[En-Nut-Discussion] Ethernut 5.0 Schematic Preview

[Alain M.]

Harald Kipp escreveu:
> Alain M. wrote:
>> has anyone considerd using the RS232 drivers (ZT3243E or ST3234E in 
>> Ethernu5) powred by 5V? It should accept 3.3V as level high without any 
>> problem, and the ARM9 (most uP) is 5V compliant...
> 
> The maximum voltage on all input pins is VDDIO+0.3V or 4V.

ST's is clearly specified at 6V. And the Input logic threshold high is 
2.4V with VCC = 5 V

>> The problem is that these chips only provide 6V for RS232, that is 
>> really low and will surely cause problems. And it is outside specs too.
> 
> There are drivers available, which do provide compliant RS232 levels out 
> of a 3.3V supply. However, we found out, that they are also somewhat 
> more sensitive to shortcuts. Not sure, if they are available with more 
> than 2 transmitters.

I will buy one and make some tests, it can be usefull is a few 
situations. I will keep you informed :)

Alain