5V output with 3.3V input

[MRoss.21]

Hi! I'm trying to control four 8520 motors with a NUCLEOf303k8. I would use two L293B for this scope, but the input voltage for my NUCLEO is 3.3V. The L293B needs an input voltage of 4,5V, at minimum. Will the NUCLEO "5V" output pin provide 5V to the L293D, its input is 3.3V?

[Uwe Bonnes]

Your question is not clear. Do yu mean input with respect to the power supply or with respect to logic level? You can kill an STM by providing 5 Volt to a non-FT input. And all STM output will be VDDIO with VDDIO mostly 3.3v and 3.6 V maximum allowed. Somehow you can reach 5 Volt output by using an FT pin,using it as open drain with a pull up to 5 Volt. But this nneds to be carefully coinsidered. Read the datasheet to find out if your device will get killed when 5 Volt supply is available while VDDIO not.

Have a look at the Nucleo schematic to see how the 5V pin is generated.

[Tesla DeLorean]

The NUCLEO is unlikely to be able to provide sufficient current. Common the grounds, and power the L293B more directly from a supply, like a battery.

The VIH for the L293B is 2.3V min, it should be able to distinguish high/low logic levels from 3.3V CMOS outputs

[MRoss.21]

Sorry, I try to rephrase the question: can I get a constant 5V output from the "+5V" pin (pin number 4 in CN4) when the NUCLEO32 is powered with a 3.3V current by a battery connected to the "+3V3" pin (pin number 14 in CN4)?

[MRoss.21]

Thanks! And can you also recommend a battery for this scope? I have looked for a 5V battery to power directly my NUCLEO, but I didn't find so much.. then I opted for a LiPo 3.7V connected to a TC1262-3.3VAB which regulates to 3.3V.

I need to power the L293 only, so could be supplying current by two simple button cell batteries connected in series a nice idea?