On Jun 6, 2009, at 1:42 AM, Ethan Dicks wrote:
Is it possible
that the DC-DC converter is playing up?
The USB serial devices I've seen have been a 1-chip design -
presumably USB, UART, and level converters all on one die, with a
few
discretes for the DC-DC converter. I don't remember seeing any
separate Maxim devices in them.
Ah... I thought I heard of a USB-TTL level async serial chip (i.e.
you
need to feed the asynch side through a MAXnnn or similar) and assumed
that's what was used in these adapters. Probably not.
I know there are "FTDI"-based USB seriual converters which would
presumably also have either an external MAXnnn or a bunch of discretes
for a charge-pump and level conversion, but I haven't dismantled any
of those.
The FTDI USB-interfaced UART that I've designed with, the FT232BM,
does not have on-chip level conversion. My design used a MAX232
powered from the system power supply. (the unit was not powered from
USB)
-Dave
--
Dave McGuire
Port Charlotte, FL