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- 28 -
Andigilog, Inc. 2006
www.andigilog.com
October 2006 - 70A05007
aSC7611
Register 5C-5Eh: Fan Thermal Zone Assignment and Spin-up Mode
Register
Address
Read/
Write
Register Name
Bit 7
(MSB)
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
(LSB)
Default
Value
Lock
5Ch
R/W
Fan 1 Configuration
ZON2
ZON1
ZON0
INV
RES
SPIN2
SPIN1
SPIN0
62
X
5Dh
R/W
Fan 2 Configuration
ZON2
ZON1
ZON0
INV
RES
SPIN2
SPIN1
SPIN0
62
X
5Eh
R/W
Fan 3 Configuration
ZON2
ZON1
ZON0
INV
RES
SPIN2
SPIN1
SPIN0
62
X
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.
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 hottest of zones 1, 2 or 3. To determine the “hottest 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 (30-32h) 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: Remote Diode 1 (processor), Zone 2: Internal Sensor, Zone 3 : Remote Diode 2
Fan Configuration
ZON[2:0]
Fan on Zone 1 auto
000
Fan on Zone 2 auto
001
Fan on Zone 3 auto
Fan always on full
010
011
Fan disabled
100
Fan controlled by hotter of Zones 2 or 3
101
Fan controlled by hottest of Zones 1, 2 or 3
110
Fan manually controlled (Test Mode)
111
Table 12 Fan Zone Setting
Bit [4] PWM Invert
Bit [4] inverts the PWM output. If set to 0, 100% duty cycle will yield an output that is always high. If set to 1, 100% duty
cycle will yield an output that is always low.
Bit [3] Reserved
Bit [2:0] Spin Up
Bits [2:0] specify the ‘spin up’ time for the fan. When a fan is being started from a stationary state, the PWM output is held at
100% duty cycle for the time specified in the table below before scaling to a lower speed.
Spin Up Time
SPIN[2:0]
0 ms
000
100 ms
250 ms
001
010
400 ms
011
700 ms
100
1000 ms
101
2000 ms
4000 ms
110
111
Table 13 Fan Spin-Up Register