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Old 22nd December 2012, 07:41 AM   #161
Jenyok is offline Jenyok  Russian Federation
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Need a good model of LM317 for simulation program LTSpice IV, all known models in internet work bad.
I tested 17 different models of LM317 in LTSpice IV and the results were bad and very bad for models.
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Old 22nd December 2012, 10:24 AM   #162
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Hi Jenyok, what was the problem with the models. Most of them are current limited and if you push them past their current limit they behave strangely. The current limit of almost all of the models is I believe 0.5A

I used the discrete model from TI and changed the params of the QP and QL transistors to get a more accurate reference voltage as follows:

.MODEL QNL NPN(EG=1.22 BF=80 RB=100 CCS=1.5PF TF=.3NS TR=6NS CJE=2PF
+ CJC=1PF VAF=100 IS=6E-13 NF=1.1623)
.MODEL QPL PNP(BF=40 RB=20 TF=.6NS TR=10NS CJE=1.5PF CJC=1PF VAF=50 IS=6E-13 NF=1.1623)

Note I don't remember how I worked out that those were the things I should change, I may have known what I was doing at the time though I probably didn't..... the end result was an improvement in the accuracy of the reference voltage though as far as I can recall.

whole model is as follows:

Quote:
*LM317 TI voltage regulator - pin order: In, Adj, Out
*TI adjustable voltage regulator pkg:TO-3
.SUBCKT LM317D 1 2 3 **Changes my be required on this line**
J1 1 3 4 JN
Q2 5 5 6 QPL .1
Q3 5 8 9 QNL .2
Q4 8 5 7 QPL .1
Q5 81 8 3 QNL .2
Q6 3 81 10 QPL .2
Q7 12 81 13 QNL .2
Q8 10 5 11 QPL .2
Q9 14 12 10 QPL .2
Q10 16 5 17 QPL .2
Q11 16 14 15 QNL .2
Q12 3 20 16 QPL .2
Q13 1 19 20 QNL .2
Q14 19 5 18 QPL .2
Q15 3 21 19 QPL .2
Q16 21 22 16 QPL .2
Q17 21 3 24 QNL .2
Q18 22 22 16 QPL .2
Q19 22 3 241 QNL 2
Q20 3 25 16 QPL .2
Q21 25 26 3 QNL .2
Q22A 35 35 1 QPL 2
Q22B 16 35 1 QPL 2
Q23 35 16 30 QNL 2
Q24A 27 40 29 QNL .2
Q24B 27 40 28 QNL .2
Q25 1 31 41 QNL 5
Q26 1 41 32 QNL 50
D1 3 4 DZ
D2 33 1 DZ
D3 29 34 DZ
R1 1 6 310
R2 1 7 310
R3 1 11 190
R4 1 17 82
R5 1 18 5.6K
R6 4 8 100K
R7 8 81 130
R8 10 12 12.4K
R9 9 3 180
R10 13 3 4.1K
R11 14 3 5.8K
R12 15 3 72
R13 20 3 5.1K
R14 2 24 12K
R15 24 241 2.4K
R16 16 25 6.7K
R17 16 40 12K
R18 30 41 130
R19 16 31 370
R20 26 27 13K
R21 27 40 400
R22 3 41 160
R23 33 34 18K
R24 28 29 160
R25 28 32 3
R26 32 3 .1
C1 21 3 30PF
C2 21 2 30PF
C3 25 26 5PF
CBS1 5 3 2PF
CBS2 35 3 1PF
CBS3 22 3 1PF
.MODEL JN NJF(BETA=1E-4 VTO=-7)
.MODEL DZ D(BV=6.3)
.MODEL QNL NPN(EG=1.22 BF=80 RB=100 CCS=1.5PF TF=.3NS TR=6NS CJE=2PF
+ CJC=1PF VAF=100 IS=6E-13 NF=1.1623)
.MODEL QPL PNP(BF=40 RB=20 TF=.6NS TR=10NS CJE=1.5PF CJC=1PF VAF=50 IS=6E-13 NF=1.1623)
.ENDS LM317 **changes may be required on this line**
Note that this model still has the 0.5A limitation.

Tony.
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Old 22nd December 2012, 06:43 PM   #163
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Quote:
Originally Posted by Jenyok View Post
Need a good model of LM317 for simulation program LTSpice IV, all known models in internet work bad.
I tested 17 different models of LM317 in LTSpice IV and the results were bad and very bad for models.
When simulating the LM317 you have to remember that the voltage is referenced between Vout and Adjust. (i.e. not ground)

Put a 1 ohm resistor between the voltage divider and the adjust pin and drive 1mA across this resistor. Gives you 1mV of perturbation voltage.
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Old 23rd December 2012, 11:57 AM   #164
Jenyok is offline Jenyok  Russian Federation
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Thanks mate.
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Old 24th December 2012, 04:46 AM   #165
Jenyok is offline Jenyok  Russian Federation
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I tested various models of LM317 (18 different models), founded in internet.
Results are in atteched files ZIP.
Output voltage must be ~= 15 Volts for R1 = 5.17 kOhm R2 = 470 Ohm .
Load current is 0 ... 0.7 (0.6) A step 10 mA .
More realistic model is LM317-TEST1 .
LIB and ASY files must be placed in "C:\PROGRAM FILES\LTC\LTSPICEIV\LIB\SYM\EXTRA\VOLREG" .
LM317_2.ZIP ... LM317_6.ZIP are ZIP files with JPG pictures of testing results.
.
I think that results are bad and very bad for all models of LM317 .
Attached Files
File Type: zip LM317_1.zip (26.8 KB, 58 views)
File Type: zip LM317_2.zip (694.8 KB, 23 views)
File Type: zip LM317_3.zip (689.6 KB, 16 views)
File Type: zip LM317_4.zip (678.6 KB, 12 views)
File Type: zip LM317_5.zip (669.5 KB, 17 views)
File Type: zip LM317_6.zip (335.0 KB, 23 views)

Last edited by Jenyok; 24th December 2012 at 05:01 AM.
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Old 24th December 2012, 11:30 AM   #166
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Hi Jenyok. I assume that you're not happy with the output voltage dropping with increasing current? Have you done any real world tests to ensure that this is not something that happens with a real LM317?

I ran a sim on the model I had and the results seem well within spec for an LM317

15.27566V @20mA
15.27147 @ 500mA

actual difference = 0.00419

0.3% of 15V = 0.045V (load regulation is specified as max 0.3%)

Picture attached. Or have I missed something?

Tony.
Attached Images
File Type: png lm317_vvsl.png (20.5 KB, 511 views)
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Old 24th December 2012, 11:53 AM   #167
Jenyok is offline Jenyok  Russian Federation
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Yes, simple tests are of the output voltage dropping with increasing current from 0 ... 0.7 A .
.
Value 0.3% and 0.00419 Volt or 4.19 mVolts seems to me, that LM317 is a very bad as a voltage regulator (stabilizator).
.
I am very unsuccessfull that current value from 0 ... 20 mA gives about 10 mVolts dropping of output voltage. I don't understand, why ?

Last edited by Jenyok; 24th December 2012 at 12:01 PM.
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Old 24th December 2012, 12:37 PM   #168
blu_glo is offline blu_glo  England
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You have to pull *at least* 10mA according to the datasheet for the regulation figures to be accurate. No regulator I know of gives +/- 0mV at zero current draw. You can avoid this by ensuring a 10-20mA minimum current pull (e.g.load suitable resistor permanently accross the output) or maybe your circuit already draws this minimum amount; in which case you don't have cause for concern. Beleive me, I've done all sorts of discrete regulator circuits; it's one of the first things you learn when building them in PRACTICE.
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Old 24th December 2012, 03:19 PM   #169
Jenyok is offline Jenyok  Russian Federation
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One more inproved LM317 circuit.
Output voltage is about ~= +15 Volts.
Output load current is about from ~= 30 mA to 1 A .
AL307 is a Green LED 2.13 V , 5 ... 10 mA .
Attached Images
File Type: jpg Draft3_2.jpg (508.4 KB, 498 views)

Last edited by Jenyok; 24th December 2012 at 03:27 PM.
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Old 24th December 2012, 05:52 PM   #170
Jenyok is offline Jenyok  Russian Federation
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Try to simulate our circuit, see results of simulation and compare results with LM317 as a power reg.
Output voltage ~= + - 15 Volts .
Output load current ~= 0 ... 1 A .
ASC file of circuit for LTSpice IV is in ZIP file.
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