Info!! Comparison Dc-Dc Converter’S Usable Power

Power render manufacturers rarely purpose the term “usable power” inwards their AC-DC production literature, but it is used oftentimes when referring to a DC-DC converter’s functioning against temperature. Is it simply a fancy reference to a de-rating curve? As usual, earlier nosotros answer that question, nosotros ask to facial expression a lilliputian deeper.

An AC-DC ability supply, similar the TDK-Lambda’s LS50 series, has a de-rating “curve” equally shown below. It tin attain notice deliver amount ability at 50C ambient too it de-rates linearly to 70% charge at 70C. (The knee articulation points of the nautical chart vary from production to production but non usually dramatically betwixt competitors of similar products.)

The nautical chart is real unproblematic because the LS50 does non require whatever forced air, too has a metallic illustration that is used equally a oestrus sink and to provide a score of physical protection.

Looking at TDK-Lambda’s iQG ¼ brick DC-DC converter, nosotros tin attain notice meet a much to a greater extent than complex laid of de-rating curves.

To hold out fair, the manufacture criterion ¼ brick has migrated from a production where 50W output ability was leading edge, to products that are fast approaching 1000W. The emphasis for DC-DC converters has been lay on bundle size. Even when fitted amongst an integral baseplate, similar TDK-Lambda’s iQG ¼ brick (shown below), the iQG’s book is 1.6 cubic inches, compared to the LS50’s 21 cubic inches. That is 10 times the output ability inwards less than a 1/10th of the volume.

The “brick” vogue DC-DC converters are designed to hold out either conduction cooled (to a mutual depression temperature plate), or forced air cooled, often without an external oestrus sink. The charge per unit of measurement of airflow available volition depend on the user’s application, too and then a lay out of functioning curves are provided. It tin attain notice hold out noticed that inwards to a greater extent than or less cases for depression airflow conditions, de-rating has already occurred already at 30C ambient.

Usable ability actually refers to the gradient too initiatory off indicate of the de-rating curve. Often Engineers volition focus on the output electrical flow of the converter, too select a higher power, to a greater extent than expensive product, expecting to significantly amend performance. This is where “usable power” comes into play.

Below is a simplified couplet of curves for 2m/s airflow. The blueish employment is for a 12V 67A (800W) DC-DC converter, too the greenish employment for the TDK-Lambda 12V 42A (500W) converter. The 800W model is 1.6 times to a greater extent than powerful at depression ambient temperatures, but inwards the xanthous expanse at higher ambient the ratio drops to 1.35 times at 70C too 1.24 times at 75C. (Typically customers move DC-DC converters inwards the 65 to 80C range.)

Although the 800W converter has to a greater extent than available power, the 500W unit of measurement has to a greater extent than usable power, demonstrated past times a much less steep de-rating curve. It tin attain notice hold out seen that at higher ambient temperatures, it would hold out to a greater extent than terms effective to purpose the 500W converter.