REG OFFSET
NAME
Fan Control
(hex)
58
DESCRIPTION
Fan Control Register
Bit[0] Fan 1 Clock Source Select
Default = 0x50
on VTR POR
(R/W)
This bit and the Fan 1 Clock Multiplier bit is used with The
Fan 1 Clock Select bit in the Fan 1 register (0x56) to
determine the fan speed FOUT
.
See “Different Modes for
Fan” table (Table 50) in “Fan Speed Control and
Monitoring” section.
Bit[1] Fan 2 Clock Source Select
This bit and the Fan 2 Clock Multiplier bit is used with The
Fan 2 Clock Select bit in the Fan 2 register (0x57) to
determine the fan speed FOUT
.
See “Different Modes for
Fan” table (Table 50) in “Fan Speed Control and
Monitoring” section.
Bit[2] Fan 1 Clock multiplier
0=No multiplier used
1=Double the fan speed selected by bit 0
this register and bit 7 of the FAN1
of
register
Bit[3] Fan 2 Clock multiplier
0=No multiplier used
1=Double the fan speed selected by bit 1
this register and bit 7 of the FAN2 register
of
Bit[5:4] The FAN1 count divisor. Clock scalar for adjusting
the tachometer count. Default = 2.
00: divisor = 1
01: divisor = 2
10: divisor = 4
11: divisor = 8
Bit[7:6] The FAN2 count divisor. Clock scalar for adjusting
the tachometer count. Default = 2.
00: divisor = 1
01: divisor = 2
10: divisor = 4
11: divisor = 8
Fan1 Tachometer
Register
59
Fan Tachometer Register 1
Bit]7:0] The 8-bit FAN1 tachometer count. The number of
counts of the internal clock per pulse of the fan. The count
value is computed from Equation 1. This value is the final
(maximum) count of the previous pulse (latched). The
value in this register may not be valid for up to 2 pulses
following a write to the preload register.
Fan Tachometer Register 2
Bit[7:0] The 8-bit FAN2 tachometer count. The number of
counts of the internal clock per pulse of the fan. The count
value is computed from Equation 1. This value is the final
(maximum) count of the previous pulse (latched). The
value in this register may not be valid for up to 2 pulses
following a write to the preload register.
Fan Preload Register 1
(R)
Default = 0x00
on VTR POR
Fan2 Tachometer
Register
5A
(R)
Default = 0x00
on VTR POR
Fan1 Preload
Register
5B
Bit[7:0] The FAN1 tachometer preload. This is the initial
value used in the computation of the FAN1 count. Writing
this register resets the tachometer count.
(R/W)
Default = 0x00
on VTR POR
Fan2 Preload
Register
5C
Fan Preload Register 2
Bit[7:0] The FAN2 tachometer preload. This is the initial
value used in the computation of the FAN2 count. Writing
this register resets the tachometer count.
(R/W)
Default = 0x00
on VTR POR
Page 140
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