ADT7467ARQZ-R7 datasheet(42/77 Pages) ONSEMI

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ADT7467

Rev. 3 | Page 42 of 77 | www.onsemi.com

STEP 3: TMIN SETTINGS FOR THERMAL

CALIBRATION CHANNELS

TMIN is the temperature at which the fans start to turn on when

using automatic fan control mode. The speed at which the fan

runs at TMIN is programmed later. The TMIN values chosen are

temperature-channel specific, for example, 25°C for ambient

channel, 30°C for VRM temperature, and 40°C for processor

temperature.

TMIN is an 8-bit value, either twos complement or Offset 64, that

can be programmed in 1°C increments. There is a TMIN register

associated with each temperature measurement channel:

Remote 1, local, and Remote 2 temperature. Once the TMIN

value is exceeded, the fan turns on and runs at the minimum

PWM duty cycle. The fan turns off once the temperature has

dropped below TMIN − THYST.

To overcome fan inertia, the fan spins up until two valid TACH

rising edges are counted. See the Fan Start-Up Timeout section

for more details. In some cases, primarily for psychoacoustic

reasons, it is desirable that the fan never switch off below TMIN.

When set, Bits <7:5> of the Enhanced Acoustics Register 1

(0x62) keep the fans running at the PWM minimum duty cycle

if the temperature falls below TMIN.

TMIN Registers

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

when the temperature is 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

when the temperature is 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

when the temperature is below TMIN – THYST.

ADT7467ARQZ-R7 Datasheet(PDF) 42 Page - ON Semiconductor