ADM1030ARQ-REEL7 ON Semiconductor, ADM1030ARQ-REEL7 Datasheet - Page 14

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ADM1030ARQ-REEL7

Manufacturer Part Number
ADM1030ARQ-REEL7
Description
IC SNSR TEMP/FAN PWM CTRL 16QSOP
Manufacturer
ON Semiconductor
Datasheet

Specifications of ADM1030ARQ-REEL7

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
ADM1030
It should be noted however, that changing the minimum PWM
duty cycle affects the control loop behavior.
Slope 1 of Figure 10 shows T
chosen is 40 C. In this case, the fan’s PWM duty cycle will vary
over the range 33% to 100%. The fan will run full-speed at
40 C. If the minimum PWM duty cycle at which the fan runs at
T
Case 2, where the minimum PWM duty cycle is reprogrammed
from 33% (default) to 53%.
The fan will actually reach full-speed at a much lower tempera-
ture, 28 C. Case 3 shows that when the minimum PWM duty
cycle was increased to 73%, the temperature at which the fan
ran full-speed was 16 C. So the effect of increasing the mini-
mum PWM duty cycle, with a fixed T
that the fan will actually reach full-speed (T
temperature than T
In Automatic Fan Speed Control Mode, the register that
holds the minimum PWM duty cycle at T
Config Register (Register 0x22). Table VII shows the relation-
ship between the decimal values written to the Fan Speed Config
Register and PWM duty cycle obtained.
Figure 10. Effect of Changing Minimum Duty Cycle on
Control Loop with Fixed T
MIN
is changed, its effect can be seen on Slopes 2 and 3. Take
Decimal Value
00
01
02
03
04
05
06
07
08
09
10 (0x0A)
11 (0x0B)
12 (0x0C)
13 (0x0D)
14 (0x0E)
15 (0x0F)
Table VII. Programming PWM Duty Cycle
100
93
87
80
73
66
60
53
47
40
33
T
MIN
MIN
0
+ T
RANGE
MIN
16
MIN
. How can T
and T
TEMPERATURE –
set to 0 C and the T
PWM Duty Cycle
0%
7%
14%
20%
27%
33% (Default)
40%
47%
53%
60%
67%
73%
80%
87%
93%
100%
MIN
28
RANGE
MIN
and fixed T
MAX
MAX
, is the Fan Speed
Values
) at a lower
40
C
be calculated?
Rev. 2 | Page 14 of 29 | www.onsemi.com
RANGE
RANGE
, is
60
–14–
The temperature at which the fan will run full-speed (100%
duty cycle) is given by:
where,
T
T
Max DC = Maximum Duty Cycle (100%) = 15 decimal.
Min DC = Duty Cycle at T
T
Example 1
T
Min DC = 53% = 8 decimal (Table VII)
Calculate T
T
T
T
T
Example 2
T
Min DC = 73% = 11 Decimal (Table VII)
Calculate T
T
T
T
T
Example 3
T
Min DC = 33% = 5 Decimal (Table VII)
Calculate T
T
T
T
T
In this case, since the Minimum Duty Cycle is the default 33%,
the equation for T
T
T
T
T
MAX
MIN
RANGE
MIN
MAX
MAX
MAX
MIN
MAX
MAX
MAX
MIN
MAX
MAX
MAX
MAX
MAX
MAX
MAX
MAX
MAX
MAX
T
MAX
= Temperature at which fan runs full-speed.
= Temperature at which fan will turn on.
= PWM Duty Cycle versus Temperature Slope.
= 0 C, T
= T
= 0 + ((100% DC – 53% DC) ¥ 40/10)
= 0 + ((15 – 8) ¥ 4) = 28
= 28
= 0 C, T
= T
= 0 + ((100% DC – 73% DC) ¥ 40/10)
= 0 + ((15 – 11) ¥ 4) = 16
= 16
= 0 C, T
= T
= 0 + ((100% DC – 33% DC) ¥ 40/10)
= 0 + ((15 – 5) ¥ 4) = 40
= 40
= T
= T
= T
= T
MAX
MAX
MAX
= T
Config Register (default = 33% = 5 decimal).
MIN
MIN
MIN
MIN
MIN
MIN
MIN
C (As seen on Slope 1 of Figure 10)
.
.
.
MIN
C (As seen on Slope 2 of Figure 10)
C (As seen on Slope 3 of Figure 10)
MAX
+ T
+ ((Max DC – Min DC) ¥ T
+ ((Max DC – Min DC) ¥ T
+ ((Max DC – Min DC) ¥ T
+ ((Max DC – Min DC) ¥ T
+ ((15 – 5) ¥ T
+ (10 ¥ T
+ ((Max DC – Min DC) ¥ T
RANGE
RANGE
RANGE
reduces to:
RANGE
= 40 C
= 40 C
= 40 C
RANGE
MIN
, programmed into Fan Speed
RANGE
/10)
/10)
RANGE
RANGE
RANGE
RANGE
RANGE
/10)
/10)
/10)
/10)
/10)
REV. A

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