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design | Looking for a better LM386 Spice model


There are 2 messages in this thread.

You are currently looking at messages 1 to 2.

Looking for a better LM386 Spice model - Bitrex - 2010-05-14 03:38:00

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(Isf Xti=3 Eg=1.11 Vaf0
+ Bf@0 Ise=0 Ne=1.5 Ikf=0 Nk=.5 Xtb=1.5 Var0
+ Br=1 Isc=0 Nc=2 Ikr=0 Rc=0 Cjc=2p Mjc=.3333
+ Vjc=.75 Fc=.5 Cje=5p Mje=.3333 Vje=.75 Trn
+ Tf=1n Itf=1 Xtf=0 Vtf)

.model ddpnp PNP(Isf Xti=3 Eg=1.11 Vaf0
+ Bf 0 Ise=0 Ne=1.5 Ikf=0 Nk=.5 Xtb=1.5 Var0
+ Br=1 Isc=0 Nc=2 Ikr=0 Rc=0 Cjc=2p Mjc=.3333
+ Vjc=.75 Fc=.5 Cje=5p Mje=.3333 Vje=.75 Trn
+ Tf=1n Itf=1 Xtf=0 Vtf)

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


Re: Looking for a better LM386 Spice model - Bitrex - 2010-05-14 04:33:00

  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(Isf Xti=3 Eg=1.11 Vaf0
> + Bf@0 Ise=0 Ne=1.5 Ikf=0 Nk=.5 Xtb=1.5 Var0
> + Br=1 Isc=0 Nc=2 Ikr=0 Rc=0 Cjc=2p Mjc=.3333
> + Vjc=.75 Fc=.5 Cje=5p Mje=.3333 Vje=.75 Trn
> + Tf=1n Itf=1 Xtf=0 Vtf)
> 
> .model ddpnp PNP(Isf Xti=3 Eg=1.11 Vaf0
> + Bf 0 Ise=0 Ne=1.5 Ikf=0 Nk=.5 Xtb=1.5 Var0
> + Br=1 Isc=0 Nc=2 Ikr=0 Rc=0 Cjc=2p Mjc=.3333
> + Vjc=.75 Fc=.5 Cje=5p Mje=.3333 Vje=.75 Trn
> + Tf=1n Itf=1 Xtf=0 Vtf)
> 
> .ends
> *----------end of subcircuit model-----------
>