W83781D Datasheet, PDF (6/53 Pages) Winbond – MONITORING IC

W83781D
1. GENERAL DESCRIPTION
PRELIMINARY
The W83781D is a hardware status monitoring IC for personal computers, server computers, or
microprocessor based systems. W83781D can be used to monitor several critical hardware
parameters of the system, including power supply voltages, fan speeds, and temperatures, which are
very important for a high-end computer system to work stable and properly. W83781D provides both
ISA and I²C^TM serial bus interface.
A 8-bit analog-to-digital converter (ADC) was built inside W83781D. The W83781D can monitor 3
external thermistor temperature sensors, 5 positive analog voltage inputs, two inverting inputs (for
monitoring negative voltages), and also three fan tachometer outputs. There is also one input for
case open detection circuits.
With the application software, the users can read all the monitored parameters of system from time to
time. The application software could be the popular Intel^TM LDCM (LANDesk Client Management) or
Winbond s application software. Also the users can set up the upper and lower limits of these
monitored parameters and to activate two programmable and maskable interrupts. An optional beep
tone could be used as warning signal when the monitored parameters is out of the preset range.
Additionally, 5 VID inputs are provided to read the VID of CPU (such as Pentium^TM II) if applicable.
This is to provide the Vcore correction automatically. Also W83781D uniquely provides an optional
feature: early stage (before BIOS was load) beep warning. This is to detect if the fatal elements
present --- VcoreA, +3.3V voltage fail, and the system can not be boomed up.
2. FEATURES
2.1 Monitoring Items
• 3 thermal inputs from remote thermistors
• 5 positive voltage inputs (typical for +12V, +5V, +3.3V, VcoreA, VcoreB)
• 2 op amps for negative voltage monitoring (typical for -12V, -5V)
• 3 fan speed monitoring inputs
• Case open detection input
• WATCHDOG comparison of all monitored values
• Programmable hysteresis and setting points for all monitored items
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Publication Release Date : Nov. 1997
Revision 0.60