Lpc2000

Hi
We have just received the IAR LPC2106 eval board, and are having 
trouble with power-up resets. I am using the NOHAU PSU that came 
with our other eval board which doesn't have a particularly fast 
rise-time.

I need to lay a board out, but can anyone recommend a decent reset 
device that they have used. MAXIM do some good ones but their lead 
time can be very long.

cheers
Simon

The Microchip MCP120T is really easy to use. digikey has them in stock, 
they have an open drain reset output so they are really easy to 
interface to existing circuits (just don't for get the pullup!).

Shannon

On Jun 6, 2004, at 12:51 PM, itsjustimpossible wrote:

> Hi
> We have just received the IAR LPC2106 eval board, and are having
> trouble with power-up resets. I am using the NOHAU PSU that came
> with our other eval board which doesn't have a particularly fast
> rise-time.
>
> I need to lay a board out, but can anyone recommend a decent reset
> device that they have used. MAXIM do some good ones but their lead
> time can be very long.
>
> cheers
> Simon
>
>
>
>
>
> Yahoo! Groups Links
>
>
>
>
>

>>  I need to lay a board out, but can anyone recommend a decent reset
 device that they have used. MAXIM do some good ones but their lead
 time can be very long. <<

LM809 works for me and is easy to get hold of.

Thanks for both the suggestions, this gives me a couple of options 
to look at.
cheers
Simon
--- In lpc2000@yahoogroups.com, Robert Wood <robert.wood@a...> wrote:
> 
> >>  I need to lay a board out, but can anyone recommend a decent 
reset

>  device that they have used. MAXIM do some good ones but their lead
>  time can be very long. <<
> 
> LM809 works for me and is easy to get hold of.

--- In lpc2000@yahoogroups.com, Shannon Holland <holland@l...> wrote:
> The Microchip MCP120T is really easy to use. digikey has them in stock, 
> they have an open drain reset output so they are really easy to 
> interface to existing circuits (just don't for get the pullup!).
> 
> Shannon
> 
> On Jun 6, 2004, at 12:51 PM, itsjustimpossible wrote:
> 
> > Hi
> > We have just received the IAR LPC2106 eval board, and are having
> > trouble with power-up resets. I am using the NOHAU PSU that came
> > with our other eval board which doesn't have a particularly fast
> > rise-time.
> >
> > I need to lay a board out, but can anyone recommend a decent reset
> > device that they have used. MAXIM do some good ones but their lead
> > time can be very long.
> >
> > cheers
> > Simon
> >
> >
> >
> >
> >
> > Yahoo! Groups Links
> >
> >
> >
> >
> >Yes, Microchip has few more devices like MCP809/810 and you caln
also find ON SEMI MAX809TTR.
My problem is that I would like to use 'faster' reset, with reset
delay time up to 100ms. By datasheet 2114 needs min 10 ms. For
Microchip circuit time delay is 140 ms min, up to 0.5 sec(!) max.
Any idea/recomendation? Again, I am little bit sceptical to use rC
circuit reset in professional stand-alone application.

Regards,
Miodrag

Miodrag,

Try a Texas Instruments TPS3306-20-Q1. It resets with a 100ms pulse.
There are also other versions that have a reset of different values.

regards,
Charles


--- In lpc2000@yahoogroups.com, "maestral64" <maestral64@y...> wrote:
> 
> --- In lpc2000@yahoogroups.com, Shannon Holland <holland@l...> wrote:
> > The Microchip MCP120T is really easy to use. digikey has them in
stock, 

> > they have an open drain reset output so they are really easy to 
> > interface to existing circuits (just don't for get the pullup!).
> > 
> > Shannon
> > 
> > On Jun 6, 2004, at 12:51 PM, itsjustimpossible wrote:
> > 
> > > Hi
> > > We have just received the IAR LPC2106 eval board, and are having
> > > trouble with power-up resets. I am using the NOHAU PSU that came
> > > with our other eval board which doesn't have a particularly fast
> > > rise-time.
> > >
> > > I need to lay a board out, but can anyone recommend a decent reset
> > > device that they have used. MAXIM do some good ones but their lead
> > > time can be very long.
> > >
> > > cheers
> > > Simon
> > >
> > >
> > >
> > >
> > >
> > > Yahoo! Groups Links
> > >
> > >
> > >
> > >
> > >Yes, Microchip has few more devices like MCP809/810 and you caln
> also find ON SEMI MAX809TTR.
> My problem is that I would like to use 'faster' reset, with reset
> delay time up to 100ms. By datasheet 2114 needs min 10 ms. For
> Microchip circuit time delay is 140 ms min, up to 0.5 sec(!) max.
> Any idea/recomendation? Again, I am little bit sceptical to use rC
> circuit reset in professional stand-alone application.
> 
> Regards,
> Miodrag

maestral64 wrote:

>My problem is that I would like to use 'faster' reset, with reset
>delay time up to 100ms. By datasheet 2114 needs min 10 ms. For
>Microchip circuit time delay is 140 ms min, up to 0.5 sec(!) max.
>Any idea/recomendation? Again, I am little bit sceptical to use rC
>circuit reset in professional stand-alone application.
>
>Regards,
>Miodrag
>
Shouldn't this have been a new thread???

The problem with reset chips is that they are overly expensive (why?) 
and customized. I find it cheaper to employ an 8-pin micro 
(PIC12F,LPC900)complete with power-on timer/brown-out detect etc. I can 
configure these for my reset threshold, reset time etc. These micros are 
typically stand-alone, not requiring any external circuitry such as 
crystal etc to operate.

PLUS!, there is always the bonus of having it monitor the coms line and 
being able to reset or ISP the main processor as well as being able to 
operate as an independant configurable watchdog.

Summary:
Configurable intelligent watchdog/reset/monitor *costs less* than a 
fixed reset chip.

my2cents
*Peter*




-- 
No virus found in this outgoing message.
Checked by AVG Anti-Virus.
Version: 7.0.300 / Virus Database: 265.8.6 - Release Date: 2/7/05

--- In lpc2000@yahoogroups.com, "maestral64" <maestral64@y...> wrote:
> 
> --- In lpc2000@yahoogroups.com, Shannon Holland <holland@l...> 
wrote:
> > The Microchip MCP120T is really easy to use. digikey has them in 
stock, 
> > they have an open drain reset output so they are really easy to 
> > interface to existing circuits (just don't for get the pullup!).
> > 
> > Shannon
> > 
> > On Jun 6, 2004, at 12:51 PM, itsjustimpossible wrote:
> > 
> > > Hi
> > > We have just received the IAR LPC2106 eval board, and are having
> > > trouble with power-up resets. I am using the NOHAU PSU that came
> > > with our other eval board which doesn't have a particularly fast
> > > rise-time.
> > >
> > > I need to lay a board out, but can anyone recommend a decent 
reset
> > > device that they have used. MAXIM do some good ones but their 
lead
> > > time can be very long.
> > >
> > > cheers
> > > Simon
> > >
> > >
> > >
> > >
> > >
> > > Yahoo! Groups Links
> > >
> > >
> > >
> > >
> > >Yes, Microchip has few more devices like MCP809/810 and you caln
> also find ON SEMI MAX809TTR.
> My problem is that I would like to use 'faster' reset, with reset
> delay time up to 100ms. By datasheet 2114 needs min 10 ms. For
> Microchip circuit time delay is 140 ms min, up to 0.5 sec(!) max.
> Any idea/recomendation? Again, I am little bit sceptical to use rC
> circuit reset in professional stand-alone application.
> 
> Regards,
> Miodrag

How about the Texas Instruments TPS383x (x = 6, 7, 8) series?

HTH,

Jan

--- In lpc2000@yahoogroups.com, "jan_c_weber" <jan.weber@b...> wrote:
> 
> --- In lpc2000@yahoogroups.com, "maestral64" <maestral64@y...> wrote:
> > 
> > --- In lpc2000@yahoogroups.com, Shannon Holland <holland@l...> 
> wrote:
> > > The Microchip MCP120T is really easy to use. digikey has them in 
> stock, 
> > > they have an open drain reset output so they are really easy to 
> > > interface to existing circuits (just don't for get the pullup!).
> > > 
> > > Shannon
> > > 
> > > On Jun 6, 2004, at 12:51 PM, itsjustimpossible wrote:
> > > 
> > > > Hi
> > > > We have just received the IAR LPC2106 eval board, and are having
> > > > trouble with power-up resets. I am using the NOHAU PSU that came
> > > > with our other eval board which doesn't have a particularly fast
> > > > rise-time.
> > > >
> > > > I need to lay a board out, but can anyone recommend a decent 
> reset
> > > > device that they have used. MAXIM do some good ones but their 
> lead
> > > > time can be very long.
> > > >
> > > > cheers
> > > > Simon
> > > >
> > > >
> > > >
> > > >
> > > >
> > > > Yahoo! Groups Links
> > > >
> > > >
> > > >
> > > >
> > > >Yes, Microchip has few more devices like MCP809/810 and you caln
> > also find ON SEMI MAX809TTR.
> > My problem is that I would like to use 'faster' reset, with reset
> > delay time up to 100ms. By datasheet 2114 needs min 10 ms. For
> > Microchip circuit time delay is 140 ms min, up to 0.5 sec(!) max.
> > Any idea/recomendation? Again, I am little bit sceptical to use rC
> > circuit reset in professional stand-alone application.
> > 
> > Regards,
> > Miodrag
> 
> How about the Texas Instruments TPS383x (x = 6, 7, 8) series?
> 
> HTH,
> 
> Jan



Well, 
I found something that looks like perfect solution (and I am always 
concerned when I think something is perfect) - TPS70751 and TPS70851.
5V to 3.3V and 1.8V (dual output) plus  MR and Enable input and RESET
output. 1.2$/1K, 2.18Euro in Digikey. I am checking voltage thresholds
 for reset at the moment. 
Again, that has no sense with new LPC213xx (I am thinking a lot should
I just switch SCH which is almost at the end to new micro.) 
TPS383x is nice IC ( I used it with MSP430) but has one bad feature -
threshold voltage for reset is 2.93V nominal(2.84-2.99).
ARM in general(LPC21xx as well)works from 3-3.6V so 2.93V it could
cause bad reset. 

Miodrag

Charles,

Reset threshold for that device is 2.93V for 3.3V(as standard for TI
supervisors)which is too low for ARM processors (3.0V min). I am not
sure about 1.8V threshold- did you try this with LPC211x?

Regards,
Miodrag

--- In lpc2000@yahoogroups.com, "charlesgrenz" <charles.grenz@s...> wrote:

> 
> Miodrag,
> 
> Try a Texas Instruments TPS3306-20-Q1. It resets with a 100ms pulse.
> There are also other versions that have a reset of different values.
> 
> regards,
> Charles
> 
> 
> --- In lpc2000@yahoogroups.com, "maestral64" <maestral64@y...> wrote:
> > 
> > --- In lpc2000@yahoogroups.com, Shannon Holland <holland@l...> wrote:
> > > The Microchip MCP120T is really easy to use. digikey has them in
> stock, 
> > > they have an open drain reset output so they are really easy to 
> > > interface to existing circuits (just don't for get the pullup!).
> > > 
> > > Shannon
> > > 
> > > On Jun 6, 2004, at 12:51 PM, itsjustimpossible wrote:
> > > 
> > > > Hi
> > > > We have just received the IAR LPC2106 eval board, and are having
> > > > trouble with power-up resets. I am using the NOHAU PSU that came
> > > > with our other eval board which doesn't have a particularly fast
> > > > rise-time.
> > > >
> > > > I need to lay a board out, but can anyone recommend a decent reset
> > > > device that they have used. MAXIM do some good ones but their lead
> > > > time can be very long.
> > > >
> > > > cheers
> > > > Simon
> > > >
> > > >
> > > >
> > > >
> > > >
> > > > Yahoo! Groups Links
> > > >
> > > >
> > > >
> > > >
> > > >Yes, Microchip has few more devices like MCP809/810 and you caln
> > also find ON SEMI MAX809TTR.
> > My problem is that I would like to use 'faster' reset, with reset
> > delay time up to 100ms. By datasheet 2114 needs min 10 ms. For
> > Microchip circuit time delay is 140 ms min, up to 0.5 sec(!) max.
> > Any idea/recomendation? Again, I am little bit sceptical to use rC
> > circuit reset in professional stand-alone application.
> > 
> > Regards,
> > Miodrag

This is definitely very interesting idea I heard some time ago. 
I am considering that as well.
There is also 68HC908 which is automotive approved.
Only critical thing is reset of this small devices (micros) reliability.
It will be bad if small micro would not be properly reseted.
If I have some time in future I will try to apply test with few
thousands resets - ideally on different temperatures(-20, +70) to see
what is reliability (or there is guarantie from manufacturer about this?)

Miodrag

--- In lpc2000@yahoogroups.com, Peter Jakacki <peterjak@t...> wrote:
> maestral64 wrote:
> 
> >My problem is that I would like to use 'faster' reset, with reset
> >delay time up to 100ms. By datasheet 2114 needs min 10 ms. For
> >Microchip circuit time delay is 140 ms min, up to 0.5 sec(!) max.
> >Any idea/recomendation? Again, I am little bit sceptical to use rC
> >circuit reset in professional stand-alone application.
> >
> >Regards,
> >Miodrag
> >
> Shouldn't this have been a new thread???
> 
> The problem with reset chips is that they are overly expensive (why?) 
> and customized. I find it cheaper to employ an 8-pin micro 
> (PIC12F,LPC900)complete with power-on timer/brown-out detect etc. I can 
> configure these for my reset threshold, reset time etc. These micros
are 

> typically stand-alone, not requiring any external circuitry such as 
> crystal etc to operate.
> 
> PLUS!, there is always the bonus of having it monitor the coms line and 
> being able to reset or ISP the main processor as well as being able to 
> operate as an independant configurable watchdog.
> 
> Summary:
> Configurable intelligent watchdog/reset/monitor *costs less* than a 
> fixed reset chip.
> 
> my2cents
> *Peter*
> 
> 
> 
> 
> -- 
> No virus found in this outgoing message.
> Checked by AVG Anti-Virus.
> Version: 7.0.300 / Virus Database: 265.8.6 - Release Date: 2/7/05

At 10:10 AM 2/8/05 +1000, Peter Jakacki wrote:

>maestral64 wrote:
>
> >My problem is that I would like to use 'faster' reset, with reset
> >delay time up to 100ms. By datasheet 2114 needs min 10 ms. For
> >Microchip circuit time delay is 140 ms min, up to 0.5 sec(!) max.
> >Any idea/recomendation? Again, I am little bit sceptical to use rC
> >circuit reset in professional stand-alone application.

<snip>

>The problem with reset chips is that they are overly expensive (why?)
>and customized. I find it cheaper to employ an 8-pin micro
>(PIC12F,LPC900)complete with power-on timer/brown-out detect etc. I can
>configure these for my reset threshold, reset time etc. These micros are
>typically stand-alone, not requiring any external circuitry such as
>crystal etc to operate.
>
>PLUS!, there is always the bonus of having it monitor the coms line and
>being able to reset or ISP the main processor as well as being able to
>operate as an independant configurable watchdog.
>
>Summary:
>Configurable intelligent watchdog/reset/monitor *costs less* than a
>fixed reset chip.


But to how low a voltage do they operate.  A good reset chip will provide a 
low output down to about 0.8V.  It would be a real problem if the 8 pin 
micro's brown-out circuitry kicked in and caused the reset line to float at 
say 1.7V.  I suppose you could reverse the problem and use a resistive 
pulldown and override that with a positive output but then you need to know 
how high a resistance you can use and still provide a reset voltage 
(particularly at low VCC), is that specced anywhere?

Robert

" 'Freedom' has no meaning of itself.  There are always restrictions,
be they legal, genetic, or physical.  If you don't believe me, try to
chew a radio signal. "

                         Kelvin Throop, III

Robert Adsett wrote:

>But to how low a voltage do they operate.  A good reset chip will provide a 
>low output down to about 0.8V.  It would be a real problem if the 8 pin 
>micro's brown-out circuitry kicked in and caused the reset line to float at 
>say 1.7V.  I suppose you could reverse the problem and use a resistive 
>pulldown and override that with a positive output but then you need to know 
>how high a resistance you can use and still provide a reset voltage 
>(particularly at low VCC), is that specced anywhere?
>

Yes, I always use a resistive pulldown for that very reason, but why do 
worry about how high a resistance? Granted, I usually use between 10K 
and 100K which is never a problem with a CMOS input. There are in fact 
two CMOS inputs in this state, the reset micro's reset output(input), 
and the main reset input. The reset line can only see a low as there is 
no voltage source from the reset micro even down to very low voltages.

I've scoped this before under all kinds of nasty power up/downs. A 
circuit that is intrinsically in reset unless all systems are go is a 
very safe way to handle the reset.

This way works extremely well and permits ISP/reset over remote links. 
Well, that's the way I handle things in this area and others may have 
their own ideas. But that's what these discussions are good for, it's a 
real melting pot of ideas and experiences. Although.... there's the 
occasional flame that shoots up and chars a few bits too... :)

*Peter*



-- 
No virus found in this outgoing message.
Checked by AVG Anti-Virus.
Version: 7.0.300 / Virus Database: 265.8.6 - Release Date: 2/7/05

At 01:55 AM 2/9/05 +1000, Peter Jakacki wrote:

>Robert Adsett wrote:
>
> >But to how low a voltage do they operate.  A good reset chip will provide a
> >low output down to about 0.8V.  It would be a real problem if the 8 pin
> >micro's brown-out circuitry kicked in and caused the reset line to float at
> >say 1.7V.  I suppose you could reverse the problem and use a resistive
> >pulldown and override that with a positive output but then you need to know
> >how high a resistance you can use and still provide a reset voltage
> >(particularly at low VCC), is that specced anywhere?
> >
>
>Yes, I always use a resistive pulldown for that very reason, but why do
>worry about how high a resistance? Granted, I usually use between 10K
>and 100K which is never a problem with a CMOS input.

If it's that high I don't worry.  I just want to keep the input below 1/2 a 
volt or so (at 10K that's 50uA, sounds doable).  A good deal of my 
hesitance is that I simply haven't sat down and worked it through.  This helps.


<snip>
>I've scoped this before under all kinds of nasty power up/downs.

That's good to hear.

>A circuit that is intrinsically in reset unless all systems are go is a
>very safe way to handle the reset.

That's what I'm looking for.


>This way works extremely well and permits ISP/reset over remote links.


I've always liked that idea.  Also if you incorporate a real watchdog in 
the processor it should be simple to add an output latch so you can flag 
that the watchdog has fired (nice for some timing related debugging).

>Well, that's the way I handle things in this area and others may have
>their own ideas. But that's what these discussions are good for, it's a
>real melting pot of ideas and experiences.


Melt away :)

Robert

" 'Freedom' has no meaning of itself.  There are always restrictions,
be they legal, genetic, or physical.  If you don't believe me, try to
chew a radio signal. "

                         Kelvin Throop, III