F75386
5
6
GND
PWR
VCC
Ground
ALERT#
FANIN
OD12 / INts VCC
This is a multi-function pin. Power-on default is ALERT# function.
When it acts as ALERT# function, it will be asserted when the
temperature exceeds its high limit or goes below its low limit.
When it is as FANIN function, it is for monitoring the fan speed.
(5V-tolerance)
7
8
SDA
SCL
INts/OD12 VCC
Serial bus data
(5V-tolerance)
INts
VCC
Serial bus clock
(5V-tolerance)
6. Functional Description
6.1 General Description
The F75386 is a temperature sensor IC with fan speed monitoring and controlling function which is specific
designed for notebook etc. An 11-bit analog-to-digital converter (ADC) was built inside F75386. The F75386 can
provide 2 remote temperature sensor and 1 local temperature sensor. The remote temperature sensor can be
performed by CPU/GPU thermal diode or transistor 2N3906. The F75386 can also provide alert signals for
system protection which is optional with fan speed monitoring and controlling. The users can set up the upper
and lower limits (alarm thresholds) of all monitored parameters and this chip will issue warning messages for
system when there is something wrong with monitored items. As for fan speed control, the fan speed will be
related to temperature variation. The F75386 can use PWM duty cycle output to automatically control fan speed.
There are 8 steps PWM duty cycle output for users to program according to the temperature variation.
6.2 Access Interface
The F75386 can be connected to a compatible 2-wire serial system management bus as a slave device under the
control of the master device, using two device terminals SCL and SDA. The F75386 supports SMBus protocol of, “Write
Byte”, “Read Byte”, both with or without Packet Error checking(PEC) which is calculated using CRC-8. For detail
information about PEC, please check SMBus 1.1 specification. The F75386 supports 25ms timeout for no activity on
the SMBus. This timeout function is programmed at 22h bit7 and default is disabled. F75386 also supports Alert
Response Address(ARA) protocol.The operation of the protocol is described with details in the following sections.
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F75386
July, 2007
V0.27P
FINTEK [ FEATURE INTEGRATION TECHNOLOGY INC. ]
