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Re: [lpc2100] MAX3232 problems?

2004-01-07 by David Willmore

> Do the CAPS have the right polarity ?
> Pay attention: Pin 6 is the - side of the CAP, GND this time the '+' side.
> Same thing for Pin 2: - side to VCC 3.3 and + side to Pin 2.

Used ceramic caps.  Thought they were too small, so I replaced them with
4.7uF tants--which I was very sure to follow the data sheet and get the
polarity right.  So, that's probably not it.

The datasheet shows the V+ cap going to ground on the - side, but Leon's
board has it going to Vcc.  That shouldn't make a difference, but it's
a little difference that I noticed.

> But usually when something above is wrong, the CAPS go hops (really, i saw
> tantals burning...).

They didn't do that, so one thing went right.  Ever seen a 'lytic go?  It's
like confetti. :)

> Have you used 3.3V as supply voltage for the MAX and the CAPS ? But i had a
> look at Maxim website and MAX3232 can also be driven by 5V. So this is not a
> problem.

It's running from the 3.3V supply on the board.

> The RS232 and TTL side is not exchanged ?

Uhhh, didn't look like it.  Take a look at the board layout on Leon's website
for verification?

Cheers,
David

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