Product # PQ60120HPA20
Phone 1-888-567-9596
www.synqor.com
Doc.# 005-2HP612K Rev. F
08/12/09
Page 9
Input:
Output:
Current:
Package:
35-75 V
12 V
20 A
Half-brick
Technical Specification
BASICOPERATIONANDFEATURES
The PowerQor series converter uses a two-stage power
conversion topology. The first stage is a buck-converter that
keepstheoutputvoltageconstantovervariationsinline,load,
and temperature. The second stage uses a transformer to
providethefunctionsofinput/outputisolationandvoltagestep-
downtoachievethelowoutputvoltagerequired.
Both the first stage and the second stage switch at a fixed
frequencyforpredictableEMIperformance.Rectificationofthe
transformer’soutputisaccomplishedwithsynchronousrectifiers.
These devices, which are MOSFETs with a very low on-state
resistance,dissipatefarlessenergythanSchottkydiodes.This
is the primary reason that the PowerQor converter has such
highefficiency,evenatverylowoutputvoltagesandveryhigh
outputcurrents.
Dissipationthroughouttheconverterissolowthatitdoesnot
requireaheatsinkforoperation.Sinceaheatsinkisnotrequired,
the PowerQor converter does not need a metal baseplate or
potting material to help conduct the dissipated energy to the
heatsink.ThePowerQorconvertercanthusbebuiltmoresimply
andreliablyusinghighyieldsurfacemounttechniquesonaPCB
substrate.
The PowerQor series of half-brick, quarter-brick and eighth-
brickconvertersusestheindustrystandardfootprintandpin-out
configuration.
CONTROLFEATURES
REMOTE ON/OFF (Pin 2):TheON/OFFinput,Pin2,permits
theusertocontrolwhentheconverterisonoroff.Thisinput
isreferencedtothereturnterminaloftheinputbus,Vin(-).
Therearetwoversionsoftheconverterthatdifferbythesense
ofthelogicusedfortheON/OFFinput.
In the positive logic version, the ON/OFF input is active high
(meaningthatahighturnstheconverter on).Inthenegative
logicversion,theON/OFFsignalisactivelow(meaningthata
lowturnstheconverteron).FigureAdetailsfivepossiblecircuits
for driving the ON/OFF pin. Figure B is a detailed look of the
internalON/OFFcircuitry.
REMOTE SENSE(+) (Pins 8 and 6): The SENSE(+) inputs
correctforvoltagedropsalongtheconductorsthatconnectthe
converter’soutputpinstotheload.
Pin 8 should be connected to Vout(+) and Pin 6 should be
connectedtoVout(-)atthepointontheboardwhereregulation
is desired. A remote connection at the load can adjust for a
voltage drop only as large as that specified in this datasheet,
thatis
[Vout(+)-Vout(-)]–[Vsense(+)-Vsense(-)]<
SenseRange%xVout
Pins 8 and 6 must be connected for proper regulation of
the output voltage. If these connections are not made, the
converterwilldeliveranoutputvoltagethatisslightlylowerthan
itsspecifiedvalue.
Figure A: Various circuits for driving the ON/OFF pin.
Open Collector Enable Circuit
Remote Enable Circuit
Direct Logic Drive
Negative Logic
(Permanently Enabled)
ON/OFF
Vin(_
)
ON/OFF
Vin(_
)
ON/OFF
5V
TTL/
CMOS
Vin(_
)
Vin(_
)
Positive Logic
(Permanently Enabled)
ON/OFF
Vin(_
)
TTL
5V
50k
274k
50k
ON/OFF
Vin(_)
Vin(+)
100pF
Figure B: Internal ON/OFF pin circuitry
PQ60120HPA20 Application Section