EMC2103 Standard Microsystems Corporation, EMC2103 Datasheet - Page 45

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

RPM-Based Fan Controller with HW Thermal Shutdown
Datasheet
SMSC EMC2103
6.7
ADDR
15h **
14h
R/W
R/W
RW
The Beta Configuration Register controls advanced temperature measurement features of the External
Diode channels.
If External Diode 1 is selected as the hardware shutdown measurement channel (see
then the External Diode 1 Beta register will be read only. If the internal diode is selected, then this
register can be written normally. Likewise, if the External Diode 2 channel is selected (EMC2103-2
only) then this register can be written normally. Finally, if External Diode 2 is selected as the hardware
shutdown measurement channel (EMC2103-2 only), then the External Diode 2 Beta Configuration
Register will be read only.
Writing to a read only register will have no affect. The data will be ignored.
Bit 4 - AUTOx - Enables the Automatic Beta detection algorithm for the External Diode X channel.
Bits 2 - 0 - BETAx[2:0] - hold a value that corresponds to a range of betas that the Beta Compensation
circuitry can compensate for. These three bits will always show the current beta setting used by the
circuitry. If the AUTO bit is set (default), then these bits may be overwritten with every temperature
conversion. If the AUTO bit is not set, then the value of these bits is used to drive the beta
compensation circuitry. In this case, these bits should be set with a value corresponding to the lowest
expected value of beta for the PNP transistor being used as a temperature sensing device.
See
circuitry is disabled. In this condition, the diode channels will function with default current levels and
will not automatically adjust for beta variation. This mode is used when measuring a discrete 2N3904
transistor or AMD thermal diode.
If the External Diode 3 channel is enabled, it will always use a beta setting of 111b.
The Beta Configuration Registers are Software Locked.
Beta Configuration Register
‘0’ - The Automatic Beta detection algorithm is disabled. The BETAx[3:0] bit settings will be used
to control the beta compensation circuitry.
‘1’ (default) - The Automatic Beta detection algorithm is enabled. The circuitry will automatically
detect the transistor type and beta values and configure the BETAx[3:0] bits for optimal
performance.
Table 6.11
External Diode 1
External Diode 2
Configuration **
Configuration
REGISTER
Beta
Beta
for supported beta ranges. A value of 111b indicates that the beta compensation
Table 6.9 Ideality Factor Look-Up Table (continued)
Table 6.10 Beta Configuration Register
B7
SETTING
-
-
16h
17h
DATASHEET
B6
-
-
45
B5
-
-
FACTOR
1.0133
1.0146
AUT
AUT
B4
O1
O2
B3
-
-
B2
BETA1[2:0]
BETA2[2:0]
B1
Revision 0.85 (01-29-08)
B0
Section
DEFAULT
10h
10h
5.1.1)