EMC1046 Standard Microsystems Corp., EMC1046 Datasheet - Page 30

• Manufacturer Part Number: EMC1046
• Description: 1 Degree C Multiple Temperature Sensor With Beta Compensation And Hottest Of Thermal Zones
• Manufacturer: Standard Microsystems Corp.

Revision 0.66 (06-02-08)
ADDR.
71h
2
0
0
0
0
1
1
1
1
R/W
R/W
These registers are used to set the Beta Compensation factor that is used for the External Diode
channels.
Bit 3 - AUTOx - Enables the Beta Compensation factor autodetection function.
Bit 2-0 - BETAx[2:0] - These bits always reflect the current beta configuration settings. If autodetection
circuitry is enabled, then these bits will be updated automatically and writing to these bits will have no
effect. If the autodetection circuitry is disabled, then these bits will determine the beta configuration
setting that is used for their respective channels.
Care should be taken when setting the BETAx[2:0] bits when the autodetection circuitry is disabled. If
the Beta Compensation factor is set at a beta value that is higher than the transistor beta, then the
circuit may introduce measurement errors. When measuring a discrete thermal diode (such as
2N3904) or a CPU diode that functions like a discrete thermal diode (such as an AMD processor
diode), then the BETAx[2:0] bits should be set to ‘111b’.
‘0’ - The Beta Compensation Factor autodetection circuitry is disabled. The External Diode will
always use the Beta Compensation factor set by the BETAx[2:0] bits.
‘1’ (default) - The Beta Compensation factor autodetection circuitry is enabled. At the beginning of
every conversion, the optimal Beta Compensation factor setting will be determined and applied.
The BETAx[2:0] bits will be automatically updated to indicate the current setting.
BETAX[2:0]
Diode 4 Beta
Configuration
REGISTER
External
1
0
0
1
1
0
0
1
1
Table 5.15 Beta Compensation Look Up Table
Table 5.14 Beta Configuration Register
B7
-
0
0
1
0
1
0
1
0
1
B6
1°C Multiple Temperature Sensor with Beta Compensation and Hottest of Thermal Zones
-
DATASHEET
B5
-
30
B4
-
AUTO4
B3
MINIMUM BETA
B2
Disabled
< 0.176
< 0.111
< 0.08
< 0.29
< 0.48
< 2.33
< 0.9
BETA4[2:0]
B1
SMSC EMC1046/EMC1047
B0
DEFAULT
Datasheet
08h