Technical
Specification
IQ24-HP Family
APPLICATION CONSIDERATIONS
Input System Instability:
This condition can occur because
Application Circuits: Figure C provides a typical circuit diagram
any dc-dc converter appears incrementally as a negative which details the input filtering and voltage trimming.
resistance load. A detailed application note titled “Input System
Instability” is available on the SynQor website which provides
an understanding of why this instability arises, and shows the
preferred solution for correcting it.
V
in(+)
External
Input
Filter
Electrolytic
Capacitor
V
out(+)
V
sense(+)
R
trim-up
or
V
in
ON/OFF
Trim
V
sense( )
_
R
trim-down
C
load
I
load
V
in(
_
)
V
out(
_
)
Figure C: Typical application circuit (negative logic unit, permanently enabled).
Input Filtering and External Capacitance:
Figure D
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 on the Electrical Characteristics
page. More detailed information is available in the application note
titled “EMI Characteristics” on the SynQor website.
L
V
in(+)
C
V
in(
_
)
Figure D: Internal Input Filter Diagram (component values
listed on the specifications page).
Product # IQ24xxxHPxxx
Phone 1-888-567-9596
www.synqor.com
Doc.# 005-0005229 Rev. A
05/26/09
Page 26
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