2500V Power Amplifier Addresses the Demand for Expanded Voltage Supply in ATE Applications

The introduction of new technologies like GaN and SiC has forced the power electronics industry to look again at the best available options for working with voltage levels beyond the 1000V level. For more than a decade, Apex Microtechnology has been supplying power operational amplifiers that can operate on supply voltages up to 1200V, but customers continue to express the need for greater performance. To answer this challenge, the company’s existing product portfolio of high voltage amplifiers had to be expanded. With a concerted focus on evolving the design technology of its hybrid products, the design engineers at Apex have now achieved another first in power electronics. Introducing the PA99 – an off-the-shelf, single package, 2500V power operational amplifier that addresses the demand for high voltage operation required by power supply and test equipment manufacturers.

PA99 Introduction and Highlights

When starting the development of the PA99, the design engineers at Apex Microtechnology looked at new topologies that use level shifting and optical decoupling of the input and output stage to optimize power consumption and to enable the implementation of high voltage MOSFET for the output stage. However, it turned out that such solutions would come with restrictions that would limit the use of such a product in a real world system, either in terms of the types of load suitable to be connected to the amplifier or in terms of the overall driving circuitry. As result, the design team went back to a cascaded topology that has proven highly reliable in several other of the company’s high voltage hybrids, making the PA99 capable of operating on voltage supplies of up to 2500V and providing output voltages beyond 2400V.

In terms of output current, the PA99 is designed to provide at least 20mA continuous and up to 50mA PEAK as long as the device is operated within its SOA (safe operating area). An output current limit function can be set through external resistors to prevent runaway currents. Temperature monitoring is provided through a temperature sensing diode and under typical operating conditions, the PA99 can achieve slew rates of 25-35V/µs.

Power-DIP Package

Board space in any power supply or ATE application comes at a minimum, and the feedback received during a survey of the market requested that the amplifier be housed in a package that would utilize a very small footprint while still meeting the stringent design rules for high voltage components. In-house evaluations conducted by the Apex design team showed that the smallest footprint could be achieved by using a hermetically sealed Power-DIP package. Her-

metic sealing allows for filling the inside of the package with inert gas, thus reducing the required package height and optimizing the spacing of inside components. The Power-DIP also enables efficient cool-

ing of the operational amplifier when operating in conditions where power loss within the device is significant. Apex Microtechnology worked closely with one of its package suppliers to develop a 12-pin Power-DIP package suitable for the performance rigors of the PA99 while providing a suitable footprint that meets stringent board space requirements.

Target Applications

The PA99 has been designed as a general-purpose operational amplifier. It can operate with symmetric or asymmetric supplies, as long as the voltage between the positive and the negative supply rail do not exceed the maximum supply voltage specification. The PA99 is also fully capable of sourcing and sinking current; therefore, the PA99 can be used in a wide variety of applications -- driving resistive, inductive, capacitive loads, or any combination thereof.

About Apex Microtechnology

Apex Microtechnology, a subsidiary of HEICO Corporation, is based in Tucson, Arizona. Apex designs and manufactures precision power analog monolithic, hybrid and open frame components for a wide range of industrial, test and measurement, medical, aerospace and military applications. Apex Microtechnology is a recognized leader for consistently developing products that lead the industry in terms of performance, quality, and reliability.

Founded in 1980, Apex Microtechnology was acquired in 2007 by Cirrus Logic. Following a five-year tenure as a division of the Austin, Texas, based developer of complex chip designs, Apex Microtechnology was returned to a stand-alone corporation in 2012 with its sale to a private investor group led by Alerion Capital Group, a private equity and management advisory firm located in Scottsdale, Arizona. In 2018, Apex was acquired by HEICO Corporation as a part of their Electronics Technologies Group.

This article originally appeared in the Bodo’s Power Systems magazine.