W83L785R Datasheet, PDF (10/38 Pages) Winbond – WINBOND H/W MONITORING IC FOR NOTEBOOK

W83L785R/W83L785G
6. FUNCTIONAL DESCRIPTION
6.1 General Description
The W83L785R/G provides most 4 analog positive inputs, 2 fan speed monitors, 2 sets for fan PWM
(Pulse Width Modulation) control, 2 remote thermal inputs from remote thermistors or 2N3904
transistors or Pentium^TM II (Deschutes) thermal diode outputs. W83L785R/G also provides software
power down this chip to save power, but I2C interface is still working. When W83L785R/G starts the
monitor function on the chip, the Watch Dog machine monitors every function and store the value to
registers. If the monitor value exceeds the limit value, the interrupt status will be set to 1.
6.2 Access Interface
The W83L785R/G provides I²C Serial Bus to read/write internal registers. In the W83L785R/G, the I2C
address defined value is 0101101.
6.2.1 The first serial bus access timing is shown as follow:
(a) Serial bus write to internal address register followed by the data byte
0
SCL
780
78
SDA
0
Start By
Master
10110
Frame 1
Serial Bus Address Byte
SCL (Continued)
1 R/W
D7 D6 D5 D4 D3 D2 D1 D0
Ack
Ack
by
Frame 2
by
785R
785R
Internal Index Register Byte
0
78
SDA (Continued)
D7 D6 D5 D4 D3 D2 D1 D0
Frame 3
Data Byte
Ack
bbyy
778845RR
Stop
by
Master
Figure 1. Serial Bus Write to Internal Address Register followed by the Data Byte
(b) Serial bus read form internal address register followed by the data byte
SCL
0
780
78
SDA
0
Start By
Master
10110
Frame 1
Serial Bus Address Byte
1 R/W
D7 D6 D5 D4 D3 D2 D1 D0
ack
by
785R
Frame 2
Internal Index Register Byte
ack
by
785R
SCL(Continued)
012345678012345678
SDA(Continued)
0
1
0
1
1
0
1 _R/W
D7 D6 D5 D4 D3 D2 D1 D0
Frame 3
Serial Bus Byte
ack
by
785R
Frame 4
Data Byte
by
784R
Aacckk
by
Stop by
Master
785R
Figure 2. Serial Bus read from Internal Address Register followed by the Data Byte
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