MJW25 SERIES
DC/DC CONVERTER 25W, Highest Power Density
Total Power International, Inc.
Test Setup
Input Reflected-Ripple Current Test Setup
Input reflected-ripple current is measured with a inductor Lin (4.7μH) and Cin (220μF, ESR < 1.0Ω 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.
To Oscilloscope
+Vin
+Out
+
+
Lin
DC / DC
Converter
Current
Probe
Load
Battery
Cin
-Vin
-Out
Peak-to-Peak Output Noise Measurement Test
Use a 1μF ceramic capacitor and a 10μF tantalum 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
+Out
Copper Strip
Single Output
DC / DC
Converter
Resistive
Load
Cout
Scope
-Vin
-Out
Copper Strip
Technical Notes
Remote On/Off
Positive logic remote on/off turns the module on during a logic high voltage on the remote on/off pin, and off during a logic low. To turn the power module on and off,
the user must supply a switch to control the voltage between the on/off terminal and the -Vin terminal. The switch can be an open collector or equivalent. A logic low is
0V to 1.2V. A logic high is 3.5V to 12V. The maximum sink current at the on/off terminal (Pin 6) during a logic low is -500uA. The maximum allowable leakage current
of a switch connected to the on/off terminal (Pin 6) at logic high (3.5V to 12V) is 10mA.
Overcurrent Protection
To provide hiccup mode protection in a fault (output overload) condition, the unit is equipped with internal current limiting circuitry and can endure overload for an
unlimited duration.
Overvoltage Protection
The output overvoltage clamp consists of control circuitry, which is independent of the primary regulation loop, that monitors the voltage on the output terminals.
The control loop of the clamp has a higher voltage set point than the primary loop. This provides a redundant voltage control that reduces the risk of output
overvoltage. The OVP level can be found in the output data.
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.
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
Ω at 100 KHz) capacitor of a 10μF for the 24V and 48V devices.
+
+Vin
+Out
+
DC / DC
Converter
DC Power
Source
Load
Cin
-
-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 4.7μF capacitors at the output.
+
+Vin
-Vin
+Out
Single Output
DC / DC
Converter
DC Power
Source
Cout
Load
-
-Out
Maximum Capacitive Load
The MJW25 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 sheet.
Thermal Considerations
Many conditions affect the thermal performance of the power module, such as orientation, airflow over the module and board spacing. To avoid exceeding the
maximum temperature rating of the components inside the power module, the case temperature must be kept below 105℃. The derating curves are determined from
measurements obtained in a test setup.
Position of air velocity
probe and thermocouple
Air Flow
50mm / 2in
15mm / 0.6in
DUT
Total Power International, Inc
Toll Free: 877-646-0900
www.total-power.com
TOTAL-POWER [ TOTAL POWER INTERNATIONAL ]
