Unregulated DC/DC converters integrate short circuit protection

Quite frequently, one or two units of unregulated DC/DC converters usually get returned due to defect. This even happens in stable applications that have no design weaknesses. Once replaced, the new DC/DC converter works fine with the application. But, are DC/DC converters unreliable products that cause problems? Or is it the end user’s misuse?

This article discusses galvanic isolation from a different point of view. Targeted at engineers designing interface application for industrial applications, this article offers solutions that can help increase the satisfaction of both design engineers and end users.

Choice of component is critical for galvanic isolation. DC/DC converter is always a two-sided blade between specifications, later reliability in the field and costs. It is necessary that the output voltages of the DC/DC converter be indicated externally at plugs for powering sensors or remote applications. For mass-produced DC/DC converters, this means sudden death because the typical converter (unregulated, 0.5W to 2W) does not have continuous short circuit protection.

For interface applications, absolute value of output voltage is usually a minor interest. An overload or short circuit protection, however, is an important feature. This feature is only available in regulated, wide input range converters, which can adjust primary oscillators from a feedback loop back from the output and detect overload or short circuit on output and take corrective action.

In terms of prices, regulated DC/DC converters are expensive, whereas unregulated DC/DC converters are basement-priced, plentiful, and are better suited to applications where power sensitivity is not important. In most cases, misuse of unregulated 1W DC/DC converters can cause failure of the end-product.

P-OPTION SOLUTION

To solve this, RECOM has added continuous short circuit protection options to all its Econoline series of unregulated DC/DC converters between 0.25W and 2W. In addition to its conventional converters, RECOM offers the P-option: P, which stands for “Protected”, enables the DC/DC converter, although still an unregulated and cheap product, to withstand short circuits on output or output overloading to a certain extent without damage and at a much lower cost compared to regulated units.

The DC/DC converters with P-option are balanced, especially because transformers in the primary oscillator and the core material of transformers are chosen in a combination that allows overloading or short circuits without the need for all the overhead and costs. The significant higher saturation current of the transformer during high output current can be driven continuously by the transistor without causing failure. The well-known input short circuit of failed converter can be history now.

RECOM’s solution is as simple as it sounds. All specifications of its DC/DC converters stay the same both for the standard as for with the P-option version. So far, RECOM has convinced its interface-application customers to experience the benefits of this solution, which increases the reliability of the product with relatively low price.