1°C Temperature Sensor with Beta Compensation
Datasheet
6.12 Beta Configuration Registers
Table 6.14 Beta Configuration Registers
ADDR.
R/W
REGISTER
B7
B6
B5
B4
B3
B2
B1
B0
DEFAULT
External Diode
1 Beta
Configuration
25h
R/W
-
-
-
-
ENABLE
BETA[2:0]
08h
This register is used to set the Beta Compensation factor that is used for the external diode channel.
Bit 3 - ENABLE - Enables the Beta Compensation factor autodetection function.
‘0’ - The Beta Compensation Factor autodetection circuitry is disabled. The External Diode will
always use the Beta Compensation factor set by the BETA[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 BETA[2:0] bits will be automatically updated to indicate the current setting.
Bit 2-0 - BETA[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 BETA[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 BETA[2:0] bits should be set to ‘111b’.
Table 6.15 CPU Beta Values
BETA[2:0]
HEX
ENABLE
2
1
0
MINIMUM BETA
0.11
0h
1h
2h
3h
4h
5h
6h
7h
0
0
0
0
0
0
0
0
1
0
0
0
0
1
1
1
1
X
0
0
1
1
0
0
1
1
X
0
1
0
1
0
1
0
1
X
0.18
0.25
0.33
0.43
1.00
2.33
Disabled
Autodetection
8h - Fh
SMSC EMC1402
Revision 1.16 (03-15-07)
DATA3S3HEET
SMSC [ SMSC CORPORATION ]
