EMC1053 Standard Microsystems Corp., EMC1053 Datasheet - Page 15

• Manufacturer Part Number: EMC1053
• Description: 1 Degree C Triple Temperature Sensor With Resistance Error Correction & Hotter Of Two Zones
• Manufacturer: Standard Microsystems Corp.

1°C Triple Temperature Sensor with Resistance Error Correction & Hotter of Two Zones
Datasheet
APPLICATION NOTE: When monitoring a substrate transistor or CPU diode and beta compensation is enabled, the
SMSC EMC1053
3.7
3.8
3.9
When monitoring the thermal diode of an AMD K8 processor, the Resistance Error Correction must be
disabled for accurate temperature measurements. This is accomplished by clearing the REC bit in the
configuration 2 register (see
with AMD Processors” for more details.
The Beta Compensation function can be programmed to eliminate temperature errors caused by beta
variation in modern, low beta transistors used for monitoring processor temperatures.
beta as differing currents are applied to temperature transistors can cause significant temperature
errors in monitoring devices. As modern processor geometries shrink the trend is for transistor betas
to decrease, which exacerbates temperature errors.
By default, this functionality is disabled. It can be enabled by writing any value other than 07h in the
Beta Configuration Registers (see
Discrete transistors, with collector connected to base to form a diode, are generally immune to these
temperature errors because of high (>100) betas. A beta variation of 10% from low current to high
current, when beta equals 100, induces approximately 0.12° error at 100°C. However for a low beta
(1.0) substrate transistor used for processor temperature measurement, a beta variation of 10% from
low to high current induces approximately 6.12° error at 100°C.
When measuring an AMD K8 processor, the Beta Compensation circuitry must be disabled. See
Section
for more details.
The EMC1053 default is for a diode ideality factor of 1.008 which is common for a 2N3904 diode and
for many processor transistors. When a diode or transistor is used that has a different ideality factor
value than 1.008 a temperature error is induced that is a linear function of temperature. Previous
solutions for this mismatch in ideality factor has been to supply a programmable offset to the
temperature reading which corrects the error at a single temperature but causes a residual error at all
other temperatures. The EMC1053 ideality factor register corrects this mismatch error at all
temperatures (see
The EMC1053 detects a fault if the DP pin is left floating or is shorted to VDD. In the case of a diode
fault, the corresponding status bit will be set and the output data will be set at 400h.
Beta Compensation
Programmable Ideality Factor
Diode Faults
4.8. Please see SMSC Application note “13.16 - Using the EMC1043 with AMD Processors”
Ideality Factor should not be adjusted. Beta Compensation automatically corrects for most
ideality errors.
Section
4.7).
Section
Section
DATASHEET
4.5). Please see Application note “13.16 - Using the EMC1043
15
4.11).
Revision 1.44 (04-14-08)
Changes in