ADT7473_11 ONSEMI [ON Semiconductor], ADT7473_11 Datasheet - Page 41

• Manufacturer Part Number: ADT7473_11
• Description: dbCOOL Remote Thermal Monitor and Fan Control
• Manufacturer: ONSEMI [ON Semiconductor]

temperature at which the fan reaches full speed) by setting
T
THERM Registers
Register 0x6A, Remote 1 THERM Temperature Limit =
0xA4 (100°C default)
Register 0x6B, Local THERM Temperature Limit = 0xA4
(100°C default)
Register 0x6C, Remote 2 THERM Temperature Limit =
0xA4 (100°C default)
Step 8: T
the temperature measured has dropped back below T
before the fan turns off. The premise for temperature
hysteresis (T
chatter or cycle on and off regularly whenever temperature
is hovering at about the T
THERM
T
HYST
to that limit (for example, 70°C).
HYST
is the amount of extra cooling a fan provides after
HYST
for Temperature Channels
) is that, without it, the fan would merely
MIN
setting.
Figure 62. How T
THERM
http://onsemi.com
MIN
Relates to Automatic Fan Control
41
Hysteresis Registers
Register 0x6D, Remote 1 Local Temperature Hysteresis
Register
Bits [7:4] Remote 1 temperature hysteresis (4°C default)
Bits [3:0] Local temperature hysteresis (4°C default)
Register 0x6E, Remote 2 Temperature Hysteresis Register
Bits [7:4] Remote 2 temperature hysteresis (4°C default)
values are programmable from 1°C to 15°C. It is not
recommended that hysteresis values 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.
needed for the system to cool down or heat up as the fan turns
on and off. Values of hysteresis are programmable in the
range 1°C to 15°C. Larger values of T
from chattering on and off. The T
at 4°C.
Because each hysteresis setting is four bits, hysteresis
The T
HYST
value chosen determines the amount of time
HYST
HYST
default value is set
prevent the fans