Documentation/hwmon/adt7475.rst

39 	- Jordan Crouse
40 	- Hans de Goede
41 	- Darrick J. Wong (documentation)
42 	- Jean Delvare
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56 The ADT747x uses the 2-wire interface compatible with the SMBus 2.0
58 temperatures and two (2) or more voltages. It has four (4) 16-bit counters
59 for measuring fan speed. There are three (3) PWM outputs that can be used
60 to control fan speed.
62 A sophisticated control system for the PWM outputs is designed into the
63 ADT747x that allows fan speed to be adjusted automatically based on any of the
64 three temperature sensors. Each PWM output is individually adjustable and
65 programmable. Once configured, the ADT747x will adjust the PWM outputs in
67 This feature can also be disabled for manual control of the PWM's.
69 Each of the measured inputs (voltage, temperature, fan speed) has
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104 in0  2.5VIN (22) 2.5VIN (22) -         -
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116 The ADT747x has a 10-bit ADC and can therefore measure temperatures
122 an optimal configuration for the automatic PWM control.
124 Fan Speed Control
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127 The driver exposes two trip points per PWM channel.
129 - point1: Set the PWM speed at the lower temperature bound
130 - point2: Set the PWM speed at the higher temperature bound
132 The ADT747x will scale the PWM linearly between the lower and higher PWM
135 PWM outputs, and a given PWM output can be controlled by several temperature
136 channels. As a result, the ADT747x may compute more than one PWM value
138 fan speed) is applied. PWM values range from 0 (off) to 255 (full speed).
140 Fan speed may be set to maximum when the temperature sensor associated with
141 the PWM control exceeds temp#_max.
143 At Tmin - hysteresis the PWM output can either be off (0% duty cycle) or at the
145 `pwm[1-*]_stall_disable sysfs attribute`. A value of 0 means the fans will shut
149 This allows smoothing of the fan speed transition. To set the transition time
150 set the value in ms in the `temp[1-*]_smoothing` sysfs attribute.
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155 The nVidia binary driver presents an ADT7473 chip via an on-card i2c bus.