May be this question was already asked, sorry but I don’t found…
I would like to use the S7V7F5 regulator to power in 5V a little robot (OttoDIY+) with an Arduino Nano. Can this type of alimentation be used without damage for your regulator when the Nano is both powered by your regulator and the USB connection ?
In this situation the USB brings a 4.7V power to the 5V line (there is a protection Schottky diode) hence connected to the S7V7F5 output. Thank’s
Hi.
You should never directly connect the outputs of two sources. It sounds like you have added a diode to the Nano’s 5V line to protect it. Adding a similar diode to the output of the regulator would work, but it would also lower the voltage and defeat the purpose. Another approach would be to use a power multiplexer like the TPS2113A or FPF1320. Possibly the simplest thing would be to use a regulator with a higher voltage output and supply your Nano through VIN instead. If you post information about your power supply and current requirements, I can see if we have any appropriate higher voltage regulators.
-Claire
Many thanks Claire for your response and your propositions of Pololu power multiplexers.
I joined a little schematic of the alimentation for OttoDIY+ :
As you can see, its components are distributed in the Nano board and in a shield. So there are many ways to power the robot, using 5V, VIN, DC or USB inputs.
The 5V input sounds like to be the more direct way because finally, 5V is required both by the ATMege328P of the Nano board and the different components of the robot (4 micro MG90S servos, a Bluetooth module, sensors, etc.).
I used first a classical 5V PC alimentation : it works well ! But your S7V7F5 with 4x1.5V AA Alkaline battery no : I think because it does’nt accept the variations of current when the servos are activated (I measured until 600mA with a tester) to maintain a sufficient voltage for the ATMega328P. May be a classical solution would be to power separately in 5V the servos and the other components,using another S7V7F5 ? Or a more tolerant 5V regulator without any separation ?
However, I observed that a simple 9V Alkaline battery connected to the VIN input works well equally : the LDO 5V regulator (AMS 1117 5.0) looks like to support the 4 servos : may be the simplest solution…
But I’ll transmit your remark about the source outputs connection and your suggestions of Pololu power multiplexers to the OttoDIY community, in view to have a safe powering solution, when the robot is powered both by VIN or 5V inputs and by USB : considering the max intensity here (>600mA), I imagine that isn’t a good option to use a PC USB only to power the robot. Best regards. Jac
In general it is probably best, for power concerns and things like noise, to power your servos off a separate supply. However, if your servos only draw 600mA total, I expect that to be well within what the S7V7F5 can handle. I also expect the S7V7F5 to be better than a linear regulator. You might check the voltage of your alkaline batteries or try a fresh pair or some rechargable NiMH instead.
-Claire