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From: Joerg on 5 Aug 2010 17:46 Grant wrote: > On Thu, 05 Aug 2010 09:36:05 -0700, John Larkin <jjlarkin(a)highNOTlandTHIStechnologyPART.com> wrote: > >> On Wed, 04 Aug 2010 16:10:24 +1000, Grant <omg(a)grrr.id.au> wrote: >> [...] > >>> You can run the mux chip at 6V? Clamp to 5V at the front for mux, >>> look after the ADC separately on other side of mux? >> I can run DG408-type mux chips at +12. One recent board, I ran them at >> +-17, by bootstrapping 5-volt DC-DC converters on top of my +-12 >> rails. A whole nother story. > > Used to be +/- 10V signals on +/- 15V rails was plenty for everyone ;) Same with cars. Nowadays everyone "needs" 150-200 horses to commute to work. Back when I was a kids dad pulled a 1.2-ton travel trailer with a 55HP car, family of five in the car, lots of luggage, food, a tent, plus an inflatable boat inside the trailer. [...] > > Did you measure ESR diodes to see of they leak low enough? > > Spec (Philips) says 5 or 10uA over temperature for HCMOS tristate > outputs, 20mA I/O diode, 70mA for bus driver Vcc, Gnd. Seems too > much? Under normal temps around 70-80F it's usually well under 1uA. [...] -- Regards, Joerg http://www.analogconsultants.com/ "gmail" domain blocked because of excessive spam. Use another domain or send PM.
From: Jim Thompson on 5 Aug 2010 19:04 On Thu, 05 Aug 2010 14:46:44 -0700, Joerg <invalid(a)invalid.invalid> wrote: >Grant wrote: >> On Thu, 05 Aug 2010 09:36:05 -0700, John Larkin <jjlarkin(a)highNOTlandTHIStechnologyPART.com> wrote: >> >>> On Wed, 04 Aug 2010 16:10:24 +1000, Grant <omg(a)grrr.id.au> wrote: >>> > >[...] > >> >>>> You can run the mux chip at 6V? Clamp to 5V at the front for mux, >>>> look after the ADC separately on other side of mux? >>> I can run DG408-type mux chips at +12. One recent board, I ran them at >>> +-17, by bootstrapping 5-volt DC-DC converters on top of my +-12 >>> rails. A whole nother story. >> >> Used to be +/- 10V signals on +/- 15V rails was plenty for everyone ;) > > >Same with cars. Nowadays everyone "needs" 150-200 horses to commute to >work. Back when I was a kids dad pulled a 1.2-ton travel trailer with a >55HP car, family of five in the car, lots of luggage, food, a tent, plus >an inflatable boat inside the trailer. > > [snip] On level ground, with a tail-wind ?:-) I prefer 345hp myself... 25+MPG at a steady 80MPH :-) As for MUX protection, how about simple-minded... http://www.analog-innovations.com/SED/MUX_Protection.pdf Diodes, transistors, resistors, capacitors: users-choice. ...Jim Thompson -- | James E.Thompson, CTO | mens | | Analog Innovations, Inc. | et | | Analog/Mixed-Signal ASIC's and Discrete Systems | manus | | Phoenix, Arizona 85048 Skype: Contacts Only | | | Voice:(480)460-2350 Fax: Available upon request | Brass Rat | | E-mail Icon at http://www.analog-innovations.com | 1962 | Spice is like a sports car... Performance only as good as the person behind the wheel.
From: Joerg on 5 Aug 2010 19:56 Jim Thompson wrote: > On Thu, 05 Aug 2010 14:46:44 -0700, Joerg <invalid(a)invalid.invalid> > wrote: > >> Grant wrote: >>> On Thu, 05 Aug 2010 09:36:05 -0700, John Larkin <jjlarkin(a)highNOTlandTHIStechnologyPART.com> wrote: >>> >>>> On Wed, 04 Aug 2010 16:10:24 +1000, Grant <omg(a)grrr.id.au> wrote: >>>> >> [...] >> >>>>> You can run the mux chip at 6V? Clamp to 5V at the front for mux, >>>>> look after the ADC separately on other side of mux? >>>> I can run DG408-type mux chips at +12. One recent board, I ran them at >>>> +-17, by bootstrapping 5-volt DC-DC converters on top of my +-12 >>>> rails. A whole nother story. >>> Used to be +/- 10V signals on +/- 15V rails was plenty for everyone ;) >> >> Same with cars. Nowadays everyone "needs" 150-200 horses to commute to >> work. Back when I was a kids dad pulled a 1.2-ton travel trailer with a >> 55HP car, family of five in the car, lots of luggage, food, a tent, plus >> an inflatable boat inside the trailer. >> >> > [snip] > > On level ground, with a tail-wind ?:-) > > I prefer 345hp myself... 25+MPG at a steady 80MPH :-) > > As for MUX protection, how about simple-minded... > > http://www.analog-innovations.com/SED/MUX_Protection.pdf > > Diodes, transistors, resistors, capacitors: users-choice. > The right one looks quite busy WRT to SMT placement costs. The left one is nice but you might want to up the cap to 10uF or so in case the mother of all spikes comes waltzing in. -- Regards, Joerg http://www.analogconsultants.com/ "gmail" domain blocked because of excessive spam. Use another domain or send PM.
From: Jim Thompson on 5 Aug 2010 20:01 On Thu, 05 Aug 2010 16:56:36 -0700, Joerg <invalid(a)invalid.invalid> wrote: >Jim Thompson wrote: >> On Thu, 05 Aug 2010 14:46:44 -0700, Joerg <invalid(a)invalid.invalid> >> wrote: >> >>> Grant wrote: >>>> On Thu, 05 Aug 2010 09:36:05 -0700, John Larkin <jjlarkin(a)highNOTlandTHIStechnologyPART.com> wrote: >>>> >>>>> On Wed, 04 Aug 2010 16:10:24 +1000, Grant <omg(a)grrr.id.au> wrote: >>>>> >>> [...] >>> >>>>>> You can run the mux chip at 6V? Clamp to 5V at the front for mux, >>>>>> look after the ADC separately on other side of mux? >>>>> I can run DG408-type mux chips at +12. One recent board, I ran them at >>>>> +-17, by bootstrapping 5-volt DC-DC converters on top of my +-12 >>>>> rails. A whole nother story. >>>> Used to be +/- 10V signals on +/- 15V rails was plenty for everyone ;) >>> >>> Same with cars. Nowadays everyone "needs" 150-200 horses to commute to >>> work. Back when I was a kids dad pulled a 1.2-ton travel trailer with a >>> 55HP car, family of five in the car, lots of luggage, food, a tent, plus >>> an inflatable boat inside the trailer. >>> >>> >> [snip] >> >> On level ground, with a tail-wind ?:-) >> >> I prefer 345hp myself... 25+MPG at a steady 80MPH :-) >> >> As for MUX protection, how about simple-minded... >> >> http://www.analog-innovations.com/SED/MUX_Protection.pdf >> >> Diodes, transistors, resistors, capacitors: users-choice. >> > >The right one looks quite busy WRT to SMT placement costs. Which is why I asked about using arrays early on. >The left one >is nice but you might want to up the cap to 10uF or so in case the >mother of all spikes comes waltzing in. I don't believe spikes were the issue... simple over-range protection for a MUX. ...Jim Thompson -- | James E.Thompson, CTO | mens | | Analog Innovations, Inc. | et | | Analog/Mixed-Signal ASIC's and Discrete Systems | manus | | Phoenix, Arizona 85048 Skype: Contacts Only | | | Voice:(480)460-2350 Fax: Available upon request | Brass Rat | | E-mail Icon at http://www.analog-innovations.com | 1962 | Spice is like a sports car... Performance only as good as the person behind the wheel.
From: John Larkin on 5 Aug 2010 21:11
On Thu, 5 Aug 2010 04:39:59 -0500, "Tim Williams" <tmoranwms(a)charter.net> wrote: ><miso(a)sushi.com> wrote in message >news:37c28984-3697-42e3-b1e9-30edbfe39f3b(a)j8g2000yqd.googlegroups.com... >> But you have to provide two new power rails? This isn't a passive >> solution. At some point you are just better off buying the protection >> diodes, probably from both a cost and reliability standpoint. > >What's hard about this? I've been doing this for years, I hope it's not >novel? >http://myweb.msoe.edu/williamstm/Images/Input_Protection.png >Clamp diodes unmarked, substitute as desired. What's hard is that I'd need 256 low-leakage diodes. That's a lot of parts. The clamp rails are easy. One way to make them is to use regular 3-terminal voltage regulators "upside down", dumping current into ground. There are lots of ways to make the sink rails; I'd only need two for the entire board. John |