User Manual

Functional Description (Continued)
13.10 VID/Fan Divisor Register—Address 47h
Power on default –
<
7:4
>
is 0101, and
<
3:0
>
is mapped to VID
<
3:0
>
Bit Name Read/Write Description
0-3 VID
<
3:0
>
Read Only The VID
<
3:0
>
inputs from the Pentium/PRO power supplies that indicate the
operating voltage (e.g. 1.5V to 2.9V).
4-5 FAN1 RPM
Control
Read/Write FAN1 Speed Control.
<
5:4
>
= 00 - divide by 1;
<
5:4
>
= 01 - divide by 2;
<
5:4
>
= 10 - divide by 4;
<
5:4
>
= 11 - divide by 8.
6-7 FAN2 RPM
Control
Read/Write FAN2 Speed Control.
<
7:6
>
= 00 - divide by 1;
<
7:6
>
= 01 - divide by 2;
<
7:6
>
= 10 - divide by 4;
<
7:6
>
= 11 - divide by 8.
13.11 Serial Bus Address Register— Address 48h
Power on default – Serial Bus address
<
6:0
>
= 010 11(A1)(A0) and
<
7
>
= 0 binary
Bit Name Read/Write Description
0-1 Serial Bus
Address
Read Only Serial Bus address
<
1:0
>
=A1A0
2-6 Serial Bus
Address
Read/Write Serial Bus address
<
6:2
>
= 010 11
7 Reserved Read/Write
13.12 VID4 Register—Address 49h
Power on default –
<
7:1
>
= 100 000,
<
0
>
= VID4.
Bit Name Read/Write Description
0 VID4 Read Only VID4 input from Pentium/PRO power supply that indicate the operating voltage of
the processor (e.g. 1.5V to 2.9V).
1-7 Reserved Read/Write
13.13 Temperature Configuration Register— Address 4Bh
Power on default –
<
7:0
>
= 0000 0001 binary
Bit Name Read/Write Description
0-1 Temperature
Interrupt Mode
Select Bits
Read/Write The state of these bits select the interrupt mode for INT as described below.
<
1:0
>
=00or
<
1:0
>
= 11: Repetitive Interrupt Mode
<
1:0
>
= 01: One-Time Interrupt Mode
<
1:0
>
= 10: Comparator Mode
2-6 Reserved Read/Write
7 Temperature
Resolution
Read Only For 8-bit plus sign temperature resolution:
<
7
>
= LSB ( 0.5˚C)
LM81
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