#16 Wrong W1L and DSO_W0R timings for DS2490 chip

[Pavel Parkhomenko]

There is a set of PARMSET_W1L_ and PARMSET_DSO_W0R_ constants for DS2490 in which it seems to be erroneously copied timings from DS2480 chip.

Right timings are listed in http://datasheets.maxim-ic.com/en/ds/DS2490.pdf, page 16. We have done the little investigation using an oscilloscope and found out that it is true that, for example, W1L ranges from 4 to 11 us instead of 8 to 15 us as per current ow_ds2490.c

Attached is the patch fixing W1L and DSO_W0R timings.
Please note that I didn't touch "Change by Michael Markstaller from datasheet" because I didn't measure what is the actual slew rate on power off. However, datasheet states that is equals to 0.83 V/us but not 1.10 as Michael had written.

[Paul Alfille]

Thank you for the report and the patch.

Paul Alfille

On Thu, Dec 20, 2012 at 5:21 AM, Pavel Parkhomenko
heavyrail@users.sf.netwrote:

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• [patches:#16] http://sourceforge.net/p/owfs/patches/16/ Wrong W1L and
  DSO_W0R timings for DS2490 chip*

Status: open
Created: Thu Dec 20, 2012 10:21 AM UTC by Pavel Parkhomenko
Last Updated: Thu Dec 20, 2012 10:21 AM UTC
Owner: nobody

There is a set of PARMSET_W1L_ and PARMSET_DSO_W0R_ constants for DS2490
in which it seems to be erroneously copied timings from DS2480 chip.

Right timings are listed in
http://datasheets.maxim-ic.com/en/ds/DS2490.pdf, page 16. We have done
the little investigation using an oscilloscope and found out that it is
true that, for example, W1L ranges from 4 to 11 us instead of 8 to 15 us as
per current ow_ds2490.c

Attached is the patch fixing W1L and DSO_W0R timings.
Please note that I didn't touch "Change by Michael Markstaller from
datasheet" because I didn't measure what is the actual slew rate on power
off. However, datasheet states that is equals to 0.83 V/us but not 1.10 as
Michael had written.

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[Paul Alfille]

Applied