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

02/24/2010

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

Page 5 of 6

DMW Ultra Wide Series

Single and Dual Output

4:1 Ultra Wide Input Voltage Range

Up to 15.3 Watts DC/DC Converters

Rev C

+

DC Power

Source

-

+Vin

+Out

DC / DC Converter

-Vin

-Out

+

Load

Cin

DESIGN & FEATURE CONSIDERATIONS

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 -0.7V to 0.8V.

A logic high is 2.5V to 5.5V.

The maximum sink current at on/off terminal during a logic low is -1mA. The maximum allowable leakage current of the switch at on/off terminal (2.5 to

5.5V) is 50µA.

Over Current 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 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. A 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 < 1.0Ω at 100KHz) capacitor of a 6.8µF for the 24V and 48V input devices.

Maximum Capacitive Load

The DMW 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 220µF maximum capacitive load for dual outputs and 470µF

capacitive load for single outputs. The maximum capacitance can be found in the Model Selection Guide.

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 0-500 KHz.

Peak-to-Peak Output Noise Measurement Test

Use a Cout 0.47µF 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.

To Oscilloscope

+

+

Lin

Battery

Cin

+Vin

+Out

DC / DC

Converter

-Vin

-Out

Current

Probe

Load

Scope

+Vin

+Out

Dual Output

DC / DC

Com.

Converter

-Vin

-Out

Copper Strip

Scope

Cout

Cout

Resistive

Load

Copper Strip

Copper Strip

+Vin

+Out

Single Output

DC / DC

Converter

-Vin

-Out

Copper Strip

Cout

Copper Strip

Scope Resistive

Load