Datasheet

cui.com
date 11/07/2014 │ page 21 of 36CUI Inc │ SERIES: NQB-D │ DESCRIPTION: FULLY REGULATED ADVANCED BUS CONVERTERS
Operating information
This product is equipped with a PMBus interface. The
product incorporates a wide range of readable and
congurable power management features that are simple
to implement with a minimum of external components.
Additionally, the product includes protection features that
continuously safeguard the load from damage due to
unexpected system faults. A fault is also shown as an alert
on the SALERT pin. The following product parameters can
continuously be monitored by a host: Input voltage, output
voltage/current, duty cycle and internal temperature.
The product is delivered with a default conguration
suitable for a wide range operation in terms of input
voltage, output voltage, and load. The conguration is
stored in an internal Non-Volatile Memory (NVM). All
power management functions can be recongured using
the PMBus interface. Please contact your local CUI Power
Modules representative for design support of custom
congurations or appropriate SW tools for design and
down-load of your own congurations.
Power Management Overview
The NQB consists of two different product families
designed for two different input voltage ranges, 36 to 75
Vdc and 40 to 60 Vdc, see ordering information.
The input voltage range 36 to 75 Vdc meets the
requirements of the European Telecom Standard ETS 300
132-2 for normal input voltage range in –48 and –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.
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. The turn on and turn off levels of the product can be
recongured using the PMBus interface
Turn-off Input Voltage
The products are tted with a congurable remote control
function. The primary 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 remote control
functions can also be congured using the PMBus.
Remote Control (RC)
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 standard 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 or disabled via the 0xE3
command. The logic option for the primary remote control is
congured via 0xE3 command using the PMBus.
The CTRL-pin can be congured as remote control via the
PMBus interface. In the default conguration the CTRL-
pin is disabled and oating. The output can be congured
to internal pull-up to 3.3 V using the MFR_MULTI_PIN_
CONFIG (0xF9) PMBus command. The CTRL-pin can be left
open when not used. The logic options for the secondary
remote control can be positive or negative logic. The logic
option for the secondary remote control is congured
via ON_OFF_CONFIG (0x02) command using the PMBus
interface, see also MFR_MULTI_PIN_CONFIG section.
Remote Control (secondary side)
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.
Input and Output Impedance
When powering loads with signicant 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 specication.
The ESR of the capacitors is a very important parameter.
Stable operation is guaranteed with a veried ESR value of
External Decoupling Capacitors
For more information, please visit the product page.