f75363 Feature Integration Technology Inc., f75363 Datasheet - Page 7

• Manufacturer Part Number: f75363
• Description: ?1o C Accuracy Temperature Sensor Ic With Fan Speed Control
• Manufacturer: Feature Integration Technology Inc.

F75363
6. Functional Description
6.1 General Description
6.2 Access Interface
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6
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The F75363 is a temperature sensor IC with PWM duty cycle output which is specific designed for graphic cards etc.
An 11-bit analog-to-digital converter (ADC) was built inside F75363. This chip provides 1 remote temperature sensor
and 1 local temperature sensor. The remote temperature sensor can be performed by CPU/GPU thermal diode or
transistor 2N3906. Users can set up the upper and lower limits (alarm thresholds) of monitored parameters and this
chip can also issue warning messages for system protection when there is something wrong with monitored items. As
for fan speed control, the F75363 can use PWM duty cycle output to automatically control fan speed. The fan speed
control is related to temperature variation. There is 8-step lookup table for users to program PWM duty cycle output to
control fan speed according to the temperature variation.
The F75363 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 F75363 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. F75363 supports 25ms timeout for no activity on
the SMBus. This timeout function is programmed at 22h bit7 and default is disabled. F75363 also supports Alert
Response Address (ARA) protocol.
The operation of the protocol is described with details in the following sections.
(a)
SMBus write to internal address register followed by the data byte
GND
ALERT# / FANIN
SDA
SCL
PWR
POD
(5V-tolerance)
IN
(5V-tolerance)
IN
ts
t s ( 5 V - t o l e r a n c e )
/POD
12
/ IN
12
ts
-3-
Ground
This is a multi-function pin. Power-on default is ALERT#
function. When it is used 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.
Serial bus data
Serial bus clock
F75363
July, 2007
V0.27P