♦
The heat sink should be made of a good heat conducting material, such as aluminum and
copper.
♦
The larger the surface area, the better the radiation. Therefore, heat sinks usually have a
ridged surface or special coatings to make a larger surface area.
♦
Use the longest and thickest possible heat sink for best convection.
Heat sinks are best attached to the converter’s surface, where the difference in temperature
between the surface and the ambient is largest. The use of heat conductive material between
the heat sink and the converter
’s
surface to make a better contact and to improve heat
conductance is suggested. To avoid case distortion, please do not affix the heat sink too firmly to
the converter case.
(3) Forced Air Cooling
In some systems, where a heat sink does not effectively reduce the ambient temperature, a fan
is used to improve the heat radiation. Fans can lower the surface temperature of the converter,
but large fans also occupy extra space in the system. It is important to select a suitable fan size,
where the speed of the fan will determines how effective it is. The faster the speed, the better
the effect on reducing radiated heat. As high speed will also cause increased noise, there is a
need to balance the choice between the how effective the fan is against how much audible noise
it generates.
A long, rectangular shaped AC/DC converter should use a horizontal fan, and channeled heat
sinks should use vertical fans, in order to encourage air flow through the channels.
5. Input Under Voltage Impact
5.1 Block Diagram of AC/DC Converter
5.2 Impact to Converter Reliability
The input voltage range of MORNSUN’s AC/DC converters is 85~264VAC or 120~370VDC.
When the converter is operated within the rated input voltage range, the output current can be
used up to the maximum rated specification.
The total output power is I
o
x V
o
.
If the converter is operated with an input voltage that is under the rated voltage, offering the
same output power of I
o
x V
o
, causes the current (Is) at the transistor (S) to be increased.
Long term operation under this condition will damage the transistor (S).
MORNSUN [ MORNSUN SCIENCE& TECHNOLOGY LTD. ]
