Datasheet

35 second Smoothing Filter
OUTPUT
100
80
60
40
20
0
5 10 15 20
25
30 35 40
0
1.0
0.8
0.6
0.4
0.2
TIME (s)
INPUT
INPUT
OUTPUT
LM96000
www.ti.com SNAS234C –APRIL 2004–REVISED MARCH 2013
RAN [3:0] Range (°C)
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 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
62h R/W Min/Off, OFF3 OFF2 OFF1 RES ZN1E ZN1-2 ZN1-1 ZN1-0 00h ✓
Zone1
Spike
Smoothi
ng
63h R/W Zone2, ZN2E ZN2-2 ZN2-1 ZN2-0 ZN3E ZN3-2 ZN3-1 ZN3-0 00h ✓
Zone3
Spike
Smoothi
ng
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 LM96000. If these spikes are not ignored, the CPU fan (if connected to LM96000) 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.
Figure 10. What LM96000 Auto Fan Control Sees With and Without Spike Smoothing
Copyright © 2004–2013, Texas Instruments Incorporated Submit Documentation Feedback 25
Product Folder Links: LM96000