Reset IC for a 68000 ?

J

jamma-plusser

Guest
I have a 20 year old PCB with a dodgy custom chip which, as one of its
functions, provides the initial power on reset to a 68000 CPU.

It's only the reset part of the custom IC that is faulty, therefore I
was thinking of severing the track from the custom IC's reset pin to
the 68000 and adding in a modern, small reset IC.

What type of IC would be suitable for a 10 MHz 68000 CPU?

I can find various types in my online parts catalog:

http://uk.farnell.com/

but am not sure which one would be suitable for the 68000.

They are available in various forms - all I want is something small
that preferably only requires power with a Reset line output. I see
there are even some that look like transistors which would make them
nice and easy to the board (as opposed to a 4 or 8 pin DIL device).

Thanks
 
On Wed, 07 Jan 2009 17:05:28 GMT, jamma-plusser@hotmail.com
(jamma-plusser) wrote:

I have a 20 year old PCB with a dodgy custom chip which, as one of its
functions, provides the initial power on reset to a 68000 CPU.

It's only the reset part of the custom IC that is faulty, therefore I
was thinking of severing the track from the custom IC's reset pin to
the 68000 and adding in a modern, small reset IC.

What type of IC would be suitable for a 10 MHz 68000 CPU?

I can find various types in my online parts catalog:

http://uk.farnell.com/

but am not sure which one would be suitable for the 68000.

They are available in various forms - all I want is something small
that preferably only requires power with a Reset line output. I see
there are even some that look like transistors which would make them
nice and easy to the board (as opposed to a 4 or 8 pin DIL device).
Click to expand...
Microchip's MCP100 is a candidate. TO-92 package, active reset line
(vice open collector), reasonably cheap and available.

erm the 68K's reset *is* active low? It's been a while ...

--
Rich Webb Norfolk, VA
 
On Wed, 07 Jan 2009 12:15:43 -0500, Rich Webb
<bbew.ar@mapson.nozirev.ten> wrote:


Microchip's MCP100 is a candidate. TO-92 package, active reset line
(vice open collector), reasonably cheap and available.
Click to expand...
Many thanks. There are so many though! Which one out of this lot (not
SMT/SMD though):

http://uk.farnell.com/jsp/search/results.jsp?N=0&Ntk=gensearch_001&Ntt=MCP100&Ntx=&isGoback=false&isRedirect=false

erm the 68K's reset *is* active low? It's been a while ...
Click to expand...
Yup, active low (so is high when the 68000 is working okay).


Cheers!
 
On Wed, 07 Jan 2009 18:42:59 GMT, jamma-plusser@hotmail.com
(jamma-plusser) wrote:

On Wed, 07 Jan 2009 12:15:43 -0500, Rich Webb
bbew.ar@mapson.nozirev.ten> wrote:


Microchip's MCP100 is a candidate. TO-92 package, active reset line
(vice open collector), reasonably cheap and available.

Many thanks. There are so many though! Which one out of this lot (not
SMT/SMD though):

http://uk.farnell.com/jsp/search/results.jsp?N=0&Ntk=gensearch_001&Ntt=MCP100&Ntx=&isGoback=false&isRedirect=false
Click to expand...
Depends on where you want the reset point. From what they have
available, I'd go with the -475 flavor; that's 4.50 <= Vtrip <= 4.75.
The "DI" and "HI" suffixes only indicate different pin-out options, so
you may as well go with the cheaper one if it will fit.

--
Rich Webb Norfolk, VA
 
In article <4964df85.334992046@news.zen.co.uk>, jamma-
plusser@hotmail.com says...
I have a 20 year old PCB with a dodgy custom chip which, as one of its
functions, provides the initial power on reset to a 68000 CPU.

It's only the reset part of the custom IC that is faulty, therefore I
was thinking of severing the track from the custom IC's reset pin to
the 68000 and adding in a modern, small reset IC.

What type of IC would be suitable for a 10 MHz 68000 CPU?

I can find various types in my online parts catalog:

http://uk.farnell.com/

but am not sure which one would be suitable for the 68000.

They are available in various forms - all I want is something small
that preferably only requires power with a Reset line output. I see
there are even some that look like transistors which would make them
nice and easy to the board (as opposed to a 4 or 8 pin DIL device).

Thanks


Dallas has the DS1233 IC and it works with the Motorola ICs that use a
Click to expand...
bidirectional /RESET line, like the 68K family.
It comes in a 3 pin TO-92 package, so easy to hook up.
We use them by the 1000s on the HC11 family and I would be more than
happy to throw a couple in an envelope for you. The one that triggers
on 4.75V should work just dandy.
 
On Wed, 07 Jan 2009 15:04:43 -0500, Rich Webb
<bbew.ar@mapson.nozirev.ten> wrote:

Depends on where you want the reset point. From what they have
available, I'd go with the -475 flavor; that's 4.50 <= Vtrip <= 4.75.
The "DI" and "HI" suffixes only indicate different pin-out options, so
you may as well go with the cheaper one if it will fit.
Click to expand...
Will do, thanks.
 
On Wed, 7 Jan 2009 16:51:05 -0500, WangoTango
<asgard24@mindspring.com> wrote:


Dallas has the DS1233 IC and it works with the Motorola ICs that use a
bidirectional /RESET line, like the 68K family.
It comes in a 3 pin TO-92 package, so easy to hook up.
We use them by the 1000s on the HC11 family and I would be more than
happy to throw a couple in an envelope for you. The one that triggers
on 4.75V should work just dandy.
Click to expand...
Thanks for the kind offer - I'm in the UK, how about you?
 
In article <49652968.354045015@news.zen.co.uk>, jamma-
plusser@hotmail.com says...
On Wed, 7 Jan 2009 16:51:05 -0500, WangoTango
asgard24@mindspring.com> wrote:


Dallas has the DS1233 IC and it works with the Motorola ICs that use a
bidirectional /RESET line, like the 68K family.
It comes in a 3 pin TO-92 package, so easy to hook up.
We use them by the 1000s on the HC11 family and I would be more than
happy to throw a couple in an envelope for you. The one that triggers
on 4.75V should work just dandy.


Thanks for the kind offer - I'm in the UK, how about you?

Nope, and I have my newsgroup reader set up to suppress the full header
Click to expand...
information on the posts or I would have realized that. Amazing what
information you can suppress with the right combination of switches.
I could still do it, but there is no telling how long it would take to
get there and in what shape the parts would be in by that time too.
 
On Thu, 8 Jan 2009 11:44:22 -0500, WangoTango
<asgard24@mindspring.com> wrote:


Nope, and I have my newsgroup reader set up to suppress the full header
information on the posts or I would have realized that. Amazing what
information you can suppress with the right combination of switches.
I could still do it, but there is no telling how long it would take to
get there and in what shape the parts would be in by that time too.
Click to expand...
Not to worry, thanks anyhow. I'll keep looking.

Appreciate your offer of help though!
 
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