ADM1033ARQZ-REEL7 ON Semiconductor, ADM1033ARQZ-REEL7 Datasheet - Page 23

• 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

Fan Response Register
the current fan speed, comparing it with the programmed fan
speed, and then updating the drive signal applied to the fan.
The rate at which the ADM1033 looks at and updates the
drive signal is determined by the fan response register.
Different fans have different inertias and respond to a
changing drive signal more or less quickly than others. The
fan response register allows the user to tailor the ADM1033
to a particular fan to prevent situations like overshoot.
can make to the drive signal per second. Table 23 lists the
available options.
Look−up Table: Modes of Operation
operation used to determine the behavior of the system:
•
•
Manual Mode
The software can program the required fan speed value or
the target fan speed to the ADM1033, which then outputs
that fan speed.
Programming Target Fan Speed
TACH count for N poles or a TACH count for one full
rotation of the fan, assuming the number of poles is
programmed correctly in the Configuration 3 Register
(Address 0x03).
Table 23. Fan Response Codes
Table 24. Conversion Rates
The ADM1033 fan speed controller operates by reading
The user programs the number of updates the ADM1033
The ADM1033 look−up table has two different modes of
In manual mode, the ADM1033 is under software control.
In this mode, the user programs the target fan speed as a
Use the following steps to program the target fan speed:
Manual mode
Look−up table
<6:4>
<2:0>
1. Place the ADM1033 into manual mode. Set Bit 7
Bit #
Code
7
3
000
001
010
100
101
011
110
111
(Table/SW) of Configuration Register 1
(Address 0x01) = 0.
Reserved
Reserved
Reserved
Fan 1 Response
1.25 updates/second
2.5 updates/second = default
5 updates/second
10 updates/second
20 updates/second
40 updates/second
80 updates/second
160 updates/second
Update Rate
Function
http://onsemi.com
23
Example 1: If the desired speed for Fan 1 is 5000 rpm,
program the following value to the TACH count registers:
Example 2: If the desired speed for Fan 2 is 3500 rpm,
program the following value to the TACH pulse period
registers:
Look−up Table
temperature−to−fan speed profile. There are 24 registers in
the look−up table; 8 for temperature and 16 for target fan
speed (each target fan speed is two registers). In total, there
are eight available points.
table. The ADM1033 can be programmed to make the fan
speed run at discrete speeds and jump to the new fan speed
once the temperature threshold is crossed. Or, it can linearly
ramp the TACH count between the two temperature
thresholds.
looks like if all eight points are used on the one curve.
programmed to run at discrete speeds. The ADM1033 spins
the fan at its new speed once a threshold is crossed.
Table 25. Registers to be Programmed
TACH COUNT 8
TACH COUNT 7
TACH COUNT 6
TACH COUNT 5
TACH COUNT 4
TACH COUNT 3
TACH COUNT 2
TACH COUNT 1
Fan 1
Fan 1
TACH Count = (f x 60)/R
The ADM1033 allows the user to program a
There are two options when programming the look−up
Figure 40 and Figure 41 show what the look−up table
Figure 40 shows the transfer curve when the fan is
Fan
where:
TACH Count = (f x 60)/5000
TACH Count = 983d = 0x03D7
TACH Count = (f x 60)/3500
TACH Count = 1404d = 0x057C
2. Program the target TACH count (fan speed) using
Figure 40. Programming the Look−up Table in
FAN SPEED
the following equation:
f = clock frequency = 81.92 kHz
R = required RPM value
Look−up Table FS1, MSB
Look−up Table FS1, LSB
Discreet Fan Speeds Mode
Description
T1
T2
T3
T4
T5
Address
T6
0x2A
0x2B
T7
TEMPERATURE
T8
Value
0xD7
0x03