Nano minimum voltage

[arden]

Know officially the nano needs 5v
Has anyone played with the minimum voltage you can get away with

Wondering if I can run them off one 18650 ?

If not will use 2 plus a 7805

[kimot]

Why "plus" 7805.
Nano has got voltage regulator on board.
Original Arduinos 7805 I think, clones LM1117 usually.

[electrik]

If you use an ISP programmer, you can reprogram the fuses and use it on lower voltages also. Upto 1.8v but also 3.3v

[bjacobse]

@arden said in Nano minimum voltage:

Know officially the nano needs 5v
Has anyone played with the minimum voltage you can get away with

You don't need to play around, as the first thing to do is to read the datasheet for the CPU, a nano like the other original/classic Arduino's are using AtMega328p, then you get knowledge what is possible.
Datasheet: The device operates between 1.8-5.5 volts.
and this means to bypass/remove the voltage regulator on the Nano board

http://ww1.microchip.com/downloads/en/DeviceDoc/ATmega48A-PA-88A-PA-168A-PA-328-P-DS-DS40002061A.pdf

[kimot]

@bjacobse said in Nano minimum voltage:

Datasheet: The device operates between 1.8-5.5 volts.
and this means to bypass/remove the voltage regulator on the Nano board

But it do NOT means with 16Mhz crystal on Arduino Nano ...

[bjacobse]

@kimot said in Nano minimum voltage:

But it do NOT means with 16Mhz crystal on Arduino Nano ...

Well the AtMega328 has an option to use internal RC oscillation and hence don't need to use the 16MHZ crystal.
yes we agree that with low voltage you must use 1MHz, -> 8MHZ div8

From the link I have provided above, read chap 9.6:
Calibrated Internal RC Oscillator
By default, the Internal RC Oscillator provides an approximate 8.0MHz clock. Though voltage and temperature
dependent, this clock can be very accurately calibrated by the user. See Table 29-9 on page 313 for more
details. The device is shipped with the CKDIV8 Fuse programmed. See ”System Clock Prescaler” on page 45
for more details.
This clock may be selected as the system clock by programming the CKSEL Fuses as shown in Table 9-11. If
selected, it will operate with no external components.

And yes it's possible and maybe needed to calibrate the internal RC, that you need to test

And yes you need also to change fuse for BOD (Brown out detection) as this by default close down the ATMega328 below 2.7V
read chap 10.2: BOD Disable

[zboblamont]

@arden With so many more efficient boosters available than stock voltage regulators I have to question the wisdom of detuning any device to accommodate the power supply for all but the most extreme requirements.
With the Nano's USB converter constantly sucking power it is the least frugal device of the newer Arduinos, the pro-mini has a wealth of information on reducing sleep load power with LED and VR removed, perhaps a change in approach may be worthwhile ?

[bjacobse]

@zboblamont said in Nano minimum voltage:

@arden With so many more efficient boosters available than stock voltage regulators I have to question the wisdom of detuning any device to accommodate the power supply for all but the most extreme requirements.
With the Nano's USB converter constantly sucking power it is the least frugal device of the newer Arduinos, the pro-mini has a wealth of information on reducing sleep load power with LED and VR removed, perhaps a change in approach may be worthwhile ?

Yes I fully agree, but if Arden only have those Nano available, he can use those with extra effort to remove all those not needed current consumption IC's

[zboblamont]

@bjacobse Granted that is what he has, but it's a lot more effort reducing a Nano to pro-mini compared to the cost of a getting a pro-mini to begin surgery to start with... We all have devices bought with good intention gathering dust as we learn.... ;)
One of these days will get a Nano to play with, but had dismissed it for battery applications from the start of this adventure and have seen no reason to reconsider that conclusion since.. For testbed or PSU applications, fine, but for battery applications?...
As the Limerick man advised the driver seeking directions to Dublin, " I wouldn't start from here" :)