- 17 -
© Andigilog, Inc. 2006
www.andigilog.com
October 2006 - 70A06010
aSC7621
Temperature Measurement
Diode temperatures are measured with a precision Delta-VBE methodology converted to a digital temperature reading by a
10-bit sigma-delta converter. PECI interface to the CPU provide Digital Thermometer readings of substrate temperature. The
measurement system provides a means for assigning any of the temperature inputs to a Temperature Zone. The user may
set limits on these readings to be continuously monitored and alarm bits set when they are exceeded. Separately, the
measurements are also delivered to the automatic fan control system to adjust fan speed. The following registers contain the
readings from the internal and remote sensors.
Registers 25-10h, 26-15h and 27-0Eh: Temperature Zone Readings (10-Bit, 2’s Complement Reporting)
Register
Address
Read/
Write
Register Name
Bit 7
(MSB)
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
(LSB)
Default
Value
25h
R
Zone 1 Temper-
ature (MS Byte)
9
8
7
6
5
4
3
2
N/A
10h
R
Zone 1 Temper-
ature (LS Byte)
1
0
X
X
X
X
X
X
N/A
26h
R
Zone 2 Temper-
ature (MS Byte)
9
8
7
6
5
4
3
2
N/A
15h
R
Zone 2 Temper-
ature (LS Byte)
1
0
X
X
X
X
X
X
N/A
27h
R
Zone 3 Temper-
ature (MS Byte)
9
8
7
6
5
4
3
2
N/A
16h
R
Zone 3 Temper-
ature (LS Byte)
1
0
X
X
X
X
X
X
N/A
33h
R
Zone 4 Temper-
ature (MS Byte)
9
8
7
6
5
4
3
2
N/A
17h
R
Zone 4 Temper-
ature (LS Byte)
1
0
X
X
X
X
X
X
N/A
The Temperature Zone registers reflect the current temperature of the internal and remote diodes or PECI CPU Digital
Thermometers. Filtering is applied to all readings and this is described in the Spike & Smoothing Filter section below. Any
temperature input may be assigned to any zone, according to the settings in the Zone Assignment Registers, [02h] and
[03h]. The default assignment is as follows:
Zone 1 Temperature register reports the temperature measured by the thermal diode connected to the Remote 1- and
Remote 1+ pins if either:
1.
PECI monitoring is disabled (register [40h] bit 4=0)
2.
PECI monitoring is enabled but in legacy mode, (register [36h] bit 4, LEG = 0).
If PECI Monitoring is enabled (register [40h] bit 4=1) AND legacy mode is LEG = legacy mode (register [36h] bit 4, LEG = 1),
the register reports the highest Digital Thermometer reading by the processor.
Zone 2 Temperature register reports the temperature measured by the internal (junction) temperature sensor.
Zone 3 Temperature register reports the temperature measured by the thermal diode connected to the second set of Remote
2- and Remote 2+ pins.
Zone 4 reports temperatures as follows:
1.
By default and if PECI temperature is disabled (register [36h] bit 4, LEG = 0) the Zone 4 register is not used. In this
case, special temperature value of 80h will be reported to indicate that no temperature is available. If this zone is
associated with any fan PWM controller(s), this will result in these controller(s) being overridden to 100% duty cycle.
No error bits will be set in the Interrupt Status Registers.
2.
If PECI Monitoring is enabled [40h] bit 4=1) AND legacy mode is in standard mode (register [36h] bit 4, LEG = 0),
the register will report the highest Digital Thermometer reading by the processor.
3.
Temperatures are represented as 10-bit, 2’s complement, signed numbers, in degrees Celsius, as shown below in
Table 3.
4.
If PECI Monitoring is enabled [40h] bit 4=1) AND legacy mode is in legacy mode (register [36h] bit 4, LEG = 1), the
register will report the temperature measured by the thermal diode connected to the Remote 1- and Remote 1+
pins.
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