SMBus Fan Control with 1°C Accurate Temperature Monitoring
Datasheet
.
IHIGH
ILOW
Resistance
Error
Input
Filter &
ΔΣ
ADC
CPU
substrate
PNP
Correction
Sampler
Figure 5.3 Block Diagram of Temperature Monitoring Circuit
Figure 5.3 shows a block diagram of the temperature measurement circuit. As shown, the EMC2101
incorporates a delta-sigma analog to digital converter that integrates the temperature diode voltage
from multiple bias currents.
The external temperature diodes can be connected as shown in Figure 5.4.
to
to
to
DP
DP
DP
to
DN
to
to
DN
DN
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
Figure 5.4 External Diode configurations
5.5.1
Temperature Measurement Results and Data
The results of the internal and external temperature measurements are stored in the internal and
external temperature registers respectively. These are then compared with the values stored in the
High Limit Registers. The internal temperature measurements are stored in 8-bit format while the
external temperature measurements are stored in 11-bit format.
Revision 2.53 (03-13-07)
SMSC EMC2101
DATA2S2HEET
SMSC [ SMSC CORPORATION ]
