EMC2103 Standard Microsystems Corporation, EMC2103 Datasheet - Page 22

• Manufacturer Part Number: EMC2103
• Description: Rpm-based Fan Controller with HW Thermal Shutdown
• Manufacturer: Standard Microsystems Corporation

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APPLICATION NOTE: Current only flows when the TRIP_SET pin is being monitored. At all other times, the internal
APPLICATION NOTE: The TRIP_SET pin circuitry is designed to use a 1% resistor externally. Using a 1% resistor
Revision 0.85 (01-29-08)
5.1.1
5.1.2
PULL UP RESISTOR
SHDN_SEL Pin
The EMC2103 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
Note 5.1
TRIP_SET Pin
The EMC2103’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
an input voltage on the TRIP_SET pin which is translated into a temperature ranging from 65°C to
127°C as shown in
< 4.7k Ohm
> 33k Ohm
6.8k Ohm
10k Ohm
15k Ohm
22k Ohm
reference voltage is removed and the TRIP_SET pin will be pulled down to ground.
will result in the Thermal / Critical Shutdown temperature being decoded correctly. If a 5%
resistor is used, then the Thermal / Critical Shutdown temperature may be decoded with as
much as ±1°C error.
For the EMC2103-1, the decode for a 22k Ohm resistor on the SHDN_SEL pin will be to
use the External Diode 1 channel in Diode Mode (the same as the decode for a 6.8k Ohm
resistor) as the hardware shutdown device.
Table 5.2
Table 5.1 SHDN_SEL Pin Decode
External Diode 1 Simple Mode -
Beta compensation disabled, REC
disabled - recommended for AMD
CPU diodes
External Diode 1 Diode Mode -
Beta compensation disabled, REC
enabled
External Diode 1 Transistor Mode -
Beta compensation enabled, REC
enabled - recommended for Intel
45nm and 65mn CPU diodes
Internal Diode
External Diode 2 Transistor Mode -
Beta Compensation enabled, REC
enabled (EMC2103-2 only) See
Note 5.1
External Diode 1 Transistor Mode -
Beta compensation enabled, REC
enabled
MODE OF OPERATION
DATASHEET
Table
22
5.1.
Figure
RPM-Based Fan Controller with HW Thermal Shutdown
5.2. The value of this resistor is used to create
Host control via SMBus
Host control via SMBus
Host control via SMBus
Host control via SMBus
Host control via SMBus
Host control via SMBus
CONFIGURATION MECHANISM
SMSC EMC2103
Datasheet