Low noise, high current multi-rail linear power supply unit for airborne applications

This electronic design case study describes the design of an extremely compact high power density linear power supply unit (PSU) by Slipstream Engineering Design Ltd on behalf of Teledyne Defence and Space Ltd using Linear Technology components.

Project Background
With a challenging development timescale and faced with a competitive product bid process our client, Teledyne Defence and Space, were under pressure to deliver a prototype system that required an extremely compact and high-density power supply unit (PSU). With a requirement to generate multiple linear supplies with high output currents, the PSU design was a key element of the overall product.

Teledyne Defence and Space passed over the specification to Slipstream Engineering Design, engaging our company to design, prototype and test the required PSU.

Compact high power density linear PSU: The Design Challenge

Taking the specification it was clear the PSU requirements were significant and would require an innovative approach. The key design challenges were as follows:

  • Linear supply with high output current of 12A @30-35V
  • Multiple supplies to be generated (4 in total)
  • Very high power density of 7W/ cm3
  • Permitted PSU footprint of 41mm X 43mm
  • Total permitted ceiling height 5mm
  • Significant heat generation (25°C rise above ambient)
  • Conduction cooling through base only.

Design Implementation
Using Linear Technology devices, Slipstream Engineering Design answered the design challenge by exploiting the power sharing features of the LT3080EDD. Taking the design to the extremes, the 30-35V supply uses an array of 16 devices whilst the 8V supply user an array of 9 devices. This was coupled with cutting edge bare PCB technology (HDI class 6). An arrangement of blind and buried stacked micro vias with copper fill were shown by simulation to fulfil the challenging thermal dissipation requirements.

Extremely Compact High Power Density Linear PSU

From concept to completed PCB layout, Slipstream Engineering Design completed the major design activity within 4 weeks. Testing of the PSU (following successful and straight forward integration into the product) demonstrated the expected performance, especially from a thermal management perspective. The PSU was shown to operate over a temperature range of –40 to 80°C.

Slipstream Design exploiting power sharing features of the LT3080EDD


Download the pdf of this Design Case Study here: Design Case Study Compact Power Supply Unit

Further information can be found at: http://www.linear.com/product/LT3080

Linear Technology

Teledyne Defence & Space