On Sat, 13 Sep 2014 10:21:49 -0700, John Larkin <jlarkin@highlandtechnology.com> wrote:>On Fri, 12 Sep 2014 22:52:21 -0400, krw@attt.bizz wrote: > >>On Fri, 12 Sep 2014 10:58:49 -0700, Jim Thompson >><To-Email-Use-The-Envelope-Icon@On-My-Web-Site.com> wrote: >> >>>I need a rail-to-rail I/O OpAmp, 5V Vcc is fine, slow speed setting a >>>current mirror. >> >>What specs? >> >>>What would you guys in the discrete world recommend as being >>>well-behaved, no peculiarities, etc? (And readily available ;-) >> >>I've been using the MicroChip MCP6294, mainly because they're cheap >>but the specs matter. > >That looks OK for non-critical stuff. The single MCP6291 in SOT23 is >around 40 cents in quantity. (I like singles, usually.) Somewhere >there ought to be a really cheap workhorse opamp, ten cents maybe.I'm paying less than that for the quad. Less than half for the single (though I haven't used any). Yeah, it's a general purpose opamp with nothing special going for it except its cost. It is R-R I/O, which command a premium over others. I can get non R-R opamps from NJR for well under $.10 but they're pretty old-school bipolars. I'm trying to keep my analog rail under 5V, which kinda dictates R-R.
RRIO OpAmp Recommendation?
Started by ●September 12, 2014
Reply by ●September 13, 20142014-09-13
Reply by ●September 13, 20142014-09-13
On 9/13/2014 8:27 PM, Jim Thompson wrote:> On Sat, 13 Sep 2014 19:43:20 -0400, Phil Hobbs > <pcdhSpamMeSenseless@electrooptical.net> wrote: > >> On 9/13/2014 1:21 PM, John Larkin wrote: >>> On Fri, 12 Sep 2014 22:52:21 -0400, krw@attt.bizz wrote: >>> >>>> On Fri, 12 Sep 2014 10:58:49 -0700, Jim Thompson >>>> <To-Email-Use-The-Envelope-Icon@On-My-Web-Site.com> wrote: >>>> >>>>> I need a rail-to-rail I/O OpAmp, 5V Vcc is fine, slow speed setting a >>>>> current mirror. >>>> >>>> What specs? >>>> >>>>> What would you guys in the discrete world recommend as being >>>>> well-behaved, no peculiarities, etc? (And readily available ;-) >>>> >>>> I've been using the MicroChip MCP6294, mainly because they're cheap >>>> but the specs matter. >>> >>> That looks OK for non-critical stuff. The single MCP6291 in SOT23 is >>> around 40 cents in quantity. (I like singles, usually.) Somewhere >>> there ought to be a really cheap workhorse opamp, ten cents maybe. >>> >>> >> >> Already exists. LM358, $0.09 in quantity 1 from Newark. And it's a >> dual! ;) >> >> http://octopart-clicks.com/click/vptrack?ak=68b25f31&sig=077166e&vpid=1 >> 16013415 >> >> Cheers >> >> Phil Hobbs > > But not RRIO. > > ...Jim Thompson >Picky, picky. Cheers Phil Hobbs -- Dr Philip C D Hobbs Principal Consultant ElectroOptical Innovations LLC Optics, Electro-optics, Photonics, Analog Electronics 160 North State Road #203 Briarcliff Manor NY 10510 hobbs at electrooptical dot net http://electrooptical.net
Reply by ●September 14, 20142014-09-14
"Phil Hobbs" <pcdhSpamMeSenseless@electrooptical.net> wrote in message news:5414D698.9030000@electrooptical.net...> Already exists. LM358, $0.09 in quantity 1 from Newark. And it's a > dual! ;) > > http://octopart-clicks.com/click/vptrack?ak=68b25f31&sig=077166e&vpid=1 > 16013415Speaking of, I've been looking for "single supply" (includes ground) or RRIO chips with higher supply voltage (12V minimum, >16 preferred for reliability). Catch is: needs more GBW than an LM358. Closest I've seen is CA3130, but it seems rather obscure (almost everything CA- is utterly obsolete, though Intersil still seems to be supporting a few). There was one or two from TI or LT that meet or exceed (particularly in offset), but they're no cheaper. Decomp or current feedback would be fine (it's for gain ~ 50, GBW >= 25MHz), but both are like hens' teeth, or have way too much GBW (video amps, etc.). Tim -- Seven Transistor Labs Electrical Engineering Consultation Website: http://seventransistorlabs.com
Reply by ●September 14, 20142014-09-14
On 9/13/2014 11:33 PM, Tim Williams wrote:> "Phil Hobbs" <pcdhSpamMeSenseless@electrooptical.net> wrote in message > news:5414D698.9030000@electrooptical.net... >> Already exists. LM358, $0.09 in quantity 1 from Newark. And it's a >> dual! ;) >> >> http://octopart-clicks.com/click/vptrack?ak=68b25f31&sig=077166e&vpid=1 >> 16013415 > > Speaking of, I've been looking for "single supply" (includes ground) or > RRIO chips with higher supply voltage (12V minimum, >16 preferred for > reliability). Catch is: needs more GBW than an LM358. > > Closest I've seen is CA3130, but it seems rather obscure (almost > everything CA- is utterly obsolete, though Intersil still seems to be > supporting a few).I remember those. The CA3140 was more or less the same part, but with a bipolar totem-pole output stage. The CA3100 was magic back in about 1980--it was the only amp we could find that could handle multiple channel PSK data in a 3-MHz bandwidth with acceptable intermod. TI makes a bunch of quite reasonable higher-voltage op amps, e.g. the OPA188/2188/4188 chopamps. Cheers Phil Hobbs> > There was one or two from TI or LT that meet or exceed (particularly in > offset), but they're no cheaper. > > Decomp or current feedback would be fine (it's for gain ~ 50, GBW >= > 25MHz), but both are like hens' teeth, or have way too much GBW (video > amps, etc.). > > Tim >-- Dr Philip C D Hobbs Principal Consultant ElectroOptical Innovations LLC Optics, Electro-optics, Photonics, Analog Electronics 160 North State Road #203 Briarcliff Manor NY 10510 hobbs at electrooptical dot net http://electrooptical.net
Reply by ●September 15, 20142014-09-15
"Phil Hobbs" <pcdhSpamMeSenseless@electrooptical.net> wrote in message news:5414D698.9030000@electrooptical.net...> On 9/13/2014 1:21 PM, John Larkin wrote: >> On Fri, 12 Sep 2014 22:52:21 -0400, krw@attt.bizz wrote: >> >>> On Fri, 12 Sep 2014 10:58:49 -0700, Jim Thompson >>> <To-Email-Use-The-Envelope-Icon@On-My-Web-Site.com> wrote: >>> >>>> I need a rail-to-rail I/O OpAmp, 5V Vcc is fine, slow speed setting a >>>> current mirror. >>> >>> What specs? >>> >>>> What would you guys in the discrete world recommend as being >>>> well-behaved, no peculiarities, etc? (And readily available ;-) >>> >>> I've been using the MicroChip MCP6294, mainly because they're cheap >>> but the specs matter. >> >> That looks OK for non-critical stuff. The single MCP6291 in SOT23 is >> around 40 cents in quantity. (I like singles, usually.) Somewhere >> there ought to be a really cheap workhorse opamp, ten cents maybe. >> >> > > Already exists. LM358, $0.09 in quantity 1 from Newark. And it's a dual! > ;) > > http://octopart-clicks.com/click/vptrack?ak=68b25f31&sig=077166e&vpid=1 > 16013415 > > Cheers > Phil Hobbs >But the LM358 doesn't use any bias, and so there is crossover distortion at the mid point if used in a linear application such as audio. Maybe that's not an issue for other applications? -Bill --- news://freenews.netfront.net/ - complaints: news@netfront.net ---
Reply by ●September 15, 20142014-09-15
On 9/14/2014 11:55 PM, Bill Bowden wrote:> "Phil Hobbs" <pcdhSpamMeSenseless@electrooptical.net> wrote in message > news:5414D698.9030000@electrooptical.net... >> On 9/13/2014 1:21 PM, John Larkin wrote: >>> On Fri, 12 Sep 2014 22:52:21 -0400, krw@attt.bizz wrote: >>> >>>> On Fri, 12 Sep 2014 10:58:49 -0700, Jim Thompson >>>> <To-Email-Use-The-Envelope-Icon@On-My-Web-Site.com> wrote: >>>> >>>>> I need a rail-to-rail I/O OpAmp, 5V Vcc is fine, slow speed setting a >>>>> current mirror. >>>> >>>> What specs? >>>> >>>>> What would you guys in the discrete world recommend as being >>>>> well-behaved, no peculiarities, etc? (And readily available ;-) >>>> >>>> I've been using the MicroChip MCP6294, mainly because they're cheap >>>> but the specs matter. >>> >>> That looks OK for non-critical stuff. The single MCP6291 in SOT23 is >>> around 40 cents in quantity. (I like singles, usually.) Somewhere >>> there ought to be a really cheap workhorse opamp, ten cents maybe. >>> >>> >> >> Already exists. LM358, $0.09 in quantity 1 from Newark. And it's a dual! >> ;) >> >> http://octopart-clicks.com/click/vptrack?ak=68b25f31&sig=077166e&vpid=1 >> 16013415 >> >> Cheers >> Phil Hobbs >> > > But the LM358 doesn't use any bias, and so there is crossover distortion at > the mid point if used in a linear application such as audio. Maybe that's > not an issue for other applications? > > -BillFor nine cents in onesies, he expects perfection. An arrant varlet, forsooth. ;) LM358s and 324s are occasionally useful, but usually in unipolar applications, true. A figure of merit for a given design is how crappy an amplifier you can use and have it still work well. Cheers Phil Hobbs -- Dr Philip C D Hobbs Principal Consultant ElectroOptical Innovations LLC Optics, Electro-optics, Photonics, Analog Electronics 160 North State Road #203 Briarcliff Manor NY 10510 hobbs at electrooptical dot net http://electrooptical.net
