PAQ
B-246
・All specifications are subject to change without notice.
PAQ100S48-*/B**Instruction Manual
1. Output Derating
There is no restriction on mounting direction but there
should be enough consideration for airflow so that heat
does not accumulate around the power module vicinity.De-
termine external components configuration and mounting
direction on PCB such that air could flow through power
module at forced air cooling or convection cooling. By
maintaining baseplate temperature below 100℃, operation
is possible. But according to the models, output derating
is needed as shown in figure 1-1. Measure baseplate tem-
perature at center of baseplate as indicated in fig.1-2. For
better improvement of power module reliability, more derat-
ing of baseplate temperature when using is recommended.
100
80
60
40
20
0
−40
−20
0
20
40
60
80
100
1.2V,1.8V model
2.5V,3.3V,5V model
Baseplate Temperature (℃)
Load (%)
Fig.1-1 PAQ100S48/B Output Derating
Temperature
Measuring Point of
Baseplate
Fig.1-2 Temperature Measuring Point of Baseplate
Forced cooling to power module improve radiation capa-
bility more than convection cooling. Figure 1-3 indicates
thermal resistance value between baseplate and air at
standard vertical mounting. For details on standard vertical
mounting, refer to “PAQ-S48 Series Instruction Manual”
Figure 1-4 to 1-8 indicates power dissipation (Pd) of each
models at following condition.
Output Voltage:
Nominal value
Ambient Temperature: 60℃
An example of thermal design using these condition is
shown as follows.
1 Example of Thermal design
Calculate minimum necessary air velocity at following con-
dition.
Use Model:
PAQ100S48-5/B
Input Voltage:
48V
Maximum Output Current:
15A
Maximum Ambient Temperature: 65℃
Mounting Method:
Standard Vertical Mounting
Power dissipation is as shown in Fig.1-8
Pd=9.0 (W)
Maximum baseplate temperature (Tbp) at output current
15A is as shown in Fig. 1-1
Tbp=95 (℃ )
Therefore
Tbp=Ta+θbp−a × Pd
Ta： Ambient temperature (℃ )
θbp−a：Thermal Resistance (℃ /W)
(Baseplate - Air)
Equation is as follows.
θbp−a=
Tbp−Ta
=3.33
（℃ /W）
Pd
Air Velocity is as shown in Fig.1-3.
Air Velocity=0.8 (m/s)
This is minimum necessary air velocity at above condition.
Measure actual baseplate temperature and verify it is
same as the design. If there are discrepancy, re-check
each condition and re-design.
Note
1） Data shown in Fig.1-3 to 1-8 is the typical value and
it changes depending on measurement condition.
Recommend to design with sufficient margin against
calculation value.
2） When the condition of input voltage and output volt-
age are different and it is impossible to determine
power dissipation (Pd) from Fig.1-4 to 1-8, calculate
power dissipation as follows.
Pd=Pin−Pout= 100−η ×Pout
η
Pin:
Input Power (W)
Pout: Output Power (W)
η:
Efficiency (%)
Note
● This instruction manual describes only changed items from
the standard model’
s instruction manual.
● Please refer to “PAQ-S48 Series instruction manual”
more
details.
● PAQ-S Instruction Manual
B-237Page
● PAQ65D Instruction Manual
B-250Page
Содержание PAQ100S48-1R2
Страница 36: ...B 260...
