ADT7473ARQZ-1 ON Semiconductor, ADT7473ARQZ-1 Datasheet - Page 41

• Manufacturer Part Number: ADT7473ARQZ-1
• Description: IC THERM MON FAN CTRLR 16-QSOP
• Manufacturer: ON Semiconductor
• Series: dBCool®r

Specifications of ADT7473ARQZ-1

• Function: Fan Control, Temp Monitor
• Topology: ADC, Comparator, Fan Speed Counter, Multiplexer, Register Bank
• Sensor Type: External & Internal
• Sensing Temperature: -40°C ~ 125°C, External Sensor
• Output Type: SMBus™
• Output Alarm: No
• Output Fan: Yes
• Voltage - Supply: 3 V ~ 3.6 V
• Operating Temperature: -40°C ~ 125°C
• Mounting Type: Surface Mount
• Package / Case: 16-QSOP
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

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