EVAL-ADT7467EBZ ON Semiconductor, EVAL-ADT7467EBZ Datasheet - Page 45

• 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

STEP 6: T
T
control occurs once the programmed T
been exceeded. T
value, that is, a T
33%. If PWM
changes.
The T
procedure:
1.
2.
3.
4.
RANGE
Determine the maximum operating temperature for that
channel (for example, 70°C).
Through experimentation, determine the fan speed (PWM
duty cycle value) that does not exceed the temperature at
the worst-case operating points. (For example, 70°C is
reached when the fans are running at 50% PWM duty
cycle.)
Determine the slope of the required control loop to meet
these requirements.
The ADT7467 evaluation software can graphically
program and visualize this functionality. Ask your local
Analog Devices sales representative for details.
RANGE
is the range of temperature over which automatic fan
PWM
100%
50%
33%
100%
or fan control slope is determined by the following
0%
RANGE
Figure 61. T
MIN
0%
MIN
Figure 62. Adjusting PWM
RANGE
is increased or decreased, the effective T
RANGE
FOR TEMPERATURE CHANNELS
RANGE
T
of 40°C holds true only for PWM
MIN
is a temperature slope, not an arbitrary
T
MIN
Parameter Affects Cooling Slope
30°C
40°C
T
MIN
RANGE
TEMPERATURE
Affects T
MIN
temperature has
RANGE
Rev. 3 | Page 45 of 77 | www.onsemi.com
MIN
RANGE
=
T
is changed, T
same. The higher the PWM
T
temperature.
For a given T
at full speed, which varies with the PWM
calculated.
where:
T
T
Max DC is the maximum duty cycle (100%) = 255 decimal.
Min DC is equal to PWM
T
Example 1: Calculate T, given that T
and PWM
Example 2: Calculate T
and PWM
Example 3: Calculate T
and PWM
RANGE
RANGE
MAX
MIN
RANGE
T
is the temperature at which the fan turns on.
T
T
T
T
T
T
T
T
T
T
T
T
is the temperature at which the fan runs full speed.
MAX
MAX
MAX
MAX
MAX
MAX
MAX
MAX
MAX
MAX
MAX
MAX
MAX
, that is, the fan reaches full speed (100%) at a lower
is the duty PWM duty cycle vs. temperature slope.
is implemented as a slope, which means that as PWM
100%
Figure 63. Increasing PWM
= T
= T
= 30°C + (100% − 10%) × 40°C/170
= 30°C + (255 − 26) × 40°C/170
= 84°C (Effective T
= T
= 30°C + (100% − 25%) × 40°C/170
= 30°C + (255 − 64) × 40°C/170
= 75°C (Effective T
= T
= 30°C + (100% − 33%) × 40°C/170
= 30°C + (255 − 85) × 40°C/170
= 70°C (Effective T
MIN
MIN
MIN
50%
33%
25%
10%
0%
RANGE
RANGE
MIN
MIN
MIN
MIN
= 10% duty cycle = 26 (decimal).
= 25% duty cycle = 64 (decimal).
= 33% duty cycle = 85 (decimal).
+ (Max DC − Min DC) × T
+ (Max DC − Min DC) × T
+ (Max DC − Min DC) × T
+ (Max DC − Min DC) × T
changes, but the actual slope remains the
value, the temperature at which the fan runs
T
MAX
MAX
MIN
, given that T
, given that T
MIN
MIN
.
RANGE
RANGE
RANGE
30°C
value, the smaller the effective
MIN
40°C
= 54°C)
= 45°C)
= 40°C)
45°C
Changes Effective T
MIN
54°C
MIN
MIN
= 30°C, T
= 30°C, T
= 30°C, T
MIN
RANGE
RANGE
RANGE
RANGE
value, can be easily
RANGE
/170
/170
/170
/170
RANGE
RANGE
ADT7467
RANGE
= 40°C,
= 40°C,
= 40°C,
MIN