid TACH Count
TACH Target (read / write)
Fan Minimum Drive
Valid TACH Count
Valid TACH Count
-
Valid TACH Count
-
TACH Target (read
only)
TACH Reading
-
TACH Reading
-
TACH Reading
TACH Reading
Look Up Table Drive /
Temperature Settings (read
only)
Look up Table Drive /
Temperature Settings
(read only)
-
DRIVE_FAIL_CNT[1:0] and
Drive Band Fail Registers
-
DRIVE_FAIL_CNT[1:0]
and Drive Band Fail
Registers
5.3
5.4
PWM Fan Driver
The EMC2104 supports two PWM output drivers. These output drivers can be configured
independently to operate as an open-drain (default) or push-pull driver and can be configured with
normal or inverse polarity. Additionally, the each PWM driver frequency is programmable with ranges
from 9.5Hz to 26kHz in four programmable frequency bands.
Fan Control Look-Up Table
The EMC2104 uses a look-up table to apply a user-programmable fan control profile based on
measured temperature to each fan driver. In this look-up table, each temperature channel is allowed
Revision 1.74 (05-08-08)
SMSC EMC2104
DATA2S6HEET
SMSC [ SMSC CORPORATION ]
