BQ4H480FTX64 Datasheet, PDF (10/14 Pages) –

Applications Section
Input: 230-400 V
Output: 48 V
Current: 64 A
Package: Full-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 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: 31 V, 28 V, 24 V, 12 V, 9.6 V, or
6 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.
15.0 V
385 Vdc
230-400 Vdc
Front End
BusQor
Converter
48 Vdc
12.0 V
7.5 V
5.0 V
Typical User Board
3.3 V
NiQor
Converters
Loads
Figure A: Example of Intermediate Bus Architecture using isolated or non-
isolated converters.
CONTROL FEATURES
REMOTE ON/OFF (Pin 4): The ON/OFF input, Pin 4,
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.
5V
82.5K
ON/OFF
10K
PIN4
TO ENABLE
CIRCUITRY
PIN5 ^{IN RTN}
Figure B: Internal ON/OFF pin circuitry
SYNCHRONIZATION: The MCOTS converter’s switching
frequency can be synchronized to an external frequency
source that is in the 400 kHz to 500 kHz range. A pulse train
at the desired frequency should be applied to the CLK SYNC
pin (pin 3) with respect to the INPUT RETURN (pin 5). This
pulse train should have a duty cycle in the 20% to 80%
range. Its low value should be below 0.8 V to be guaranteed
to be interpreted as a logic low, and its high value should be
above 2.0 V to be guaranteed to be interpreted as a logic
high. The transition time between the two states should be
less than 300 ns.
If the MCOTS converter is not to be synchronized, the CLK
SYNC pin should be left open circuit. The converter will
then operate in its free-running mode at a frequency of
approximately 550 kHz (twice the switching frequency).
If, due to a fault, the CLK SYNC pin is held in either a
logic low or logic high state continuously, or the CLK SYNC
frequency is outside the 500-600 kHz range, the MCOTS
converter will revert to its free-running frequency.
3.3V
PIN 3
5K
CLK SYNC 5K
TO SYNC
CIRCUITRY
PIN 5
IN RTN
Figure C: Equivalent circuit looking into the CLK SYNC pin with respect to
the IN RTN (input return) pin.
Product # BQ4H480FTx64
Phone [phone]
www.synqor.com
Doc.#005-0006678 Rev. 5
07/18/16
Page 10