Input:
35-75 V
Output:
12 V
Current:
4 A
Package:
Eighth-brick
Technical Specification
BASIC OPERATION AND FEATURES
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,
are two versions of the converter that differ by the sense of the
logic used for the ON/OFF input.
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 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.
Vin(-). There
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.
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 PowerQor converter has such high effi-
ciency, even at very low output voltages and very high output cur-
rents.
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.
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 pot-
ting 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.
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
The PowerQor series of eighth-brick, quarter-brick and half-brick
converters uses the industry standard footprint and pin-out con-
figuration.
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 voltage
ON/OFF
ON/OFF
ON/OFF
_
_
_
Vin( )
Vin( )
Vin( )
Vin(+)
5V
Positive Logic
(Permanently Enabled)
Negative Logic
(Permanently Enabled)
Remote Enable Circuit
274k
5V
ON/OFF
ON/OFF
50k
TTL
TTL/
CMOS
ON/OFF
100pF
50k
_
Vin( )
_
_
Vin( )
Vin( )
Open Collector Enable Circuit
Direct Logic Drive
Figure A: Various circuits for driving the ON/OFF pin.
Figure B: Internal ON/OFF pin circuitry
Product # PQ60120EML04
Phone 1-888-567-9596
www.synqor.com
Doc.# 005-2EM612E Rev. C
04/25/06
Page 9
SYNQOR [ SYNQOR WORLDWIDE HEADQUARTERS ]
