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I have LT1086 5V regulator

what is the Vin min to provide 5V output?( assume load current 500mA -800mA)

I tested it worked for 6V Vin,

but datasheet does not mention anything about Vin min

https://www.analog.com/media/en/technical-documentation/data-sheets/1086ffs.pdf

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    \$\begingroup\$ The typical dropout voltage is right on the front page, for various temperatures and currents. Worst case is also specified. Combine for a good guess at worst-case @500~800mA. Dropout is the input-output at which the regulator entirely stops regulating. For best performance give it somewhat more than that to work with. \$\endgroup\$ Jan 26, 2020 at 9:32

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You can consider the drop out voltage parameter to be a design constraint. For a output voltage of 5 V, 6.5 V should be the minimum input voltage.

Please note that, the 1.5 V is the drop considering load current of 1.5A. for a lower load current, the drop will be lesser.

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  • \$\begingroup\$ Also note that the dropout voltage takes effect in less than a millisecond: if your input is usually greater than 6.5, but occasionally spikes down to less, those downward excursions will affect your regulated 5V line. \$\endgroup\$
    – TimWescott
    Jan 26, 2020 at 14:52

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