ADT7473 Analog Devices, Inc., ADT7473 Datasheet - Page 56

• Manufacturer Part Number: ADT7473
• Description: Dbcool Remote Thermal Monitor And Fan Controller
• Manufacturer: Analog Devices, Inc.

ADT7473
Figure 74 shows remote temper
c
which corresponds to the fastest ra
temperat e read g is available
it takes approximately 0.76 seconds to go from 33% duty cycle to
100%
increa
Figur
affects the contro
slower
fan t
appr
ycle for enhanced acoustics m
120
100
140
120
100
80
60
40
20
80
60
40
20
o achiev ull
oxima
0
0
e 75 s
duty
ses ve rapidl
0
0
. Be
Fig
Fig
ur
cause
ure 74. nhanced Acoustic
cyc
tely 4
hows ow changing t
ure 75 nhanced Acoust
ry
R
R
e f
TEMP
le (f
TEMP
th
.4
. E
in
E
h
(
l loop. The o
ull speed). Ev
°C)
( ° C)
e ramp ra
running speed.
seconds for the fan to
y, the fan ra
PWM CYCLE (
TIME (s)
TIME (s)
te is redu d, it ta
ode. The ramp rate is set to 48,
verall response of the fan is
en tho h the te
ature plotted against PWM duty
mps up o full sp
every
ics M
he ramp rate f m 48 t
s Mo
mp rate. Assume that a new
PWM DUTY CYCLE (%)
In this case, takes
ode wi
ug
115 m
de
%)
ce
t
with Ra
reach full speed
th Ra
s. W
mp
kes lo
mp
mp Rate 8
ro
eed
it
ith th
4.4
Rate = 4
eratur
gradually.
nger for the
ese
0.76
=
e
o 8
settings
140
120
100
80
60
40
20
0
120
100
80
60
40
20
0
8
.
Rev. A | Page 56 of 76
,
Figure 76 shows the PWM output response for a ramp rate of 2.
In this instance, the fan took about 17.6 seconds to reach full
running speed.
Fi
wi
ot r contro arameters remain he same. W
ra p rate se
sp d.
As Figure 74 to Figure 77 show, the rate at which the fan reacts
to mperatu change
th
faster the fan reaches the newly calculated fan speed.
gur
he
m
e enha
ee
th
te
12
10
140
120
10
80
60
40
20
80
60
40
20
0
0
0
0
0
the slow t ramp
e 77 sh
0
0
Figur
Figure 77. Enhanced Acoustics Mode with Ramp Rate = 1
nce
R
TE
MP
d aco
ows
lec
l p
e 76
R
re
es
TEMP
(°C)
ted, it takes 35 se nds for the
. Enhanced Acousti
how t
ustic
(°C)
he c
s regist
rat
is
e. The
dependent on the ra
ontro
TIME (s)
TIME (s)
ers
P
PWM DUTY CYCLE
l lo
WM
ram
co
cs M
. The
t
op reacts to temperature
DUTY CYCLE
ode with Ram
p rate is s
higher t
17.6
et to 1
mp ra
ith th
he ram
(%)
fan t
(%)
p Ra
35
o reach full
e slo est
te = 2
te se cted in
, wh e all
p r
140
120
100
80
60
40
20
0
120
100
80
60
40
20
0
w
ate, t
le
il
he