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

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

CMMM Series

2:1 Input Voltage Ranges

18~30 Watt, Single Output

Chassis Mount DC/DC Converter

Rev A

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. A capacitor mounted close to the power module helps ensure

stability of the unit, it is recommended to use a good quali

ty low Equivalent Series Resistance (ESR < 1.0Ω at 100KHz)

capacitor of a 33μF for the 12V input models and a 10μF for the 24V and 48V input models.

+

+Out

-Out

+Vin

-Vin

DC / DC

Converter

Load

DC Power

Source

+

-

Cin

Maximum Capacitive Load

The CMMM Series has a 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

330μF maximum capacitive load for 12V and 15V outputs and 10,000μF capacitive load for 3.3V and 5V outputs. The

maximum capacitance can be found in the Output Voltage / Current Rating Chart.

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.

+Out

-Out

+Vin

-Vin

DC / DC

Converter

Load

Battery

+

Lin

+

Cin

To Oscilloscope

Current

Probe

Capacitor Cin offsets possible battery impedance.

Current ripple is measured at the input terminals of the module. Measurement bandwidth is 0 ~ 500KHz.

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