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Power Supply/Standby Power

Mission Critical Power Control Demands Robust Transformer Design

Precision control of voltage levels within a defined topology is the design goal of the power control/power management subsystem/power supply. The voltage is used to control the timing of events (gating power on and off, data timing/synchronization, pulse generation, timing and duty cycle, timing and pulse width, etc.) required to achieving the operational parameters as defined by the target platform design criteria. Primary design considerations at the subsystem level should include voltage stability/regulation, frequency stability, waveform skew, and edge control /sharpness of the leading and trailing edge of the output waveforms.

Considerations at the component level require special attention to the stability of the electromagnetic devices used. The primary concern is controlling their parasitic values, which can reduce the need for compensation components while improving overall system stability. Through the use of Finite Element Analysis and Spice Circuit Simulations it is possible to refine core geometries beyond accepted norms. It also provides for the optimization of material versus performance, resulting in a lower cost device. Bicron’s TTP (Tunable Transformer Platform) design environment has achieved Switch Mode power supply efficiencies of 95% and power density improvements of 30%.

Another critical factor in system design pertains to MTBF. Many transformer manufacturers use a single dielectric strength test as a means for assuring long term reliability. This is a flawed approach best remedied by Corona (partial discharge) abatement for elevated system voltages, along with designing with an overall system BIL rating in mind.

The nine main types of components that are used in these applications are pulse transformers, gate drive transformers, isolation transformers, and Inductors (also referred to as chokes), switch mode, buck boost, flyback, feed forward and inverter. BIL and/or Corona Free ratings of these devices will have a direct impact on reliability, MTBF, and related warranties.

Primary Design Considerations Summary

  • Transformer subsystem stability/efficiency
  • MTBF
  • Waveform skew and edge control
  • Control of Parasitic Values
  • Corona abatement
  • BIL
  • Cooling costs (materials/space)
  • Power Density (Power Supplies)