Datasheet

Zone n
Min PWM
or
OFF
PWM duty cycle
linearly increasing as
temperature increases
PWM duty cycle linearly
deacreasing as
temperature decreases
PWM duty cycle linearly
decreasing as
temperature decreases
All Zones
100% PWM
Zone n
100% PWM
Zone n PWM set to
Min FanSpeed (64h-
66h)
Zone n PWM set to
Min FanSpeed (64h-
66h)
Fan Temp Limit - Hysteresis
Hysteresis is 0
o
C-15
o
C (6Dh-6Eh)
Fan Temp Limit
(67h-69h)
Fan Temp Limit +
Range
Range is 2
o
C to 80
o
C (5Fh-61h)
Absolute Limit
(6Ah-6Ch)
Temperature
Cold
Hot
LM96000
www.ti.com SNAS234C –APRIL 2004–REVISED MARCH 2013
Table 5. Fan Spin-Up Register
SPIN[2:0] Spin Up Time
000 0 sec
001 100 ms
010 250 ms
011 400 ms
100 700 ms
101 1000 ms
110 2000 ms
111 4000 ms
4.15 Registers 5F-61h: Auto Fan Speed Range, PWM Frequency
Register Read/ Register Bit 7 Bit 0 Default
Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Lock?
Address Write Name (MSB) (LSB) Value
5Fh R/W Zone1 RAN3 RAN2 RAN1 RAN0 HLFRQ FRQ2 FRQ1 FRQ0 C4h ✓
Range/F
an1
Frequen
cy
60h R/W Zone2 RAN3 RAN2 RAN1 RAN0 HLFRQ FRQ2 FRQ1 FRQ0 C4h ✓
Range/F
an2
Frequen
cy
61h R/W Zone3 RAN3 RAN2 RAN1 RAN0 HLFRQ FRQ2 FRQ1 FRQ0 C4h ✓
Range/F
an3
Frequen
cy
In Auto Fan Mode, when the temperature for a zone is above the Temperature Limit (Registers 67-69h) and
below its Absolute Temperature Limit (Registers 6A-6Ch), the speed of a fan assigned to that zone is determined
as follows.
When the temperature reaches the Fan Temp Limit for a zone, the PWM output assigned to that zone will be
Fan PWM Minimum. Between Fan Temp Limit and (Fan Temp Limit + Range), the PWM duty cycle will increase
linearly according to the temperature as shown in Figure 9 below. The PWM duty cycle will be 100% at (Fan
Temp Limit + Range).
Figure 9. Fan Activity above Fan Temp Limit
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