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Spice model LM386

Roff

Well-Known Member
#2
No guarantees:
Code:
* 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-----------
 

Optikon

New Member
#3
FYI on that model

* 1. The following model behavior shows good agreement with the
* LM386 data sheet values:
*
* a) Quiescent power supply current;
* b) High frequency response at low gain setting;
* c) Power-supply rejection ratio, both bypassed and unbypassed;
* d) Voltage gain, both with pins 1&8 shorted and open; and
* e) Total harmonic distortion.
*
* 2. The model has the following discrepancies:
*
* f) High-gain frequency response looks somewhat more wideband
* than the actual device;
* g) Peak-to-peak output voltage swing is a bit more than the
* data sheet value- in other words, the model drives
* closer to the rails; and
* h) Input bias current in this model is only about 7 nA,
* compared with the 250 nA "typical" value mentioned in
* the data sheet.
*
* 3. The frequency response characteristics of this LM386 model
* can be adjusted somewhat by changing C1, the rolloff capacitor in
* the voltage gain stage. It could also be made more realistic by
* tweaking transistor model parameters Cjc, Cje, Tr and Tf,
* although this can get pretty hairy.
*
* 4. Likewise, output drive capability could be made more
* realistic by tweaking transistor model parameters; again, this is
* hairy.
*
 
Thread starter #4
Thanks

Hi , thanks for the help but I am new to this. Has anyone got a complete model ready to go so I can just us it in my software program
 
#5
habbott said:
Hi , thanks for the help but I am new to this. Has anyone got a complete model ready to go so I can just us it in my software program
You were given a complete model that is ready to use by RonH.

If you don't know how to connect the model, that's a different problem but the model is as complete as it'll ever be.
 
#7
I'm having a couple of problems using this model.

I tried simulating it and got the following error:

Fatal Error: Unknown subcircuit called in:
xu1 n002 0 n007 0 n004 n001 n008 n003 lm386.sub

I'm using exactly the model posted by Roff, the symbol and schematic are attached.

Have I made an error with the symbol or schematic?

I've never drawn a sybol in LTSpice before so I just edited the generic op-amp file accordingly.

Symbol file:
Code:
Version 4
SymbolType CELL
LINE Normal -64 -63 64 0
LINE Normal -64 65 64 0
LINE Normal -64 -63 -64 65
LINE Normal -60 -48 -52 -48
LINE Normal -60 48 -52 48
LINE Normal -56 52 -56 44
LINE Normal -48 -80 -48 -55
LINE Normal -48 80 -48 57
LINE Normal -44 -68 -36 -68
LINE Normal -40 -72 -40 -64
LINE Normal -44 68 -36 68
LINE Normal -16 -39 -16 -64
LINE Normal 0 32 0 48
LINE Normal 48 -8 48 -32
TEXT -51 1 Left 0 LM386
SYMATTR Prefix X
SYMATTR Description Low power audio amplifier
SYMATTR ModelFile LM386.sub
SYMATTR SpiceModel LM386.sub
PIN -16 -64 LEFT 8
PINATTR PinName g1
PINATTR SpiceOrder 1
PIN -64 -48 NONE 0
PINATTR PinName In-
PINATTR SpiceOrder 2
PIN -64 48 NONE 0
PINATTR PinName In+
PINATTR SpiceOrder 3
PIN -48 80 NONE 0
PINATTR PinName V-
PINATTR SpiceOrder 4
PIN 64 0 NONE 0
PINATTR PinName OUT
PINATTR SpiceOrder 5
PIN -48 -80 NONE 0
PINATTR PinName V+
PINATTR SpiceOrder 6
PIN 0 48 LEFT 8
PINATTR PinName bp
PINATTR SpiceOrder 7
PIN 48 -32 LEFT 8
PINATTR PinName g8
PINATTR SpiceOrder 8
 

Attachments

Roff

Well-Known Member
#8
This seems to work:
Code:
Version 4
SymbolType CELL
LINE Normal -64 -63 64 0
LINE Normal -64 65 64 0
LINE Normal -64 -63 -64 65
LINE Normal -60 -48 -52 -48
LINE Normal -60 48 -52 48
LINE Normal -56 52 -56 44
LINE Normal -48 -80 -48 -55
LINE Normal -48 80 -48 57
LINE Normal -44 -68 -36 -68
LINE Normal -40 -72 -40 -64
LINE Normal -44 68 -36 68
LINE Normal -16 -39 -16 -64
LINE Normal 0 32 0 48
LINE Normal 48 -8 48 -32
SYMATTR Value LM386
SYMATTR Prefix X
SYMATTR ModelFile LM386.sub
SYMATTR Value2 LM386
SYMATTR Description Low power audio amplifier
PIN -16 -64 LEFT 8
PINATTR PinName g1
PINATTR SpiceOrder 1
PIN -64 -48 NONE 0
PINATTR PinName In-
PINATTR SpiceOrder 2
PIN -64 48 NONE 0
PINATTR PinName In+
PINATTR SpiceOrder 3
PIN -48 80 NONE 0
PINATTR PinName V-
PINATTR SpiceOrder 4
PIN 64 0 NONE 0
PINATTR PinName OUT
PINATTR SpiceOrder 5
PIN -48 -80 NONE 0
PINATTR PinName V+
PINATTR SpiceOrder 6
PIN 0 48 LEFT 8
PINATTR PinName bp
PINATTR SpiceOrder 7
PIN 48 -32 LEFT 8
PINATTR PinName g8
PINATTR SpiceOrder 8
You can also do it as in the attached file if you don't want to create a symbol. The 8 pin symbol is in the Misc library.
 

Attachments

#9
Thanks Roff.

Do you know where I had gone wrong (apart from not including a value for C4 which shouldn't have given me that error)?
 

MrAl

Well-Known Member
Most Helpful Member
#10
Hi,


I think what he meant was that he wants a model that actually models
all of the characteristics, not just some of them.
 
#11
I think this is close enough for now.

The main discrepancy I've noticed is that this model only has a gain of about 168 rather than the 200 suggested on the datasheet.
 

Roff

Well-Known Member
#12
Thanks Roff.

Do you know where I had gone wrong (apart from not including a value for C4 which shouldn't have given me that error)?
Compare the file I gave you with the file you posted. I took yours and edited it until it looked like LM555.asy.:D
 
#13
Hello. I'm resurrecting an old thread because this advice here came as close to anything yet for solving my problem.

I got an LF412 model from National Semiconductor's site which I read was compatible with LTspice, but I can't make it work. I tried every method mentioned here, and the error is always the same, so I think the problem is in the model itself, which isn't as ready for LTspice as I was led to believe. I'm new to spice in general and can only learn from something if it works, so can anyone put it right for me?

Ideally I'd like it in the form that lets me put an LF412.asy file in lib\sym\misc and an LF412.sub file in lib\sub, same as the LM386 files I found in this thread.

Code:
*//////////////////////////////////////////////////////////////////////
* (C) National Semiconductor, Inc.
* Models developed and under copyright by:
* National Semiconductor, Inc.

*/////////////////////////////////////////////////////////////////////
* Legal Notice: This material is intended for free software support.
* The file may be copied, and distributed; however, reselling the
*  material is illegal

*////////////////////////////////////////////////////////////////////
* For ordering or technical information on these models, contact:
* National Semiconductor's Customer Response Center
*                 7:00 A.M.--7:00 P.M.  U.S. Central Time
*                                (800) 272-9959
* For Applications support, contact the Internet address:
*  amps-apps@galaxy.nsc.com
* ///////////////////////////////////////////////////////////////////
* User Notes:
*
* 1. Input resistance (Rin) for these JFET op amps is 1TOhm.  Rin is
*    modeled by assuming the option GMIN=1TOhm.  If a different (non-
*    default) GMIN value is needed, users may recalculate as follows:
*    Rin=(R1||GMIN+R2||GMIN), where R1=R2,
*    to maintain a consistent Rin model.

*//////////////////////////////////////////////////////////
*LF412 LOW OFFSET, LOW DRIFT DUAL JFET INPUT OP-AMP MODEL
*//////////////////////////////////////////////////////////
*
* connections:    non-inverting input
*                 |   inverting input
*                 |   |   positive power supply
*                 |   |   |   negative power supply
*                 |   |   |   |   output
*                 |   |   |   |   |
*                 |   |   |   |   |
.SUBCKT LF412/NS  1   2  99  50  28
*
*Features:
*Fast settling time (.01%) =           2uS
*High bandwidth =                     3MHz
*High slew rate =                   10V/uS
*Low offset voltage =                  1mV
*Low supply current =                1.8mA
*NOTE: Model is for single device only and simulated
*      supply current is 1/2 of total device current.
*
****************INPUT STAGE**************
*
IOS 2 1 25.0P
*^Input offset current
CI1 1 0 3P
CI2 2 0 3P
R1 1 3 1E12
R2 3 2 1E12
I1 99 4 1.0M
J1 5 2 4 JX
J2 6 7 4 JX
R3 5 50 650
R4 6 50 650
*Fp2=28 MHZ
C4 5 6 4.372P
*
***********COMMON MODE EFFECT***********
*
I2 99 50 800UA
*^Quiescent supply current
EOS 7 1 POLY(1) 16 49 1E-3 1
*Input offset voltage.^
R8 99 49 80K
R9 49 50 80K
*
*********OUTPUT VOLTAGE LIMITING********
V2 99 8 2.13
D1 9 8 DX
D2 10 9 DX
V3 10 50 2.13
*
**************SECOND STAGE**************
*
EH 99 98 99 49 1
G1 98 9 5 6 20E-3
R5 98 9 10MEG
VA3 9 11 0
*Fp1=18 HZ
C3 98 11 857.516P
*
***************POLE STAGE***************
*
*Fp=30 MHz
G3 98 15 9 49 1E-6
R12 98 15 1MEG
C5 98 15 5.305E-15
*
*********COMMON-MODE ZERO STAGE*********
*
G4 98 16 3 49 1E-8
L2 98 17 144.7M
R13 17 16 1K
*
**************OUTPUT STAGE**************
*
F6  99 50 VA7 1
F5  99 23 VA8 1
D5  21 23 DX
VA7 99 21 0
D6  23 99 DX
E1  99 26 99 15 1
VA8 26 27 0
R16 27 28 50
V5  28 25 0.646V
D4  25 15 DX
V4  24 28 0.646V
D3  15 24 DX
*
***************MODELS USED**************
*
.MODEL DX D(IS=1E-15)
.MODEL JX PJF(BETA=1.183E-3 VTO=-.65 IS=50E-12)
*
.ENDS
*$


For context, here's my LF412.asy file, an edit of opamp2.asy made on the basis of the advice given earlier in this thread... I understand that the number and order of pins is important, and I've checked this and it does match.

Code:
Version 4
SymbolType CELL
LINE Normal -32 32 32 64
LINE Normal -32 96 32 64
LINE Normal -32 32 -32 96
LINE Normal -28 48 -20 48
LINE Normal -28 80 -20 80
LINE Normal -24 84 -24 76
LINE Normal 0 32 0 48
LINE Normal 0 96 0 80
LINE Normal 4 44 12 44
LINE Normal 8 40 8 48
LINE Normal 4 84 12 84
WINDOW 0 16 32 Left 0
WINDOW 3 16 96 Left 0
SYMATTR Value LF412
SYMATTR Prefix X
SYMATTR ModelFile LF412.sub
SYMATTR Value2 LF412
SYMATTR Description LF412 Low offset, low drift dual JFET input Op-Amp
PIN -32 80 NONE 0
PINATTR PinName In+
PINATTR SpiceOrder 1
PIN -32 48 NONE 0
PINATTR PinName In-
PINATTR SpiceOrder 2
PIN 0 32 NONE 0
PINATTR PinName V+
PINATTR SpiceOrder 3
PIN 0 96 NONE 0
PINATTR PinName V-
PINATTR SpiceOrder 4
PIN 32 64 NONE 0
PINATTR PinName OUT
PINATTR SpiceOrder 5
 
Last edited:
#14
That asy file post isn't my first. First one won't go through because of the moderation queue, so I don't know why the second one did go through. That system is making it imposible for me to post in a coherent way. I reposted the first once I saw the second appear so that the second makes sense. Neither copy of the first post have appeared yet, and I can't do a thing about it without stirring a mess further.


EDIT:
Managed to overcome it once I'd seen this one come through also, I slipped the first into the previous one via the edit mechanism, so it should make sense now.
 
Last edited:

Roff

Well-Known Member
#15
The only problem I found was a mismatch in your subcircuit names between the .sub file and the .asy file. The .sub file uses LF412/NS, while the .asc file uses LF412. You have to change one or the other, as they must be identical.

Here is the critical line in the .sub file:
.SUBCKT LF412/NS 1 2 99 50 28

It worked for me when I deleted "/NS".
 
Last edited:
#16
If you don't know how to connect the model, that's a different problem but the model is as complete as it'll ever be.
I'd like to know that. I've never tried to import a model. I only used spice when I was in college (untill now ) I'm using LTSpice.
 
#17
Great stuff. Thankyou. It works. I kept the original name though, and changed BOTH occurences in my asy file. I'll experiment to see if only one reference is needed there, it's easier to learn if I see how I break it, now that it works.

BrownOut, if the model is designed to be compatible (as Texas Instruments and National Semiconductors' models are) it looks like using a copy of the NE555's asy file supplied with LTspice as a template will help. Just make sure the pins count and order match, the SYMATTR ModelFile line names the 'sub' file you're using for the model, and the Value and Value2 lines both use the same name as the model uses on its opening .subckt line. There might be refinements but that looks like enough to get going.
 
Last edited:
#18
This seems to work:
Code:
Version 4
SymbolType CELL
LINE Normal -64 -63 64 0
LINE Normal -64 65 64 0
LINE Normal -64 -63 -64 65
LINE Normal -60 -48 -52 -48
LINE Normal -60 48 -52 48
LINE Normal -56 52 -56 44
LINE Normal -48 -80 -48 -55
LINE Normal -48 80 -48 57
LINE Normal -44 -68 -36 -68
LINE Normal -40 -72 -40 -64
LINE Normal -44 68 -36 68
LINE Normal -16 -39 -16 -64
LINE Normal 0 32 0 48
LINE Normal 48 -8 48 -32
SYMATTR Value LM386
SYMATTR Prefix X
SYMATTR ModelFile LM386.sub
SYMATTR Value2 LM386
SYMATTR Description Low power audio amplifier
PIN -16 -64 LEFT 8
PINATTR PinName g1
PINATTR SpiceOrder 1
PIN -64 -48 NONE 0
PINATTR PinName In-
PINATTR SpiceOrder 2
PIN -64 48 NONE 0
PINATTR PinName In+
PINATTR SpiceOrder 3
PIN -48 80 NONE 0
PINATTR PinName V-
PINATTR SpiceOrder 4
PIN 64 0 NONE 0
PINATTR PinName OUT
PINATTR SpiceOrder 5
PIN -48 -80 NONE 0
PINATTR PinName V+
PINATTR SpiceOrder 6
PIN 0 48 LEFT 8
PINATTR PinName bp
PINATTR SpiceOrder 7
PIN 48 -32 LEFT 8
PINATTR PinName g8
PINATTR SpiceOrder 8
You can also do it as in the attached file if you don't want to create a symbol. The 8 pin symbol is in the Misc library.
Use your given code how to creat a new symbol?Would you like to show me the step.thank you.I a newer to LTspice.Thank you very much.
 
#19
Select 'New Symbol' from the 'File' menu.

You can use my LM386 symbol if you like, just rename the attached text file to LM386.ASY and add to the 'LT Spice/lib/sym/misc' directory.
 

Attachments

#20
On the subject of new symbols....

I'd find it more convenient to use the LTspice standard op-amp three-pin symbol with the five-pin LF412 model (and others). Can it be done? I imagine there might be a way to tell it that hidden supply pins are connected to something without having to see them in the schematic but I have no idea if, let alone how... I really want to do it because it's a lot of clutter having to show those supply pins. :)

(And, off-topic, I've been hunting for several days now for a laser diode model, and one for the CA3140. If anyone can point the way, please do. Even a guide to editing a diode model to change Vf and other crucial parameters will help me, I'm at a loss so far because spice parameters seem to bean no clear relation to values in data sheets!).
 

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