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From: Bitrex on 14 May 2010 03:38
I'm using the only model of the LM386 I was able to find on the Web in
LTSpice, but discovered that it has a major flaw: the output doesn't sit
anywhere near halfway between Vcc and ground. I'd be thrilled anyone
has access to a better model, or could explain how to correct this one?
Thanks.





* lm386 subcircuit model follows:

************************************original* IC pins: 2 3 7 1
8 5 6 4
* IC pins: 1 2 3 4 5 6 7 8
* | | | | | | | |
..subckt lm386 g1 inn inp gnd out vs byp g8
************************************original*.subckt lm386 inn inp byp
g1 g8 out vs gnd

* input emitter-follower buffers:

q1 gnd inn 10011 ddpnp
r1 inn gnd 50k
q2 gnd inp 10012 ddpnp
r2 inp gnd 50k

* differential input stage, gain-setting
* resistors, and internal feedback resistor:

q3 10013 10011 10008 ddpnp
q4 10014 10012 g1 ddpnp
r3 vs byp 15k
r4 byp 10008 15k
r5 10008 g8 150
r6 g8 g1 1.35k
r7 g1 out 15k

* input stage current mirror:

q5 10013 10013 gnd ddnpn
q6 10014 10013 gnd ddnpn

* voltage gain stage & rolloff cap:

q7 10017 10014 gnd ddnpn
c1 10014 10017 15pf

* current mirror source for gain stage:

i1 10002 vs dc 5m
q8 10004 10002 vs ddpnp
q9 10002 10002 vs ddpnp

* Sziklai-connected push-pull output stage:

q10 10018 10017 out ddpnp
q11 10004 10004 10009 ddnpn 100
q12 10009 10009 10017 ddnpn 100
q13 vs 10004 out ddnpn 100
q14 out 10018 gnd ddnpn 100

* generic transistor models generated
* with MicroSim's PARTs utility, using
* default parameters except Bf:

..model ddnpn NPN(Is=10f Xti=3 Eg=1.11 Vaf=100
+ Bf=400 Ise=0 Ne=1.5 Ikf=0 Nk=.5 Xtb=1.5 Var=100
+ Br=1 Isc=0 Nc=2 Ikr=0 Rc=0 Cjc=2p Mjc=.3333
+ Vjc=.75 Fc=.5 Cje=5p Mje=.3333 Vje=.75 Tr=10n
+ Tf=1n Itf=1 Xtf=0 Vtf=10)

..model ddpnp PNP(Is=10f Xti=3 Eg=1.11 Vaf=100
+ Bf=200 Ise=0 Ne=1.5 Ikf=0 Nk=.5 Xtb=1.5 Var=100
+ Br=1 Isc=0 Nc=2 Ikr=0 Rc=0 Cjc=2p Mjc=.3333
+ Vjc=.75 Fc=.5 Cje=5p Mje=.3333 Vje=.75 Tr=10n
+ Tf=1n Itf=1 Xtf=0 Vtf=10)

..ends
*----------end of subcircuit model-----------

From: Bitrex on 14 May 2010 04:33

Disregard - I'm not sure what I did wrong but the circuit now has its
output sitting at approximately the correct voltage. User error.


Bitrex wrote:
> I'm using the only model of the LM386 I was able to find on the Web in
> LTSpice, but discovered that it has a major flaw: the output doesn't sit
> anywhere near halfway between Vcc and ground. I'd be thrilled anyone
> has access to a better model, or could explain how to correct this one?
> Thanks.
>
>
>
>
>
> * lm386 subcircuit model follows:
>
> ************************************original* IC pins: 2 3 7 1
> 8 5 6 4
> * IC pins: 1 2 3 4 5 6 7 8
> * | | | | | | | |
> .subckt lm386 g1 inn inp gnd out vs byp g8
> ************************************original*.subckt lm386 inn inp byp
> g1 g8 out vs gnd
>
> * input emitter-follower buffers:
>
> q1 gnd inn 10011 ddpnp
> r1 inn gnd 50k
> q2 gnd inp 10012 ddpnp
> r2 inp gnd 50k
>
> * differential input stage, gain-setting
> * resistors, and internal feedback resistor:
>
> q3 10013 10011 10008 ddpnp
> q4 10014 10012 g1 ddpnp
> r3 vs byp 15k
> r4 byp 10008 15k
> r5 10008 g8 150
> r6 g8 g1 1.35k
> r7 g1 out 15k
>
> * input stage current mirror:
>
> q5 10013 10013 gnd ddnpn
> q6 10014 10013 gnd ddnpn
>
> * voltage gain stage & rolloff cap:
>
> q7 10017 10014 gnd ddnpn
> c1 10014 10017 15pf
>
> * current mirror source for gain stage:
>
> i1 10002 vs dc 5m
> q8 10004 10002 vs ddpnp
> q9 10002 10002 vs ddpnp
>
> * Sziklai-connected push-pull output stage:
>
> q10 10018 10017 out ddpnp
> q11 10004 10004 10009 ddnpn 100
> q12 10009 10009 10017 ddnpn 100
> q13 vs 10004 out ddnpn 100
> q14 out 10018 gnd ddnpn 100
>
> * generic transistor models generated
> * with MicroSim's PARTs utility, using
> * default parameters except Bf:
>
> .model ddnpn NPN(Is=10f Xti=3 Eg=1.11 Vaf=100
> + Bf=400 Ise=0 Ne=1.5 Ikf=0 Nk=.5 Xtb=1.5 Var=100
> + Br=1 Isc=0 Nc=2 Ikr=0 Rc=0 Cjc=2p Mjc=.3333
> + Vjc=.75 Fc=.5 Cje=5p Mje=.3333 Vje=.75 Tr=10n
> + Tf=1n Itf=1 Xtf=0 Vtf=10)
>
> .model ddpnp PNP(Is=10f Xti=3 Eg=1.11 Vaf=100
> + Bf=200 Ise=0 Ne=1.5 Ikf=0 Nk=.5 Xtb=1.5 Var=100
> + Br=1 Isc=0 Nc=2 Ikr=0 Rc=0 Cjc=2p Mjc=.3333
> + Vjc=.75 Fc=.5 Cje=5p Mje=.3333 Vje=.75 Tr=10n
> + Tf=1n Itf=1 Xtf=0 Vtf=10)
>
> .ends
> *----------end of subcircuit model-----------
>
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