Rev B

DCMSAU1 SERIES

1 Watt DC/DC Power Converters

10/23/2013

Wall Industries, Inc. • 37 Industrial Drive, Exeter, NH 03833 • Tel: 603-778-2300 • Toll Free: 888-597-9255 • Fax 603-778-

9797

website: www.wallindustries.com • e-mail: sales@wallindustries.com

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DESIGN CONSIDERATIONS

Input Reflected-Ripple Current Test Setup

Input reflected-ripple current is measured with an inductor Lin (4.7µH) and Cin (220µF, ES

R < 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.

Peak-to-Peak Output Noise Measurement Test

Use a 0.33µF 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.

TEST SETUP

Maximum Capacitive Load

The DCMSAU1 series has a limitation of maximum connected capacitance on the output. The power module may be

operated in current limiting mode during start-up, affecting the ramp-up and the start-up time. The maximum capacitance can

be found in the Model Selection Table.

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 <

1.0Ω at 100 KHz)

capacitor of 2.2µF for 5VDC input models, 1.0µF for 12VDC input models, and 0.47µF for 24VDC input models.

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 1.5µF capacitors at the output.