ADT7475ARQZ ON Semiconductor, ADT7475ARQZ Datasheet - Page 33

• 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

Enhanced Acoustics Register 1 (0x62)
Bit 7 (MIN3) = 0, PWM3 is off (0% PWM duty cycle) when
temperature is below T
Bit 7 (MIN3) = 1, PWM3 runs at PWM3 minimum duty
cycle below T
Bit 6 (MIN2) = 0, PWM2 is off (0% PWM duty cycle) when
temperature is below T
Step 4: PWM
fan in the system runs. It is also the start speed for each fan
under automatic fan control once the temperature rises
above TMIN. For maximum system acoustic benefit,
PWM
fan used, the PWM
duty cycle range. This value can be found through fan
validation.
PWM
MIN
MIN
should be as low as possible. Depending on the
AMBIENT TEMP
is the minimum PWM duty cycle at which each
REMOTE 2 =
REMOTE 1 =
MIN
MIN
VRM TEMP
CPU TEMP
LOCAL =
100%
for Each PWM (Fan) Output
− T
0%
MIN
HYST
MIN
MIN
setting is usually in the 20% to 33%
THERMAL CALIBRATION
THERMAL CALIBRATION
THERMAL CALIBRATION
.
T
− T
− T
T
T
T
MIN
MIN
MIN
MIN
HYST
HYST
.
.
Figure 48. Understanding the T
T
T
T
RANGE
RANGE
RANGE
100%
100%
100%
0%
0%
0%
MUX
http://onsemi.com
33
PWM
PWM
PWM
MIN
MIN
MIN
Bit 6 (MIN2) = 1, PWM2 runs at PWM2 minimum duty
cycle below T
Bit 5 (MIN1) = 0, PWM1 is off (0% PWM duty cycle) when
temperature is below T
Bit 5 (MIN1) = 1, PWM1 runs at PWM1 minimum duty
cycle below T
CONFIG
CONFIG
CONFIG
TACHOMETER 1
MEASUREMENT
TACHOMETER 2
MEASUREMENT
TACHOMETER 3
MEASUREMENT
PWM
PWM
PWM
GENERATOR
GENERATOR
GENERATOR
MIN
Figure 49. PWM
AND 4
PWM
PWM
PWM
PWM
Parameter
100%
MIN
0%
MIN
MIN
− T
− T
ENHANCEMENT)
ENHANCEMENT)
ENHANCEMENT)
PWM Duty Cycle
(ACOUSTIC
(ACOUSTIC
(ACOUSTIC
T
HYST
HYST
CONTROL
CONTROL
CONTROL
MIN
MIN
RAMP
RAMP
RAMP
MIN
.
.
− T
Determines Minimum
HYST
TEMPERATURE
.
PWM1
TACH1
PWM2
TACH2
PWM3
TACH3
FRONT CHASSIS
REAR CHASSIS
CPU FAN SINK