Environmental Monitoring and Control Device
Datasheet
6.6.2
SHUTDOWN MODE
This is a low power mode in which bias currents are ‘off’ and the Hardware Monitor Block is not operating.
In this mode, the A/D converter and monitoring cycle will be turned off. Serial bus communication is still
possible with any register in the Hardware Monitor Block while in this low-power mode.
6.7
Analog Voltage Measurement
EMC6D101 monitors power supplies +2.5V, +5V, +12V, Vccp, and VCC
EMC6D100 monitors additional power supplies +3.3V, +1.5V, +1.8V
The Hardware Monitor Block contains inputs for directly monitoring the power supplies (+12 V, +5 V,
+3.3V, +2.5V, +1.8V, +1.5V, +Vccp and VCC). These inputs are scaled internally to a internal reference
source, converted via an 8 bit successive approximation register ADC or a Delta-Sigma ADC (Analog-to-
Digital Converter), and scaled such that the correct value refers to 3/4 scale or 192 decimal (except the
Vccp input). This removes the need for external resistor dividers and allows for a more accurate means of
measurement since the voltages are referenced to a known value. Since any of these inputs can be above
VCC or below Ground, they are not diode protected to the power rails. The measured values are stored in
the Reading registers and compared with the Limit registers. The status bits in the Interrupt Status
Register 1, 2 and 3 are set if the measured values are outside (or equal to) the programmed limits.
The Vccp voltage input measures the processor voltage, which will lie in the range of 0V to 3.0V.
The following table shows the values of the analog inputs that correspond to the min and max output
codes of the A/D converter. For a complete list of the ADC conversions see Appendix B.
INPUT VOLTAGE
+12VIN
+5VIN
<0.026
VCC/3.3VIN
<0.017
+2.5VIN
<0.013
+1.8VIN
<0.009
+1.5VIN
<0.008
+VCCP
<0.012
Min Value (Corresponds <0.062
to A/D output 00000000)
Max Value (Corresponds >15.938
to A/D output 11111111)
>6.640
>4.383
>3.320
>2.391
>1.992
>2.988
6.8
Voltage ID
VID0-VID4 digital inputs are used to store processor Voltage ID codes (for processor operating voltage) in
the VID0-4 register (43h). These VIDs can be read out by the management system using the SMBus
interface.
6.9
Temperature Measurement
Temperatures are measured internally by bandgap temperature sensor and externally using two sets of
diode sensor pins (for measuring two external temperatures). See subsections below.
Note: The temperature sensing circuitry for the two remote diode sensors is calibrated for a Pentium
diode.
6.9.1 INTERNAL TEMPERATURE MEASUREMENT
Internal temperature can be measured by bandgap temperature sensor. The measurement is converted
into digital format by internal ADC. This data is converted in two’s complement format since both negative
and positive temperature can be measured. This value is stored in Internal (Zone 2) Temperature Reading
register (26h) and compared to the Temperature Limit registers (50h – 51h). If this value violates the
SMSC EMC6D100/EMC6D101
Page 26
Rev. 09-09-04
DATASHEET
SMSC [ SMSC CORPORATION ]
