Technical
Specification
IQ36-HP Family
Startup Inhibit Period:ꢀTheꢀStartupꢀInhibitꢀPeriodꢀensuresꢀthatꢀ Whenꢀ theꢀ ON/OFFꢀ pinꢀ goesꢀ highꢀ afterꢀ t2,ꢀ theꢀ Startupꢀ Inhibitꢀ
theꢀconverterꢀwillꢀremainꢀoffꢀforꢀapproximatelyꢀ200ꢀmsꢀwhenꢀitꢀisꢀ Period has elapsed, and the output turns on within the typical
shut down for any reason. When an output short is present, this Turn-OnꢀTime.
generatesꢀ aꢀ 5ꢀ Hzꢀ “hiccupꢀ mode,”ꢀ whichꢀ preventsꢀ theꢀ converterꢀ
from overheating. In all, there are seven ways that the converter
canꢀbeꢀshutꢀdown,ꢀinitiatingꢀaꢀStartupꢀInhibitꢀPeriod:
Thermal Considerations: The maximum operating base-plate
temperature, TB,ꢀisꢀ100ꢀºC.ꢀAsꢀlongꢀasꢀtheꢀuser’sꢀthermalꢀsystemꢀ
keeps TB <ꢀ100ꢀºC,ꢀtheꢀconverterꢀcanꢀdeliverꢀitsꢀfullꢀratedꢀpower.
•ꢀ InputꢀUnder-VoltageꢀLockout
•ꢀ InputꢀOver-VoltageꢀShutdown
•ꢀ OutputꢀOver-VoltageꢀProtection
•ꢀ OverꢀTemperatureꢀShutdown
•ꢀ CurrentꢀLimit
Aꢀpowerꢀderatingꢀcurveꢀcanꢀbeꢀcalculatedꢀforꢀanyꢀheatsinkꢀthatꢀisꢀ
attached to the base-plate of the converter. It is only necessary
toꢀdetermineꢀtheꢀthermalꢀresistance,ꢀRTHBA, of the chosen heatsink
between the base-plate and the ambient air for a given airflow
rate. This information is usually available from the heatsink
vendor. The following formula can the be used to determine the
maximum power the converter can dissipate for a given thermal
conditionꢀifꢀitsꢀbase-plateꢀisꢀtoꢀbeꢀnoꢀhigherꢀthanꢀ100ꢀºC.
•ꢀ ShortꢀCircuitꢀProtection
•ꢀ TurnedꢀoffꢀbyꢀtheꢀON/OFFꢀinput
FigureꢀEꢀshowsꢀthreeꢀturn-onꢀscenarios,ꢀwhereꢀaꢀStartupꢀInhibitꢀ
Period is initiated at t0, t1, and t2:
100 ºCꢀ-ꢀTA
Pmax
=
dissꢀꢀꢀꢀꢀꢀꢀRTH
BA
Beforeꢀtimeꢀt0,ꢀwhenꢀtheꢀinputꢀvoltageꢀisꢀbelowꢀtheꢀUVLꢀthreshold,ꢀ
theꢀunitꢀisꢀdisabledꢀbyꢀtheꢀInputꢀUnder-VoltageꢀLockoutꢀfeature.ꢀ
WhenꢀtheꢀinputꢀvoltageꢀrisesꢀaboveꢀtheꢀUVLꢀthreshold,ꢀtheꢀInputꢀ
Under-VoltageꢀLockoutꢀisꢀreleased,ꢀandꢀaꢀStartupꢀInhibitꢀPeriodꢀisꢀ
initiated.ꢀꢀAtꢀtheꢀendꢀofꢀthisꢀdelay,ꢀtheꢀON/OFFꢀpinꢀisꢀevaluated,ꢀ
and since it is active, the unit turns on.
Thisꢀvalueꢀofꢀpowerꢀdissipationꢀcanꢀthenꢀbeꢀusedꢀinꢀconjunctionꢀ
withꢀtheꢀdataꢀshownꢀinꢀFigureꢀ2ꢀtoꢀdetermineꢀtheꢀmaximumꢀloadꢀ
currentꢀ(andꢀpower)ꢀthatꢀtheꢀconverterꢀcanꢀdeliverꢀinꢀtheꢀgivenꢀ
thermal condition.
Forꢀconvenience,ꢀpowerꢀderatingꢀcurvesꢀforꢀanꢀencasedꢀconverterꢀ
without a heatsink and with a typical heatsink are provided for
each output voltage.
Atꢀtimeꢀt1,ꢀtheꢀunitꢀisꢀdisabledꢀbyꢀtheꢀON/OFFꢀpin,ꢀandꢀitꢀcannotꢀ
beꢀenabledꢀagainꢀuntilꢀtheꢀStartupꢀInhibitꢀPeriodꢀhasꢀelapsed.
V
in
Under-Voltageꢀ
LockoutꢀTurn-
OnꢀThreshold
ON/OFF
(negꢀlogic)
ON
OFF
ON
OFF
ON
9ms (typical
turnꢀonꢀtime)
V
out
200ms
(typicalꢀstart-upꢀ
inhibitꢀperiod)
200ms
200ms
t
t0
t1
t2
Figure E: Startup Inhibit Period (turn-on time not to scale)
Product # IQ36xxxHPXxx
Phone 1-888-567-9596
www.synqor.com
Doc.# 005-0005231 Rev. A
05/26/09
Page 29
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