> > Queestion as topic :  does anyone here know of a microcontroller that
> > can operate with supply and I/O between 4 and 7 volts ?
> 
> Microchip produces "HV" variants (high voltage) of some of their PIC
> chips.  IIRC they work at up to 14V, but at least they are good to
> run off 9V batteries.
> 
> > Of course I could regulate the supply but then I would also need to
> > opto-isolate all the I/O which is not viable.
> 
> If you IO doesnt exceed 7V, you dont necessarily have to optoisolate.
> The 74VHC family can be used as cheap levelconverter.
> 
> Marc

Thanks to Marc and all who responded.  I will investigate the Goal &
Microchip parts and other suggestions re level shifting and
regulation.

Thanks again,

David

David wrote:
>>>Of course I could regulate the supply but then I would also need to
>>>opto-isolate all the I/O which is not viable.
>>
>>You don't need to opto-isolate, just level-shift.  Many existing ICs can
>>do that.  In fact, many PC CPU runs below 2V and level-shift to 3.3V/5V.
>>Many microcontroller runs below 2V for much lower operating power. some
>>has open-collector outputs to aid lvel-shifting.
>>
> 
> 
> I mispoke thanks for pointing that out.  Of course any level-shifting
> method would do, not just opto-isolating the I/O.  However I want it
> all done on the MCU,  'cos otherwise it'll treble the board area (<
> 1"" square) and also treble the costs.  I'm certain this can't be an
> unusual requirement - is there really no MCU currently available with
> higher than 5(ish) volts tolerant I/O ?

There are some, but not many.

  Highest IO spec I've seen is 100V and 300V on
VERSA HV100, HV300 see
http://www.goalasic.com/productguide.html

  Also Fairchild make uC with 12V regulators, and IIRC Microchip did
an OTP one.  SiLabs hae parts with +/-60V Analog IP pins.

  Atmel's MARC4 family is specified to 6.5V Vcc [operate]

  So higher voltage can clearly be done, but normally the CPU Core is 
not designed for high voltage operation, as it is more power efficent to 
regulate the core power, but maybe offer higher IO voltages.

  STm and Motorola have CMOS+Power FAB processes, that can integrate
uC + PowerMOSFETS for high volume users.

  Anything over 5.5V these days is unusual, but maybe someone will
join Goal in offering a "CPU + ULN2003" in one package ?

  -jg

"Norm Dresner" <ndrez@att.net> schrubbelte:

>So, if you had actually used Google

...which I actually did -- but thanks anyway.

-peter

--

> Queestion as topic :  does anyone here know of a microcontroller that
> can operate with supply and I/O between 4 and 7 volts ?

Microchip produces "HV" variants (high voltage) of some of their PIC
chips.  IIRC they work at up to 14V, but at least they are good to
run off 9V batteries.

> Of course I could regulate the supply but then I would also need to
> opto-isolate all the I/O which is not viable.

If you IO doesnt exceed 7V, you dont necessarily have to optoisolate.
The 74VHC family can be used as cheap levelconverter.

Marc

"David" <mangled_us@yahoo.com> skrev i meddelandet
news:fdf3b9b2.0410240417.3c0d02b7@posting.google.com...
> > Since I/O is beteen 4 and 7 volts, why do you not connect the GND of the
> > Micro to 4 Volts.
> > Most CPUs will handle that.
>
> Hi Ulf,  thanks for responding.
>
> I take it from your answer that Atmel don't have such a chip in their
> armoury ?  I'm interested to hear from a chip mfr what the reasons
> behind this might be ?  Of course I understand that CPU performance is
> all optimised for certain voltages and that device densities would
> suffer.  But still... a device with a higher supply and I/O voltage
> tolerance must surely have many applications ?  Anything that runs of
> batteries would be easier to design, for instance.  So how about
> persuading the chaps back at base for us ?  :-)

No, as others have mentioned, the cost makes the device unattractive.
To handle 7 Volt inside a transistor, you have to use processes
which are (today) totally unsuitable cost wise
Battery operated equipment is moving in the other direction to conserve
power.

Remember:

    P = C * U^2

So reduction off voltage is the most important factor in battery management.
You can use an regulator to reduce the voltage from a high voltage device.
You do not need to use the high voltage for I/O.




>
> Regards,
>
> David




-- 
Best Regards
Ulf at atmel dot com
These comments are intended to be my own opinion and they
may, or may not be shared by my employer, Atmel Sweden.

On 24 Oct 2004 05:17:17 -0700, mangled_us@yahoo.com (David) wrote:

>But still... a device with a higher supply and I/O voltage
>tolerance must surely have many applications ? 

I do not see much need in a higher supply voltage, but higher I/O
voltages would be nice. I think that the largest problem is due to the
common use of multifunction pins, i.e. pins that can be programmed
both as inputs or outputs, which requires a lot of electronics on the
pin. Designing such pins for high I/O voltages would cause a lot of
reverse biasing problems. 

However, if dedicated input on output pins are used, the outputs could
be simply open collector(drain) types, in which the external I/O
voltage could be quite high, provided that there are no real or
parasitic diodes from the output pin (collector/drain) to the Vdd. If
the pin can sink sufficient currents (>20 mA) LEDs and small relays
could be driven directly. 

On the input side a high current protection diode would be required
between each input and Vdd and the input can be used as voltage input,
if the input voltage is always between 0 and Vdd or as a current
input, with an external series resistor, if the input voltage can
swing above Vdd. An extra resistor from input to ground may be needed
to move the "low" state threshold sufficiently low.

A CPU with a low internal power consumption can be driven with a
series resistor and a shunting zener from any voltage. The zener
should keep the Vdd below the maximum allowed Vdd and should be big
enough, so that it can also dissipate the total worst case input pin
current flowing trough the external series resistors through the input
protection diodes to Vdd and through the zener to ground

As such, I do not see a problem if the CPU core Vdd is quite low
(1.5-3.3V) but it sure would be nice to have (high voltage tolerant)
_current_ inputs and outputs (instead of voltage I/O).

Paul

"David" <mangled_us@yahoo.com> wrote in message 
news:fdf3b9b2.0410240417.3c0d02b7@posting.google.com...
>> Since I/O is beteen 4 and 7 volts, why do you not connect the GND of the
>> Micro to 4 Volts.
>> Most CPUs will handle that.
>
> Hi Ulf,  thanks for responding.
>
> I take it from your answer that Atmel don't have such a chip in their
> armoury ?  I'm interested to hear from a chip mfr what the reasons
> behind this might be ?  Of course I understand that CPU performance is
> all optimised for certain voltages and that device densities would
> suffer.  But still... a device with a higher supply and I/O voltage
> tolerance must surely have many applications ?  Anything that runs of
> batteries would be easier to design, for instance.  So how about
> persuading the chaps back at base for us ?  :-)
> Regards,
> David

Unfortunately for your design, the entire semiconductor world has been 
shifting to smaller dies sizes, lower power contraints,
and lower voltages. Pretty soon the 1.8v systems will be common place. That 
is what is driving the market now.
As for running off of batteries, many systems run off of one Lithium-Ion 
cell at 3.7v quite readily.
Many other battery powered systems use one 1.2v or two 1.2v cells and use 
DC-DC converters to
generate higher voltages such as for LCD back lighting and such. Thus the 
old four, six and eight cell battery designs have
all been replaced by the one or two cell battery designs.
Flash card devices all run at 3.3v or less now.
So unfortunately there is simply no market for 10v MCU's anymore. The 
manufacturers aren't going to make something
that doesn't make a profit for them. It costs many millions of dollars for a 
factory to tool up to make the chips.
You can't make obsolete chips if no one wants them.
Even if you wanted to buy several million 10v MCU's. none of the 
manufacturers would be able to accomodate you as they
have all been switching to ever smaller die sizes and equipment and no one 
has old chip manufacturing facilities left to make these kind of large die 
high power chips anymore.

mangled_us@yahoo.com (David) wrote in message news:<fdf3b9b2.0410240417.3c0d02b7@posting.google.com>...
> > Since I/O is beteen 4 and 7 volts, why do you not connect the GND of the
> > Micro to 4 Volts.
> > Most CPUs will handle that.
> 
> Hi Ulf,  thanks for responding.  
> 
> I take it from your answer that Atmel don't have such a chip in their
> armoury ?  I'm interested to hear from a chip mfr what the reasons
> behind this might be ?  Of course I understand that CPU performance is
> all optimised for certain voltages and that device densities would
> suffer.  But still... a device with a higher supply and I/O voltage
> tolerance must surely have many applications ?  Anything that runs of
> batteries would be easier to design, for instance.  So how about
> persuading the chaps back at base for us ?  :-)
> 
> Regards,
> 
> David

Well Dave, most chip mfr designs are a result of solving THEIR
problems, not ours (even though their "Mission Statements" would have
you believe otherwise). Or maybe they solve their top buyers (auto
mfr) problems, but thats about it (and they kick and fight the whole
way in any case).

CPU's that work under wide voltages ranges would make our life much
easier, but would cause them big headaches. Likewise for
microcontrollers with floating point, or at least a fixed point CPU
with a friggin divide instruction (i.e., where is the divide ARM?, oh
Thumb2 thanks finally).

But nooooo, they like to make nice sleek simple CPU's that solves all
their problem (the origins of the wacky RISC craze), in return, we
have to pay the price by wasting our time trying to figure out how to
optimize a binary divide algorithm (see related thread in this
newsgroup) all because they want to save some die space so they can
include a 20th serial inteface that no one needs (but is easy to
implement). Or we have to waste our time rewriting/rethinking all our
algorithms to not use a divide. Or deal with the headaches of fixed
point math and the typically non portable C code that goes along with
it(what are we still in the 1970's?).

I'm sure all the reasons why this is so is because it makes the most
sense for FORD or others who buy millions of these chips who require
the lowest recurring cost and thus is less concerned about NRE
(software development). Why if I want floating point do I have to buy
a 388 pin 1 mm ball grid array microcontroller to get it (MPC565 with
has more serial ports then I can count on two hands)? Because its best
for FORD, for embedded products which sell in the thousands or ten's
of thousands, most of chips out there don't make much sense and you
have a snowballs chance in hell changing it. Just my opinion.

mangled_us@yahoo.com (David) wrote in message news:<fdf3b9b2.0410240417.3c0d02b7@posting.google.com>...
> > Since I/O is beteen 4 and 7 volts, why do you not connect the GND of the
> > Micro to 4 Volts.
> > Most CPUs will handle that.
> 
> Hi Ulf,  thanks for responding.  
> 
> I take it from your answer that Atmel don't have such a chip in their
> armoury ? 

Most Atmel fab processes top at 5.5V/6V.

> I'm interested to hear from a chip mfr what the reasons
> behind this might be ?

Different fab requirements for CPU and IO.

> Of course I understand that CPU performance is
> all optimised for certain voltages and that device densities would
> suffer.  But still... a device with a higher supply and I/O voltage
> tolerance must surely have many applications ?  Anything that runs of
> batteries would be easier to design, for instance.  So how about
> persuading the chaps back at base for us ?  :-)

Nop, can't even get them to provide 5V flash memories, instead of
3.3V/1.8V.  We tried and failed.

> 
> Regards,
> 
> David