SQ60120QPA28 Datasheet, PDF (9/12 Pages) SynQor Worldwide Headquarters – Quarter-brick DC-DC Converter

Technical Specification
Input: 36-75 V
Output: 12 V
Current: 28 A
Package: Quarter-brick
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 lev-
els 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, signifi-
cant 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 univer-
sally 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 cur-
rent. 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 accor-
dance with the input voltage range of the non-isolated converters
being employed.
3.3 V
48Vdc
42-53V
BusQor ^12Vdc
Converter
2.5 V
1.8 V
1.5 V
Typical User Board
0.9 V
NiQor _Loads
Converters
48Vdc
Front
End
Figure A: Example of Intermediate Bus Architecture using
BusQor bus converter and NiQor non-isolated converters
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.
Vin+
On/Off
Vin-
+5V
124k
49.9k
100k
5V
TTL
Figure B: Internal ON/OFF pin circuitry
PROTECTION FEATURES
Input Under-Voltage Lockout: The converter is designed
to turn off when the input voltage is too low, helping avoid an
input system instability problem, described in more detail in the
application note titled “Input System Instability” available on the
SynQor website. The lockout circuitry is a comparator with DC
hysteresis. When the input voltage is rising, it must exceed the
typical Turn-On Voltage Threshold value (listed on the specifica-
tion page) before the converter will turn on. Once the converter is
on, the input voltage must fall below the typical Turn-Off Voltage
Threshold value before the converter will turn off. Also see
Figure E.
Output Current Limit: The output of the BusQor module is
electronically protected against output overloads. When an
overload current greater than the “DC Current-Limit Inception”
specification is drawn from the output, the output of the BusQor
will shutdown to zero volts after the 1 ms have elapsed (see
Figure C). The shutdown period lasts for a typical period of 200
ms (Figure D) after which the BusQor tries to power up again.
If the overload persists, the output voltage will go through
Product # SQ60120QPA28
Phone [phone]
www.synqor.com
Doc.# 005-2SQ612J Rev. B
06/17/09
Page 9