ADT7467ARQZ-R7 datasheet(50/77 Pages) ONSEMI

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ADT7467

Rev. 3 | Page 50 of 77 | www.onsemi.com

Enhanced Acoustics Register 1 (0x62)

Bit 7 (MIN3) = 0, PWM3 is off (0% PWM duty cycle) when the

temperature is below TMIN − THYST.

Bit 7 (MIN3) = 1, PWM3 runs at PWM3 minimum duty cycle

below TMIN − THYST.

Bit 6 (MIN2) = 0, PWM2 is off (0% PWM duty cycle) when the

temperature is below TMIN − THYST.

Bit 6 (MIN2) = 1, PWM2 runs at PWM2 minimum duty cycle

below TMIN − THYST.

Bit 5 (MIN1) = 0, PWM1 is off (0% PWM duty cycle) when the

temperature is below TMIN − THYST.

Bit 5 (MIN1) = 1, PWM1 runs at PWM1 minimum duty cycle

below TMIN − THYST.

STEP 9: OPERATING POINTS FOR

TEMPERATURE CHANNELS

The operating point for each temperature channel is the

optimal temperature for that thermal zone. The hotter each

zone is allowed to be, the more quiet the system, because the

fans are not required to run as fast. The ADT7467 increases or

decreases fan speeds as necessary to maintain the operating

point temperature, allowing for system-to-system variations

and eliminating the need to design for the worst case. If a

sensible operating point value is chosen, any TMIN value can be

selected in the system characterization. If the TMIN value is too

low, the fans run sooner than required and the temperature is

below the operating point. In response, the ADT7467 increases

TMIN to keep the fans off longer and to allow the temperature

zone to approach the operating point. Likewise, too high a TMIN

value causes the operating point to be exceeded, and, in turn,

the ADT7467 reduces TMIN to turn the fans on sooner to cool

the system.

Programming Operating Point Registers

There are three operating point registers, one for each tempera-

ture channel. These 8-bit registers allow the operating point

temperatures to be programmed with 1°C resolution.

Operating Point Registers

default)

OPERATING

POINT

REAR CHASSIS

FRONT CHASSIS

CPU FAN SINK

LOCAL =

VRM TEMP

PWM1

PWM2

TACH1

TACH2

TACH3

PWM3

REMOTE 1 =

AMBIENT TEMP

REMOTE 2 =

CPU TEMP

MUX

THERMAL CALIBRATION

TMIN

TRANGE

THERMAL CALIBRATION

100%

TMIN

TRANGE

THERMAL CALIBRATION

100%

TMIN

TRANGE

TACHOMETER 1

MEASUREMENT

PWM

CONFIG

PWM

MIN

RAMP

CONTROL

(ACOUSTIC

ENHANCEMENT)

PWM

GENERATOR

TACHOMETER 2

MEASUREMENT

PWM

CONFIG

PWM

MIN

RAMP

CONTROL

(ACOUSTIC

ENHANCEMENT)

PWM

GENERATOR

TACHOMETER 3

AND 4

MEASUREMENT

PWM

CONFIG

PWM

MIN

RAMP

CONTROL

(ACOUSTIC

ENHANCEMENT)

PWM

GENERATOR

100%

Figure 69. Operating Point Value Dynamically Adjusts Automatic Fan Control Settings

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