W83781D Datasheet, PDF (12/53 Pages) Winbond – MONITORING IC

7. FUNCTIONAL DESCRIPTION
W83781D
PRELIMINARY
7.1 General Description
The W83781D provides 5 analog positive inputs, 2 analog negative input, 3 fan speed monitors or fan
ON/OFF control, 3 thermistor voltage inputs, case open detection and beep function output when the
monitor value exceed the set limit value. When start the monitor function on the chip, the watch dog
machine monitor every function and store the value to registers. If the monitor value exceeds the limit
value, the interrupt status will be set to 1.
The W83781D provides two interface for microprocessor to read/write internal registers. The first
interface use ISA Bus to access which the ports of low byte (bit2~bit0) are defined in the port 5h and
6h. The high byte of these ports is decoded by Chip Select (CS#), the general decoded address is set
to port 295h and port 296h. These two ports are described as following:
Port 295h: W83781D Index register port.
Port 296h: Data port.
The register structure is showed as the diagram next page.
The second interface use Serial Bus. In the W83781D has three serial bus address. That is, the first
address defined at CR48 can read/write all registers excluding Bank 1 and Bank 2 temperature 2/3
registers, the second address defined at CR4A.bit2-0 only read/write temperature sensor 2 registers,
and the third address defined at CR4A.bit6-4 only can access (read/write) temperature sensor 3
registers.
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Publication Release Date : Nov. 1997
Revision 0.60