Q48T20050-NBB0 POWER ONE, Q48T20050-NBB0 Datasheet - Page 8

• Manufacturer Part Number: Q48T20050-NBB0
• Manufacturer: POWER ONE
• Type: Step Downr

Specifications of Q48T20050-NBB0

• Number Of Outputs: 1
• Output Current: 20A
• Input Voltage: 48V
• Output Voltage: 5V
• Screening Level: Industrial
• Product Length (mm): 36.83mm
• Product Height (mm): 6.52mm
• Product Depth (mm): 58.42mm
• Mounting Style: Through Hole
• Pin Count: 8
• Package / Case: Quarter-Brick
• Lead Free Status / Rohs Status: Not Compliant

Protection Features
Input Undervoltage Lockout
Input undervoltage lockout is standard with this converter.
The converter will shut down when the input voltage drops
below a pre-determined voltage.
The input voltage must be at least 35 V for the converter to
turn on. Once the converter has been turned on, it will shut
off when the input voltage drops below 31 V. This feature is
beneficial in preventing deep discharging of batteries used in
telecom applications.
Output Overcurrent Protection (OCP)
The converter is protected against overcurrent or short cir-
cuit conditions. Upon sensing an overcurrent condition, the
converter will switch to constant current operation and
thereby begin to reduce output voltage. When the output
voltage drops below 2.5 Vdc, the converter will shut down
(Fig. 26).
Once the converter has shut down, it will attempt to restart
nominally every 100 ms with a 1% duty cycle (Fig 27). The
attempted restart will continue indefinitely until the overload
or short circuit conditions are removed or the output voltage
rises above 2.5 Vdc.
Output Overvoltage Protection (OVP)
The converter will shut down if the output voltage across
Vout(+) (Pin 8) and Vout(-) (Pin 4) exceeds the threshold of
the OVP circuitry. The OVP circuitry contains its own refer-
ence, independent of the output voltage regulation loop.
Once the converter has shut down, it will attempt to restart
every 100 ms until the OVP condition is removed.
Overtemperature Protection (OTP)
The converter will shut down under an overtemperature con-
dition to protect itself from overheating caused by operation
outside the thermal derating curves, or operation in abnor-
mal conditions such as system fan failure. After the con-
verter has cooled to a safe operating temperature, it will
automatically restart.
NOV 07, 2003 revised to NOV 20, 2006
Q48T20050 and Q48S20050 DC-DC Converter Data Sheet
Page 8 of 15
36-75 VDC Input; 5.0 VDC @ 20A Output
Safety Requirements
The converters meet North American and International
safety regulatory requirements per UL60950 and EN60950.
Basic Insulation is provided between input and output.
To comply with safety agencies requirements, an input line
fuse must be used external to the converter. A 5-A fuse is
recommended for use with this product.
Electromagnetic Compatibility (EMC)
EMC requirements must be met at the end-product system
level, as no specific standards dedicated to EMC character-
istics of board mounted component dc-dc converters exist.
However, Power-One tests its converters to several system
level standards, primary of which is the more stringent
EN55022, Information technology equipment - Radio distur-
bance characteristics - Limits and methods of measurement.
With the addition of a simple external filter (see application
notes), all versions of the Q48T/S20 converters pass the
requirements of Class B conducted emissions per EN55022
and FCC, and meet at a minimum, Class A radiated emis-
sions per EN 55022 and Class B per FCC Title 47CFR, Part
15-J. Please contact Power-One Applications Engineering
for details of this testing.
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