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

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

MSKW Series

5 Watt DC/DC Converter

Single and Dual Outputs

2:1 Wide Input Voltage Range

Rev A

DESIGN & FEATURE CONSIDERATONS

Over Current Protection

To provide protection in a fault (output over load) 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 to its specified range.

Input Source / 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 voltage on the remote on/off pin. 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 of the switch at the on/off terminal during a logic low is 300µA. The maximum sink current of the

switch at the on/off terminal = 2.5 to 5.5V is 200µA or open.

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 3.3µF for the 12V input models and a 2.2µF for the 24V and 48V input models.

+

+Out

-Out

+Vin

-Vin

DC / DC

Converter

Load

DC Power

Source

+

-

Cin

Maximum Capacitive Load

The MSKW series has a limit 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 optimal performance we recommend

100µF maximum capacitive load for dual outputs and 680µF capacitive load for single 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.