16 registers 62, 63h: min/off, spike smoothing, Functional description – Rainbow Electronics LM85 User Manual
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Functional Description
(Continued)
RAN [3:0]
Range (˚C)
0011
4
0100
5
0101
6.67
0110
8
0111
10
1000
13.33
1001
16
1010
20
1011
26.67
1100
32
1101
40
1110
53.33
1111
80
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.
4.16 Registers 62, 63h: Min/Off, Spike Smoothing
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?
62h
R/W
Min/Off, Zone1 Spike Smoothing OFF3
OFF2
OFF1
RES
ZN1E ZN1-2 ZN1-1 ZN1-0 00h
U
63h
R/W
Zone2, Zone3 Spike Smoothing
ZN2E
ZN2-2 ZN2-1 ZN2-0 ZN3E ZN3-2 ZN3-1 ZN3-0 00h
U
The Off/Min Bits [7:5] specify whether the duty cycle will be 0% or Minimum Fan Duty when the measured temperature falls below
the Temperature LIMIT register setting (see table below). OFF1 applies to fan 1, OFF2 applies to fan 2, and OFF3 applies to fan
3.
If the Remote1 or Remote2 pins are connected to a processor or chipset, instantaneous temperature spikes may be sampled by
the LM85. If these spikes are not ignored, the CPU fan (if connected to LM85) may turn on prematurely and produce unpleasant
noise. For this reason, any zone that is connected to a chipset or processor should have spike smoothing enabled.
When spike smoothing is enabled, the temperature reading registers will still reflect the current value of the temperature — not
the ‘smoothed out’ value.
ZN1E, ZN2E, and ZN3E enable temperature smoothing for zones 1, 2, and 3 respectively.
ZN1-2, ZN1-1, and ZN1-0 control smoothing time for Zone 1.
ZN2-2, ZN2-1, and ZN2-0 control smoothing time for Zone 2.
ZN3-2, ZN3-1, and ZN3-0 control smoothing time for Zone 3.
These registers become ready only when the Ready/Lock/Start/Override register Lock bit is set. Any further attempts to write to
these registers shall have no effect.
LM85
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