ADT7475ARQZ ON Semiconductor, ADT7475ARQZ Datasheet - Page 31

• Manufacturer Part Number: ADT7475ARQZ
• Description: IC REMOTE THERMAL CTRLR 16-QSOP
• Manufacturer: ON Semiconductor
• Series: dBCool®r

Specifications of ADT7475ARQZ

• Function: Fan Control, Temp Monitor
• Topology: ADC, Comparator, Fan Speed Counter, Multiplexer, Register Bank
• Sensor Type: External & Internal
• Sensing Temperature: -40°C ~ 125°C, External Sensor
• Output Type: SMBus™
• Output Alarm: No
• Output Fan: Yes
• Voltage - Supply: 3 V ~ 3.6 V
• Operating Temperature: -40°C ~ 125°C
• Mounting Type: Surface Mount
• Package / Case: 16-QSOP
• Full Temp Accuracy: +/- 0.5 C
• Digital Output - Bus Interface: Serial (3-Wire, 4-Wire)
• Maximum Operating Temperature: + 125 C
• Minimum Operating Temperature: - 40 C
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

Step 2: Configuring the Mux
the fans can be assigned to particular temperature channels.
Not only can fans be assigned to individual channels but the
behavior of the fans is also configurable. For example, fans
can be run under automatic fan control, manually under
software control, or at the fastest speed calculated by
multiple temperature channels. The mux is the bridge
between temperature measurement channels and the three
PWM outputs.
Register 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.
Automatic Fan Control Mux Options
Bits [7:5] (BHVR), Register 0x5C, Register 0x5D, and
Register 0x5E.
After the system hardware configuration is determined,
Bits [7:5] (BHVR) of Register 0x5C, Register 0x5D, and
000 = Remote 1 temperature controls PWMx
001 = local temperature controls PWMx
AMBIENT TEMP
REMOTE 1 =
REMOTE 2 =
VRM TEMP
CPU TEMP
LOCAL =
THERMAL CALIBRATION
THERMAL CALIBRATION
THERMAL CALIBRATION
T
T
T
MIN
MIN
MIN
Figure 46. Assigning Temperature Channels to Fan Channels
T
T
T
RANGE
RANGE
RANGE
100%
100%
100%
0%
0%
0%
MUX
http://onsemi.com
MUX
31
PWM
PWM
PWM
MIN
MIN
MIN
one PWM output based on multiple temperature channels.
The thermal characteristics of the three temperature zones
can be set to drive a single fan. An example is the fan turning
on when Remote 1 temperature exceeds 60°C or when the
local temperature exceeds 45°C.
Other Mux Options
Bits [7:5] (BHVR), Register 0x5C, Register 0x5D, and
Register 0x5E.
CONFIG
CONFIG
CONFIG
The fastest speed calculated options pertain to controlling
TACHOMETER 1
MEASUREMENT
TACHOMETER 2
MEASUREMENT
TACHOMETER 3
MEASUREMENT
PWM
PWM
PWM
010 = Remote 2 temperature controls PWMx
101 = Fastest speed calculated by local and Remote 2
110 = Fastest speed calculated by all three
011 = PWMx runs full speed.
100 = PWMx disabled (default).
111 = manual mode. PWMx is running under
GENERATOR
GENERATOR
GENERATOR
AND 4
PWM
PWM
PWM
temperature controls PWMx
temperature channel controls PWMx
software control. In this mode, PWM current
duty cycle registers (0x30 to 0x32) are writable
and control the PWM outputs.
ENHANCEMENT)
ENHANCEMENT)
ENHANCEMENT)
(ACOUSTIC
(ACOUSTIC
(ACOUSTIC
CONTROL
CONTROL
CONTROL
RAMP
RAMP
RAMP
PWM1
TACH1
PWM2
TACH2
PWM3
TACH3
FRONT CHASSIS
REAR CHASSIS
CPU FAN SINK