EVAL-ADT7467EBZ ON Semiconductor, EVAL-ADT7467EBZ Datasheet - Page 33

• Manufacturer Part Number: EVAL-ADT7467EBZ
• Description: BOARD EVALUATION FOR ADT7467
• Manufacturer: ON Semiconductor
• Series: dBCool®r

Specifications of EVAL-ADT7467EBZ

• Sensor Type: Temperature
• Sensing Range: -40°C ~ 120°C
• Interface: SMBus (2-Wire/I²C)
• Sensitivity: ±1.5°C
• Voltage - Supply: 3 V ~ 5.5 V
• Embedded: No
• Utilized Ic / Part: ADT7467
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

FAN SPEED CONTROL
The ADT7467 controls fan speed using two modes: automatic
and manual.
In automatic fan speed control mode, fan speed is varied with
temperature without CPU intervention once initial parameters
are set up. The advantage of this is that if the system hangs, it is
guaranteed that the system is protected from overheating. The
automatic fan speed control incorporates a feature called
dynamic T
required to program the automatic fan speed control loop. For
information on programming the automatic fan speed control
loop and the dynamic T
Control Overview section.
In manual fan speed control mode, the ADT7467 allows the
duty cycle of any PWM output to be manually adjusted. This
can be useful if the user wants to change fan speed in software
or adjust PWM duty cycle output for test purposes. Bits <7:5>
of Register 0x5C to Register 0x5E (PWM Configuration)
control the behavior of each PWM output.
PWM Configuration Register (0x5C to 0x5E)
<7:5> BHVR
In manual fan speed control mode, each PWM output can
be manually updated by writing to Register 0x30 through
Register 0x32 (PWMx current duty cycle registers).
111 = manual mode
MIN
calibration. This feature reduces the design effort
MIN
calibration, see the Automatic Fan
Rev. 3 | Page 33 of 77 | www.onsemi.com
Programming the PWM Current Duty Cycle Registers
The PWM current duty cycle registers are 8-bit registers that
allow the PWM duty cycle for each output to be set anywhere
from 0% to 100% in steps of 0.39%.
The value to be programmed into the PWM
Example 1: For a PWM duty cycle of 50%,
Example 2: For a PWM duty cycle of 33%,
PWM Current Duty Cycle Registers
Register 0x30 PWM1 current duty cycle = 0x00 (0% default)
Register 0x31 PWM2 current duty cycle = 0x00 (0% default)
Register 0x32 PWM3 current duty cycle = 0x00 (0% default)
By reading the PWMx current duty cycle registers, the user can
keep track of the current duty cycle on each PWM output even
when the fans are running in automatic fan speed control mode
or acoustic enhancement mode. See the Automatic Fan Control
Overview section for details.
Value (decimal) = PWM
Value (decimal) = 50/0.39 = 128 (decimal)
Value = 128 (decimal) or 0x80 (hexadecimal)
Value (decimal) = 33/0.39 = 85 (decimal)
Value = 85 (decimal) or 0x54 (hexadecimal)
MIN
/0.39
MIN
register is given by
ADT7467