Product # BQ55120QZB67

Phone 1-888-567-9596

www.synqor.com

Doc.# 005-0006255 Rev. C

02/10/16

Page 9

Input:

35-55V

Output:

12V

Current:

67 A

Package:

Quarter-brick

Applications Section

Applications Section

BusQor

Converter

Converters

Loads

Front End

Typical User Board

TTL

On/Off

Vin(-)

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 an unregulated

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 points 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: 12 V, 9.6 V, 7.5 V, 5 V, or 3.3

V. 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 BusQor modules act as a true dc transformer. The

output voltage is proportional to the input voltage, with a

specified “turns ratio” or voltage ratio, plus minor drop from

the internal resistive losses in the module. 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.

The BusQor architecture is very scalable, meaning multiple

bus converters can be connected directly in parallel to allow

current sharing for higher power applications.

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(-).

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.

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

and NiQor non-isolated converters

48 Vdc

35 - 55 V

12.0 Vdc

Figure B: Internal ON/OFF pin circuitry

3.3 V

100 K

10 K

220 pF

3.3 V

2.5 V

1.8 V

1.5 V

0.9 V