
Technical Specification
Product # PQ50090QGB11
Phone 1-888-567-9596
www.synqor.com
Doc.# 005-0005485 Rev. A
03/29/10
Page 9
Input:48V
Output:9.0V
Current:11A
Part No.:PQ50090QGB11
Application Section
Open Collector Enable Circuit
Remote Enable Circuit
Direct Logic Drive
Negative Logic
(Permanently
Enabled)
(Permanently
Enabled)
ON/OFF
Vin(_
)
ON/OFF
Vin(_
)
ON/OFF
5V
TTL/
CMOS
Vin(_
)
Vin(_
)
Positive Logic
ON/OFF
Vin(_
)
BASIC OPERATION AND FEATURES
The PowerQor 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 tempera-
ture. The second stage uses a transformer to provide the functions
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
resistance, dissipate far less energy than Schottky diodes. This
is the primary reason that the PowerQor converter has such high
efficiency, even at very low output voltages and very high output
currents.
Dissipation throughout the converter is so low that it does not
require a heatsink for operation. Since a heatsink is not required,
the PowerQor converter does not need a metal baseplate or
potting material to help conduct the dissipated energy to the
heatsink. The PowerQor converter can thus be built more simply
and reliably using high yield surface mount techniques on a PCB
substrate.
The PowerQor series of half-brick and quarter-brick converters
uses the industry standard footprint and pin-out configuration.
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 internal 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 connect-
ed 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
[Vout(+) - Vout(-)] – [Vsense(+) - Vsense(-)] <
Sense Range % x Vout
Pins 7 and 5 must be connected for proper regulation of the output
voltage. If these connections are not made, the converter will deliver
an output voltage that is slightly higher than its specified value.
Note: the output over-voltage protection circuit senses the voltage
across the output (pins 8 and 4) to determine when it should trigger,
not the voltage across the converter’s sense leads (pins 7 and 5).
Therefore, the resistive drop on the board should be small enough so
that output OVP does not trigger, even during load transients.
Figure A: Various circuits for driving the ON/OFF pin.
Figure B: Internal ON/OFF pin circuitry
TTL
5V
50k
162k
ON/OFF
Vin(_)
Vin(+)
100k