Multiple Channel 1°C Temperature Sensor with Beta Compensation
Datasheet
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), the
BETA[2:0] bits should be set to ‘111b’.
Table 7.15 CPU Beta Values
BETA[2:0]
HEX
ENABLEX
2
1
0
MINIMUM BETA
0.11
0h
1h
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
2h
0.25
3h
0.33
4h
0.43
5h
1.00
6h
2.33
7h
Disabled
Auto-detection
8h - Fh
7.13
External Diode Ideality Factor Register
Table 7.16 Ideality Configuration Registers
ADDR.
R/W
REGISTER
B7
B6
B5
B4
B3
B2
B1
B0
DEFAULT
External
Diode
Ideality
27h
R/W
-
-
IDEALITY[5:0]
12h
Factor
This register stores the ideality factors that are applied to the external diode. Table 7.17 defines each
setting and the corresponding ideality factor. Beta Compensation and Resistance Error Correction
automatically correct for most diode ideality errors; therefore, it is not recommended that these settings
be updated without consulting SMSC.
Table 7.17 Ideality Factor Look-Up Table (Diode Model)
SETTING
FACTOR
SETTING
FACTOR
SETTING
FACTOR
08h
09h
0Ah
0Bh
0Ch
0.9949
0.9962
0.9975
0.9988
1.0001
18h
19h
1Ah
1Bh
1Ch
1.0159
1.0172
1.0185
1.0200
1.0212
28h
29h
2Ah
2Bh
2Ch
1.0371
1.0384
1.0397
1.0410
1.0423
Revision 1.41 (02-23-12)
SMSC EMC1412
DATA3S4HEET
SMSC [ SMSC CORPORATION ]
