Deek Robot Nano Breakout board power issues?

[chrisspen]

Does anyone know what the maximum power input voltage is to one of these "Deek Robot" Nano breakout boards, and where I can find a datasheet for it?

Amazon.com: HiLetgo Nano I/O Expansion Sensor Shield for Arduino UNO R1 Nano 3.0...

In theory, it's a nice little board, but I'm having trouble finding documentation for it.

If I apply a 5.2V regulated voltage input to the board's coax power jack, all the +V pins and the Nano's 5V pin only read 3.6V, yet somehow the Arduino appears to still function correctly.

Of course, since all my sensors and actuators connected to the Arduino expect a 5V logic level, the Arduino can't actuate anything.

If instead I bypass the board's power jack and power the Arduino via it's usb jack, then the pins read a more reasonable 4.7V. Still not perfect, but enough for connected devices to work.

So I'm assuming the breakout board has some sort of really bad 5V voltage regulator circuit that's stepping down the already regulated 5V to 3.6V? That's fine, and I can remove my external regulator, but what's the maximum voltage I can give this thing? I can't find any datasheet for this mystery "Deek Robot" Chinese company, which like so many others, has vanished from the face of the planet.

[sterretje]

@chrisspen

If I apply a 5.2V regulated voltage input to the board's coax power jack, all the +V pins and the Nano's 5V pin only read 3.6V, yet somehow the Arduino appears to still function correctly.

Usually the barrel needs 7V or higher (7V..12V) for the voltage regulator to work properly.

@chrisspen

If instead I bypass the board's power jack and power the Arduino via it's usb jack, then the pins read a more reasonable 4.7V. Still not perfect, but enough for connected devices to work.

There is a protection diode on the Nano; below from the schematic:

That is the cause of the drop.

[gilshultz]

If my memory is correct that black thing under the Nano is a 5V regulator that provides 5V to all of the pins. That needs at about 6V or greater to regulate. Its input is connected to the barrel connector. Remove the Nano and try connecting the barrel connector to 7 to 12V and measure the 5V pins.

[hammy]

Yes 7v or more needed , because there is a voltage drop across the regulator, so can’t produce 5v unless it has the 7v

The Arduino may or may not work at 3.6 some will some won’t . It is out spec at that voltage , but would work ok at a lower frequency clock . ( see 328 data sheet )