QTS48T38096 DC-DC Series Data Sheet
365-Watt @ 48Vin Quarter-Brick Bus Converter
Characteristic Curves
Shutdown Feature Description
The ON/OFF pin in the QTS48T38096 converter
functions as a normal soft shutdown. It is referenced
to the –Vin pin (see Figure 3). With the positive
logic, when the ON/OFF pin is pulled low, the output
is turned off and the unit goes into a very low input
power mode.
Efficiency Vs Load
100.00
98.00
96.00
94.00
92.00
90.00
88.00
86.00
84.00
82.00
80.00
With negative logic, when the ON/OFF pin is pulled
low, the unit is turned on.
36
48
55
An open collector switch is recommended to control
the voltage between the ON/OFF pin and the -Vin
pin of the converter. The ON/OFF pin is pulled up
internally, so no external voltage source is required.
The user should avoid connecting a resistor between
the ON/OFF pin and the +Vin pin.
When the ON/OFF pin is used to achieve remote
control, the user must take care to insure that the pin
Load (%)
Figure 1. QTS48T38096 Efficiency vs. Output Load
reference for the control is really the -Vin pin. The
control signal must not be referenced ahead of EMI
filtering, or remotely from the unit. Optically coupling
the information and locating the optical coupler
directly at the module will solve any of these
problems.
Typical Application
Figure 2 shows the recommended connections for
the QTS48T38096 converter.
Note:
If the ON/OFF pin is not used, it can be left floating (positive logic),
or connected to the -Vin pin (negative logic).
Parallel Operation
The following precautions must be observed when
operating two or more QTS48T38096’s in parallel:
1. The inputs of all units must be attached to
the same voltage source
Figure 2. Typical Application of QTS48T38096
2. The PCB trace resistance into each unit
should be equalized as much as is practical.
3. The enable pins must be tied together and
operated as a single unit.
The QTS48T38096 converter does not require any
external components for proper operation. However,
if the distribution of the input voltage to the converter
contains significant inductance, a capacitor C1 may
be required to enhance performance of the
converter. A minimum of a 100 μF electrolytic
capacitor with the ESR<0.5Ω at 100 kHz is
recommended for the QTS48T38096.
4. The under voltage lockout start-up point will
vary from unit to unit, therefore the dv/dt of
the input source as it rises from 0 V to its
final value will affect the ability of the parallel
units to turn on into a load equal to more that
the maximum rated load of 1 unit. The dv/dt
of the rising edge of the input voltage must
be greater than 2V/mS. If three units are to
be operated in parallel, it is strongly
recommended that the maximum load
current be limited to the maximum current
rating of a single unit until the output voltage
exceeds 90% of the rated output voltage.
5. The accuracy of the current sharing will be
affected by the series impedance between
each unit at the load. Balancing these
Refer to the “Inrush Current Control Application
Note” on www.power-one.com for suggestions on
how to limit the magnitude of the inrush current.
For output decoupling we recommend to use a 10μF
low ESR tantalum (AVX TPSC106M025R0500 is
used in our test setup) and a 1μF ceramic
capacitors.
Note, that the capacitors do not
substitute the filtering required by the load.
MAY 20, 2005 revised to JUN 15, 2006
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