EVAL-ADT7467EBZ ON Semiconductor, EVAL-ADT7467EBZ Datasheet - Page 46

• 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

ADT7467
Example 4: Calculate T
and PWM
Selecting a T
The T
Remote 1, local, and Remote 2 temperature. Bits <7:4> (T
of Register 0x5F to Register 0x61 define the T
each temperature channel.
Table 15. Selecting a T
Bits <7:4>
0000
0001
0010
0011
0100
0101
0110
0111
1000
1001
1010
1011
1100
1101
1110
1111
1
Summary of T
When using the automatic fan control function, the
temperature at which the fan reaches full speed can be
calculated by
Equation 1 holds true only when PWM
PWM duty cycle.
Increasing or decreasing PWM
but the fan control still follows the same PWM duty cycle to
temperature slope. The effective T
be calculated using Equation 2:
where:
(Max DC − Min DC) × T
Register 0x5F configures Remote 1 T
Register 0x60 configures local T
Register 0x61 configures Remote 2 T
T
T
T
T
T
T
RANGE
MAX
MAX
MAX
MAX
MAX
MAX
= T
= 30°C + (100% − 50%) × 40°C/170
= 30°C + (255 − 128) × 40°C/170
= 60°C (Effective T
= T
= T
MIN
1
value can be selected for each temperature channel:
MIN
MIN
MIN
= 50% duty cycle = 128 (decimal).
RANGE
RANGE
+ (Max DC − Min DC) × T
+ T
+ (Max DC − Min DC) × T
Slope
RANGE
Function
MAX
T
2
2.5
3.33
4
5
6.67
8
10
13.33
16
20
26.67
32 (default)
40
53.33
80
RANGE
RANGE
, given that T
RANGE
RANGE
RANGE
Value
(°C)
/170 is the effective T
.
RANGE
RANGE
MIN
= 30°C)
RANGE
.
.
changes the effective T
MIN
MIN
for a PWM
= 30°C, T
is equal to 33%
RANGE
RANGE
RANGE
/170
/170
RANGE
MIN
value for
RANGE
Rev. 3 | Page 46 of 77 | www.onsemi.com
value can
= 40°C,
value.
RANGE
RANGE
(1)
(2)
,
)
See the Fan Speed and PWM Duty Cycle section.
Figure 64 shows PWM duty cycle vs. temperature for each
T
affects fan speed vs. temperature. As can be seen from the
graph, the effect on fan speed is nonlinear.
The graphs in Figure 64 assume that the fan starts from 0% PWM
duty cycle. The minimum PWM duty cycle, PWM
factored in to determine how the loop performs in the system.
Figure 65 shows how T
is set to 20%. It can be seen that the fan runs at about 45% fan
speed when the temperature exceeds T
RANGE
100
100
90
80
70
60
50
40
30
20
10
90
80
70
60
50
40
30
20
10
0
0
0
0
setting. The lower graph shows how each T
20
20
Figure 64. T
TEMPERATURE ABOVE T
TEMPERATURE ABOVE T
40
40
RANGE
RANGE
is affected when the PWM
60
60
vs. Fan Speed Profile
80
80
MIN
MIN
MIN
.
100
100
MIN
RANGE
120
120
, must be
MIN
setting
2°C
2.5°C
3.33°C
4°C
5°C
6.67°C
8°C
10°C
13.3°C
16°C
20°C
26.6°C
32°C
40°C
53.3°C
80°C
2°C
2.5°C
3.33°C
4°C
5°C
6.67°C
8°C
10°C
13.3°C
16°C
20°C
26.6°C
32°C
40°C
53.3°C
80°C
value