User Guide • PC3-ALLEGRO • CompactPCI
®
PlusIO CPU Board • Intel® i7-3xxx Processor
Hardware Monitor LM87
Attached to the SMBus, the PC3-ALLEGRO is provided with a hardware monitor (LM87). This device
is capable to observe the board and on-board memory temperatures, as well as several supply voltage
rails with a resolution of 8 bit. The following table shows the mapping of the voltage inputs of the
LM87 to the corresponding supply voltages of the PC3-ALLEGRO:
Input
Source
Resolution
[mV]
Register
AIN1
Processor Core Voltage
9.8
0x28
AIN2
Graphics Core Voltage
9.8
0x29
VCCP1
+1.5V
14.1
0x21
VCCP2/D2-
+1.8V
14.1
0x25
+2.5V/D2+
+1.05V
13
0x20
+3.3V
+3.3V
17.2
0x22
+5V
+5V
26
0x23
+12V
+10V
62.5
0x24
Beside the continuous measuring of temperatures and voltages the LM87 may compare these values
against programmable upper and lower boundaries. As soon as a measurement violates the allowed
value range, the LM87 can request an interrupt via the GPI13 input of the QM77 PCH (which may
result in a system management interrupt).
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