Hardware Monitoring; Figure 2-56. Hardware Monitoring Application Circuit - VIA Technologies Apollo Pro133A Design Manual

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2.5.3 Hardware Monitoring

The hardware monitoring interface includes five positive voltage sensing inputs (four external and one internal), three temperature
sensing inputs (two external and one internal), two fan-speed monitoring inputs and one chassis intrusion detection input.
Programmable control, status, monitor and alarm are supported by the VT82C686A for flexible desktop management. The
following sections provide detailed descriptions for each hardware monitor subsystem. An application circuit for hardware
monitoring is shown in Figure 2.56. In order to achieve a stable VCC3 input to the Hardware Monitoring Subsystem, a 0.1uF
decoupling capacitor should be placed as close to the Hardware Monitoring power and ground pins as possible.
VT82C686A
(South Bridge)
VSENS
VSENS
VSENS
VSENS
CHASSIS
VCCHWM
GNDHWM
Preliminary Revision 0.5, November 19, 1999
VCC2 VCCI
Mechanical Switch
FAN1
FAN2
0.1uF
TSEN1
10K ohm 1%
VREF
10K ohm 1%
TSEN2

Figure 2-56. Hardware Monitoring Application Circuit

Design Guide - VT82C694X Apollo Pro133 with VT82C686A
+5V +12V
16K 53K
ohm ohm
10K 10K
ohm ohm
Ferrite Bead
10uF
GNDHWM
Ferrite Bead
Ferrite Bead
10K ohm
Thermister
Ferrite Bead
10K ohm
Thermister
63
VCC3 VCC3
10K
ohm
4.7K 4.7K
ohm ohm
FAN
VCC3
Motherboard Design Guidelines
+12V
FAN