SCH3112I-NE SMSC [SMSC Corporation], SCH3112I-NE Datasheet - Page 258

• Manufacturer Part Number: SCH3112I-NE
• Description: LPC IO with 8042 KBC, Reset Generation, HWM and Multiple Serial Ports
• Manufacturer: SMSC [SMSC Corporation]

Rev 0.2 (09-28-04)
24.2.15
24.2.16
Register
Address
Register
Address
5Ch
5Dh
5Eh
54h
55h
56h
57h
58h
59h
Read/Write
Read/
Write
R/W
R/W
R/W
R/W
R/W
R/W
Registers 54-59h: Fan Tachometer Low Limit
Setting the Lock bit has no effect on these registers.
The Fan Tachometer Low Limit registers indicate the tachometer reading under which the
corresponding bit will be set in the Interrupt Status Register 2 register. In Auto Fan Control mode, the
fan can run at high speeds (100% duty cycle), so care should be taken in software to ensure that the
limit is low enough not to cause sporadic alerts. Note that an interrupt status event will be generated
when the tachometer reading is greater than the minimum tachometer limit.
The fan tachometer will not cause a bit to be set in the interrupt status register if the current value in
the associated Current PWM Duty registers is 00h or if the PWM is disabled via the PWM
Configuration Register.
Interrupts will never be generated for a fan if its tachometer minimum is set to FFFFh.
Registers 5C-5Eh: PWM Configuration
These registers become read only when the Lock bit is set. Any further attempts to write to these
registers shall have no effect.
Bits [7:5] Zone/Mode
Bits [7:5] of the PWM Configuration registers associate each PWM with a temperature zone.
■
■
■
■
Notes:
■
R/W
R/W
R/W
When in Auto Fan Mode, the PWM will be assigned to a zone, and its PWM duty cycle will be
adjusted according to the temperature of that zone. If ‘Hottest’ option is selected (101 or 110), the
PWM will be controlled by the hottest of zones 2 and 3, or of zones 1, 2, and 3. If one of these
options is selected, the PWM is controlled by the limits and parameters for the zone that requires
the highest PWM duty cycle, as computed by the auto fan algorithm.
When in manual control mode, the PWMx Current Duty Cycle Registers (30h-32h) become
Read/Write. It is then possible to control the PWM outputs with software by writing to these
registers. See PWMx Current Duty Cycle Registers description.
When the fan is disabled (100) the corresponding PWM output is driven low (or high, if inverted).
When the fan is Full On (011) the corresponding PWM output is driven high (or low, if inverted).
Zone 1 is controlled by Remote Diode 1 Temp Reading register
PWM 1 Configuration
PWM 2 Configuration
PWM 3 Configuration
FANTACH1 Minimum MSB
FANTACH2 Minimum MSB
FANTACH3 Minimum MSB
FANTACH1 Minimum LSB
FANTACH2 Minimum LSB
FANTACH3 Minimum LSB
Register Name
Register Name
(MSb)
ZON2
ZON2
ZON2
Bit 7
DATASHEET
LPC IO with 8042 KBC, Reset Generation, HWM and Multiple Serial Ports
(MSb)
Bit 7
ZON1
ZON1
ZON1
Bit 6
15
15
15
7
7
7
242
Bit 6
ZON0
ZON0
ZON0
Bit 5
14
14
14
6
6
6
Bit 5
13
13
13
Bit 4
5
5
5
INV
INV
INV
Bit 4
12
12
12
SUEN1
SUEN2
SUEN3
4
4
4
Bit 3
Bit 3
11
11
11
3
3
3
SPIN2
SPIN2
SPIN2
Bit 2
Bit 2
10
10
10
2
2
2
SPIN1
SPIN1
SPIN1
Bit 1
Bit 1
9
1
1
9
1
9
SPIN0
SPIN0
SPIN0
(LSb)
Bit 0
(LSb)
SMSC SCH311X
Bit 0
0
8
0
8
0
8
Datasheet
Default
Default
Value
Value
62h
62h
62h
FFh
FFh
FFh
FFh
FFh
FFh