Test Configurations

Input Reflected-Ripple Current Test Setup

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.

Peak-to-Peak Output Noise Measurement Test

Use a Cout 0.33uF 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.

Design & Feature Considerations

Maximum Capacitive Load

The MFU100 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.

For optimum performance we recommend 33uF maximum

capacitive load for devices.

The maximum capacitance can be found in the data sheet.

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[ at 100

KHz) capacitor of a 1.5uF for the 5V input devices, a 1.0uF for

the 12V input devices and a 0.47uF for the 24V devices.

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 1uF

capacitors at the output.

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 90°C.

The derating curves are determined from measurements

obtained in an experimental apparatus.

MFU100 Series

REV:4 2008/10

MINMAX

5

+Out

-Out

+Vin

-Vin

DC / DC

Converter

Load

Battery

+

Lin

+

Cin

To Oscilloscope

Current

Probe

+Out

-Out

+Vin

-Vin

Single Output

DC / DC

Converter

Resistive

Load

Scope

Copper Strip

Cout

DUT

Position of air velocity

probe and thermocouple

50mm / 2in

Air Flow

15mm / 0.6in

+

+Out

-Out

+Vin

-Vin

DC / DC

Converter

Load

DC Power

Source

+

-

Cin

+Out

-Out

+Vin

-Vin

Load

DC Power

Source

+

-

Cout

Single Output

DC / DC

Converter