ADM1030ARQ-REEL ON Semiconductor, ADM1030ARQ-REEL Datasheet - Page 17

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ADM1030ARQ-REEL

Manufacturer Part Number
ADM1030ARQ-REEL
Description
IC SNSR TEMP/FAN PWM CTRL 16QSOP
Manufacturer
ON Semiconductor
Datasheet

Specifications of ADM1030ARQ-REEL

Rohs Status
RoHS non-compliant
Function
Fan Control, Temp Monitor
Topology
ADC, Comparator, Multiplexer, Register Bank
Sensor Type
External & Internal
Sensing Temperature
0°C ~ 100°C, External Sensor
Output Type
SMBus™
Output Alarm
Yes
Output Fan
Yes
Voltage - Supply
3 V ~ 5.5 V
Operating Temperature
0°C ~ 100°C
Mounting Type
Surface Mount
Package / Case
16-QSOP

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Manufacturer
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Price
Part Number:
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Part Number:
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Manufacturer:
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Quantity:
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Figure 14 shows how changing the ramp rate from 8 to 4 affects
the control loop. The overall response of the fan is slower. Since
the ramp rate is reduced, it takes longer for the fan to achieve full
running speed. In this case, it took approximately 22 seconds for
the fan to reach full speed.
Figure 15 shows the PWM output response for a ramp rate of 2.
In this instance the fan took about 54 seconds to reach full
running speed.
REV. A
140
120
100
140
120
100
120
110
80
60
40
20
80
60
40
20
80
60
40
20
0
0
Figure 13. Filtered Mode with Ramp Rate = 8
Figure 14. Filtered Mode with Ramp Rate = 4
Figure 15. Filtered Mode with Ramp Rate = 2
0
0
0
0
R
R
R
TEMP
TEMP
TEMP
PWM DUTY CYCLE
PWM DUTY CYCLE
TIME – s
TIME – s
TIME – s
PWM DUTY CYCLE
54
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22
12
140
120
100
80
60
40
20
0
120
100
80
60
40
20
0
120
100
80
60
40
20
0
–17–
Finally, Figure 16 shows how the control loop reacts to tem-
perature with the slowest ramp rate. The ramp rate is set to 1,
while all other control parameters remain the same. With the
slowest ramp rate selected it took 112 seconds for the fan to
reach full speed.
As can be seen from Figures 13 through 16, the rate at which
the fan will react to temperature change is dependent on the
ramp rate selected in the Fan Filter Register. The higher the
ramp rate, the faster the fan will reach the newly calculated
fan speed.
Figure 17 shows the behavior of the PWM output as tempera-
ture varies. As the temperature is rising, the fan speed will ramp
up. Small drops in temperature will not affect the ramp-up func-
tion since the newly calculated fan speed will still be higher than
the previous PWM value. The Filtered Mode allows the PWM
output to be made less sensitive to temperature variations. This
will be dependent on the ramp rate selected and the ADC sample
rate programmed into the Fan Filter Register.
Figure 17. How Fan Reacts to Temperature Variation in
Filtered Mode
120
110
80
60
40
20
90
80
70
60
50
40
30
20
10
0
0
Figure 16. Filtered Mode with Ramp Rate = 1
0
R
TEMP
TIME – s
TIME – s
R
TEMP
PWM DUTY CYCLE
PWM DUTY CYCLE
ADM1030
112
140
120
100
80
60
40
20
0
90
80
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50
40
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20
10
0

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