1-wire specification

I am using a DS2438 as a battery monitor. The app notes recommend a
series 330 ohm in the DQ line for static protection. The data sheet
shows 4k7 as the master pull up resistor.

I have a Link45 serial to 1-wire interface and the cooms does not
work. A quick check shows a 1k bus pull up. So the 330 ohm is not
allowing the output from the battery to get lower than about 1.2V.

Is there actually a specified min and max for the bus pull up
resistor. I.m looking but haven't found a specification yet.

On Mon, 11 Jan 2010 11:49:46 -0700, Jim Thompson
<To-Email-Use-The-Envelope-(E-Mail Removed)/Snicker> wrote:

>On Mon, 11 Jan 2010 18:40:35 +0000, Raveninghorde
><raveninghorde@invalid> wrote:
>
>>I am using a DS2438 as a battery monitor. The app notes recommend a
>>series 330 ohm in the DQ line for static protection. The data sheet
>>shows 4k7 as the master pull up resistor.
>>
>>I have a Link45 serial to 1-wire interface and the cooms does not
>>work. A quick check shows a 1k bus pull up. So the 330 ohm is not
>>allowing the output from the battery to get lower than about 1.2V.
>>
>>Is there actually a specified min and max for the bus pull up
>>resistor. I.m looking but haven't found a specification yet.
>
>330 Ohms would imply something like 2.2K _minimum_ pull-up.
>
> ...Jim Thompson

Your math isn't too bad ;-)

I am seeing Maxim app notes for 1-wire on long cables saying 1k may be
needed. This of course doesn't work with the Maxim app notes saying
fit a 330 ohm resistor for static protection. So it looks like I have
to design for 1k pull up. Just wish I could find a spec giving min
and max figures.

Who writes app notes? Certainly no one who knows what they are doing.

In article <(E-Mail Removed) t>,
WangoTango <(E-Mail Removed)> wrote:
....
>I still remember the convoluted spec on the NMOS MC68705P3S port A.
>I went something like this :
>
>"The PORT A pull up option, available on the masked part, is not
>optional on the ceramic (CS) part"
>
>OK, does that mean it is always in place, or not available?
>When I called the regional FAE he didn't know either.

Should be buried in the spec sheet somewhere. Dig, dig, dig ...
ADI-1031, October, 1984.

Compare the 6805P2 and 68705P3 "Port DC Characteristics" pages in the
back. There's only one section for the 705P3 Port A characteristics.
But for the P2, there are two. So find the one that's the best match.
"Iih" for Port A in the 705P3 matched the characteristics of "Iih"
for port A on the the P2 "with CMOS Drive Enabled". So, always enabled.

Took me about 5 minutes to answer a question that's 25 years obselete. ;-)

Mark Zenier (E-Mail Removed)
Googleproofaddress(account:mzenier provider:eskimo domain:com)

In article <(E-Mail Removed) t>,
WangoTango <(E-Mail Removed)> wrote:
>In article <(E-Mail Removed)>, (E-Mail Removed) says...
>> In article <(E-Mail Removed) t>,
>> WangoTango <(E-Mail Removed)> wrote:
>> ...
>> >I still remember the convoluted spec on the NMOS MC68705P3S port A.
>> >I went something like this :
>> >
>> >"The PORT A pull up option, available on the masked part, is not
>> >optional on the ceramic (CS) part"
>> >
>> >OK, does that mean it is always in place, or not available?
>> >When I called the regional FAE he didn't know either.
>>
>> Should be buried in the spec sheet somewhere. Dig, dig, dig ...
>> ADI-1031, October, 1984.
>>
>> Compare the 6805P2 and 68705P3 "Port DC Characteristics" pages in the
>> back. There's only one section for the 705P3 Port A characteristics.
>> But for the P2, there are two. So find the one that's the best match.
>> "Iih" for Port A in the 705P3 matched the characteristics of "Iih"
>> for port A on the the P2 "with CMOS Drive Enabled". So, always enabled.
>>
>> Took me about 5 minutes to answer a question that's 25 years obselete. ;-)
>>
>> Mark Zenier (E-Mail Removed)
>> Googleproofaddress(account:mzenier provider:eskimo domain:com)
>
>The point was that there should be a bit more clarity to begin with, not
>that the question couldn't be answered with some digging.
>
>And, shouldn't there be TWO listing for PORTA also?
>One for the masked part when the customer opts for the optional option
>and one for when they don't?

I thought that's what I said. " But for the P2, there are two. "
Meaning, they have two sections in the MC6805P2 (and 'P4 and 'P6)
"Port DC Electrical Characteristics" table of the spec sheet, one
for "Port A with CMOS Drive enabled", and one for "Port C and
Port A with CMOS Drive Disabled". Giving VOL, VOH, VIL, and VIH
under various conditions. The "drive enabled" section matches
the '705P3' table in having both the additional "VOH with a 10 uA load"
spec, and having the higher IIH spec.

Mark Zenier (E-Mail Removed)
Googleproofaddress(account:mzenier provider:eskimo domain:com)

On Thu, 14 Jan 2010 20:08:29 GMT, (E-Mail Removed) (Mark
Zenier) wrote:

>In article <(E-Mail Removed) t>,
>WangoTango <(E-Mail Removed)> wrote:
>>In article <(E-Mail Removed)>, (E-Mail Removed) says...
>>> In article <(E-Mail Removed) t>,
>>> WangoTango <(E-Mail Removed)> wrote:
>>> ...
>>> >I still remember the convoluted spec on the NMOS MC68705P3S port A.
>>> >I went something like this :
>>> >
>>> >"The PORT A pull up option, available on the masked part, is not
>>> >optional on the ceramic (CS) part"
>>> >
>>> >OK, does that mean it is always in place, or not available?
>>> >When I called the regional FAE he didn't know either.
>>>
>>> Should be buried in the spec sheet somewhere. Dig, dig, dig ...
>>> ADI-1031, October, 1984.
>>>
>>> Compare the 6805P2 and 68705P3 "Port DC Characteristics" pages in the
>>> back. There's only one section for the 705P3 Port A characteristics.
>>> But for the P2, there are two. So find the one that's the best match.
>>> "Iih" for Port A in the 705P3 matched the characteristics of "Iih"
>>> for port A on the the P2 "with CMOS Drive Enabled". So, always enabled.
>>>
>>> Took me about 5 minutes to answer a question that's 25 years obselete. ;-)
>>>
>>> Mark Zenier (E-Mail Removed)
>>> Googleproofaddress(account:mzenier provider:eskimo domain:com)
>>
>>The point was that there should be a bit more clarity to begin with, not
>>that the question couldn't be answered with some digging.
>>
>>And, shouldn't there be TWO listing for PORTA also?
>>One for the masked part when the customer opts for the optional option
>>and one for when they don't?
>
>I thought that's what I said. " But for the P2, there are two. "
>Meaning, they have two sections in the MC6805P2 (and 'P4 and 'P6)
>"Port DC Electrical Characteristics" table of the spec sheet, one
>for "Port A with CMOS Drive enabled", and one for "Port C and
>Port A with CMOS Drive Disabled". Giving VOL, VOH, VIL, and VIH
>under various conditions. The "drive enabled" section matches
>the '705P3' table in having both the additional "VOH with a 10 uA load"
>spec, and having the higher IIH spec.
>
>Mark Zenier (E-Mail Removed)
>Googleproofaddress(account:mzenier provider:eskimo domain:com)

Mark, I think your answer was tight and targeted at the OP's
first post well. I think Asgard24's response tried to change
the subject, writing "The point was that there should be a
bit more clarity to begin with, not that the question
couldn't be answered with some digging." That hadn't been
the OP's point, but it was a point Asgard24 tried to turn it
into for reasons I don't fathom well.

You were right to write as you did. It was on point and
nicely said.

Jon