EAGLE Netlist conversion

Paul Rako · Feb 22, 2005

Well the funniest post was one suggesting that I work at Maxim,
seeing as how I just spent over 3 years at National Semi and that
I consider Maxim to be a despicable company (although they
do have a few nice parts, if you can get ever get them).

I guess I was trying to say that the existence of an entire
product line at Maxim suggests this function is one worth paying
for. The fellow who posted (correctly) that I didn't even mention
switch bounce was right on the money as to why a cap and resistor
can get you into trouble. Of course if the chip at least has POR
circuitry and a POR reset pin then the cap and resistor may be fine,
as long as the datasheet says so.

Similarly I was not very clear about the process used-- I never meant
to say you need an analog process. I am just saying the circuit needs
to be designed at the transistor level. Digital simulators can
be as simple as on/off indication with a little timing thrown in. That
just is not enough when the power rails are all over that place. No,
there are plenty of fine POR circuits done in CMOS for digital.

If JT has a circuit that he can vary process corners it looks like he
understands the grief of doing a POR. I have worked with a lot of
digital guys that just can't comprehend that gate-level SPICE just
does not work when the rails are at 1.7 volts. Heck, Bob Pease would
say that analog SPICE doesn't work much better (;^o)-

Hot-swap circuits are equally non-trivial. Did the card get stuck
in for a millisecond, then yanked out, then stuck back in-- what is
the state of all the circuits on both the mother and daughtercard..
ect ect ect

Paul

Tim Shoppa wrote:

Suggestions?

Many of the recent Microchip PIC power-on-resets use a digital counter
internally. I'm guessing that they're working within confines similar
to what you have and also they're trying to keep power consumption
while asleep to a minimum and deal with brownout recovery. I don't
know the details but they must be taking on-chip clock in the 10's or
100's of kHz to tick everything along.

What requirements do you have regarding power consumption while asleep,
brownout recovery, ?

Tim.

John Fields · Feb 22, 2005

On Tue, 22 Feb 2005 08:51:06 -0700, Jim Thompson
<thegreatone@example.com> wrote:

Anyone have pointers on how to make your own screens for sand blasting
/ frosting glass?

All my surfing yields lots of commercial level equipment at $2K+

I have hand cut my own by printing onto stick-on labels, then cutting
out with an X-Acto knife.

However I have 60 pieces to do this time, making hand-cutting a wee
bit of a chore.

---
Why don't you make an honest-to-god template and use it over and over
again?

--
John Fields

Keith Williams · Feb 22, 2005

In article <6drm11lo7k4pad5b1rcuooknfh6bqchodh@4ax.com>,
thegreatone@example.com says...

On Tue, 22 Feb 2005 16:57:16 GMT, Paul Rako
s_p_ortsterpa_u_l@yahoo.com> wrote:

[snip]

If JT has a circuit that he can vary process corners it looks like he
understands the grief of doing a POR.

I've been thru MUCH grief in my design lifetime, that's why I'm
cautious as hell.

I have worked with a lot of
digital guys that just can't comprehend that gate-level SPICE just
does not work when the rails are at 1.7 volts.

Digital guys are amusing, aren't they ?

I guess we are (but the bank and the boss enjoy the humor). At least
my stuff goes *poof* with the rails at 1.7V, so using spice isn't all
that interesting at 1.7V. ;-)

Heck, Bob Pease would
say that analog SPICE doesn't work much better (;^o)-

I think Bob is becoming over-exaggerative in his old age. Picks
absurd examples. Must be running out of material for his column.

(Of course I'm a young man compared to Bob. He graduated MIT in 1961,
I graduated MIT in 1962

Hot-swap circuits are equally non-trivial. Did the card get stuck
in for a millisecond, then yanked out, then stuck back in-- what is
the state of all the circuits on both the mother and daughtercard..
ect ect ect

Paul

[snip]

My application isn't hot-swap, but it's similar... even has a
charge-pump, which turned out to be helpful in making the POR timing
;-)

Does your charge-pump operate with 1.7V rails? ;-) .25V?

--
Keith

Allan Herriman · Feb 22, 2005

On Tue, 22 Feb 2005 18:20:23 +0000 (UTC), kensmith@green.rahul.net
(Ken Smith) wrote:

In article <76lm11h5etplekhmjph2rmtvvn9h3aubvn@4ax.com>,
[...]
In my experience, ASICs that need reset to be active for a number of
clocks will have logic to implement that function internally.

I guess you don't use the 8051. The Philips ones are he one example I can
think of straight off the top where the reset must be held for N clock
cycles. The Atmel ones seem to take it a step further. They get messed
up if the reset double pulses on the assert edge. I think that must be
something to do with the ISP functions.

I have used 8051 variants in a number of products. They've always
worked because the reset generator had a minimum pulse width that is
greater than the oscillator start time.

I take your point though: in an 8051 based design, it might be a good
thing to keep it in reset until the oscillator starts, in case the
crystal has unusual parameters and takes a long time to start.

How would one go about making a 'crystal start' detector for an 8051?
We don't want to load either of the xtal pins, and (IIRC) outputs like
ALE won't be toggling while the reset is active.

Even going back a quarter century, the Intel 8284 clock generator (for
the 8086) had logic to synchronise the reset to the system clock and
provide minimum pulse widths, etc.

So there's another example of a reset that needed to be held and synced.
The fact that Intel provided the function on an external chip says
something, I'm not sure what, about doing it inside the micro.

I think it says that in the days when 16000 transistors was a big
chip, you should move as much stuff as possible off board.

Regards,
Allan

Jim Thompson · Feb 22, 2005

On Tue, 22 Feb 2005 13:27:05 -0500, Keith Williams <krw@att.bizzzz>
wrote:

In article <6drm11lo7k4pad5b1rcuooknfh6bqchodh@4ax.com>,
thegreatone@example.com says...
[snip]

My application isn't hot-swap, but it's similar... even has a
charge-pump, which turned out to be helpful in making the POR timing
;-)

Does your charge-pump operate with 1.7V rails? ;-) .25V?

480)460-2350 | |
| E-mail Address at Website Fax

Ken Smith · Feb 22, 2005

In article <76lm11h5etplekhmjph2rmtvvn9h3aubvn@4ax.com>,
[...]

In my experience, ASICs that need reset to be active for a number of
clocks will have logic to implement that function internally.

I guess you don't use the 8051. The Philips ones are he one example I can
think of straight off the top where the reset must be held for N clock
cycles. The Atmel ones seem to take it a step further. They get messed
up if the reset double pulses on the assert edge. I think that must be
something to do with the ISP functions.

Even going back a quarter century, the Intel 8284 clock generator (for
the 8086) had logic to synchronise the reset to the system clock and
provide minimum pulse widths, etc.

So there's another example of a reset that needed to be held and synced.
The fact that Intel provided the function on an external chip says
something, I'm not sure what, about doing it inside the micro.

--
--
kensmith@rahul.net forging knowledge

Jim Thompson · Feb 22, 2005

On Tue, 22 Feb 2005 19:14:49 +0000, Clint Sharp
<clint@clintsmc.demon.co.uk> wrote:

In message <gvkm111ehdtqhg4sonu8d16o8jin3k2snf@4ax.com>, Jim Thompson
thegreatone@example.com> writes
Anyone have pointers on how to make your own screens for sand blasting
/ frosting glass?

All my surfing yields lots of commercial level equipment at $2K+

I have hand cut my own by printing onto stick-on labels, then cutting
out with an X-Acto knife.

However I have 60 pieces to do this time, making hand-cutting a wee
bit of a chore.

Thanks!

...Jim Thompson
Jim, why not find your local sign maker and see if they can cut out some
vinyl shapes for you?

Several people have suggested that. I'll check it out. My wife comes
up with this sort of customized-frosted-glass project often enough,
maybe I should invest in my own cutter, particularly now that I'm
officially a registered Girl Scout, I'm the cookie "mom" this year

480)460-2350 | |
| E-mail Address at Website Fax

Rich Grise · Feb 22, 2005

On Tue, 22 Feb 2005 22:10:10 +1100, Allan Herriman wrote:

On Tue, 22 Feb 2005 10:40:56 GMT, Rich Grise <richgrise@example.net
On Tue, 22 Feb 2005 04:10:28 +0000, Paul Rako wrote:
over a range of temperatures and loads. This is really a
design challenge so don't take it lightly.

What's wrong with a 1 uF cap from the POR pin to ground, with,
say, a 10K pullup?

Rich, I am unable to tell whether you were being sarcastic, or whether
you really don't know why an RC circuit is a bad reset generator (in
general).

At the time, I was entirely serious. A cap and 10K pullup works just
fine on, say, a 6502. I've been perusing the thread, and am slowly being
dragged kicking and screaming into the 21st century. ;-)

Thanks!
Rich

Rich Grise · Feb 22, 2005

On Tue, 22 Feb 2005 18:20:23 +0000, Ken Smith wrote:

In article <76lm11h5etplekhmjph2rmtvvn9h3aubvn@4ax.com>,
[...]
In my experience, ASICs that need reset to be active for a number of
clocks will have logic to implement that function internally.

I guess you don't use the 8051. The Philips ones are he one example I can
think of straight off the top where the reset must be held for N clock
cycles. The Atmel ones seem to take it a step further. They get messed
up if the reset double pulses on the assert edge. I think that must be
something to do with the ISP functions.

Even going back a quarter century, the Intel 8284 clock generator (for
the 8086) had logic to synchronise the reset to the system clock and
provide minimum pulse widths, etc.

So there's another example of a reset that needed to be held and synced.
The fact that Intel provided the function on an external chip says
something, I'm not sure what, about doing it inside the micro.

It says that Intel was staffed by idiots, or people who were so anxious
to get _something_ working, that they jumped on the first design that
actually shuttled data around, damn the clocking - full steam ahead!

Thanks,
Rich

Rich Grise · Feb 22, 2005

On Tue, 22 Feb 2005 15:20:51 +0000, Michael A. Terrell wrote:

Rich Grise wrote:
On Tue, 22 Feb 2005 04:10:28 +0000, Paul Rako wrote:
....
over a range of temperatures and loads. This is really a
design challenge so don't take it lightly.

What's wrong with a 1 uF cap from the POR pin to ground, with,
say, a 10K pullup?

Thanks,
Rich

If you ever had to troubleshoot equipment built that way you would
never ask that question. The VTR interfaces for a video editing system
at WACX in Orlando was designed for a reset generator chip, then they
left out the chip and used a crappy R/C reset. The equipment worked
when it was new but a couple years later it would only reset one out of
20 or more attempts. You could play around with the R/C values and make
it work for a couple weeks, but they finally agreed to let me mod the
equipment by stuffing the missing parts on the board and eliminated the
problems.

But notice the operative phrase here - "designed for a reset generator
chip". That particular chip does, in fact, need a proper reset, as has
been covered in other posts in the thread.

I was talking about the kinds of chips that they made in the '80s, where
there was a pin specifically designed to take a cap and R, and has a
Schmitt trigger, and the whole chip is designed to get reset by that
little circuit.

But, as I've said in another post, I'm slowly being dragged, kicking and
screaming, into the 21st century. ;-)

Speaking of which, there was a family of "reset generator" chips once -
did they fade away too?

Thanks!
Rich

Spehro Pefhany · Feb 22, 2005

On Tue, 22 Feb 2005 19:43:30 GMT, the renowned Rich Grise
<richgrise@example.net> wrote:

I wondered, "WTF MEMS???" so I looked it up.

Sh*t man f*ck - it ain't that far from reality! Nanomachines! Buckytubes!
The one-atom motor!

Or is that a whole nother level of reality?

Thanks,
Rich

MEMS is already reality. AFAIUI, the first killer app was
accelerometers for automotive air bags.

Best regards,
Spehro Pefhany
--
"it's the network..." "The Journey is the reward"
speff@interlog.com Info for manufacturers: http://www.trexon.com
Embedded software/hardware/analog Info for designers: http://www.speff.com

Spehro Pefhany · Feb 22, 2005

On Tue, 22 Feb 2005 19:25:46 GMT, the renowned Rich Grise
<richgrise@example.net> wrote:

At the time, I was entirely serious. A cap and 10K pullup works just
fine on, say, a 6502. I've been perusing the thread, and am slowly being
dragged kicking and screaming into the 21st century. ;-)

It only works just fine some of the time- when you control the power
on/off sequencing just so. If your 6502 is doing something critical,
and especially if it's suppose to be running unattended 24/7 with no
supervision you *need* a real reset circuit.

Best regards,
Spehro Pefhany
--
"it's the network..." "The Journey is the reward"
speff@interlog.com Info for manufacturers: http://www.trexon.com
Embedded software/hardware/analog Info for designers: http://www.speff.com

Jim Thompson · Feb 22, 2005

On Tue, 22 Feb 2005 15:01:49 -0500, Keith Williams <krw@att.bizzzz>
wrote:

In article <c1vm119m9fhregkak342gsrdupevesdiq6@4ax.com>,
thegreatone@example.com says...
On Tue, 22 Feb 2005 13:27:05 -0500, Keith Williams <krw@att.bizzzz
wrote:

In article <6drm11lo7k4pad5b1rcuooknfh6bqchodh@4ax.com>,
thegreatone@example.com says...
[snip]

My application isn't hot-swap, but it's similar... even has a
charge-pump, which turned out to be helpful in making the POR timing
;-)

Does your charge-pump operate with 1.7V rails? ;-) .25V?

The specification requires 1.65V <= VDD <= 5.5V, over process corners
and -40°C to +105°C

I PASS ;-)

I chose .25V because one POR circuit requirement was for an active low
to be guaranteed above a .25V VCC, until the power supply was within
spec and stable for some period. Forcing a low voltage with a .25V
rail, under worst case conditions, wasn't an easy thing to guarantee.

A low VTH N-Channel?

My usual way is to generate a LOW for the region VTH < VDD < BG-Ref*
plus a time-out.

* BG-Ref = bandgap reference

In this case I need a POR to last until the charge-pump has reached
final value, WITHOUT loading the charge-pump with any current.

If you think the obvious, you will guess my solution, but I can't
confirm or deny it ;-)

...Jim Thompson
--
| James E.Thompson, P.E. | mens |
| Analog Innovations, Inc. | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| Phoenix, Arizona Voice

480)460-2350 | |
| E-mail Address at Website Fax

Jim Thompson · Feb 22, 2005

On Tue, 22 Feb 2005 14:56:47 -0500, Spehro Pefhany
<speffSNIP@interlogDOTyou.knowwhat> wrote:

On Tue, 22 Feb 2005 19:43:30 GMT, the renowned Rich Grise
richgrise@example.net> wrote:

I wondered, "WTF MEMS???" so I looked it up.

Sh*t man f*ck - it ain't that far from reality! Nanomachines! Buckytubes!
The one-atom motor!

Or is that a whole nother level of reality?

Thanks,
Rich

MEMS is already reality. AFAIUI, the first killer app was
accelerometers for automotive air bags.

Best regards,
Spehro Pefhany

480)460-2350 | |
| E-mail Address at Website Fax

Jim Thompson · Feb 22, 2005

On Tue, 22 Feb 2005 14:59:37 -0500, Spehro Pefhany
<speffSNIP@interlogDOTyou.knowwhat> wrote:

On Tue, 22 Feb 2005 19:25:46 GMT, the renowned Rich Grise
richgrise@example.net> wrote:

At the time, I was entirely serious. A cap and 10K pullup works just
fine on, say, a 6502. I've been perusing the thread, and am slowly being
dragged kicking and screaming into the 21st century. ;-)

It only works just fine some of the time- when you control the power
on/off sequencing just so. If your 6502 is doing something critical,
and especially if it's suppose to be running unattended 24/7 with no
supervision you *need* a real reset circuit.

Best regards,
Spehro Pefhany

I had a SMPS on a GenRad portable tester that I bragged couldn't be
killed.

So a smart-aleck came along and did a machine-gun staccato with the
ON/OFF switch, and flame erupted ;-)

So I fixed his ass... I added some circuitry to the ON/OFF switch path
that limited the recycle time to a safe value.

...Jim Thompson
--
| James E.Thompson, P.E. | mens |
| Analog Innovations, Inc. | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| Phoenix, Arizona Voice

480)460-2350 | |
| E-mail Address at Website Fax

Ken Smith · Feb 22, 2005

In article <r6um11pb6li1fk3q6fm7efi4c2t96pdt9h@4ax.com>,
Allan Herriman <allan.herriman.hates.spam@ctam.com.au.invalid> wrote:

On Tue, 22 Feb 2005 18:20:23 +0000 (UTC), kensmith@green.rahul.net
(Ken Smith) wrote:

[...]
How would one go about making a 'crystal start' detector for an 8051?
We don't want to load either of the xtal pins, and (IIRC) outputs like
ALE won't be toggling while the reset is active.

I wasn't using the 8051's oscillator in the case where it was an issue.

I just did the RESET logic inside a CPLD. It worked ok. Normally, the
8051s RC reset works fine.

You can load the osc-out pin of the 8051 with a CMOS gate without causing
serious trouble. CMOS gates have less capacitance than you normally hook
to that node.

So there's another example of a reset that needed to be held and synced.
The fact that Intel provided the function on an external chip says
something, I'm not sure what, about doing it inside the micro.

I think it says that in the days when 16000 transistors was a big
chip, you should move as much stuff as possible off board.

OR: It says that the CPU designer screwed up and they didn't want to turn
the mask again.

The 8080 had an instruction that was an almost 16 bit subtract. It didn't
borrow correctly. I suspect that they changed the data sheet rather than
fix a broken subtract.

--
--
kensmith@rahul.net forging knowledge

Spehro Pefhany · Feb 22, 2005

On Tue, 22 Feb 2005 13:31:50 -0700, the renowned Jim Thompson
<thegreatone@example.com> wrote:

On Tue, 22 Feb 2005 14:56:47 -0500, Spehro Pefhany
speffSNIP@interlogDOTyou.knowwhat> wrote:

On Tue, 22 Feb 2005 19:43:30 GMT, the renowned Rich Grise
richgrise@example.net> wrote:

I wondered, "WTF MEMS???" so I looked it up.

Sh*t man f*ck - it ain't that far from reality! Nanomachines! Buckytubes!
The one-atom motor!

Or is that a whole nother level of reality?

Thanks,
Rich

MEMS is already reality. AFAIUI, the first killer app was
accelerometers for automotive air bags.

Best regards,
Spehro Pefhany

My circuit that needed the POR has a MEMS... can't say what however
;-)

...Jim Thompson

Tease!

Best regards,
Spehro Pefhany
--
"it's the network..." "The Journey is the reward"
speff@interlog.com Info for manufacturers: http://www.trexon.com
Embedded software/hardware/analog Info for designers: http://www.speff.com

Jim Thompson · Feb 22, 2005

On Tue, 22 Feb 2005 15:35:05 -0500, Keith Williams <krw@att.bizzzz>
wrote:

In article <n95n11h8okl22dkpafcfk9bcjp78j169gh@4ax.com>,
thegreatone@example.com says...
[snip]
I chose .25V because one POR circuit requirement was for an active low
to be guaranteed above a .25V VCC, until the power supply was within
spec and stable for some period. Forcing a low voltage with a .25V
rail, under worst case conditions, wasn't an easy thing to guarantee.

A low VTH N-Channel?

Well, it was 30 years ago, so no low Vt's. It wasn't my circuit, but
IIRC Germanium NPNs were the only solution that worked, barely. (and
what a PITA to get them approved, even then). ;-)

My usual way is to generate a LOW for the region VTH < VDD < BG-Ref*
plus a time-out.

* BG-Ref = bandgap reference

Seems reasonable. I guess with a 0Vt you should be able to get a
decent POR circuit.

In this case I need a POR to last until the charge-pump has reached
final value, WITHOUT loading the charge-pump with any current.

If you think the obvious, you will guess my solution, but I can't
confirm or deny it ;-)

Well, I'm one of those humorous digital guys, so what do I know? ...but
if I had to guess, I'd guess a mirror.

480)460-2350 | |
| E-mail Address at Website Fax

Michael A. Terrell · Feb 22, 2005

Rich Grise wrote:

On Tue, 22 Feb 2005 19:38:31 +0000, Michael A. Terrell wrote:

Jim Thompson wrote:

now that I'm
officially a registered Girl Scout, I'm the cookie "mom" this year

Jim Thompson

Don't take any cookie recipes from Rich!

May I ask what this is supposed to mean?

Thanks,
Rich

Its a joke, son! I say, a Joke!

Actually I just wanted to see if you would notice.

--
Beware of those who suffer from delusions of adequacy!

Michael A. Terrell
Central Florida

Michael A. Terrell · Feb 22, 2005

Rich Grise wrote:

But notice the operative phrase here - "designed for a reset generator
chip". That particular chip does, in fact, need a proper reset, as has
been covered in other posts in the thread.

I was talking about the kinds of chips that they made in the '80s, where
there was a pin specifically designed to take a cap and R, and has a
Schmitt trigger, and the whole chip is designed to get reset by that
little circuit.

But, as I've said in another post, I'm slowly being dragged, kicking and
screaming, into the 21st century. ;-)

Speaking of which, there was a family of "reset generator" chips once -
did they fade away too?

Thanks!
Rich

Rich, it was a 6502 which is not a recent part. It was popular in
the early '80s. They also used the 6522 and several other chips I could
swipe from an unwanted VIC-20 computer. In fact, I lifted the reset
circuit from the VIC-20 service manual.

--
Beware of those who suffer from delusions of adequacy!

Michael A. Terrell
Central Florida

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