ADM1033ARQZ-REEL7 ON Semiconductor, ADM1033ARQZ-REEL7 Datasheet - Page 24

• Manufacturer Part Number: ADM1033ARQZ-REEL7
• Description: IC THERM/FAN SPEED CTRLR 16-QSOP
• Manufacturer: ON Semiconductor

Specifications of ADM1033ARQZ-REEL7

• Function: Fan Control, Temp Monitor
• Topology: ADC, Comparator, Multiplexer, Register Bank
• Sensor Type: External & Internal
• Sensing Temperature: -40°C ~ 125°C, External Sensor
• Output Type: SMBus™
• Output Alarm: Yes
• Output Fan: Yes
• Voltage - Supply: 3 V ~ 3.6 V
• Operating Temperature: -40°C ~ 125°C
• Mounting Type: Surface Mount
• Package / Case: 16-QSOP
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

Speeds option is chosen. At temperature T1, the fan runs at
Fan Speed 1. As the temperature increases, the fan speed
increases until it reaches Fan Speed 2 at T2.
point in the look−up table, the fan speed remains at the
highest speed until the temperature drops below the T7
temperature value. When the look−up table is split in two,
the same applies.
succession, the fan speed moves to the next highest
programmed temperature as the temperature increases.
Similarly, when the temperature decreases, it ignores
programmed higher temperatures and jumps to the next lower
temperature. Therefore, the temperature−to−fan speed profile
for increasing and decreasing temperature can be different.
option to use between two and eight points for the fan. If the
user just wants to program a transfer curve (and knows the
starting
temperature, and maximum speed), then all the user needs
to program are four parameters: T1, T2, FS1, and FS2. The
remainder of the look−up temperature thresholds should
remain at their default values of +191°C. If required, the FS3
Figure 41. Programming the Look−up Table in Linear
TACH COUNT 8
TACH COUNT 7
TACH COUNT 6
TACH COUNT 5
TACH COUNT 4
TACH COUNT 3
TACH COUNT 2
TACH COUNT 1
TACH COUNT 2 TO 8
Figure 41 shows the transfer curve if the Linear Fan
Once the temperature exceeds the highest temperature
If the temperatures in T1 to T8 are not programmed in
When programming the look−up table, the user has the
FAN SPEED
TACH COUNT 1
Figure 42. Programming Two Points on the
FAN SPEED
temperature,
T1
Fan Speeds Mode
Look−up Table
T2
T1
TEMPERATURE
T3
minimum
T4
T5
T2
speed,
T6
T7
TEMPERATURE
T (3 TO 8) = °C
T8
maximum
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should be programmed with the same value as FS2 to give
the flat curve, if required. Or, the fan speeds can be left at the
default value of 0. However, it is normal to program a
THERM limit as well. Once this temperature is exceeded
and the boost bit is set, the fan run to full speed. This
overrides the look−up table.
Setting Up the Look−up Table in Linear Mode
the TACH count decreases linearly (and therefore the fan
speed increases) with temperature.
speed increases with temperature to FS
T
When Discrete/Linear Speed (Bit 2) is set to 0, the fan runs
at a new speed once the temperature threshold is exceeded.
Setting Which Temperature Channel Controls a Fan
controlled by either the local temperature, or by the Remote 1
temperatures.
Look−up Table Hysteresis
look−up table. The advantage of this is apparent if the
temperature is cycling around one of the threshold
temperatures and causing the fan speed to switch between
the two speeds, particularly when the look−up table is
configured in discrete mode. It would not be as important in
the linear mode.
Table 26. Look−up Table Register Address
Table 27. Drive BHVR Bits
X+1
x
1
2
3
4
5
6
7
8
When Discrete/Linear Speed (Bit 2) is set to 1 (default),
Example: At temperature T
Alternatively, the fan can be run at discrete fan speeds.
Fan Behavior Register (Address 0x07)
Bits <1:0> = DRIVE1 Behavior (D1B)
The ADM1033 can be configured so that Fan 1 can be
The user can program a hysteresis to be applied to the
Bits
00
01
10
11
.
Temperature, x
Local Temperature Controls Fan
Remote 1 Temperature Controls Fan
Reserved
Fan Runs at Full Speed
0x22
0x23
0x24
0x25
0x26
0x27
0x28
0x29
DRIVE x BHVR
X
, the fans run at FS
FSx, LSB
0x2A
0x2C
0x2E
0x30
0x32
0x34
0x36
0x38
X+1
at temperature
FSx, MSB
0x2B
0x2D
0x2F
0x31
0x33
0x35
0x37
0x39
X
and fan