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LM386 & Spice

Started by Unknown April 19, 2015
On 20/04/15 23.44, Jim Thompson wrote:
...
> What? No long-throw 2" speakers ?>:-} > > ...Jim Thompson
>2" Long-throw like this?: https://www.youtube.com/watch?v=cBxTyGe9ed4 or this: https://www.youtube.com/watch?v=0yuCtJ2sXO0 Glenn
Tim Wescott <seemywebsite@myfooter.really> wrote:
> On Sun, 19 Apr 2015 05:08:15 -0700, tabbypurr wrote: > >> I need to sim an LM386 amp to see what decoupling caps are neded for >> stability on end of life batteries. Is there a Spice model for this >> anywhere? My LTSpice seems to lack any of the IC models I'm likely to >> use. >> >> >> NT > > Wow -- is that still being used in new production, or is it just used when > people are reading old project magazines?
Valcom still uses it in their 8" talkback ceiling speakers. -- ,-. Give More expect less Love More \_/ argue less Listen More talk less {|||)< Don Kuenz Laugh More complain less Dream More / \ doubt less Hope More fear less `-' Breathe More whine less
Glenn wrote...
> > On 20/04/15 18.21, Tim Wescott wrote: >... >> You may end up with a lower BOM cost and less board space with a rail-rail >> op-amp and a NPN-PNP transistor pair, assuming that there's not a more >> modern audio amp chip that'll do ya. > > Another circuits that comes to mind: > Art of Electronics, 3rd edition > page 318: The Monticelli circuit. [ Figure 5.35 ] > Patent 5. jul 1984: http://www.google.com/patents/US4570128 > > [4] D. M. Monticelli, A quad CMOS single-supply op amp with > rail-to-rail output swing, IEEE J. Solid-State Circuits, > vol. SC-21, no. 6, pp. 1026-1034, Dec. 1986.
I'm a big fan of Monticelli's output stage, but it relies on multiple area-matched transistors, as you get in an IC, but not so easily in a discrete circuit. It'd be cool to find a high-current op-amp with a Monticelli output stage, but this would probably not be an inexpensive part. -- Thanks, - Win
On 21 Apr 2015 09:00:52 -0700, Winfield Hill
<hill@rowland.harvard.edu> wrote:

>Glenn wrote... >> >> On 20/04/15 18.21, Tim Wescott wrote: >>... >>> You may end up with a lower BOM cost and less board space with a rail-rail >>> op-amp and a NPN-PNP transistor pair, assuming that there's not a more >>> modern audio amp chip that'll do ya. >> >> Another circuits that comes to mind: >> Art of Electronics, 3rd edition >> page 318: The Monticelli circuit. [ Figure 5.35 ] >> Patent 5. jul 1984: http://www.google.com/patents/US4570128 >> >> [4] D. M. Monticelli, A quad CMOS single-supply op amp with >> rail-to-rail output swing, IEEE J. Solid-State Circuits, >> vol. SC-21, no. 6, pp. 1026-1034, Dec. 1986. > > I'm a big fan of Monticelli's output stage, but it relies > on multiple area-matched transistors, as you get in an IC, > but not so easily in a discrete circuit. It'd be cool to > find a high-current op-amp with a Monticelli output stage, > but this would probably not be an inexpensive part.
Interesting. I'll spin it up and check stability. ...Jim Thompson -- | James E.Thompson | mens | | Analog Innovations | et | | Analog/Mixed-Signal ASIC's and Discrete Systems | manus | | San Tan Valley, AZ 85142 Skype: skypeanalog | | | Voice:(480)460-2350 Fax: Available upon request | Brass Rat | | E-mail Icon at http://www.analog-innovations.com | 1962 | I love to cook with wine. Sometimes I even put it in the food.
On Tue, 21 Apr 2015 09:22:03 -0700, Jim Thompson
<To-Email-Use-The-Envelope-Icon@On-My-Web-Site.com> wrote:

>On 21 Apr 2015 09:00:52 -0700, Winfield Hill ><hill@rowland.harvard.edu> wrote: > >>Glenn wrote... >>> >>> On 20/04/15 18.21, Tim Wescott wrote: >>>... >>>> You may end up with a lower BOM cost and less board space with a rail-rail >>>> op-amp and a NPN-PNP transistor pair, assuming that there's not a more >>>> modern audio amp chip that'll do ya. >>> >>> Another circuits that comes to mind: >>> Art of Electronics, 3rd edition >>> page 318: The Monticelli circuit. [ Figure 5.35 ] >>> Patent 5. jul 1984: http://www.google.com/patents/US4570128 >>> >>> [4] D. M. Monticelli, A quad CMOS single-supply op amp with >>> rail-to-rail output swing, IEEE J. Solid-State Circuits, >>> vol. SC-21, no. 6, pp. 1026-1034, Dec. 1986. >> >> I'm a big fan of Monticelli's output stage, but it relies >> on multiple area-matched transistors, as you get in an IC, >> but not so easily in a discrete circuit. It'd be cool to >> find a high-current op-amp with a Monticelli output stage, >> but this would probably not be an inexpensive part. > >Interesting. I'll spin it up and check stability. > > ...Jim Thompson
I retrieved a copy of the Monticelli paper... lots of feed-forward gimmicks required to keep it stable... but it's of sufficient interest that I will thoroughly dissect it. ...Jim Thompson -- | James E.Thompson | mens | | Analog Innovations | et | | Analog/Mixed-Signal ASIC's and Discrete Systems | manus | | San Tan Valley, AZ 85142 Skype: skypeanalog | | | Voice:(480)460-2350 Fax: Available upon request | Brass Rat | | E-mail Icon at http://www.analog-innovations.com | 1962 | I love to cook with wine. Sometimes I even put it in the food.
Jim Thompson wrote...
> Jim Thompson wrote: >> Winfield Hill wrote: >>> Glenn wrote... >>>> >>>> Another circuits that comes to mind: >>>> Art of Electronics, 3rd edition >>>> page 318: The Monticelli circuit. [ Figure 5.35 ] >>>> Patent 5. jul 1984: http://www.google.com/patents/US4570128 >>>> >>>> [4] D. M. Monticelli, A quad CMOS single-supply op amp with >>>> rail-to-rail output swing, IEEE J. Solid-State Circuits, >>>> vol. SC-21, no. 6, pp. 1026-1034, Dec. 1986. >>> >>> I'm a big fan of Monticelli's output stage, but it relies >>> on multiple area-matched transistors, as you get in an IC, >>> but not so easily in a discrete circuit. It'd be cool to >>> find a high-current op-amp with a Monticelli output stage, >>> but this would probably not be an inexpensive part. >> >> Interesting. I'll spin it up and check stability. > > I retrieved a copy of the Monticelli paper... lots of > feed-forward gimmicks required to keep it stable... > but it's of sufficient interest that I will thoroughly > dissect it.
I like it for it's DC stability and predictability, and it's class AA otput characteristics. But it's still a transconductance current out, even if well controlled. So when dealing with capacitive loads it's doubly important to add the necessary internal (capacitive) feedback to drive down the open-loop output impedance, at high frequencies. The Zout plots you typically see are quite revealing. -- Thanks, - Win
On 21 Apr 2015 09:00:52 -0700, Winfield Hill
<hill@rowland.harvard.edu> wrote:

>Glenn wrote... >> >> On 20/04/15 18.21, Tim Wescott wrote: >>... >>> You may end up with a lower BOM cost and less board space with a rail-rail >>> op-amp and a NPN-PNP transistor pair, assuming that there's not a more >>> modern audio amp chip that'll do ya. >> >> Another circuits that comes to mind: >> Art of Electronics, 3rd edition >> page 318: The Monticelli circuit. [ Figure 5.35 ] >> Patent 5. jul 1984: http://www.google.com/patents/US4570128 >> >> [4] D. M. Monticelli, A quad CMOS single-supply op amp with >> rail-to-rail output swing, IEEE J. Solid-State Circuits, >> vol. SC-21, no. 6, pp. 1026-1034, Dec. 1986. > > I'm a big fan of Monticelli's output stage, but it relies > on multiple area-matched transistors, as you get in an IC, > but not so easily in a discrete circuit. It'd be cool to > find a high-current op-amp with a Monticelli output stage, > but this would probably not be an inexpensive part.
Here's the class-AB power booster (+/-100mA) design I did a few years back... it's RRIO, unity gain... <http://www.analog-innovations.com/SED/CMOS_Power_OpAmp_100mA.png> ...Jim Thompson -- | James E.Thompson | mens | | Analog Innovations | et | | Analog/Mixed-Signal ASIC's and Discrete Systems | manus | | San Tan Valley, AZ 85142 Skype: skypeanalog | | | Voice:(480)460-2350 Fax: Available upon request | Brass Rat | | E-mail Icon at http://www.analog-innovations.com | 1962 | I love to cook with wine. Sometimes I even put it in the food.
Jim Thompson wrote...
> > > Here's the class-AB power booster (+/-100mA) design > I did a few years back... it's RRIO, unity gain... > > <http://www.analog-innovations.com/SED/CMOS_Power_OpAmp_100mA.png>
How much loop gain does your power booster have (at DC), and what's its bandwidth and slew rate? -- Thanks, - Win
On 27 Apr 2015 03:38:37 -0700, Winfield Hill
<hill@rowland.harvard.edu> wrote:

>Jim Thompson wrote... >> >> >> Here's the class-AB power booster (+/-100mA) design >> I did a few years back... it's RRIO, unity gain... >> >> <http://www.analog-innovations.com/SED/CMOS_Power_OpAmp_100mA.png> > > How much loop gain does your power booster have > (at DC), and what's its bandwidth and slew rate?
That was some years ago, I'll have to revisit it. But I remember it was in an integrator loop with signal at 200kHz. ...Jim Thompson -- | James E.Thompson | mens | | Analog Innovations | et | | Analog/Mixed-Signal ASIC's and Discrete Systems | manus | | San Tan Valley, AZ 85142 Skype: skypeanalog | | | Voice:(480)460-2350 Fax: Available upon request | Brass Rat | | E-mail Icon at http://www.analog-innovations.com | 1962 | I love to cook with wine. Sometimes I even put it in the food.
On 27 Apr 2015 03:38:37 -0700, Winfield Hill
<hill@rowland.harvard.edu> wrote:

>Jim Thompson wrote... >> >> >> Here's the class-AB power booster (+/-100mA) design >> I did a few years back... it's RRIO, unity gain... >> >> <http://www.analog-innovations.com/SED/CMOS_Power_OpAmp_100mA.png> > > How much loop gain does your power booster have > (at DC), and what's its bandwidth and slew rate?
Worst-case slow device models, hot (170&#2013266096;C), 15 Ohms (200mA, resistive load)... DC Loop Gain: 40dB GBW: 12MHz 45&#2013266096; Phase Margin Slew rate: 5V/usec Swing: Within 150mV of each rail Output stage (class-AB) overlap current: 4mA ...Jim Thompson -- | James E.Thompson | mens | | Analog Innovations | et | | Analog/Mixed-Signal ASIC's and Discrete Systems | manus | | San Tan Valley, AZ 85142 Skype: skypeanalog | | | Voice:(480)460-2350 Fax: Available upon request | Brass Rat | | E-mail Icon at http://www.analog-innovations.com | 1962 | I love to cook with wine. Sometimes I even put it in the food.