Dual RPM-Based PWM Fan Controller with Hardware Thermal Shutdown
Datasheet
when the temperature drops below the high limit. The ALERT# pin will be asserted and released
normally.
Bit 3 - SYS3 - Enables the high temperature limit for the External Diode 3 channel to trigger the Critical
/ Thermal Shutdown circuitry (see Section 6.1).
Bit 2 - SYS2 - Enables the high temperature limit for the External Diode 2 channel to trigger the Critical
/ Thermal Shutdown circuitry (see Section 6.1).
Bit 1 - SYS1 - Enables the high temperature limit for the External Diode 1 channel to trigger the Critical
/ Thermal Shutdown circuitry (see Section 6.1).
Bit 0 - APD - This bit enables the Anti-parallel diode functionality on the External Diode 3 pins (DP3
and DN3).
‘0’ (default) - The Anti-parallel diode functionality is disabled. The External Diode 3 channel can be
configured for any type of diode
‘1’ - The Anti-parallel diode functionality is enabled. Both the External Diode 3 and 4 channels are
configured to support a diode or diode connected transistor (such as a 2N3904).
APPLICATION NOTE: When the APD diode is enabled, there will be a delay of a full temperature update before
any comparisons and functionality associated with the External Diode 4 channel will be
implemented. This includes the SYS4 bit operation, limit comparisons, and look up table
comparisons.
6.10
Configuration 2 Register
Table 6.13 Configuration 2 Register
ADDR
21h
R/W
REGISTER
B7
B6
B5
B4
B3
B2
B1
B0
DEFAULT
DIS_
DYN
DIS_
TO
DIS_
AVG
R/W
Config 2
-
QUEUE[1:0]
CONV[1:0]
0Eh
The Configuration 2 Register controls conversion rate of the temperature monitoring as well as the
fault queue. This register is software locked.
Bit 6 - DIS_DYN - Disables the Dynamic Averaging Feature.
‘0’ (default) - The Dynamic Averaging function is enabled. The conversion time for all temperature
channels is scaled based on the chosen conversion rate to maximize accuracy and immunity to
random temperature measurement variation.
‘1’ - The Dynamic Averaging function is disabled. The conversion time for all temperature channels
is fixed regardless of the chosen conversion rate.
Bit 5 - DIS_TO - Disables the SMBus time out function for the SMBus client (if enabled).
‘0’ (default) - The SMBus time out function is enabled.
‘1’ - The SMBus time out function is disabled allowing the device to be fully I2C compliant.
Bit 4 - DIS_AVG - Disables digital averaging of the External Diode 1 channel.
‘0’ (default) - The External Diode 1 channel has digital averaging enabled. The temperature data
is the average of the previous four measurements.
‘1’ - The External Diode 1 channel has digital averaging disabled. The temperature data is the last
measured data.
Bits 3-2 - QUEUE[1:0] - Determines the number of consecutive out of limit conditions that are
necessary to trigger an interrupt. Each measurement channel has a separate fault queue associated
with the high limit, low limit, and diode fault condition except the internal diode.
Revision 1.74 (05-08-08)
SMSC EMC2104
DATA5S6HEET
SMSC [ SMSC CORPORATION ]
