Lpc2000

----- Original Message ----- 
From: "David Willmore" <willmore@...>
To: <lpc2100@yahoogroups.com>
Sent: Wednesday, January 07, 2004 9:43 PM
Subject: [lpc2100] MAX3232 problems?


>
> I finally have one of Leon's lpc210x proto boards assembled.
> The problem is the MAX3232 runs warm and seems to be drawing
> 150mA or so--it varies a bit.
>
> The lpc2106 runs at ambient and has detectable 10MHz on its
> clock pins.  Removing the MAX3232 from the board causes it
> to use very little current ~10mAh, so I'm assuming the CPU
> is okay.
>
> Is there some common failure mode these things experience?
> I'm pretty sure there was no reverse voltage, etc.  Could
> a poorly connected cap do this?
>
> I *really* want to talk to this thing, but if the serial
> interface won't work....

It sounds as if the MAX3232 has failed, it shouldn't take anything like that
amount of current and shouldn't be warm. Many years ago I had quite frequent
failures of the earlier version of this type of chip, caused by connecting
the host machine to my board whilst the host was powered up. The current
chips have ESD protection and seem a lot more robust.

Check the voltages on the charge pump capacitors, if they are wrong (IIRC
they should be about +/- 5V and +/- 12V) it won't work. Make sure you
haven't got any shorts. Have you tried a new chip?

Leon
--
Leon Heller, G1HSM
Email: aqzf13@...
My low-cost Philips LPC210x ARM development system:
http://www.geocities.com/leon_heller/lpc2104.html