Technical Specification
BASIC OPERATION AND FEATURES
The
PowerQor
series converter 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 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 trans-
former’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.
Input:
Output:
Current:
Package:
CONTROL FEATURES
35-75 V
5.0 V
30 A
Quarter-brick
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
correct for voltage drops along the conductors that connect the
converter’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
[
Vout(+) - Vout(-)
]
–
[V
sense(+) -
V
sense(-)
]
<
Sense Range % x Vout
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 higher than its specified
value.
Note: the output over-voltage protection circuit senses the volt-
age 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.
ON/OFF
ON/OFF
ON/OFF
Vin(
_
)
Remote Enable Circuit
Vin(
_
)
Negative Logic
(Permanently Enabled)
Vin(
_)
Positive Logic
(Permanently Enabled)
V
in(
+
)
274k
ON/OFF
50k
5V
ON/OFF
5V
ON/OFF
TTL
TTL/
CMOS
100pF
50k
V
in(
_
)
Vin(
_
)
Vin(
_
)
Open Collector Enable Circuit
Direct Logic Drive
Figure B:
Internal ON/OFF pin circuitry
Figure A:
Various circuits for driving the ON/OFF pin.
Product # PQ60050QTA30
Phone 1-888-567-9596
www.synqor.com
Doc.# 005-2QT650C Rev. E
05/20/09
Page 9
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