参数资料
| 型号： | ADT7468ZEVB |
| 厂商： | ON Semiconductor |
| 文件页数： | 50/81页 |
| 文件大小： | 0K |
| 描述： | BOARD EVAL FOR ADT7468 |
| 标准包装： | 1 |
| 其它名称： | EVAL-ADT7468EB EVAL-ADT7468EB-ND |
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ADT7468
Note on 4-Wire Fans
The control range for 4-wire fans is much wider than that of
2-wire or 3-wire fans. In many cases, 4-wire fans can start with
a PWM drive of as little as 20%.
100
90
80
70
60
50
40
30
20
10
The fans remain running at 100% until the temperature drops
below T THERM minus hysteresis, where hysteresis is the number
programmed into the hysteresis Registers 0x6D and 0x6E. The
default hysteresis value is 4°C.
The T THERM limit should be considered the maximum worst-case
operating temperature of the system. Because exceeding any
T THERM limit runs all fans at 100%, it has very negative acoustic
effects. Ultimately, this limit should be set up as a fail-safe, and
one should ensure that it is not exceeded under normal system
operating conditions.
Note that the T THERM limits are nonmaskable and affect the fan
speed regardless of how automatic fan control settings are
configured. This allows some flexibility, because a T RANGE value
can be selected based on its slope, while a hard limit (such as
0
0
10
20
30
40
50
60
70
80
90
100
70°C), can be programmed as T MAX (the temperature at which
100
90
80
70
60
50
40
30
20
10
TEMPERATURE ABOVE T MIN
the fan reaches full speed) by setting T THERM to that limit (for
example, 70°C).
THERM Registers
Reg. 0x6A, Remote 1 THERM limit = 0xA4 (100°C default)
Reg. 0x6B, Local THERM limit = 0xA4 (100°C default)
Reg. 0x6C, Remote 2 THERM limit = 0xA4 (100°C default)
Hysteresis Registers
Reg. 0x6D, Remote 1, local hysteresis register
<7:4>, Remote 1 temperature hysteresis (4°C default)
0
0
10
20
30 40 50 60 70
TEMPERATURE ABOVE T MIN
80
90
100
<3:0>, Local temperature hysteresis (4°C default)
Figure 67. T RANGE and % Fan Speed Slopes for VRM, Ambient, and
CPU Temperature Channels
STEP 7: T THERM FOR TEMPERATURE CHANNELS
T THERM is the absolute maximum temperature allowed on a
temperature channel. Above this temperature, a component
such as the CPU or VRM might be operating beyond its safe
operating limit. When the temperature measured exceeds
T THERM , all fans are driven at 100% PWM duty cycle (full speed)
Reg. 0x6E, Remote 2 Temperature Hysteresis Register
<7:4>, Remote 2 temperature hysteresis (4°C default)
Because each hysteresis setting is four bits, hysteresis values are
programmable from 1°C to 15°C. It is recommended that
hysteresis values never be programmed to 0°C, because this
disables hysteresis. In effect, this would cause the fans to cycle
between normal speed and 100% speed, creating unsettling
acoustic noise.
to provide critical system cooling.
Rev. 3 | Page 50 of 81 | www.onsemi.com
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相关代理商/技术参数 |
参数描述 |
|---|---|
| ADT7470 | 制造商:AD 制造商全称:Analog Devices 功能描述:Temperature Sensor Hub and Fan Controller |
| ADT7470_13 | 制造商:AD 制造商全称:Analog Devices 功能描述:Temperature Sensor Hub and Fan Controller |
| ADT7470ARQ | 制造商:Analog Devices 功能描述:Temp Sensor Digital Serial (I2C) 16-Pin QSOP |
| ADT7470ARQ-REEL | 制造商:Rochester Electronics LLC 功能描述: 制造商:Analog Devices 功能描述: |
| ADT7470ARQ-REEL7 | 制造商:Analog Devices 功能描述:Temp Sensor Digital Serial (I2C) 16-Pin QSOP T/R |
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