PAQ Datasheet, PDF (12/16 Pages) Murata Manufacturing Co., Ltd. – Up to 150W 29.8V Nom Output Quarter-Brick Isolated DC-DC Converter with 2:1 Wide Input Range

PAQ Series
Up to 150W 29.8V Nom Output Quarter-Brick Isolated
DC-DC Converter with 2:1 Wide Input Range
TECHNICAL NOTES
Input Fusing
Certain applications and/or safety agencies may require fuses at the inputs of
power conversion components. Fuses should also be used when there is the
possibility of sustained input voltage reversal which is not current-limited. For
greatest safety, we recommend a fast blow fuse installed in the +Vin input
supply line.
The installer must observe all relevant safety standards and regulations. For
safety agency approvals, install the converter in compliance with the end-user
safety standard.
Input Under-Voltage Shutdown and Start-Up Threshold
Under normal start-up conditions, converters will not begin to regulate properly
until the rising input voltage exceeds and remains at the Start-Up Threshold
Voltage (see Specifications). Once operating, converters will not turn off until
the input voltage drops below the Under-Voltage Shutdown Limit. Subsequent
restart will not occur until the input voltage rises again above the Start-Up
Threshold. This built-in hysteresis prevents any unstable on/off operation at a
single input voltage.
Users should be aware however of input sources near the Under-Voltage
Shutdown whose voltage decays as input current is consumed (such as capaci-
tor inputs), the converter shuts off and then restarts as the external capacitor
recharges. Such situations could oscillate. To prevent this, make sure the operat-
ing input voltage is well above the UV Shutdown voltage AT ALL TIMES.
Start-Up Delay
Assuming that the output current is set at the rated maximum, the Vin to Vout Start-
Up Delay (see Specifications) is the time interval between the point when the rising
input voltage crosses the Start-Up Threshold and the fully loaded regulated output
voltage enters and remains within its specified regulation band. Actual measured
times will vary with input source impedance, external input capacitance, input volt-
age slew rate and final value of the input voltage as it appears at the converter.
These converters include a soft start circuit to moderate the duty cycle of the
PWM controller at power up, thereby limiting the input inrush current.
The On/Off Remote Control interval from inception to VOUT regulated assumes
that the converter already has its input voltage stabilized above the Start-Up
Threshold before the On command. The interval is measured from the On com-
mand until the output enters and remains within its specified regulation band.
The specification assumes that the output is fully loaded at maximum rated
current.
inductance. Excessive input inductance may inhibit operation. The DC input
regulation specifies that the input voltage, once operating, must never degrade
below the Shut-Down Threshold under all load conditions. Be sure to use
adequate trace sizes and mount components close to the converter.
I/O Filtering, Input Ripple Current and Output Noise
All models in this converter series are tested and specified for input reflected
ripple current and output noise using designated external input/output compo-
nents, circuits and layout as shown in the figures below. External input capaci-
tors (CIN in the figure) serve primarily as energy storage elements, minimizing
line voltage variations caused by transient IR drops in the input conductors.
Users should select input capacitors for bulk capacitance (at appropriate fre-
quencies), low ESR and high RMS ripple current ratings. In the figure below, the
CBUS and LBUS components simulate a typical DC voltage bus. Specific system
configurations may require additional considerations. Please note that the val-
ues of CIN, LBUS and CBUS may vary according to the specific converter model.
TO
OSCILLOSCOPE
CURRENT
PROBE
+Vin
+
LBUS
VIN ^–
+
CBUS
CIN
–
−Vin
CIN = 33μF, ESR < 200mΩ @ 100kHz
CBUS = 220μF, 100V
LBUS = 12μH
Figure 2. Measuring Input Ripple Current
In critical applications, output ripple and noise (also referred to as periodic and
random deviations or PARD) may be reduced by adding filter elements such
as multiple external capacitors. Be sure to calculate component temperature
rise from reflected AC current dissipated inside capacitor ESR. In figure 3, the
two copper strips simulate real-world printed circuit impedances between the
power supply and its load. In order to minimize circuit errors and standardize
tests between units, scope measurements should be made using BNC connec-
tors or the probe ground should not exceed one half inch and soldered directly
to the fixture.
Input Source Impedance
These converters will operate to specifications without external components,
assuming that the source voltage has very low impedance. Since real-world
voltage sources have finite impedance, performance is improved by adding
external filter components. Sometimes only a small ceramic capacitor is suffi-
cient. Since it is difficult to totally characterize all applications, some experi-
mentation may be needed. Note that external input capacitors must accept
high speed switching currents.
Because of the switching nature of DC/DC converters, the input of these
converters must be driven from a source with both low AC impedance and
adequate DC input regulation. Performance will degrade with increasing input
+Vout
C1
−Vout
C2
SCOPE
RLOAD
C1 = 1μF
C2 = 10μF
LOAD 2-3 INCHES (51-76mm) FROM MODULE
Figure 3. Measuring Output Ripple and Noise (PARD)
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MDC_PAQ Series.A02 Page 12 of 16