HBA48T12280 Power-One, HBA48T12280 Datasheet - Page 5

• Manufacturer Part Number: HBA48T12280
• Description: Hba48t12280 Dc-dc Converter 36-75 Vdc Input; 28 Vdc @ 12.5 A Output
• Manufacturer: Power-One

Operations
Input and Output Impedance
These power converters have been designed to be
stable with a minimum external output capacitor of
220 µF when used in low inductance input and
output circuits.
lower than -20 ºC, use 3 x 220 µF capacitors rated at
50V to reduce ESR. Use Nichicon UPW1H221MPD
or equivalent.
In many applications, the inductance associated with
the distribution from the power source to the input of
the converter can affect the stability of the converter.
It is recommended that a 33 µF capacitor with a
voltage rating of 100 VDC and an ESR <0.1 Ω be
used across the input of the HBA48T12280 to
ensure stability of the converter. At temperatures
< -20 ºC, use 2 X 33 µF capacitors to reduce the
effective ESR of the input capacitance.
In applications where decoupling capacitance is
distributed at the load, the power converter will
exhibit stable operation with up to the maximum
admissible
connected.
(Refer to “Output Specifications” table for value of
C
Remote Sense
The
compensates for voltage drops occurring between
the output pins of the converter and the load. The
SENSE(–) and SENSE(+) pins should be connected
at the load or at the point where regulation is
required (see Figure A).
Caution:
If remote sensing is not utilized, the SENSE(–) pin
connected to the Vout(–) pin, and the SENSE(+) pin must be
connected to the Vout(+) pin to ensure the converter will regulate
at the specified output voltage. If these connections are not made,
the converter will deliver an output voltage that is slightly higher
than the specified data sheet value.
BCD.00009.1 Rev. AA, 20-Oct-09
VIN
EXT
)
remote
Figure A: Remote sense circuit configuration.
external
sense
When
ON/OFF
VIN (+)
VIN (-)
CASE
feature
(Top View)
load
the ambient temperature is
SENSE (+)
SENSE (-)
VOUT (+)
capacitance
VOUT (-)
TRIM
of
the
Rw
Rw
converter
must be
(C
HBA48T12280 DC-DC Converter Data Sheet
EXT
36-75 VDC Input; 28 VDC @ 12.5 A Output
Rload
Page 5 of 14
)
Because the sense leads carry minimal current,
large traces on the end-user board are not required.
However, sense traces should be run side by side
and located close to a ground plane to minimize
system noise and ensure optimum performance.
The converter’s output overvoltage protection (OVP)
circuitry senses the voltage across Vout(+) and
Vout(-), and not across the +/– sense lines, so the
resistance (and resulting voltage drop) between the
output pins of the converter and the load should be
minimized to prevent unwanted triggering of the
OVP.
When utilizing the remote sense feature, care must
be taken not to exceed the maximum allowable
output power capability of the converter, which is
equal to the product of the nominal output voltage
and the allowable output current for the given
conditions.
When using remote sense, the output voltage at the
converter can be increased by as much as 5% above
the nominal rating in order to maintain the required
voltage across the load. Therefore, the designer
must, if necessary, decrease the maximum current
(originally obtained from the derating curves) by the
same percentage to ensure the converter’s actual
output power remains at or below the maximum
allowable output power.
ON/OFF Control
Models designated Negative Logic Enable turn the
converter off during a logic –high or open-circuit and
on during a logic-low or a short from the on/off pin to
–Vin.
Models designated Positive Logic Enable turn the
converter off during a logic-low or a short from on/off
pin to –Vin and on during a logic-high or open circuit.
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