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I am utilizing a development board that has an expansion header. The header brings out a 2.5 VDC power rail that is sourced from a buck converter SMPS. I need to use this 2.5 VDC, run it through a boost converter, and generate 3.3 VDC, where I will run a light load (about 50 milliamperes).

Are there any issues with attaching the output of a buck converter to the input of a boost converter?

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  • \$\begingroup\$ Generally there are no issues daisy chaining converters, given that the output and input requirements of both are fulfilled. 2.5V is a relatively low voltage however but you should be able to find something appropriate. \$\endgroup\$ – Stonie Feb 20 '18 at 14:03
  • \$\begingroup\$ Does 0 volts also come out? Is the 0 volts used as a signal reference for sensitive circuits (?) because if it is you might hit significant noise problems. \$\endgroup\$ – Andy aka Feb 20 '18 at 14:21
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A boost converter is just another load to whatever is sourcing its input power. As long as that source can handle the current demand, it should be fine.

Make sure that the second switcher has a good cap physically close to its input. The lowers the impedance of the supply locally. Switchers can draw input current in pulses, which can cause the local voltage to dip each pulse, and also cause voltage noise in general.

That all said, there may be another supply available that the 2.5 V is made from, that would be better for making the 3.3 V supply from also.

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In general there are no issues in connecting the output of one kind of power supply to another as long as the load specifications of the source supply are not exceeded. Adding a boost supply will potentially increase the noise on the source supply, so you should make sure that the input to the boost supply is well bypassed.

Since your current requirements are so low, you might consider using a switched capacitor boost regulator, since it can potentially be lower noise than an inductor based boost regulator.

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