Latest radiation hardened power management products solve new design challenges

March 27, 2012 // By Josh Broline, Bernard Theju, Nick van Vonno
Josh Broline, Bernard Theju, Nick van Vonno, Intersil Corporation focuses on radiation hardened power management products and how they solve new design challenges.

The space industry has an increasing demand for advanced power management products that can survive harsh radiation environments and still provide “commercial-like” high performance capability. The Low Dropout Regulator (LDO) is often the device of choice when the load requirements are under 2Amps or when an easy to implement solution is desired. High sensitivity RF amplifier applications also dictate the use of LDOs over a switching regulator due to output noise performance capabilities. A switching regulator is a great fit when stepping down to a low voltage or when the current requirement exceeds 2A, necessitating a more efficient solution. With the adoption of next generation core processing solutions for satellite applications, such as FPGAs, the total power requirements and regulation tolerances are challenging designers to look beyond what is available today. For example, load current requirements are going up as core voltages are going down and voltage tolerances are being reduced from +/-10 percent to +/-5 percent in some cases. A power supply to meet this +/-5 percent tolerance -- with an output voltage accuracy over static and dynamic operation, temperature range, load transient response and single event transient performance – requires a next generation solution. For example, the Virtex V FPGA uses a core voltage of 1.0V +/-5 percent and an auxiliary supply voltage of 2.5V +/-5 percent.

Figure 1: A typical power system arrangement for an FPGA
The tight regulation specification required by FPGAs requires that the tolerances of the band gap reference of a switching regulator be accurate over the entire input and output operating voltage. Using a proportional to absolute temperature (PTAT) band gap and on-chip trimming can achieve this goal in monolithic power devices. The overall tolerance of the regulator is based on the device band gap accuracy, external setting resistor tolerances, and the effects of operating over the desired temperature range. If the initial accuracy of the device is fixed, for example +/-1.5 percent
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