ADM1027ARQZ-REEL ON Semiconductor, ADM1027ARQZ-REEL Datasheet - Page 29

• Manufacturer Part Number: ADM1027ARQZ-REEL
• Description: IC REMOTE THERMAL CTRLR 24QSOP
• Manufacturer: ON Semiconductor
• Series: dBCool®r

Specifications of ADM1027ARQZ-REEL

• Function: Fan Control, Temp Monitor
• Topology: ADC, Comparator, Fan Speed Counter, Multiplexer, Register Bank
• Sensor Type: External & Internal
• Sensing Temperature: 0°C ~ 105°C, External Sensor
• Output Type: SMBus™
• Output Alarm: No
• Output Fan: Yes
• Voltage - Supply: 3 V ~ 5.5 V
• Operating Temperature: 0°C ~ 105°C
• Mounting Type: Surface Mount
• Package / Case: 24-QSOP
• Full Temp Accuracy: +/- 1 C
• Digital Output - Bus Interface: Serial (2-Wire, 3-Wire)
• Maximum Operating Temperature: + 105 C
• Minimum Operating Temperature: 0 C
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

Step 2
Configuring the Mux: Which Temperature Controls Which Fan?
Having decided on the system hardware configuration, the fans
can be assigned to particular temperature channels. Not only
can fans be assigned to individual channels, but how a fan
behaves is configurable. For example, fans can run under
automatic fan control, manually (software control), or can run
at the fastest speed calculated by multiple temperature channels.
The MUX is the bridge between temperature measurement
channels and the three PWM outputs.
Bits <7:5> (BHVR bits) of Registers 0x5C, 0x5D, and 0x5E
(PWM configuration registers) control the behavior of the fans
connected to the PWM1, PWM2, and PWM3 outputs. The
values selected for these bits determine how the MUX connects
a temperature measurement channel to a PWM output.
REV. A
AMBIENT TEMP
REMOTE 1 =
REMOTE 2 =
VRM TEMP
CPU TEMP
LOCAL =
T
T
T
MIN
MIN
MIN
THERMAL CALIBRATION
THERMAL CALIBRATION
THERMAL CALIBRATION
Figure 28. Assigning Temperature Channels to Fan Channels
T
T
T
RANGE
RANGE
RANGE
100%
100%
0%
100%
0%
0%
Rev. 3 | Page 29 of 56 | www.onsemi.com
MUX
MUX
–29–
PWM
PWM
PWM
Automatic Fan Control Mux Options
<7:5> (BHVR) REGISTERS 0x5C, 0x5D, 0x5E
000 = Remote 1 temp controls PWMx
001 = Local temp controls PWMx
010 = Remote 2 temp controls PWMx
101 = Fastest speed calculated by local and remote 2 temp
controls PWMx
110 = Fastest speed calculated by all three temperature channels
controls PWMx
The fastest speed calculated options refer to the ability to con-
trol one PWM output based on multiple temperature channels.
While the thermal characteristics of the three temperature zones
can be set up differently, they can drive a single fan. An example
would be if the fan turns on when Remote 1 temp exceeds 60rC
or local temp exceeds 45rC.
Other Mux Options
<7:5> (BHVR) REGISTERS
011 = PWMx runs full-speed (default).
100 = PWMx disabled.
111 = Manual Mode. PWMx is run under software control. In
this mode, PWM duty cycle registers (Reg. 0x30 to 0x32) are
writable and control the PWM outputs.
MIN
MIN
MIN
TACHOMETERS 3
MEASUREMENT
TACHOMETER 1
TACHOMETER 2
ENHANCEMENT
MEASUREMENT
ENHANCEMENT
MEASUREMENT
ENHANCEMENT
(ACOUSTIC
(ACOUSTIC
(ACOUSTIC
CONTROL
CONTROL
CONTROL
AND 4
RAMP
RAMP
RAMP
GENERATOR
GENERATOR
GENERATOR
CONFIG
CONFIG
CONFIG
PWM
PWM
PWM
PWM
PWM
PWM
0x5C, 0x5D, 0x5E
PWM1
TACH1
PWM2
TACH2
PWM3
TACH3
ADM1027
CPU
FANSINK
FRONT
CHASSIS
REAR
CHASSIS