Product # SQ60120QPB33

Phone 1-888-567-9596

www.synqor.com

Doc.# 005-0005266 Rev. G

05/13/15

Page 10

Technical

Specification

SQ60120QPB33

Application Section

Application Section

BASIC OPERATION AND FEATURES

With voltages dropping and currents rising, the economics

of an Intermediate Bus Architecture (IBA) are becoming

more attractive, especially in systems requiring multiple

low voltages. IBA systems separate the role of isolation and

voltage scaling from regulation and sensing. The BusQor

series bus converter provides isolation and a coarse voltage

step down in one compact module, leaving regulation to

simpler, less expensive non-isolated converters.

In Figure A below, the BusQor module provides the isolation

stage of the IBA system. The isolated bus then distributes

power to the non-isolated buck regulators to generate the

required voltage levels at the point of load. In this case, the

bucks are represented with SynQor’s NiQor series of non-

isolated dc-dc converters. In many applications requiring

multiple low voltage outputs, significant savings can be

achieved in board space and overall system costs.

When designing an IBA system with bus converters, the

designer can select from a variety of bus voltages. While

there is no universally ideal bus voltage, most designs

employ one of the following: 12V, 9V, 7.5V, 5V, or 3.3V.

Higher bus voltages can lead to lower efficiency for the buck

regulators but are more efficient for the bus converter and

provide lower board level distribution current. Lower bus

voltages offer the opposite trade offs.

SynQor’s SQ BusQor modules accept the full 48/60V

telecom bus voltage and have a narrow output voltage

range compatible with many non-isolated point of load

converters. When used in IBA systems, the output variation

of the BusQor must be in accordance with the input voltage

range of the non-isolated converters being employed.

BusQor

Converter

NiQor

Converters

Loads

48Vdc

Front End

Typical User Board

3.3V

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 B is a

detailed look of the internal ON/OFF circuitry.

TTL

ON/OFF

2.5V

1.8V

1.5V

0.9V

12Vdc

48Vdc

36-75V

Figure A: Example of Intermediate Bus Architecture using BusQor bus converter

and NiQor non-isolated converters

5V

+5V

124k

49.9k

100k

Figure B: Internal ON/OFF pin circuitry