Wall Industries, Inc. 5 Watson Brook Road Exeter, NH 03833

11/14/2011

603-778-2300 www.wallindustries.com Fax 603-778-9797

Page 7 of 8

MMW Series

Single and Dual Output

4:1 Input Voltage Range

25~30 Watt DC/DC Converter

Rev C

TEST CONFIGURATIONS

Input Reflected-Ripple Current Test Setup

Input reflected-ripple current is measured with an inductor Lin (4.7μH) and Cin (220μF, ESR < 1.0Ω at 100KHz) 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 ~ 500KHz.

+Out

-Out

+Vin

-Vin

DC / DC

Converter

Load

Battery

+

Lin

+

Cin

To Oscilloscope

Current

Probe

Peak-to-Peak Output Noise Measurement Test

Use a Cout 1.0μF ceramic capacitor.

Scope measurement should be made by using a BNC socket; measurement bandwidth is 0 ~ 20MHz. Position the load

between 50mm and 75mm from the DC/DC Converter.

+Out

-Out

+Vin

-Vin

Single Output

DC / DC

Converter

Resistive

Load

Scope

Copper Strip

Cout

+Out

-Out

+Vin

-Vin

Dual Output

DC / DC

Converter

Resistive

Load

Scope

Copper Strip

Cout

Com.

Scope

Cout

Output Ripple Reduction

A good quality low ESR capacitor placed as close as possible 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.

+Out

-Out

+Vin

-Vin

Load

DC Power

Source

+

-

Cout

Single Output

DC / DC

Converter

+Out

-Out

+Vin

-Vin

Load

DC Power

Source

+

-

Cout

Com.

Dual Output

DC / DC

Converter

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°C. The derating curves are determined from measurements obtained in an experimental

apparatus.

DUT

Position of air velocity

probe and thermocouple

50mm / 2in

Air Flow

15mm / 0.6in