MCW1000 Series
Input Source Impedance
Test Configurations
The power module should be connected to a low
ac-impedance input source. Highly inductive source
impedances can affect the stability of the power module.
In applications where power is supplied over long lines and
output loading is high, it may be necessary to use a capacitor
at the input to ensure startup.
Input Reflected-Ripple Current Test Setup
To Oscilloscope
+Vin
+Out
+
+
Lin
DC / DC
Converter
Current
Probe
Load
Battery
Cin
Capacitor mounted close to the power module helps
ensure stability of the unit, it is recommended to use a good
quality low Equivalent Series Resistance (ESR < 1.0[ at 100
KHz) capacitor of a 8.2uF for the 5V input devices, a 3.3uF for
the 12V input devices and a 1.5uF for the 24V and 48V
devices.
-Vin
-Out
Input reflected-ripple current is measured with a inductor
Lin (4.7uH) and Cin (220uF, ESR < 1.0[ at 100 KHz) to
simulate source impedance.
Capacitor Cin, offsets possible battery impedance.
Current ripple is measured at the input terminals of the
module, measurement bandwidth is 0-500 KHz.
+
+Vin
DC / DC
+Out
+
DC Power
Source
Load
Converter
Peak-to-Peak Output Noise Measurement Test
Cin
-
-Vin
-Out
Use a Cout 0.47uF ceramic capacitor.
Scope measurement should be made by using a BNC
socket, measurement bandwidth is 0-20 MHz. Position the
load between 50 mm and 75 mm from the DC/DC Converter.
Output Ripple Reduction
A good quality low ESR capacitor placed as close as
practicable across the load will give the best ripple and noise
performance.
To reduce output ripple, it is recommended to use 3.3uF
capacitors at the output.
+Vin
+Out
Copper Strip
Cout
Single Output
DC / DC
Resistive
Load
Scope
Converter
-Vin
-Out
+
+Vin
-Vin
+Out
-Out
Single Output
DC / DC
DC Power
Source
Converter
Design & Feature Considerations
Maximum Capacitive Load
Cout
Load
-
The MCW1000 series has limitation of maximum
connected capacitance at the output.
The power module may be operated in current limiting
mode during start-up, affecting the ramp-up and the startup
time.
The maximum capacitance can be found in the data.
Overcurrent Protection
To provide protection in a fault (output overload) condition,
the unit is equipped with internal current limiting circuitry and
can endure current limiting for an unlimited duration. At the
point of current-limit inception, the unit shifts from voltage
control to current control. The unit operates normally once the
output current is brought back into its specified range.
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