RPM-Based Fan Controller with Multiple Temperature Zones & Hardware Thermal Shutdown
Datasheet
available that shares the DP2 and DN2 pins. When in this mode, both the external diode 2 channel
and external diode 3 channel thermal diodes must be connected as diodes.
Diode 3
Diode 2
to
DP /
DN
to
DP
to
DP
to
DP
to
DN
to
DN /
DP
to
DN
to
DN
Local Ground
Typical remote
substrate transistor
i.e. CPU substrate PNP
Typical remote
discrete NPN transistor
i.e. 2N3904
Typical remote
discrete PNP transistor
i.e. 2N3906
Anti-parallel diodes using
discrete NPN transistors
Figure 6.6 Diode Connections
6.14.1
6.14.2
Anti-Parallel Diodes
The EMC2113 supports connecting two external diodes to the DN2 / DP3 and DP2 / DN3 pins. This
second diode is connected in an anti-parallel configuration with respect to the first diode. When the
the External Diode 2 channel is measured, the anti-parallel diode will be reverse biased. Likewise,
when the External Diode 3 channel is measured, the first diode will be reverse biased. CPU diodes
should not be used with anti-parallel diode connections.
Diode Faults
The EMC2113 actively detects an open and short condition on each measurement channel. When a
diode fault is detected, the temperature data MSByte is forced to a value of 80h and the FAULT bit is
set in the Status Register. When the External Diode 2 channel is configured to operate in APD mode,
the circuitry will detect independent open fault conditions; however, a short condition will be shared
between the External Diode 2 and External Diode 3 channels.
Revision 1.2 (10-08-09)
SMSC EMC2113
DATA3S6HEET
SMSC [ SMSC CORPORATION ]
