RPM-Based Fan Controller with Multiple Temperature Zones & Hardware Thermal Shutdown
Datasheet
When the SYS_SHDN pin is asserted, it will remain asserted until the measured temperatures drop
below the respective limits minus the hysteresis. At this point, the pin will be released automatically.
6.1.2
SHDN_SEL Pin
The EMC2113 has a ‘strappable’ input (SHDN_SEL) allowing for configuration of the hardware
Critical/Thermal Shutdown input channel. The pull-up resistor used on this pin identifies which
configuration setting is used as shown in Table 6.1, "SHDN_SEL Pin Decode".
.
Table 6.1 SHDN_SEL Pin Decode
MODE / DIODE
PULL UP
RESISTOR
CHANNEL
EXTERNAL DIODE 1 CONFIG
EXTERNAL DIODE 2 CONFIG
Beta Compensation disabled
REC disabled
Beta and REC controls are locked
Beta Compensation enabled (auto)
REC enabled
Beta and REC controls are not locked
AMD CPU on
External Diode 1
< 4.7k Ohm
6.8k Ohm
10k Ohm
15k Ohm
22k Ohm
> 33k Ohm
Beta Compensation disabled
REC enabled
Beta and REC controls are locked
Beta Compensation enabled (auto)
REC enabled
Beta and REC controls are not locked
2N3904 on External
Diode 1
Intel CPU or
2N3904 on External
Diode 1
Beta Compensation enabled (auto)
REC enabled
Beta and REC controls are locked
Beta Compensation enabled (auto)
REC enabled
Beta and REC controls are not locked
Beta Compensation enabled (auto)
REC enabled
Beta and REC controls are not locked
Beta Compensation enabled (auto)
REC enabled
Beta and REC controls are not locked
Internal Diode
Intel CPU or
2N3904 on External
Diode 2
Beta Compensation enabled (auto)
REC enabled
Beta and REC controls are not locked
Beta Compensation enabled (auto)
REC enabled
Beta and REC controls are locked
Intel CPU or
2N3904 on External
Diode 1
Beta Compensation enabled (auto)
REC enabled
Beta and REC controls are not locked
Beta Compensation enabled (auto)
REC enabled
Beta and REC controls are not locked
APPLICATION NOTE: The SHDN_SEL pin decode settings with Beta Compensation enabled (auto) will support a
diode connected 2N3904 diode normally.
6.1.3
TRIP_SET Pin
The EMC2113’s TRIP_SET pin is an analog input to the Critical/Thermal Shutdown block which sets
the Thermal Shutdown temperature. The system designer creates a voltage level at the input through
a simple resistor connected to GND as shown in Figure 6.2, "Block Diagram of Critical/Thermal
Shutdown". The value of this resistor is used to create an input voltage on the TRIP_SET pin which
is translated into a temperature ranging from 65°C to 127°C.
APPLICATION NOTE: Current only flows when the TRIP_SET pin is being monitored. At all other times, the internal
reference voltage is removed and the TRIP_SET pin will be pulled down to ground.
Revision 1.2 (10-08-09)
SMSC EMC2113
DATA2S4HEET
SMSC [ SMSC CORPORATION ]
