Product # PQ60018HPA80

Phone 1-888-567-9596

www.synqor.com

Doc.# 005-2HP618K Rev. E

03/06/06

Page 9

Input:

Input:

Output:

Output:

Current:

Current:

ackage:

35-75 V

35-75 V

1.8 V

1.8 V

80 A

80 A

Half-brick

Half-brick

T

pecification

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 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 PowerQor 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 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.

The PowerQor series of half-brick, quarter-brick and eighth-brick

converters uses the industry standard footprint and pin-out con-

figuration.

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 9 and 7): The SENSE(+) inputs cor-

rect for voltage drops along the conductors that connect the con-

verter’s output pins to the load.

Pin 9 should be connected to Vout(+) and Pin 7 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

Sense Range % x Vout

Pins 9 and 7 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

Open Collector Enable Circuit

Figure A: Various circuits for driving the ON/OFF pin.

Figure B: Internal ON/OFF pin circuitry

Remote Enable Circuit

Direct Logic Drive

Negative Logic

(Permanently Enabled)

Positive Logic

(Permanently Enabled)

ON/OFF

Vin(_

)

ON/OFF

ON/OFF

Vin(_

)

ON/OFF

5V

TTL/

CMOS

Vin(_

)

ON/OFF

Vin(_)

Vin(_

)

TTL

5V

50k

274k

ON/OFF

50k

100pF