Switchmode converter

The switchmode converter range from Recom unites both the specifications and the application of the 78xx linear regulators with an efficiency of up to 97% to give a minuscule heat generation that avoids all the physical and mechanical problems associated with heat sinks and waste heat.

Just like standard linear regulators, the R-78 series has a drop-out voltage of 1.5 and an input voltage range that extends up to 34: an input range of up to 7:1. The R-78xx-0.5 series delivers an output current of up to 500 mA and R-78xx-1.0 types with up to 1 A output current are in preparation.

The output voltages are available off the shelf in values of 1.8, 2.5, 3.3, 5, 9 and 12 as standard. Non-standard values are available.

The device is accommodated in a SIP3-plastic housing and is continuous short circuit protected and incorporates a thermal shutdown protection function that switches off the converter if the internal temperature exceeds 160°C.

The protection restricts the input current with a shorted output to typically 25 mA.

The efficiency is through the use of a switchmode design using the Buck principle.

A frequent and normally justifiable point of criticism concerning switchmode designs over linear designs is the noise generated on the outputs as well as the disturbances reflected back into the input supply.

The R-78xx-0.5 series has a relatively high operating frequency of around 300 kHz which is easy to filter out internally and so generates very low inherent noise.

The switchmode converter requires no external components and has typical values of ripple and noise of 30-50 m Vpp, which can be further reduced with external filters.