ASC7512 ETC2 [List of Unclassifed Manufacturers], ASC7512 Datasheet - Page 24

• Manufacturer Part Number: ASC7512
• Description: DIGITAL TEMPERATURE SENSOR WITH INTEGRATED FAN CONTROL
• Manufacturer: ETC2 [List of Unclassifed Manufacturers]

Register
Address
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 low speeds, so care should be taken in
software to ensure that the limit is high enough not to cause sporadic alerts. The fan tachometer will not cause a bit to be
set in Interrupt Status Register 2 if the current value in Current PWM Duty registers is 00h or if the fan 1 disabled via the Fan
Configuration Register. Interrupts will never be generated for a fan if its minimum is set to FF FFh.
Given the relative insignificance of Bit 0 and Bit 1 of Tach Minimum LSB, these bits could be programmed to designate the
physical location of the fan generating the tachometer signal, as follows:
Setting the Ready/Lock/Start/Override register Lock bit has no effect on these registers.
This register becomes Read-only when the Ready/Lock/Start/Override register Lock bit is set. Any further attempts to write
to this register shall have no effect. After power up the default value is used whenever the Ready/Lock/Start/Override
register Start bit is cleared even though modifications to this register are possible.
Bits [7:5] Zone/Mode
Bits [7:5] of the Fan Configuration registers associate each fan with a temperature sensor. When in Auto Fan Mode the fan
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 (110), the fan will be controlled by the the hotter of zones 1, or 2. To determine the “hotter zone”, the
PWM level for each zone is calculated then the zone with the higher PWM value (not temperature) is selected. When in
manual control mode, the Current PWM duty register (30h) become Read/Write. It is then possible to control the PWM
outputs with software by writing to these registers. When the fan is disabled (100) the corresponding PWM output should be
driven low (or high, if inverted).
Zone 1: External Diode (processor)
Zone 2: Internal Sensor
© Andigilog, Inc. 2006
Register 54-55h: Fan Tachometer Minimum Limits
Register 5Ch: Fan Thermal Zone Assignment and Spin-up Mode
Register
Address
5Ch
54h
55h
Read/
Write
R/W
Read/
Write
R/W
Fan Configuration
Register Name
Tach Minimum LSB
Tach Minimum MSB
Register Name
CPU Cooler
Memory Controller
Chassis Front
Chassis Rear
(MSB)
ZON2
Bit 7
(MSB)
Register Name
Bit 7
15
7
Table 14 Fan Location
ZON1
Bit 6
www.andigilog.com
Bit 6
14
6
ZON0
Bit 5
- 24 -
Bit 5
13
5
Bit 4
INV
Bit 1
0
0
1
1
Bit 4
12
4
Bit 3
RES
(LSB)
Bit 0
0
1
0
1
Bit 3
SPIN2
11
Bit 2
3
Bit 2
SPIN1
10
Bit 1
2
Bit 1
(LSB)
SPIN0
August 2006 - 70A05003
Bit 0
1
9
aSC7512
(LSB)
Bit 0
Default
Value
0
8
62
Default
Value
FF
FF
Lock
X