NQB-420NWA-AN Datasheet, PDF (20/30 Pages) CUI INC – FULLY REGULATED ADVANCED BUS CONVERTERS

CUI Inc │ SERIES: NQB-N │ DESCRIPTION: FULLY REGULATED ADVANCED BUS CONVERTERS
date 02/20/2013 │ page 20 of 30
–60 Vdc systems, -40.5 to -57.0 V and –50.0 to -72 V
respectively.
At input voltages exceeding 75 V, the power loss will
be higher than at normal input voltage and T_P1 must be
limited to absolute max +125°C. The absolute maximum
continuous input voltage is 80 Vdc.
The input voltage range 40 to 60 Vdc meets the
requirements for normal input voltage range in -48 V
systems, -40.5 to -57.0 V. At input voltages exceeding
60 V, the power loss will be higher than at normal input
voltage and T_P1 must be limited to absolute max +125°C.
The absolute maximum continuous input voltage is 65 Vdc.
Turn-off Input Voltage
The product monitors the input voltage and will turn
on and turn off at predetermined levels. The minimum
hysteresis between turn on and turn off input voltage is 2
V.
Remote Control (RC)
The products are fitted with a remote control function.
The remote control is referenced to the primary negative
input connection (-In). The RC function allows the
converter to be turned on/off by an external device like a
semiconductor or mechanical switch. The RC pin has an
internal pull up resistor. The device should be capable of
sinking 0.7 mA. When the RC pin is left open, the voltage
generated on the RC pin is max
6 V. The product is provided with
“negative logic” remote control
and will be off until the RC pin is
connected to the -In. To turn on
the product the voltage between
RC pin and -In should be less
than 1 V. To turn off the product
the RC pin should be left open for
a minimum of time 150 µs, the
same time requirement applies
when the product shall turn on. In
situations where it is desired to have the product to power
up automatically without the need for control signals or a
switch, the RC pin can be wired directly to –In
Input and Output Impedance
The impedance of both the input source and the load will
interact with the impedance of the product. It is important
that the input source has low characteristic impedance.
Minimum recommended external input capacitance is 100
µF. The performance in some applications can be enhanced
by addition of external capacitance as described under
External Decoupling Capacitors.
External Decoupling Capacitors
When powering loads with significant dynamic current
requirements, the voltage regulation at the point of load
can be improved by addition of decoupling capacitors at
the load. The most effective technique is to locate low ESR
ceramic and electrolytic capacitors as close to the load
as possible, using several parallel capacitors to lower the
effective ESR. The ceramic capacitors will handle high-
frequency dynamic load changes while the electrolytic
capacitors are used to handle low frequency dynamic load
changes. Ceramic capacitors will also reduce any high
frequency noise at the load. It is equally important to
use low resistance and low inductance PWB layouts and
cabling. External decoupling capacitors will become part
of the product’s control loop. The control loop is optimized
for a wide range of external capacitance and the maximum
recommended value that could be used without any
additional analysis is found in the electrical specification.
The ESR of the capacitors is a very important parameter.
Stable operation is guaranteed with a verified ESR value
of >10 mΩ across the output connections. For further
information please contact your local CUI Power Modules
representative.
Parallel Operation (Droop Load Share, DLS)
The NQB, DLS products are variants that can be connected
in parallel. The products have a pre-configured voltage
droop: The stated output voltage set point is at no load.
The output voltage will decrease when the load current is
increased. The voltage will droop 0.6 V while load reaches
max load. This feature allows the products to be connected
in parallel and share the current with 10% accuracy. Up
to 90% of max output current can be used from each
product.
Voltage regulation DLS products
12.8
12.6
12.4
12.2
12.0
11.8
11.6
0
Module 1
Module 2
Module 1+2
10 20 30 40 50 60 70
Output Current [A]
Feed Forward Capability
The NQB products have a feed forward function
implemented that can handle sudden input voltage
changes. The output voltage will be regulated during an
input transient and will typically stay within 10% when an
input transient is applied.
Soft-start Power Up
The rise time of the ramp up is 10 ms. When starting by
applying input voltage the control circuit boot-up time
adds an additional 15 ms delay. The DLS variants have a
pre-configured ramp up time of
25 ms.
Temperature Protection (OTP, UTP)
The products are protected from thermal overload by an
internal temperature shutdown protection. When T_P1 as
defined in thermal consideration section is exceeded the
product will shut down. The product will make continuous
attempts to start up and resume normal operation
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