EMC2113 datasheet(36/85 Pages) SMSC

36 / 85 page

RPM-Based Fan Controller with Multiple Temperature Zones & Hardware Thermal Shutdown

Datasheet

Revision 1.2 (10-08-09)

SMSC EMC2113

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.

6.14.1

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.

6.14.2

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.

Figure 6.6 Diode Connections

Local Ground

Typical remote

substrate transistor

i.e. CPU substrate PNP

Typical remote

discrete PNP transistor

i.e. 2N3906

Typical remote

discrete NPN transistor

i.e. 2N3904

DP /

DN /

Anti-parallel diodes using

discrete NPN transistors

Diode 2

Diode 3

EMC2113 Datasheet(PDF) 36 Page - SMSC Corporation