PQ60240QGA05 Datasheet, PDF (9/13 Pages) SynQor Worldwide Headquarters – Quarter-brick DC/DC Converter

Technical Specification
Input: 35 - 75 V
Output: 24 V
Current: 5.0 A
Package: Quarter-brick
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 inter-
nal 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(-)] – [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 speci-
fied value.
ON/OFF
ON/OFF
ON/OFF
Vin(^_)
Remote Enable Circuit
Vin(^_)
Vin(^_)
Negative Logic
Positive Logic
(Permanently Enabled) (Permanently Enabled)
ON/OFF
5V
TTL/
CMOS
ON/OFF
Vin(^_)
Open Collector Enable Circuit
Vin(^_)
Direct Logic Drive
Figure A: Various circuits for driving the ON/OFF pin.
Product # PQ60240QGA05
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Vin(+)
ON/OFF
Vin(^_)
274k
50k
100pF
50k
5V
TTL
Figure B: Internal ON/OFF pin circuitry
Doc.# 005-2-QGA624D Rev. B 10/01/08
Page 9