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----- Original Message ----- From: "David Willmore" <> To: <> Sent: Wednesday, January 07, 2004 11:51 PM Subject: Re: [lpc2100] MAX3232 problems? > > Oops! You are right. It could cause a problem with a polarised cap. Try > > putting it the other way round. > > > > I'll correct the schematic and fix the problem if I get some more boards > > made. I'll modify > > any more boards I send out. > > > > 100 nF ceramic caps are really all that is needed. The older MAX232 needs 1 > > uF. > > I put in a 100nF chip cap for the problematic V+ cap and put in a new > MAX3232. No joy. Same results. 150mA current draw and a warm chip. > Could both of my chips be bad? I've never had this bad of luck since > I put a chip in backwards. PICs hate that. > > I've got more coming in a few days. Maybe I'll proto a good old MAX232 > and trust the tolerance of the lpc2106. :) I can't really see both chips being faulty. You must have something else wrong. Have you checked that all the capacitors are OK? I get +6 V on pin 2 and -5.6 V on pin 6, checked on two boards. I'd expect about +/- (2 x 3.3 V) less a diode drop or two as the charge pump circuit inside the chip is essentially a voltage doubler on the output of an oscillator. Leon -- Leon Heller, G1HSM Email: My low-cost Philips LPC210x ARM development system: http://webspace.webring.com/people/jl/leon_heller//lpc2104.html |
MAX3232 problems?
Started by ●January 7, 2004
Reply by ●January 7, 20042004-01-07
