ADM1030ARQ-REEL ON Semiconductor, ADM1030ARQ-REEL Datasheet - Page 13

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

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

Once the Automatic Fan Speed Control Loop parameters have
been chosen, the ADM1030 device may be programmed. The
ADM1030 is placed into Automatic Fan Speed Control Mode
by setting Bit 7 of Configuration Register 1 (Register 0x00).
The device powers up into Automatic Fan Speed Control
Mode by default. The control mode offers further flexibility
in that the user can decide which temperature channel/chan-
nels control the fan.
Bits 6, 5
00
11
When Bits 5 and 6 of Config Register 1 are both set to 1, it
offers increased flexibility. The local and remote temperature
channels can have independently programmed control loops
with different control parameters. Whichever control loop
calculates the fastest fan speed based on the temperature being
measured, drives the fan.
Figure 9 shows how the fan’s PWM duty cycle is determined by
two independent control loops. This is the type of Auto Mode
Fan Behavior seen when Bits 5 and 6 of Config Register 1 are
set to 11. Figure 9a shows the control loop for the Local Tem-
perature channel. Its T
and its T
thus be 60 C. Figure 9b shows the control loop for the Remote
Temperature channel. Its T
T
value will be 80 C.
Consider if both temperature channels measure 40 C. Both
control loops will calculate a PWM duty cycle of 66%. There-
fore, the fan will be driven at 66% duty cycle.
If both temperature channels measure 20 C, the local channel
will calculate 33% PWM duty cycle, while the remote channel
will calculate 50% PWM duty cycle. Thus, the fan will be
driven at 50% PWM duty cycle. Consider the local temperature
measuring 60 C while the remote temperature is measuring
70 C. The PWM duty cycle calculated by the local temperature
control loop will be 100% (since the temperature = T
PWM duty cycle calculated by the remote temperature control
loop at 70 C will be approximately 90%. So the fan will run
full-speed (100% duty cycle). Remember, that the fan speed will
be based on the fastest speed calculated, and is not necessarily
based on the highest temperature measured. Depending on the
control loop parameters programmed, a lower temperature on
REV. A
RANGE
Bits 2:0
000
001
010
011
100
101
110
111
= 80 C. Therefore, the Remote Temperature’s T
RANGE
Control Operation (Config Register 1)
Remote Temperature Controls the Fan.
Maximum Speed Calculated by Local and Remote
Temperature Channels Control the Fan.
Table VI. Auto Mode Fan Behavior
value is 40 C. The local temperature’s T
Table V. Fan Spin-Up Times
Spin-Up Time
(Fan Characteristics Register 1)
200 ms
400 ms
600 ms
800 ms
1 sec
2 secs (Default)
4 secs
8 secs
MIN
MIN
value has been programmed to 20 C,
value has been set to 0 C, while its
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MAX
MAX
). The
MAX
will
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one channel, may actually calculate a faster speed, than a higher
temperature on the other channel.
PROGRAMMING THE AUTOMATIC FAN SPEED
CONTROL LOOP
1. Program a value for T
2. Program a value for the slope T
3. T
4. Program a value for Fan Spin-up Time.
5. Program the desired Automatic Fan Speed Control Mode
6. Select Automatic Fan Speed Control Mode by setting Bit 7
OTHER CONTROL LOOP PARAMETERS
Having programmed all the above loop parameters, are there
any other parameters to worry about?
T
on and ran at minimum speed. This minimum speed is 33% duty
cycle by default. If the minimum PWM duty cycle is programmed
to 33%, the fan control loops will operate as previously described.
MIN
100
Figure 9. Max Speed Calculated by Local and Remote
Temperature Control Loops Drives Fan
93
87
80
73
66
60
53
47
40
33
Behavior, i.e., which temperature channel controls the fan.
of Configuration Register 1.
T
100
MIN
MAX
0
93
87
80
73
66
60
53
47
40
33
was defined as being the temperature at which the fan switched
0
= T
MIN
20
+ T
T
20
MIN
RANGE
REMOTE TEMPERATURE –
LOCAL TEMPERATURE –
MIN
.
.
40
b.
a.
40
RANGE
.
�
C
�
C
60
T
ADM1030
MAX
70
T
= T
MAX
MIN
= T
+ T
MIN
80
RANGE
+ T
RANGE