Technical
Specification
IQ36-HP Family
APPLICATIONꢀCONSIDERATIONS
Input System Instability: This condition can occur because Application Circuits:ꢀFigureꢀCꢀprovidesꢀaꢀtypicalꢀꢀcircuitꢀdiagramꢀ
any dc-dc converter appears incrementally as a negative which details the input filtering and voltage trimming.
resistanceꢀload.ꢀAꢀdetailedꢀapplicationꢀnoteꢀtitledꢀ“InputꢀSystemꢀ
Instability”ꢀisꢀavailableꢀonꢀtheꢀSynQorꢀwebsite which provides
an understanding of why this instability arises, and shows the
preferred solution for correcting it.
Vout(+)
Vin(+)
Electrolytic
Capacitor
Vsense(+)
External
Input
Filter
Rtrim-up
Vin
Trim
or
ON/OFF
Vin(_)
Cload
Rtrim-down
Iload
Vsense(_)
Vout(_)
Figure C: Typical application circuit (negative logic unit, permanently enabled).
Input Filtering and External Capacitance: FigureꢀD provides The recommended external input capacitance is specified in the
a diagram showing the internal input filter components. This filter Inputꢀ Characteristicsꢀ sectionꢀ onꢀ theꢀ Electricalꢀ Characteristicsꢀ
dramatically reduces input terminal ripple current, which otherwise page.ꢀꢀMoreꢀdetailedꢀinformationꢀisꢀavailableꢀinꢀtheꢀapplicationꢀnoteꢀ
could exceed the rating of an external electrolytic input capacitor. titled “EMIꢀCharacteristics”ꢀonꢀtheꢀSynQorꢀwebsite.
L
Vin(+)
C
Vin(_)
Figure D: Internal Input Filter Diagram (component values
listed on the specifications page).
Product # IQ36xxxHPXxx
Phone 1-888-567-9596
www.synqor.com
Doc.# 005-0005231 Rev. A
05/26/09
Page 28
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