MAX232CPE pinout different from normal MAX232?
Jan Panteltje
I get very strange results with a bunch of MAX232CPE if connected as normal MAX232
(all 16 pins DIL)?
I also found this:
http://shop.avrvi.com/images/upload/MAX232-CPE%20.pdf
looks very different from the Maxim dataheet for the MAX232.
?
TTman
same pinout.
Differences are the type/size of cap you put round them...
"Jan Panteltje" <pNaonSt...@yahoo.com> wrote in message
news:is5lbd$pk3$1...@news.albasani.net...
Jan Panteltje
<pcw1...@ntlworld.com> wrote in <is5lvs$62a$1...@dont-email.me>:
>what's a normal MAX 232? They all have a suffix.... and they all have the
>same pinout.
That is what I thought, but these get freaking hot that way and cause a foldback
in the power supply (I tried 3).
Replacing with an older MAX232 shows no problems.
These are marked MAXIM MAX232CPE, got them from ebay UK...
Looks like a defective batch if it is not a connection issue.
I scoped the voltages, you see normal + on pin 1, and - on pin 6.
You also see the voltage converter waveforms.
But once you send data to it (from the PC serial port)
these things behave like they go into latchup!
I use IC sockets, so it is easy to compare the old (good ones) and the new (no good) ones.
Was hoping it was a connection issue.
If not, 20 chips for the dustbin.
Not a big deal, payed 10 Euro for it IIRC.
Will measure some more stuff.
tomcee
> On a sunny day (Wed, 1 Jun 2011 16:30:40 +0100) it happened "TTman"
>
> >what's a normal MAX 232? They all have a suffix.... and they all have the
> >same pinout.
>
> That is what I thought, but these get freaking hot that way and cause a foldback
> in the power supply (I tried 3).
> Replacing with an older MAX232 shows no problems.
> These are marked MAXIM MAX232CPE, got them from ebay UK...
> Looks like a defective batch if it is not a connection issue.
>
> I scoped the voltages, you see normal + on pin 1, and - on pin 6.
> You also see the voltage converter waveforms.
> But once you send data to it (from the PC serial port)
> these things behave like they go into latchup!
> I use IC sockets, so it is easy to compare the old (good ones) and the new (no good) ones.
>
> Was hoping it was a connection issue.
> If not, 20 chips for the dustbin.
> Not a big deal, payed 10 Euro for it IIRC.
> Will measure some more stuff.
In case you're interested, the intersil HIN202 (16pin DIL)
is pin compatible with the MAX232CPE and requires
only 0.1uf caps.
TomC
Jan Panteltje
<tomce...@yahoo.com> wrote in
<fcf96f88-0d1c-46f4...@d1g2000yqm.googlegroups.com>:
>On Jun 1, 12:01 pm, Jan Panteltje <pNaonStpealm...@yahoo.com> wrote:
>> On a sunny day (Wed, 1 Jun 2011 16:30:40 +0100) it happened "TTman"
>> <pcw1....@ntlworld.com> wrote in <is5lvs$62...@dont-email.me>:
>>
>> >what's a normal MAX 232? They all have a suffix.... and they all have th=
>e
>> >same pinout.
>>
>> That is what I thought, but these get freaking hot that way and cause a f=
>oldback
>> in the power supply (I tried 3).
>> Replacing with an older MAX232 shows no problems.
>> These are marked MAXIM MAX232CPE, got them from ebay UK...
>> Looks like a defective batch if it is not a connection issue.
>>
>> I scoped the voltages, you see normal + on pin 1, and - on pin 6.
>> You also see the voltage converter waveforms.
>> But once you send data to it (from the PC serial port)
>> these things behave like they go into latchup!
>> I use IC sockets, so it is easy to compare the old (good ones) and the ne=
>w (no good) ones.
>>
>> Was hoping it was a connection issue.
>> If not, 20 chips for the dustbin.
>> Not a big deal, payed 10 Euro for it IIRC.
>> Will measure some more stuff.
>
>In case you're interested, the intersil HIN202 (16pin DIL)
> is pin compatible with the MAX232CPE and requires
>only 0.1uf caps.
>
>TomC
OK, I will, if I cannot fix this, look for those too.
Thank you.
Nico Coesel
Check if you got counterfeit parts. Or maybe rebranded Sipex parts (be
sure to avoid Sipex parts).
--
Failure does not prove something is impossible, failure simply
indicates you are not using the right tools...
nico@nctdevpuntnl (punt=.)
--------------------------------------------------------------
who where
wrote:
>In case you're interested, the intersil HIN202 (16pin DIL)
> is pin compatible with the MAX232CPE and requires
>only 0.1uf caps.
Ditto the MAX202(CPE) - we switched years ago, getting away from
electrolytics in the process.
Jamie
I look at the Max205 and don't see how the voltage gets doubled on the
outs?
http://datasheets.maxim-ic.com/en/ds/MAX200-MAX213.pdf
What am i missing? Does it have internal caps?
Jamie
Joel Koltner
news:1iBFp.25739$ar1....@newsfe08.iad...
> I look at the Max205 and don't see how the voltage gets doubled on the
> outs?
> http://datasheets.maxim-ic.com/en/ds/MAX200-MAX213.pdf
It still has external capacitors -- C1 and C2 form part of a charge pump that
doubles and inverts the voltage (see figure 4); I presume they were able to
get the capacitors down to 100nF just by increasing the switching frequency.
Jamie
pins., all accounted for. None of them have anything to do with charge
pump caps? all of them are inputs/outputs ENable, shutdown, Grd and
input (5+) = 24 pins.
I must be blind, because I see no pins available for external charge
pump caps..
Jamie
Jan Panteltje
(Nico Coesel) wrote in <4de6b4ff....@news.kpnplanet.nl>:
>>OK, I will, if I cannot fix this, look for those too.
>
>Check if you got counterfeit parts. Or maybe rebranded Sipex parts (be
>sure to avoid Sipex parts).
I think I found a clue late last night...
I noticed that if I grounded the scope alligator clip on
the metal tab of the 7805 regulator, I could start the thing up
and connect it to the PC and it would work.
Without the scope it would go into latchup and the MAX + and - voltage generator would stop,
the MAX232 would get extremely hot, and the 7805 would go into folddown because of the current.
BTW my scope is NOT grounded (main lead).
So it seems the capacitance from the 7805 ground to 'the rest of the world' makes a difference.
Because the supply lines are clean, and decoupled at the pins of the MAX with 10 uF,
at the output of the 7805 with 10 uF, and further away with 220 uF(!), I started thinking 'start up problem (risetime)'.
But a MAX232 should not care about a slow rising supply, and scope would make things worse, not better.
As the RS232 ground is grounded *at the MAX pin*, and the RS232 leads are also connected directly to the MAX pins,
that could not induce anything either.
BUT further on the board is the dual transistor oscillator that drives the fluxgate core into saturation...
Now those pulses are extremely fast, and almost in the 1A region (peak),
maybe more at startup, so my theory now is that there is a huge voltage drop on the ground, nano seconds, biggest at start up,
that causes the input / output connection of the MAX232 on the PIC side to go NEGATIVE relative relative to the MAX232 ground.
This then causes latchup.
I will experiment a bit by changing the ground wiring for the fluxgate driver to a separate wire to the 7805,
so this situation cannot occur.
I cannot scope the effect, my scope is not fast enough, but this is my theory
after giving the observations some thought.
I will report if that fixes it.
Why the older MAX232 chips do not go into latchup, and these do, I dunno.
I do not see any sign of rebranding on the chips, but of course they can make labels really well the days.
This is actually the real fun part of electronics :-)
Jan Panteltje
<jamie_ka1lpa_not_v...@charter.net> wrote in
<7JBFp.19331$pi2....@newsfe11.iad>:
My datasheet, page 1:
MAX235 (MAX205) +5 5/5 0 -- Yes -- 120 No external caps
Power No. of Nominal SHDN Rx
Part Supply RS-232 No. of Cap. Value & Three- Active in Data Rate
Number (V) Drivers/Rx Ext. Caps (µF) State SHDN (kbps) Features
MAX220 +5 2/2 4 4.7/10 No -- 120 Ultra-low-power, industry-standard pinout
MAX222 +5 2/2 4 0.1 Yes -- 200 Low-power shutdown
MAX223 (MAX213) +5 4/5 4 1.0 (0.1) Yes 120 MAX241 and receivers active in shutdown
MAX225 +5 5/5 0 -- Yes 120 Available in SO
MAX230 (MAX200) +5 5/0 4 1.0 (0.1) Yes -- 120 5 drivers with shutdown
MAX231 (MAX201) +5 and 2/2 2 1.0 (0.1) No -- 120 Standard +5/+12V or battery supplies;
+7.5 to +13.2 same functions as MAX232
MAX232 (MAX202) +5 2/2 4 1.0 (0.1) No -- 120 (64) Industry standard
MAX232A +5 2/2 4 0.1 No -- 200 Higher slew rate, small caps
MAX233 (MAX203) +5 2/2 0 -- No -- 120 No external caps
MAX233A +5 2/2 0 -- No -- 200 No external caps, high slew rate
MAX234 (MAX204) +5 4/0 4 1.0 (0.1) No -- 120 Replaces 1488
MAX235 (MAX205) +5 5/5 0 -- Yes -- 120 No external caps
MAX236 (MAX206) +5 4/3 4 1.0 (0.1) Yes -- 120 Shutdown, three state
MAX237 (MAX207) +5 5/3 4 1.0 (0.1) No -- 120 Complements IBM PC serial port
MAX238 (MAX208) +5 4/4 4 1.0 (0.1) No -- 120 Replaces 1488 and 1489
MAX239 (MAX209) +5 and 3/5 2 1.0 (0.1) No -- 120 Standard +5/+12V or battery supplies;
+7.5 to +13.2 single-package solution for IBM PC serial port
MAX240 +5 5/5 4 1.0 Yes -- 120 DIP or flatpack package
MAX241 (MAX211) +5 4/5 4 1.0 (0.1) Yes -- 120 Complete IBM PC serial port
MAX242 +5 2/2 4 0.1 Yes 200 Separate shutdown and enable
MAX243 +5 2/2 4 0.1 No -- 200 Open-line detection simplifies cabling
MAX244 +5 8/10 4 1.0 No -- 120 High slew rate
MAX245 +5 8/10 0 -- Yes 120 High slew rate, int. caps, two shutdown modes
MAX246 +5 8/10 0 -- Yes 120 High slew rate, int. caps, three shutdown modes
MAX247 +5 8/9 0 -- Yes 120 High slew rate, int. caps, nine operating modes
MAX248 +5 8/8 4 1.0 Yes 120 High slew rate, selective half-chip enables
MAX249 +5 6/10 4 1.0 Yes 120 Available in quad flatpack package
J.A. Legris
> On a sunny day (Wed, 01 Jun 2011 21:58:28 GMT) it happened n...@puntnl.niks
> (Nico Coesel) wrote in <4de6b4ff.1637974...@news.kpnplanet.nl>:
Sounds to me like a grounding problem between the power supply for
your circuit and the PC itself. If the PC's ground is "floating"
you're just asking for troubles.
--
Joe
Jan Panteltje
(Nico Coesel) wrote in <4de6b4ff....@news.kpnplanet.nl>:
I will experiment a bit by changing the ground wiring for the fluxgate driver to a separate wire to the 7805,
so this situation cannot occur.
I will report if that fixes it.
I changed the wiring so the fluxgate stuff has its own supply wires,
and took a fresh MAX2322 from the same batch.
It has been working now for 10 minutes without problems?
Took a picture of a MAX that died, and you can feel with your fingernail that the
http://www.panteltje.com/pub/latchup_MAX232_img_2990.jpg
printing is in a slightly lower area than the rest of the chip.
That is the grey area, and the chip is dark black (small edge in front.
So maybe they are rebranded, do not know for sure.
Would MAXIM bother to carve out some of the package?
And these are very readable, not normal either :-)
This is fun too, but AMD makes very good chips, its still working.
http://www.panteltje.com/pub/overheated_duron_950_img_2987.jpg
I got fooled, cleaned the PC inside, started in BIOS health,
it displayed 46 C, but I did smell paper.
But it kept steady at 46 C, now I know the BIOS hanged (the CPU halted)
Cooled of, mounted correctly, been on now 12 hours or more.
Better get a spare Duron.
Jan Panteltje
Legris" <jale...@sympatico.ca> wrote in
<5a8bf541-e08b-4ed1...@w21g2000yqm.googlegroups.com>:
>On Jun 2, 5:11 am, Jan Panteltje <pNaonStpealm...@yahoo.com> wrote:
>> On a sunny day (Wed, 01 Jun 2011 21:58:28 GMT) it happened n...@puntnl.ni=
>ks
>> (Nico Coesel) wrote in <4de6b4ff.1637974...@news.kpnplanet.nl>:
>>
>> >>OK, I will, if I cannot fix this, look for those too.
>>
>> >Check if you got counterfeit parts. Or maybe rebranded Sipex parts (be
>> >sure to avoid Sipex parts).
>>
>> I think I found a clue late last night...
>> I noticed that if I grounded the scope alligator clip on
>> the metal tab of the 7805 regulator, I could start the thing up
>> and connect it to the PC and it would work.
>> Without the scope it would go into latchup and the MAX + and - voltage ge=
>nerator would stop,
>> the MAX232 would get extremely hot, and the 7805 would go into folddown b=
>ecause of the current.
>> BTW my scope is NOT grounded (main lead).
>> So it seems the capacitance from the 7805 ground to 'the rest of the worl=
>d' makes a difference.
>> Because the supply lines are clean, and decoupled at the pins of the MAX =
>with 10 uF,
>> at the output of the 7805 with 10 uF, and further away with 220 uF(!), I =
>started thinking 'start up problem (risetime)'.
>> But a MAX232 should not care about a slow rising supply, and scope would =
>make things worse, not better.
>> As the RS232 ground is grounded *at the MAX pin*, and the RS232 leads are=
> also connected directly to the MAX pins,
>> that could not induce anything either.
>> BUT further on the board is the dual transistor oscillator that drives th=
>e fluxgate core into saturation...
>> Now those pulses are extremely fast, and almost in the 1A region (peak),
>> maybe more at startup, so my theory now is that there is a huge voltage d=
>rop on the ground, nano seconds, biggest at start up,
>> that causes the input / output connection of the MAX232 on the PIC side t=
>o go NEGATIVE relative relative to the MAX232 ground.
>> This then causes latchup.
>> I will experiment a bit by changing the ground wiring for the fluxgate dr=
>iver to a separate wire to the 7805,
>> so this situation cannot occur.
>> I cannot scope the effect, my scope is not fast enough, but this is my th=
>eory
>> after giving the observations some thought.
>> I will report if that fixes it.
>> Why the older MAX232 chips do not go into latchup, and these do, I dunno.
>> I do not see any sign of rebranding on the chips, but of course they can =
>make labels really well the days.
>>
>> This is actually the real fun part of electronics :-)
>
>Sounds to me like a grounding problem between the power supply for
>your circuit and the PC itself. If the PC's ground is "floating"
>you're just asking for troubles.
Nope, it also does latchup (did) without the PC,
and the PC is of course grounded.
It is fixed now (I think), see my other reply.
Joel Koltner
> Did you actually look at the MAX205 lay out (Page 14)?
Ah, I'm sorry, no -- I was having a dyslexic moment, it seems, and read your
part number as MAX202 rather than '205.
For the MAX205, I would guess that you're correct about their using internal
capacitors... although perhaps even markedly smaller than 100nF.
---Joel