Datasheet

Application Note

Created by Traco Electronic AG Arp. www.tracopower.com Date: May 31

, 2013 / Rev.: 1.2

Page 45 / 52

20W Single & Dual Output

EMI considerations (Continued)

This Common Choke L1 has been define as follow：

■ TCK-050

L: 325mH ±35% / DCR: 35Ω, max

A: (Height): 8.8 mm, Max

■ Test condition: 100KHz / 100mV

■ Recommended through hole: Φ0.8mm

■ All dimensions in millimeters

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 C-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 10μF/100V & 10μF/100V. The

capacitor must be equipped as close as possible to the input terminals of the power module for lower impedance.

Output Over Current Protection

If excessive output currents occur in the system, circuit protection is required on all power supplies. Normally, overload current is

maintained at approximately about 150 percent of rated current for THN 20 series.

Hiccup-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 restart 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.

Output Over Voltage Protection

The output over-voltage protection consists of a Zener diode that monitors the output voltage on the feedback loop. If the

voltage on the output terminals exceeds the over-voltage protection threshold, then the Zener diode will send a current signal to

the control IC to limiting the output voltage.