Spice models for LM78xx series?

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Mike Rocket J. Squirrel Elliott

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Nov 20, 2003, 1:50:23 PM11/20/03
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I've Googled my butt off, and haven't come up with anything. I'm
surprised that this venerable series of linear voltage regulators isn't
represented with SPICE subcircuits or models. Any suggestions?

--
Mike "Rocket J Squirrel" Elliott

Chaos Master

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Nov 20, 2003, 9:21:01 PM11/20/03
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In an arcane spellbook written by the priests, labeled 'Posts of
sci.electronics.cad' I found a message from Mike Rocket J. Squirrel
Elliott[j.michael...@REMOVETHEOBVIOUSadelphiaDOT.net]:

> I've Googled my butt off, and haven't come up with anything. I'm
> surprised that this venerable series of linear voltage regulators isn't
> represented with SPICE subcircuits or models. Any suggestions?

CircuitMaker has some models for 7805/7812. You can just download the student
version or the 30-day trial and 'rip' the model libraries. I've done that. :)

--
'You receive a scroll of signature. It says:'
Chaos Master® - Posting from Porto Alegre - Brazil.
E-mail address is valid. But remove the SPAMTRAP to reply.


Y.Belenky

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Nov 21, 2003, 2:25:03 AM11/21/03
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.SUBCKT x_LM78XX Input Output Ground PARAMS:
+ Av_feedback=1665, R1_Value=1020
*
* SERIES 3-TERMINAL POSITIVE REGULATOR
*
* Note: This regulator is based on the LM78XX series of
* regulators (also the LM140 and LM340). The model
* will cause some current to flow to Node 0 which
* is not part of the actual voltage regulator circuit.
*
* Band-gap voltage source:
*
* The source is off when Vin<3V and fully on when Vin>3.7V.
* Line regulation and ripple rejection) are set with
* Rreg= 0.5 * dVin/dVbg. The temperature dependence of this
* circuit is a quadratic fit to the following points:
*
* T Vbg(T)/Vbg(nom)
* --- ---------------
* 0 .999
* 37.5 1
* 125 .990
*
* The temperature coefficient of Rbg is set to 2 * the band gap
* temperature coefficient. Tnom is assumed to be 27 deg. C and
* Vnom is 3.7V
*
Vbg 100 0 DC 7.4V
Sbg (100,101),(Input,Ground) Sbg1
Rbg 101 0 1 TC=1.612E-5,-2.255E-6
Ebg (102,0),(Input,Ground) 1
Rreg 102 101 7k
.MODEL Sbg1 VSWITCH (Ron=1 Roff=1MEG Von=3.7 Voff=3)
*
* Feedback stage
*
* Diodes D1,D2 limit the excursion of the amplifier
* outputs to being near the rails. Rfb, Cfb Set the
* corner frequency for roll-off of ripple rejection.

*
* The opamp gain is given by: Av = (Fores/Freg) * (Vout/Vbg)
* where Fores = output impedance corner frequency
* with Cl=0 (typical value about 1MHz)
* Freg = corner frequency in ripple rejection
* (typical value about 600 Hz)
* Vout = regulator output voltage (5,12,15V)
* Vbg = bandgap voltage (3.7V)
*
* Note: Av is constant for all output voltages, but the
* feedback factor changes. If Av=2250, then the
* Av*Feedback factor is as given below:
*
* Vout Av*Feedback factor
* ---- ------------------
* 5 1665
* 12 694
* 15 550
*
Rfb 9 8 1MEG
Cfb 8 Ground 265PF
Eopamp 105 0 VALUE={2250*v(101,0)+Av_feedback*v(Ground,8)}
Vgainf 200 0 {Av_feedback}
Rgainf 200 0 1
*Eopamp 105 0 POLY(3),(101,0),(Ground,8),(200,0) 0 2250 0 0 0 0 0 0 1
Ro 105 106 1k
D1 106 108 Dlim
D2 107 106 Dlim
.MODEL Dlim D (Vj=0.7)
Vl1 102 108 DC 1
Vl2 107 0 DC 1
*
* Quiescent current modelling
*
* Quiescent current is set by Gq, which draws a current
* proportional to the voltage drop across the regulator and
* R1 (temperature coefficient .1%/deg C). R1 must change
* with output voltage as follows: R1 = R1(5v) * Vout/5v.
*
Gq (Input,Ground),(Input,9) 2.0E-5
R1 9 Ground {R1_Value} TC=0.001
*
* Output Stage
*
* Rout is used to set both the low frequency output impedence
* and the load regulation.
*
Q1 Input 5 6 Npn1
Q2 Input 6 7 Npn1 10
.MODEL Npn1 NPN (Bf=50 Is=1E-14)
* Efb Input 4 VALUE={v(Input,Ground)+v(0,106)}
Efb Input 4 POLY(2),(Input,Ground),(0,106) 0 1 1
Rb 4 5 1k TC=0.003
Re 6 7 2k
Rsc 7 9 0.275 TC=1.136E-3,-7.806E-6
Rout 9 Output 0.008
*
* Current Limit
*
Rbcl 7 55 290
Qcl 5 55 9 Npn1
Rcldz 56 55 10k
Dz1 56 Input Dz
.MODEL Dz D (Is=0.05p Rs=3 Bv=7.11 Ibv=0.05u)
.ENDS
*$

Yuri.

Mike Rocket J. Squirrel Elliott

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Nov 21, 2003, 11:47:52 AM11/21/03
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Chaos Master and Y.Belenky:

Thanks!


>> I've Googled my butt off, and haven't come up with anything. I'm
>> surprised that this venerable series of linear voltage regulators
>> isn't represented with SPICE subcircuits or models. Any suggestions?

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