Test Configurations
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.
Input Reflected-Ripple Current Test Setup
To Oscilloscope
+Vin
+Out
+
+
Lin
DC / DC
Converter
Current
Probe
Load
Battery
Cin
-Vin
-Out
Input Source Impedance
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 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.
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 15uF for the 12V input devices and a
4.7uF for the 24V and 48V devices.
Peak-to-Peak Output Noise Measurement Test
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.
+
+Vin
DC / DC
+Out
+
DC Power
Source
Load
+Vin
+Out
Copper Strip
Cout
Converter
Cin
Single Output
DC / DC
Resistive
Load
-
-Vin
-Out
Scope
Converter
-Vin
-Out
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 3.9uF
capacitors at the output.
Copper Strip
Cout
+Vin
+Out
Com.
-Out
Scope
Scope
Dual Output
DC / DC
Resistive
Load
Converter
Cout
-Vin
+
+Vin
+Out
Single Output
DC / DC
DC Power
Source
Converter
Cout
Load
Design & Feature Considerations
Maximum Capacitive Load
-
-Vin
-Out
+
+Vin
+Out
The MKW1000 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.
Dual Output
Cout
Load
DC Power
Source
DC / DC Com.
Converter
-
-Vin
-Out
For optimum performance we recommend 470uF
maximum capacitive load for dual outputs and 2200uF
capacitive load for single outputs.
The maximum capacitance can be found in the data.
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