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

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

CMMMW Series

4:1 Input Voltage Ranges

18~30 Watt, Single Output

Chassis Mount DC/DC Converter

Rev A

DESIGN & FEATURE CONSIDERATIONS

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.

Over Voltage Protection

The output over voltage clamp consists of control circuitry that is dependent on the primary regulation loop that monitors the

voltage on the output terminals. The control loop of the clamp has a higher voltage set point than the primary loop. This

provides a redundant voltage control that reduces the risk of an output over voltage. The OVP level can be found in the

protection specifications.

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

+

+Out

-Out

+Vin

-Vin

DC / DC

Converter

Load

DC Power

Source

+

-

Cin

Remote On/Off

Positive logic remote on/off turns the module on during a logic high voltage on the remote on/off pin, and turns the module 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 -1V to 1.0V.

A logic high is 2.5V to 100V.

The maximum sink current at the on/off terminal (pin 4) during a logic low is -

100μA. The maximum allowable leakage

current of the switch at the on/off terminal (pin 4) during a logic high (2.5 to 100V) is 5μA.