I was thinking about making a 5V power source to charge 2 cellphones in my car. Using a couple of LM7805 connected in parallel to the 12V lighter would be easy, but if each cellphone consumes 1A, the power dissipated by each LM7805 would be around (12V - 5V) * 1A = 7W
If I connect both LM7805 in series, can I assume there will be a 6V drop on each, and therefore a power dissipation of (6V - 5V) * 1A = 1W? If so, the capacitors would be at the same places in both regulators?
Please see the attached diagram and the LM7805 datasheet.
I'm leaving aside all other components (like the security fuse and resistors) because my question is focused on the feasibility of using the regulators in series instead of parallel configuration. Also, probably a switching regulator would be a better choice to reduce the dissipation, I´m just curious if the series circuit would work.
Thanks for your comments
If I connect both LM7805 in series, can I assume there will be a 6V drop on each, and therefore a power dissipation of (6V - 5V) * 1A = 1W? If so, the capacitors would be at the same places in both regulators?
Please see the attached diagram and the LM7805 datasheet.
I'm leaving aside all other components (like the security fuse and resistors) because my question is focused on the feasibility of using the regulators in series instead of parallel configuration. Also, probably a switching regulator would be a better choice to reduce the dissipation, I´m just curious if the series circuit would work.
Thanks for your comments
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