Product # PQ60025EGL25

Phone 1-888-567-9596

www.synqor.com

Doc.# 005-2EG625B Rev. B

02/11/11

Page 12

Technical

Specification

PQ60025EGL25

Applications Section

APPLICATION CONSIDERATIONS

Input System Instability: This condition can occur

because any DC/DC converter appears incrementally as a

negative resistance load. A detailed application note titled

“Input System Instability” is available on the SynQor web

site (www.synqor.com) which provides an understanding

of why this instability arises, and shows the preferred

solution for correcting it.

Application Circuits: Figure D below provides a typical

circuit diagram which details the input filtering and voltage

trimming.

Input Filtering and External Input Capacitance:

Figure E below provides a diagram showing the internal

input filter components. This filter dramatically reduces

input terminal ripple current, which otherwise could

exceed the rating of an external electrolytic input

capacitor. The recommended external input capacitance

is specified in the “Input Characteristics” section. More

detailed information is available in the application note

titled “EMI Characteristics” on the SynQor website.

External

Input

Filter

Trim

I

load

C

load

R

trim-up

or

R

trim-down

ON/OFF

Electrolytic

Capacitor

47µF

C

L

in

Figure D: Typical application circuit (negative logic unit, permanently enabled).

Figure E: Internal Input Filter Diagram (component values listed on page 3).