I2C driver IC?

[Felix Althaus]

Hello

I know there are some i2c amplifiers that generate a better edge, but I can't find them anymore. Does anybody know any part-numbers?

Thanks
mfg
Felix
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This message was ported from CCS's old forum
Original Post ID: 9853

[R.J.Hamlett]

:=Hello
:=
:=I know there are some i2c amplifiers that generate a better edge, but I can't find them anymore. Does anybody know any part-numbers?
:=
:=Thanks
Philips does a whole family of I2C bus extenders/transceivers. You can just 'speed up the edges', for a simple drive, with any open collector Schmidt driver.
Look at the P82B96 (bus driver), P82B715 (driver), PCA9515 (bus repeater), and PCA9516 I2C hub (allows multiple I2C bus segments to be interconnected to reduce individual segment loading).
The limiting factor on an I2C 'edge', is normally the combination of bus capacitance, and pull up resistor value. The 'down' edges, generated by the drivers, are normally faster than the rising edges. You can't decrease the resistor values significantly, since then the individual devices will be unable to drive the bus low. Hence the normal answer to keeping good signalling edges, is to split the bus into multiple segments, which is what the repeater, and hub chips allow.

Best Wishes
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This message was ported from CCS's old forum
Original Post ID: 9854

[PCM programmer]

:=Hello
:=
:=I know there are some i2c amplifiers that generate a better edge, but I can't find them anymore. Does anybody know any part-numbers?
--------------------------------------------------------
Come on Felix, you have the internet just like I do. :)

This is the i2c faq which gives a part number.
<a href="http://www.esacademy.com/faq/i2c/q_and_a/faq/i2cqa2.htm" TARGET="_blank">http://www.esacademy.com/faq/i2c/q_and_a/faq/i2cqa2.htm</a>

Here is the Philips page with all their i2c extenders:
<a href="http://www.semiconductors.philips.com/selectionguides/tables/41849.html" TARGET="_blank">http://www.semiconductors.philips.com/selectionguides/tables/41849.html</a>
If you click a part number, you get a page that allows
you to buy online (scroll down to the bottom) through their
distributers. Arrow apparently will allow you to buy in qty 1.

Another source is Future Active. Do a "begins with" type
of search on: P82B715
<a href="http://www.future-active.com/" TARGET="_blank">http://www.future-active.com/</a>
If the link above doesn't work (seems to be the case sometimes)
then go to: <a href="http://www.futureelectronics.com/" TARGET="_blank">http://www.futureelectronics.com/</a>
and you'll eventually get there.
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This message was ported from CCS's old forum
Original Post ID: 9855

[Felix Althaus]

Hello

First thanks for the links.

:=Come on Felix, you have the internet just like I do.

I did search the web and I found devices like repeaters, drivers, etc (like these you recommend) but thats not what I'm looking for.
I search for a device that replaces the both pullup-resistors on the bus, resulting in better edges. I know, there is such a thing but I can't find it anymore.
And because I don't know how these devices are called in english it's a bit difficult to search the web.
May you have any other hints?

Thanks
mfg
felix
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This message was ported from CCS's old forum
Original Post ID: 9859

[R.J.Hamlett]

:=Hello
:=
:=First thanks for the links.
:=
:=:=Come on Felix, you have the internet just like I do.
:=
:=I did search the web and I found devices like repeaters, drivers, etc (like these you recommend) but thats not what I'm looking for.
:=I search for a device that replaces the both pullup-resistors on the bus, resulting in better edges. I know, there is such a thing but I can't find it anymore.
:=And because I don't know how these devices are called in english it's a bit difficult to search the web.
:=May you have any other hints?
:=
:=Thanks
:=mfg
:=felix
Such a device, is 'out of spec' for I2C, but is used on SCSI, and is an 'active negation' driver. Somebody may have been using this type of driver in an application you have seen.
This cannot be used on an I2C bus, without risking driver conflicts. It is worth getting the application notes from Philips (who _designed_ I2C), to see what is allowed...

Best Wishes
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This message was ported from CCS's old forum
Original Post ID: 9860

[Kenny]

:=Hello
:=
:=First thanks for the links.
:=
:=:=Come on Felix, you have the internet just like I do.
:=
:=I did search the web and I found devices like repeaters, drivers, etc (like these you recommend) but thats not what I'm looking for.
:=I search for a device that replaces the both pullup-resistors on the bus, resulting in better edges. I know, there is such a thing but I can't find it anymore.
:=And because I don't know how these devices are called in english it's a bit difficult to search the web.
:=May you have any other hints?
:=
:=Thanks
:=mfg
:=felix

I think Linear Technology used to make an active pullup for the i2c bus, but I couldn't find it on their site. Perhaps it was replaced by another product:
<a href="http://www.linear.com/pub/document.html?pub_type=pr&document=286" TARGET="_blank">http://www.linear.com/pub/document.html?pub_type=pr&document=286</a>

Regards
Kenny
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This message was ported from CCS's old forum
Original Post ID: 9868

[Paul Holthuizen]

:=Hello
:=
:=First thanks for the links.
:=
:=:=Come on Felix, you have the internet just like I do.
:=
:=I did search the web and I found devices like repeaters, drivers, etc (like these you recommend) but thats not what I'm looking for.
:=I search for a device that replaces the both pullup-resistors on the bus, resulting in better edges. I know, there is such a thing but I can't find it anymore.
:=And because I don't know how these devices are called in english it's a bit difficult to search the web.
:=May you have any other hints?
:=
:=Thanks
:=mfg
:=felix

Hi,

I can't find that device either although I keep reading about a device called 'Active I2C terminator'. I did find something about rolling your own using a 4066 and a couple of resistors. See attached link.

Maybe it is of use to you.

Paul
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This message was ported from CCS's old forum
Original Post ID: 9874

[Mark]

What you want is an active pullup. We use a 6mA active pullup on our I2C bus. This is very easy to do with a couple of diodes, a couple of resistors, and a PNP transitor (this of course is for each line you are trying to pullup. I can send you a simple schematic if you need one.



:=Hello
:=
:=I know there are some i2c amplifiers that generate a better edge, but I can't find them anymore. Does anybody know any part-numbers?
:=
:=Thanks
:=mfg
:=Felix
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This message was ported from CCS's old forum
Original Post ID: 9880

[Andrew Wilson Jones]

:=Hello
:=
:=I know there are some i2c amplifiers that generate a better edge, but I can't find them anymore. Does anybody know any part-numbers?
:=
:=Thanks
:=mfg
:=Felix

Have a look at this device. I2C pullup ic LTC1694 Linear Technology.

<a href="http://www.linear.com/pub/document.html?pub_type=pr&document=181" TARGET="_blank">http://www.linear.com/pub/document.html?pub_type=pr&document=181</a>

If you use it could you let me know if it works. As I have problems with a 3M I2C lead.

Andy
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This message was ported from CCS's old forum
Original Post ID: 9881

[kender]

A lot of details on the ICs discussed in this thread can be found in the Philips (NXP) AN255 "I2C & SMBus Repeaters Hubs and Extenders" http://www.standardics.nxp.com/support/documents/i2c/pdf/an255.pdf
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