ISP programming bare 8 MHz Moteino @ 5V

[zingbat]

I was wondering if it's safe to ISP program the 8 MHz moteino board at 5V, as long as there is no radio and no flash chip on it? Loading a new bootloader.

Thanks!

[Felix]

Sure, no problem. The AVR itself will be fine up to 5.5V.
The radio and FLASH MEM chips have a limit of 3.6V.

[TomWS]

Is it ok to reverse power the MCP1703 with 5V?

[Felix]

Is it ok to reverse power the MCP1703 with 5V?

Not quite following, you mean applying 5v at the output of the MCP1703? I think the answer to that would be a no.
This is about the LDO-less 8mhz version.

[TomWS]

This is about the LDO-less 8mhz version.

Ah, I missed that detail!   

Thx!

[perky]

Not quite following, you mean applying 5v at the output of the MCP1703? I think the answer to that would be a no.
This is about the LDO-less 8mhz version.

It's an interesting question whether applying 5V to the output of the MCP1703 when Vin is disconnected would actually damage it. Technically the output would be slightly above the absolute max of Vin+0.3V, but that spec assumes Vin could sink any current passing through the intrinsic diode of the P-FET. With Vin disconnected it would only sink the low quiescent current, Vin would be that intrinic diode's voltage drop below the output, and of course the output is greater than 3.3v so the P-FET itself would be off. There's a potential divider on the comparitor circuit that has a resistor to limit current for that, so I would think it probably would be OK.

Mark.