Max input voltage for ADC input on microcontroller

[lloydi12345]

For a 6V SLA I would not try to power a device from it if the Vout is less than 5.5V

You also said this one on your earlier post. Is it bad to power a device say 5v from regulated 6v lead acid battery?

 

[ericgibbs]

Yes.

I hope its alright to ask this one. Do you know what's the dead voltage level of 6v SLA batteries? So I can prompt the user that he needs to recharge the battery.

hi,
For 6V SLA batteries never let them discharge to less 5.4V, I would recommend 5.6V as a minimum then recharge

 

[ericgibbs]

You also said this one on your earlier post. Is it bad to power a device say 5v from regulated 6v lead acid battery?

I dont think I said that.???

If you used a low voltage drop 5V regulator, say one that had a drop out of 0.2V a 6V SLA battery would be OK.

A standard 7805 Vreg would not work with a 6V SLA battery.

 

[lloydi12345]

I dont think I said that.???

If you used a low voltage drop 5V regulator, say one that had a drop out of 0.2V a 6V SLA battery would be OK.

A standard 7805 Vreg would not work with a 6V SLA battery.

Sorry for the late reply, now I see. Thank you for all the explanations.

 

[Mosaic]

Just an FYI,
I applied 12V direct (25A) to a 16F ADC input. The PIC lives on. The entire ADC system is now dead though, on all inputs. It's as though the PIC has no ADC. I can do regular Digital I/O .

 

[lloydi12345]

Just an FYI,
I applied 12V direct (25A) to a 16F ADC input. The PIC lives on. The entire ADC system is now dead though, on all inputs. It's as though the PIC has no ADC. I can do regular Digital I/O .

Hi Mosaic, Did you use also any voltage divider for your 12v?

 

[be80be]

Just an FYI,
I applied 12V direct (25A) to a 16F ADC input. The PIC lives on. The entire ADC system is now dead though, on all inputs. It's as though the PIC has no ADC. I can do regular Digital I/O .

ADC can not be above VDD by more then .5 volts. If he had used a voltage divider that lower it to 5.5 volts His ADC would still work.
I have killed the ADC missed the MCLR pin and hooked it to PORTA.0 So i know you can blow it.
The chip was running code that used RA0 for ADC and I went to reprogram and popped the adc.

 

[Nigel Goodwin]

Hi Mosaic, Did you use also any voltage divider for your 12v?

Obviously not, otherwise it wouldn't have been damaged, even a simple series resistor would have protected it as well - and 12V direct from a large battery is obviously a LOT more dangerous than just 6V.