pq30033qga25 SynQor Worldwide Headquarters, pq30033qga25 Datasheet - Page 10

• Manufacturer Part Number: pq30033qga25
• Description: Quarter-brick Dc/dc Converter
• Manufacturer: SynQor Worldwide Headquarters

Product # PQ30033QGA25
T
T
BASIC OPERATION AND FEATURES
The Power Qor series converter uses a two-stage power conver-
sion topology. The first stage is a buck-converter that keeps the
output voltage constant over variations in line, load, and temper-
ature. The second stage uses a transformer to provide the func-
tions of input/output isolation and voltage step-down to achieve
the low output voltage required.
Both the first stage and the second stage switch at a fixed fre-
quency for predictable EMI performance. Rectification of the
transformer’s output is accomplished with synchronous rectifiers.
These devices, which are MOSFETs with a very low on-state resis-
tance, dissipate far less energy than Schottky diodes. This is the
primary reason that the Power Qor converter has such high effi-
ciency, even at very low output voltages and very high output cur-
rents.
Dissipation throughout the converter is so low that it does not
require a heatsink for operation. Since a heatsink is not required,
the Power Qor converter does not need a metal baseplate or pot-
ting material to help conduct the dissipated energy to the
heatsink. The Power Qor converter can thus be built more simply
and reliably using high yield surface mount techniques on a PCB
substrate.
The Power Qor series of half-brick and quarter-brick converters
uses the industry standard footprint and pin-out configuration.
echnical S
Figure A: Various circuits for driving the ON/OFF pin.
echnical S
Remote Enable Circuit
Open Collector Enable Circuit
ON/OFF
Vin( _
pecification
pecification
)
Phone [phone]
(Permanently Enabled)
ON/OFF
Vin( _
Negative Logic
)
CMOS
TTL/
ON/OFF
Vin( _
)
5V
Direct Logic Drive
(Permanently Enabled)
www.synqor.com
Positive Logic
ON/OFF
Vin( _ )
ON/OFF
Vin( _
)
CONTROL FEATURES
REMOTE ON/OFF (Pin 2): The ON/OFF input, Pin 2, permits
the user to control when the converter is on or off . This input is
referenced to the return terminal of the input bus, Vin(-). There are
two versions of the converter that differ by the sense of the logic
used for the ON/OFF input.
In the positive logic version, the ON/OFF input is active high
(meaning that a high turns the converter on ). In the negative logic
version, the ON/OFF signal is active low (meaning that a low
turns the converter on ). Figure A details five possible circuits for
driving the ON/OFF pin. Figure B is a detailed look of the inter-
nal ON/OFF circuitry.
REMOTE SENSE(+) (Pins 7 and 5): The SENSE(+) inputs cor-
rect for voltage drops along the conductors that connect the con-
verter’s output pins to the load.
Pin 7 should be connected to Vout(+) and Pin 5 should be con-
nected to Vout(-) at the point on the board where regulation is
desired. A remote connection at the load can adjust for a voltage
drop only as large as that specified in this datasheet, that is
Pins 7 and 5 must be connected for proper regulation of the out-
put voltage. If these connections are not made, the converter will
deliver an output voltage that is slightly lower than its specified
value.
Note: the output over-voltage protection circuit senses the voltage
[
Doc.# 005-2QG33LU Rev. B
Vout(+) - Vout(-)
ON/OFF
V
V
Figure B: Internal ON/OFF pin circuitry
in(+)
in( _ )
Sense Range % x Vout
P
P
]
Current:
Current:
ackage:
ackage:
Output:
Output:
–
[V
Input:
Input:
sense(+) -
50k
162k
100pF
50k
4/28/05
18-60 V
3.3 V
25 A
Quarter-brick
18-60 V
3.3 V
25 A
Quarter-brick
V
sense(-)
5V
]
TTL
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