Rail voltage

[Gramps]

Poking around this morning I found the rail voltage on the breadboard is 7 volts!!!!
What is the maximum Supply voltage for these chips?

 

[Technoman]

5V is the recommended voltage for most of these chips, still they can work at a lower value.
You may refer to this page to find the datasheets : https://picaxe.com/what-is-picaxe/picaxe-chip-labels/

e.g. the 20M2 (PIC16F1829) max operating voltage is 5.5V. The old 28X1 (16f886) was probably an exception at 6,5V.

 

[neiltechspec]

I think you may find they will tolerate higher than 5.5v as they are supplied on Military Grade chips.
(found that out when I was wanting to run a 20x2 @ 6v, military info from 'hippy')
But 7 volts is too high would probably damage them.

 

[PhilHornby]

For the Picaxe 08M2 (from the 12F1840 datasheet)

 

[Gramps]

Found my error. A nearly dead battery in the voltmeter was giving me a false reading.

 

[hippy]

A nearly dead battery in the voltmeter was giving me a false reading.

Funnily enough that's how I discovered my voltmeter battery was on its last legs when I started reading voltages which seemed unbelievably high.

I presume it's the familiar 'lowering +V causes VREF to drop which causes VIN maths to make the reading higher'. Took a while though to realise what was happening.

As noted by PhilHornby the usual recommended max voltage is 5.5V, absolute maximum 6.5V where odd things could happen, and above that you might need to buy a new PICAXE. But always check the datasheet because I recall the absolute maximum has varied across the range.

 

[Gramps]

where odd things could happen,

Ah yes! When The magic smoke appears!

 

[fernando_g]

The problem lies if one applies a slightly higher over voltage condition, which would not instantly kill the device but cause it to behave incorrectly.
This is specifically important in linear circuits like opamps, whereas a performance parameter like offset voltage could be degraded.

Ask me how I know.