Technical
Specification
IQ36-HP Family
BASICꢀOPERATIONꢀANDꢀFEATURES
CONTROLꢀFEATURES
This converter series uses a two-stage power conversion
topology. The first stage is a buck-converter that keeps the
output voltage constant over variations in line, load, and
temperature. The second stage uses a transformer to provide
theꢀ functionsꢀ ofꢀ input/outputꢀ isolationꢀ andꢀ voltageꢀ step-upꢀ orꢀ
step-down to achieve the output voltage required.
REMOTE ON/OFF (Pin 2):ꢀTheꢀON/OFFꢀinput,ꢀPinꢀ2,ꢀpermitsꢀ
the user to control when the converter is on or off. This input
isꢀ referencedꢀ toꢀ theꢀ returnꢀ terminalꢀ ofꢀ theꢀ inputꢀ bus,ꢀ Vin(-).ꢀ
TheꢀON/OFFꢀsignalꢀisꢀactiveꢀlowꢀ(meaningꢀthatꢀaꢀlowꢀturnsꢀtheꢀ
converterꢀon).ꢀFigureꢀAꢀdetailsꢀfourꢀpossibleꢀcircuitsꢀforꢀdrivingꢀ
theꢀON/OFFꢀpin.ꢀFigureꢀBꢀisꢀaꢀdetailedꢀlookꢀofꢀtheꢀinternalꢀON/
OFFꢀcircuitry.
Bothꢀ theꢀ firstꢀ stageꢀ andꢀ theꢀ secondꢀ stageꢀ switchꢀ atꢀ aꢀ fixedꢀ
frequencyꢀ forꢀ predictableꢀ EMIꢀ performance.ꢀ Rectificationꢀ ofꢀ
theꢀ transformer’sꢀ outputꢀ isꢀ accomplishedꢀ withꢀ synchronousꢀ
rectifiers.ꢀ Theseꢀ devices,ꢀ whichꢀ areꢀ MOSFETsꢀ withꢀ aꢀ veryꢀ lowꢀ
on-stateꢀ resistance,ꢀ dissipateꢀ farꢀ lessꢀ energyꢀ thanꢀ Schottkyꢀ
diodes. This is the primary reason that the converter has such
high efficiency, even at very low output voltages and very high
output currents.
REMOTE SENSE(+) (Pins 7 and 5):ꢀ Theꢀ SENSE(+)ꢀ inputsꢀ
correct for voltage drops along the conductors that connect the
converter’sꢀoutputꢀpinsꢀtoꢀtheꢀload.
Pinꢀ 7ꢀ shouldꢀ beꢀ connectedꢀ toꢀ Vout(+)ꢀ andꢀ Pinꢀ 5ꢀ shouldꢀ beꢀ
connectedꢀtoꢀVout(-)ꢀatꢀtheꢀpointꢀonꢀtheꢀboardꢀwhereꢀregulationꢀ
isꢀ desired.ꢀ Aꢀ remoteꢀ connectionꢀ atꢀ theꢀ loadꢀ canꢀ adjustꢀ forꢀ aꢀ
voltage drop only as large as that specified in this datasheet,
that is
These converters are offered totally encased to withstand harsh
environmentsꢀandꢀthermallyꢀdemandingꢀapplications.ꢀDissipationꢀ
throughout the converter is so low that it does not require a
heatsinkꢀ forꢀ operationꢀ inꢀ manyꢀ applications;ꢀ however,ꢀ addingꢀ
a heatsink provides improved thermal derating performance in
extreme situations.
[Vout(+)ꢀ-ꢀVout(-)]ꢀ–ꢀ[Vsense(+)ꢀ-ꢀVsense(-)] <
SenseꢀRangeꢀ%ꢀxꢀVout
Pinsꢀ 7ꢀ andꢀ 5ꢀ mustꢀ beꢀ connectedꢀ forꢀ properꢀ regulationꢀ ofꢀ
the output voltage. If these connections are not made, the
converter will deliver an output voltage that is slightly higher
than its specified value.
This series of converters use the industry standard footprint and
pin-out configuration.
Note:ꢀ theꢀ outputꢀ over-voltageꢀ protectionꢀ circuitꢀ sensesꢀ theꢀ
voltageꢀ acrossꢀ theꢀ outputꢀ (pinsꢀ 8ꢀ andꢀ 4)ꢀ toꢀ determineꢀ whenꢀ
itꢀ shouldꢀ trigger,ꢀ notꢀ theꢀ voltageꢀ acrossꢀ theꢀ converter’sꢀ senseꢀ
leadsꢀ(pinsꢀ7ꢀandꢀ5).ꢀꢀTherefore,ꢀtheꢀresistiveꢀdropꢀonꢀtheꢀboardꢀ
shouldꢀ beꢀ smallꢀ enoughꢀ soꢀ thatꢀ outputꢀ OVPꢀ doesꢀ notꢀ trigger,ꢀ
even during load transients.
ON/OFF
ON/OFF
Vin(_)
Vin(_)
Remote Enable Circuit
Negative Logic
(Permanently Enabled)
5V
5V
ON/OFF
50k
TTL/
CMOS
ON/OFF
Vin(_)
50k
ON/OFF
Vin(_)
Vin(_)
Open Collector Enable Circuit
Direct Logic Drive
TTL
100pF
Figure A: Various circuits for driving the ON/OFF pin.
Figure B: Internal ON/OFF pin circuitry
Product # IQ36xxxHPXxx
Phone 1-888-567-9596
www.synqor.com
Doc.# 005-0005231 Rev. A
05/26/09
Page 26
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