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Input Source Impedance

The power module should be connected to a low impedance input source. Highly inductive source impedance

can affect the stability of the power module. Input external L-C filter is recommended to minimize input

reflected ripple current. The inductor is simulated source impedance of 12µH and capacitor is Nippon chemi-con

KZE series 47µF/100V. The capacitor must as close as possible to the input terminals of the power module for

lower impedance.

Thermal Consideration

The power module operates in a variety of thermal environments. However, sufficient cooling should be

provided to help ensure reliable operation of the unit. Heat is removed by conduction, convention, and radiation

to the surrounding environment. Proper cooling can be verified by measuring the point as the figure below. The

temperature at this location should not exceed 105°C. When operating, adequate cooling must be provided to

maintain the test point temperature at or below 105°C. Although the maximum point temperature of the power

modules is 105°C, you can limit this temperature to a lower value for extremely high reliability.

DESIGN CONSIDERATIONS:

Output Over Current Protection

When excessive output currents occur in the system, circuit protection is required on all power supplies.

Normally, overload current is maintained at approximately 150% of rated current for the LANCW12 dual output

series.

Fold back-mode is a method of operation in a power supply whose purpose is to protect the power supply from

being damaged during an over-current fault condition. It also enables the power supply to operate normally when

the fault is removed.

One of the problems resulting from over current is that excessive heat may be generated in power devices;

especially MOSFET and Schottky diodes and the temperature of those devices may exceed their specified limits.

A protection mechanism has to be used to prevent those power devices from being damaged.

The operation of fold back is as follows. When the current sense circuit sees an over-current event, the output

voltage of the module will be decreased for low power dissipation and decrease the heat of the module.

Figure 3

0.625 (15.9)

Measurement shown in inches and millimeters

Figure 2

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