Bel Fuse Inc. 206 Van Vorst Street, Jersey City, NJ 07302

11

Feb. 16, 2012

Bel Power Inc., a subsidiary of Bel Fuse Inc.

NON-ISOLATED DC/DC CONVERTERS

3 Vdc – 14.4 Vdc Input, 0.6 Vdc - 5.5 Vdc /12 A Outputs

Design Considerations

Input Filtering

The SLAN-12D2Ax module should be connected to a low ac-impedance source. A highly inductive source can

affect the stability of the module. An input capacitance must be placed directly adjacent to the input pin of the

module, to minimize input ripple voltage and ensure module stability.

To minimize input voltage ripple, ceramic capacitors are recommended at the input of the module. Figure 37

shows the input ripple voltage for various output voltages at 12A of load current with 2x22 µF or 3x22 µF ceramic

capacitors and an input of 12V.

Figure 37

Note: Input ripple voltage for various output voltages with 2x22 µF or 3x22 µF ceramic capacitors at the input

(12A load). Input voltage is 12V.

Output Filtering

The SLAN-12D2Ax modules are designed for low output ripple voltage and will meet the maximum output ripple

specification with 0.1 µF ceramic and 22 µF ceramic capacitors at the output of the module. However, additional

output filtering may be required by the system designer for a number of reasons. First, there may be a need to

further reduce the output ripple and noise of the module. Second, the dynamic response characteristics may

need to be customized to a particular load step change.

To reduce the output ripple and improve the dynamic response to a step load change, additional capacitance at

the output can be used. Low ESR polymer and ceramic capacitors are recommended to improve the dynamic

response of the module. Figure 38 provides output ripple information for different external capacitance values at

various Vo and a full load current of 12A. For stable operation of the module, limit the capacitance to less than

the maximum output capacitance as specified in the electrical specification table. Optimal performance of the

module can be achieved by using the Tunable Loop

Output Voltage (Vdc)