Datasheet

LM96000
SNAS234C –APRIL 2004–REVISED MARCH 2013 www.ti.com
Setting the Ready/Lock/Start/Override register Lock bit has no effect these registers.
4.14 Registers 5C-5Eh: Fan Configuration
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
5Ch R/W Fan1 ZON2 ZON1 ZON0 INV RES SPIN2 SPIN1 SPIN0 62h ✓
Configur
ation
5Dh R/W Fan2 ZON2 ZON1 ZON0 INV RES SPIN2 SPIN1 SPIN0 62h ✓
Configur
ation
5Eh R/W Fan3 ZON2 ZON1 ZON0 INV RES SPIN2 SPIN1 SPIN0 62h ✓
Configur
ation
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 (101 or 110), the fan will be controlled by the hottest of zones 2 and 3, or
of zones 1, 2, and 3. To determine the ‘Hottest’ zone the PWM level for each zone is calculated then the the
highest PWM value is selected. When in manual control mode, the Current PWM duty registers (30h-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: External Diode 1 (processor)
Zone 2: Internal Sensor
Zone 3: External Diode 2
Table 4. Fan Zone Setting
ZON[2:0] Fan Configuration
000 Fan on zone 1 auto
001 Fan on zone 2 auto
010 Fan on zone 3 auto
011 Fan always on full
100 Fan disabled
101 Fan controlled by hottest of zones 2, 3
110 Fan controlled by hottest of zones 1, 2, 3
111 Fan manually controlled (Test Mode)
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
Bits [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 5 below before scaling to a lower speed.
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