I need to put a real-time clock on a board. I haven't needed to know anything about the market for this for years, and I see that I'm way out of date. I just need basic clock functionality that I can read and set under software control, I don't need any bells or whistles, and I don't care much about the format. What I do care about is something that I can put on the board easily and will work reliably. I could put a chip, caps, crystal and battery on the board. I see the 24-DIP sized chips that come with the flip-top, though, and they look like I could short-cut a number of production issues by using them. Does anyone have any experience with these things? Are the tops interchangeable, or do I have to use a TI top with a TI bottom, ditto for NXP, etc.? Any other positive or negative relevant experience anyone wants to share? Thanks. -- Tim Wescott Wescott Design Services http://www.wescottdesign.com Posting from Google? See http://cfaj.freeshell.org/google/ Do you need to implement control loops in software? "Applied Control Theory for Embedded Systems" gives you just what it says. See details at http://www.wescottdesign.com/actfes/actfes.html
Real Time Clock Hardware
Started by ●April 30, 2007
Reply by ●April 30, 20072007-04-30
Tim Wescott wrote:> I need to put a real-time clock on a board.Use DS1307 Vladimir Vassilevsky DSP and Mixed Signal Design Consultant http://www.abvolt.com
Reply by ●April 30, 20072007-04-30
Vladimir Vassilevsky wrote:> > > Tim Wescott wrote: > >> I need to put a real-time clock on a board. > > Use DS1307 >Do Dallas parts have the same ongoing availability nightmare associated with them that Maxim parts do? -- Tim Wescott Wescott Design Services http://www.wescottdesign.com Posting from Google? See http://cfaj.freeshell.org/google/ Do you need to implement control loops in software? "Applied Control Theory for Embedded Systems" gives you just what it says. See details at http://www.wescottdesign.com/actfes/actfes.html
Reply by ●April 30, 20072007-04-30
Tim Wescott wrote:>>> I need to put a real-time clock on a board. >> >> Use DS1307 >> > Do Dallas parts have the same ongoing availability nightmare associated > with them that Maxim parts do?This one is about as common as MAX232, so it should not be a problem at all. VLV
Reply by ●April 30, 20072007-04-30
On Mon, 30 Apr 2007 07:44:17 -0700, Tim Wescott <tim@seemywebsite.com> wrote:>I need to put a real-time clock on a board. I haven't needed to know >anything about the market for this for years, and I see that I'm way out >of date. > >I just need basic clock functionality that I can read and set under >software control, I don't need any bells or whistles, and I don't care >much about the format. > >What I do care about is something that I can put on the board easily and >will work reliably. > >I could put a chip, caps, crystal and battery on the board. I see the >24-DIP sized chips that come with the flip-top, though, and they look >like I could short-cut a number of production issues by using them. > >Does anyone have any experience with these things? Are the tops >interchangeable, or do I have to use a TI top with a TI bottom, ditto >for NXP, etc.? > >Any other positive or negative relevant experience anyone wants to share? > >Thanks.Epsom has some dips with the crystal inside and all. Just add a lithium battery and you'll be good for 10 years, maybe 20. John
Reply by ●April 30, 20072007-04-30
On Apr 30, 10:30 am, John Larkin <jjlar...@highNOTlandTHIStechnologyPART.com> wrote:> On Mon, 30 Apr 2007 07:44:17 -0700, Tim Wescott <t...@seemywebsite.com> > wrote: > > > > >I need to put a real-time clock on a board. I haven't needed to know > >anything about the market for this for years, and I see that I'm way out > >of date. > > >I just need basic clock functionality that I can read and set under > >software control, I don't need any bells or whistles, and I don't care > >much about the format. > > >What I do care about is something that I can put on the board easily and > >will work reliably. > > >I could put a chip, caps, crystal and battery on the board. I see the > >24-DIP sized chips that come with the flip-top, though, and they look > >like I could short-cut a number of production issues by using them. > > >Does anyone have any experience with these things? Are the tops > >interchangeable, or do I have to use a TI top with a TI bottom, ditto > >for NXP, etc.? > > >Any other positive or negative relevant experience anyone wants to share? > > >Thanks. > > Epsom has some dips with the crystal inside and all. Just add a > lithium battery and you'll be good for 10 years, maybe 20. > > JohnMaxim has the DS3231/DS3232 parts with a temperature compensated crystal. I am using the DS3231 on one of my boards and have been pleased with it. You do pay for the integration, however. -Michael
Reply by ●April 30, 20072007-04-30
On Apr 30, 10:44?am, Tim Wescott <t...@seemywebsite.com> wrote: Hey Tim, The DS1307 is a reliable choice and we use it here. Very straightforward one-wire communication, very good accuracy, etc... Can run on a crystal (32 khz), or the expensive (and very accurate) companion DS32KHz TCXO Also, straightforward to hook a backup battery, etc.. Note: If using the high stab osc., tucked away in a non-obvious app note somewhere is a caution to use a high value resistor between the two parts to avoid excessive current drain when operating on a coin cell. Be sure to review if you choose the 1307. One drawback is that the 1307 requires 5-volts. If you have that avail, then no problem. But if not, take a look at the DS32B35. (DS32C35) Maxim sent me a datasheet on this a while ago and I recall it looked rather promising. It should be in production by now?? We may switch to it.? It was an "all-in-one" unit. RTC, TCXO time base, Non-Volatile memory, etc... Which means even though it has the bells and whistles, it might negate the need for hardware elsewhere. Was even or better on pricing than the 1307. Comes in a SO-20 package. FYI - sometimes 1307's in DIP's can get scarce (which I suspect is due to RoHS?), but pretty soon that will likely be the case with all things DIP.....? -mpm
Reply by ●April 30, 20072007-04-30
Tim Wescott wrote:> I need to put a real-time clock on a board. I haven't needed to know > anything about the market for this for years, and I see that I'm way out > of date. > > I just need basic clock functionality that I can read and set under > software control, I don't need any bells or whistles, and I don't care > much about the format. > > What I do care about is something that I can put on the board easily and > will work reliably. > > I could put a chip, caps, crystal and battery on the board. I see the > 24-DIP sized chips that come with the flip-top, though, and they look > like I could short-cut a number of production issues by using them. > > Does anyone have any experience with these things? Are the tops > interchangeable, or do I have to use a TI top with a TI bottom, ditto > for NXP, etc.? > > Any other positive or negative relevant experience anyone wants to share?If cost is an issue, look at the JRC NJU6350. Cheap as dirt, tiny and we've not had any issues with it.
Reply by ●April 30, 20072007-04-30
On 30-Apr-2007, Tim Wescott <tim@seemywebsite.com> wrote:> >> I need to put a real-time clock on a board. > > > > Use DS1307 > > > Do Dallas parts have the same ongoing availability nightmare associated > with them that Maxim parts do?We started having a tough time getting Dallas parts within a year of the Maxim takeover. I don't use any Maxim parts whatsoever. -Hershel
Reply by ●April 30, 20072007-04-30
Jim Stewart wrote:> Tim Wescott wrote: >> I need to put a real-time clock on a board. I haven't needed to know >> anything about the market for this for years, and I see that I'm way >> out of date. >> >> I just need basic clock functionality that I can read and set under >> software control, I don't need any bells or whistles, and I don't care >> much about the format. >> >> What I do care about is something that I can put on the board easily >> and will work reliably. >> >> I could put a chip, caps, crystal and battery on the board. I see the >> 24-DIP sized chips that come with the flip-top, though, and they look >> like I could short-cut a number of production issues by using them. >> >> Does anyone have any experience with these things? Are the tops >> interchangeable, or do I have to use a TI top with a TI bottom, ditto >> for NXP, etc.? >> >> Any other positive or negative relevant experience anyone wants to share? > > If cost is an issue, look at the JRC NJU6350. > Cheap as dirt, tiny and we've not had any > issues with it. > >Cost is an issue. With a projected 50/year volume, engineering cost trumps all. The less we have to mess with battery holders, crystal selection, operation at cold and hot, board layout and/or part selection difficulties -- the better. -- Tim Wescott Wescott Design Services http://www.wescottdesign.com Posting from Google? See http://cfaj.freeshell.org/google/ Do you need to implement control loops in software? "Applied Control Theory for Embedded Systems" gives you just what it says. See details at http://www.wescottdesign.com/actfes/actfes.html
