ADT7476ARQZ ON Semiconductor, ADT7476ARQZ Datasheet - Page 38

• Manufacturer Part Number: ADT7476ARQZ
• Description: IC REMOTE THERMAL CTRLR 24QSOP
• Manufacturer: ON Semiconductor
• Series: dBCool®r

Specifications of ADT7476ARQZ

• 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: 24-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 3—T
Channels
under automatic fan control. The speed at which the fan runs
at T
temperature channel specific, for example, 25°C for
ambient channel, 30°C for VRM temperature, and 40°C for
processor temperature.
64, which can be programmed in 1°C increments. A T
register is associated with each temperature measurement
channel: Remote 1, local, and Remote 2 temperature. Once
the T
minimum PWM duty cycle. The fan turns off once the
temperature has dropped below T
TACH rising edges are counted. See the Fan Startup
Timeout section for more details. In some cases, primarily
for psycho−acoustic reasons, it is desirable that the fan never
switch off below T
Acoustics Register 1 (0x62) keeps the fans running at the
PWM minimum duty cycle if the temperature should fall
below T
T
T
To overcome fan inertia, the fan is spun up until two valid
MIN
MIN
MIN
MIN
is the temperature at which the fans start to turn on
is an 8−bit value, either twos complement or Offset
MIN
is programmed later. The T
value is exceeded, the fan turns on and runs at the
MIN
AMBIENT TEMP
.
REMOTE 2 =
REMOTE 1 =
Settings for Thermal Calibration
VRM TEMP
CPU TEMP
LOCAL =
100%
0%
MIN
. Setting Bits [7:5] of Enhance
THERMAL CALIBRATION
THERMAL CALIBRATION
THERMAL CALIBRATION
T
T
T
T
MIN
MIN
MIN
MIN
MIN
MIN
Figure 53. Understanding the T
− T
T
T
T
RANGE
RANGE
RANGE
values chosen are
HYST
100%
100%
100%
0%
0%
0%
.
http://onsemi.com
MUX
MIN
38
PWM
PWM
PWM
MIN
MIN
MIN
T
Register 0x67, Remote 1 Temperature T
Register 0x68, Local Temperature T
Register 0x69, Remote 2 Temperature T
Enhance 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
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
MIN
CONFIG
CONFIG
CONFIG
TACHOMETER 1
MEASUREMENT
TACHOMETER 2
MEASUREMENT
TACHOMETER 3
MEASUREMENT
PWM
PWM
PWM
Registers
GENERATOR
GENERATOR
GENERATOR
MIN
AND 4
PWM
PWM
PWM
Parameter
MIN
MIN
MIN
– T
– T
– T
ENHANCEMENT)
ENHANCEMENT)
ENHANCEMENT)
HYST
HYST
HYST
(ACOUSTIC
(ACOUSTIC
(ACOUSTIC
CONTROL
CONTROL
CONTROL
MIN
MIN
MIN
RAMP
RAMP
RAMP
.
.
.
– T
– T
– T
HYST
HYST
HYST
MIN
.
.
.
PWM1
TACH1
PWM2
TACH2
PWM3
TACH3
MIN
MIN
= 0x5A (90°C)
FRONT CHASSIS
REAR CHASSIS
CPU FAN SINK
= 0x5A (90°C)
= 0x5A (90°C)