MDW1000 Series
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
on the input to insure startup.
Input reflected-ripple current is measured with a inductor
Lin (4.7uH) and Cin (220uF, ESR < 1.0[ at 100 kHz) to
simulated source impedance.
Capacitor Cin, offsets possible battery impedance.
Current ripple is measured at the input terminals of the
module, measurement bandwidth is 0-500KHz.
By using 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, capacitor mounted close to the power
module helps ensure stability of the unit.
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
-Out
+
+Vin
+Out
Copper Strip
Cout
DC Power
Source
Load
Converter
Single Output
DC / DC
Cin
Resistive
Load
Scope
-
-Vin
Converter
-Vin
-Out
Output Ripple Reduction
Copper Strip
Cout
+Vin
+Out
Com.
-Out
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 that 3.3uF
capacitors are used on output.
Scope
Scope
Dual Output
DC / DC
Resistive
Load
Converter
Cout
-Vin
+
+Vin
-Vin
+Out
-Out
Single Output
DC / DC
Design & Feature Considerations
Maximum Capacitive Load
DC Power
Source
Converter
Cout
Load
-
The MDW1000 series has limitation of maximum
connected capacitance on the output.
The power module may operate in current limiting mode
during start-up, affecting the ramp-up and the startup time.
+
+Vin
-Vin
+Out
Dual Output
Cout
Load
For optimum performance we recommend maximum
1000uF capacitive load for dual outputs and 4000uF capacitive
load for single outputs.
DC Power
Source
DC / DC Com.
Converter
-
-Out
Connect capacitors at the point of load for best
performance.
The maximum capacitance can be found in the data.
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