ADT7473ARQZ-1RL ON Semiconductor, ADT7473ARQZ-1RL Datasheet - Page 44

• Manufacturer Part Number: ADT7473ARQZ-1RL
• Description: IC REMOTE THERMAL CTLR 16QSOP
• Manufacturer: ON Semiconductor
• Series: dBCool®r

Specifications of ADT7473ARQZ-1RL

• 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

Getting the most benefit from the automatic fan control
mode involves characterizing the system to find the best
T
PWM
ADT7473/ADT7473−1’s dynamic T
however, shortens the characterization time and alleviates
tweaking the control loop settings because the device can
self−adjust during system operation.
operating zone temperatures required for the system.
Associated with this control mode are three operating point
registers, one for each temperature channel. This allows the
system thermal solution to be broken down into distinct
thermal zones. For example, CPU operating temperature is
70°C, VRM operating temperature is 80°C, and ambient
operating temperature is 50°C. The ADT7473/ADT7473−1
dynamically alters the control solution to maintain each
zone temperature as closely as possible to its target operating
point.
Operating Point Registers
Register 0x33, Remote 1 Operating Point = 0xA4
(100°C default)
Register 0x34, Local Temperature Operating Point = 0xA4
(100°C default)
Register 0x35, Remote 2 Operating Point = 0xA4
(100°C default)
the operation of the dynamic T
MIN
Dynamic T
Figure 66 shows an overview of the parameters that affect
and T
MIN
T
LOW
Figure 66. Dynamic T
value for the quietest fan speed setting. Using the
RANGE
T
MIN
MIN
OPERATING
control mode is operated by specifying the
settings for the control loop, and the best
POINT
T
HIGH
MIN
T
MIN
THERM
control loop.
Control Loop
T
MIN
RANGE
control mode,
TEMPERATURE
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44
Dynamic T
extension of the automatic fan control mode, program the
automatic fan control mode parameters first, as described in
the Step 1: Hardware Configuration section to the Step 8:
T
dynamic T
Step 9: Operating Points for Temperature Channels
optimal temperature for that thermal zone. The hotter each
zone is allowed to be, the quieter the system, because the
fans are not required to run as fast. The ADT7473/
ADT7473−1 increases or decreases fan speeds as necessary
to maintain the operating point temperature, allowing for
system−to−system variation and removing the need for
worst−case design. If a sensible operating point value is
chosen, any T
characterization. If the T
sooner than required, and the temperature is below the
operating point. In response, the ADT7473/ADT7473−1
increases T
temperature zone to get closer to the operating point.
Likewise, too high a T
to be exceeded, and in turn, the ADT7473/ADT7473−1
reduces T
Table 14. T
HYST
Parameter
Table 14 provides a brief description of each parameter.
Because the dynamic T
The operating point for each temperature channel is the
Operating
T
T
T
T
Point
THERM
RANGE
T
HIGH
LOW
MIN
for Temperature Channels section, then proceed with
MIN
MIN
MIN
MIN
MIN
to turn the fans on sooner to cool the system.
MIN
If the temperature drops below the T
an error flag is set in a status register and an
SMBALERT interrupt can be generated.
If the temperature exceeds the T
error flag is set in a status register and an
SMBALERT interrupt can be generated.
The temperature at which the fan turns on
under automatic fan speed control.
The target temperature for a particular
temperature zone. The ADT7473/ADT7473−1
attempts to maintain system temperature at
about the operating point by adjusting the T
parameter of the control loop.
If the temperature exceeds this critical limit, the
fans can be run at 100% for maximum cooling.
Programs the PWM duty cycle vs. temperature
control slope.
Control Programming
control mode programming.
to keep the fans off longer and to allow the
Control Loop Parameters
value can be selected in the system
MIN
MIN
value causes the operating point
MIN
value is too low, the fans run
Description
control mode is a basic
HIGH
LOW
limit, an
limit,
MIN