Emco High Voltage DC to DC Converters BY John Kmiec

Introduction This presentation covers the F30CT High Voltage DC- DC converter made by Emco High Voltage. This part has a 3000VDC center tapped output. The F series parts are rated at 10W and are available with output voltages from 100 to 12000V. They are also available without a center tap connection. Emco also offers a wide variety of high voltage DC-DC converters ranging from 100V to 30000V and power ratings from less than 1W to greater than 30W. These products are used for a wide variety of applications including photomultiplier tubes, mass spectrometers, and electrostatic chucks.

Typical Wafer Etcher Application

HV Power Supply Block Diagram

Circuit Details The F30CT is a proportional output converter. It is an un- regulated output design. Regulation can be achieved externally as in the above example. This device appears to be a Resonant-dc-Link Converter design. The primary side of the transformer oscillates at approximately 50kHz. The amplitude of the ac signal applied to the internal transformer is proportional to the applied DC voltage The design has a claimed efficiency of >70% and low EMI, noise, and ripple. The ripple rating of the F30CT is <1%. This design operates like a linear power supply. The size reduction is due to the 50kHz operating frequency.

High Voltage Schematic

High Voltage Data

Complete Circuit Schematic

Primary Circuit

Secondary Circuit

Conclusion The major advantage is that it is simple to use. Disadvantages to this design are that it does not have some of the benefits of a switching converter design which include efficiency and power density. Another disadvantage is the cost. The single piece price is about $140. Competitor is American High Voltage CT series. This part is rated at 5W and is available with 50 to 3000V output. More information is available at More information on Emco High Voltage products can be found at