MC34063 with small inductors
in [Design]
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From: Joerg on 7 Apr 2010 19:06 Tim Wescott wrote: > Joerg wrote: >> Spehro Pefhany wrote: >>> On Tue, 06 Apr 2010 18:00:41 -0700, the renowned Joerg >>> <invalid(a)invalid.invalid> wrote: >>> >>>> Hello Folks, >>>> >>>> Have to correct a design with a 34063 in there. Buck, VIN 16-30V, >>>> VOUT slightly under 12V, 400mA max output. And no, I don't like it >>>> much :-) >>>> >>>> One of the issues is a saturating inductor. Can't change the layout >>>> and to be able to cram one in there I probably have to drop down to >>>> 47uH, maybe 68uH if lucky. >>>> >>>> SPICE says it's ok but none of the datasheets or app notes >>>> recommends going that low. Any reason why not? >>> >>> Too slow. ... >> >> >> Although it does run in SPICE. >> > I think that one of the last things I'd trust SPICE for would be as an > indication that a chip really could run faster than its rated speed, at > least if the chip model came from the vendor. > The model is from ON Semi and I am not running the chip above its rated speed while in regulation. It's actually working (on the simulator) with a 68uH inductance and well within normal timing limits. All I was wondering is why the datasheets and app notes always prescribe higher inductance values. But you are right about models being suspicious. It does one thing it ain't supposed to be doing and I still need to get to the ground of that via the LTSpice group (this sim was with 200uH though): http://www.analogconsultants.com/ng/images/MC34063_1.png App notes and the internal schematic of the chip says that the feedback comparator can never terminate the switch during a cycle (positive dark blue ramp). And here it does just that ... -- Regards, Joerg http://www.analogconsultants.com/ "gmail" domain blocked because of excessive spam. Use another domain or send PM.
From: Jim Thompson on 7 Apr 2010 19:31 On Wed, 07 Apr 2010 16:06:35 -0700, Joerg <invalid(a)invalid.invalid> wrote: >Tim Wescott wrote: >> Joerg wrote: >>> Spehro Pefhany wrote: >>>> On Tue, 06 Apr 2010 18:00:41 -0700, the renowned Joerg >>>> <invalid(a)invalid.invalid> wrote: >>>> >>>>> Hello Folks, >>>>> >>>>> Have to correct a design with a 34063 in there. Buck, VIN 16-30V, >>>>> VOUT slightly under 12V, 400mA max output. And no, I don't like it >>>>> much :-) >>>>> >>>>> One of the issues is a saturating inductor. Can't change the layout >>>>> and to be able to cram one in there I probably have to drop down to >>>>> 47uH, maybe 68uH if lucky. >>>>> >>>>> SPICE says it's ok but none of the datasheets or app notes >>>>> recommends going that low. Any reason why not? >>>> >>>> Too slow. ... >>> >>> >>> Although it does run in SPICE. >>> >> I think that one of the last things I'd trust SPICE for would be as an >> indication that a chip really could run faster than its rated speed, at >> least if the chip model came from the vendor. >> > >The model is from ON Semi and I am not running the chip above its rated >speed while in regulation. It's actually working (on the simulator) with >a 68uH inductance and well within normal timing limits. All I was >wondering is why the datasheets and app notes always prescribe higher >inductance values. > >But you are right about models being suspicious. It does one thing it >ain't supposed to be doing and I still need to get to the ground of that >via the LTSpice group (this sim was with 200uH though): > >http://www.analogconsultants.com/ng/images/MC34063_1.png > >App notes and the internal schematic of the chip says that the feedback >comparator can never terminate the switch during a cycle (positive dark >blue ramp). And here it does just that ... Is the model in text format or is it encrypted? ...Jim Thompson -- | James E.Thompson, CTO | mens | | Analog Innovations, Inc. | et | | Analog/Mixed-Signal ASIC's and Discrete Systems | manus | | Phoenix, Arizona 85048 Skype: Contacts Only | | | Voice:(480)460-2350 Fax: Available upon request | Brass Rat | | E-mail Icon at http://www.analog-innovations.com | 1962 | The only thing bipartisan in this country is hypocrisy
From: Winfield Hill on 7 Apr 2010 19:56 Jim Thompson wrote... > > Is the model in text format or is it encrypted? The Intusoft version is in plain text. I think this is it, along with an X1 call. It's not exactly what I expected to see. E.g., who's Kehinde Omolayo? Hmm, Magnetico, Inc. Hmm, 2003, "Standex International Corp. has purchased substantially all of the assets..."; the trail grows cold. X1 7 4 5 0 8 6 7 7 MC34063AX2 { } ..SUBCKT MC34063AX2 1 2 3 4 5 6 7 8 *exempt 20030227 20395 -30736294 *BY KEHINDE OMOLAYO 2-20-03 *TERMINAL ID *SWITCH COLLECTOR=1 SWITCH EMITTER=2 TIMING CAPACITOR=3 GND=4 *COMPARATOR INVERTING INPUT=5 VCC=6 IPK SENSE=7 DRIVER COLLECTOR=8 ..MODEL DMC34063 D (CJO=2P N=0.05) ..MODEL QSWITCH NPN BF=75 CJC=2P IS=3E-9 RB=1 RC=0.45 RE=0 + VJC=.75 VJE=.75 VJS=.75 E1 10 0 5 4 1 R1 4 5 10MEG V1 20 0 PULSE 0 2 E2 11 0 3 4 1 B1 13 0 V=1M/(ABS((27.475-195M*V(12))+(36.002+244M*V(12))*V(9)- +(302.302+651M*V(12))*V(9)^2)+1F) E3 12 0 6 4 1 E4 9 0 6 7 1 R2 6 7 10MEG B2 14 0 V=1M*((-10.765-151M*V(12))+(45.344+864M*V(12))*V(9)- +(35.99+1.378*V(12))*V(9)^2+(8.341+839M*V(12))*V(9)^3) B4 15 0 V=V(9)>0.32 ? V(14) : V(13) C1 19 0 10P B5 16 0 V= V(20)<1 ? 2 : V(24)>1 ? 2 : V(19)>1 ? 0 : 2 R3 16 17 150 C2 17 0 10P B6 18 0 V=V(20)<1 ? 0 : V(24)>1 ? 0 : V(11)<(1.083-1.239*V(29)) ? 2 : + V(17)>1 ? 0 : 2 R4 18 19 150 D1 4 3 DMC34063 D2 3 6 DMC34063 C3 11 31 1N B7 4 36 I=V(17)>1 ? -(224.4U+2.359U*V(12))*0.77 : V(15)*0.77 C5 23 0 10P B9 21 0 V= V(20)<1 ? 2 : V(17)>1 ? 2 : V(26)>1 ? 0 : 2 R5 27 26 150 C6 26 0 10P B10 27 0 V=V(20)<1 ? 0 : V(17)>1 ? 0 : V(10)<1.25 ? 2 : V(23)>1 ? 0 : 2 R6 21 23 150 B12 33 0 V=V(11)>(1.148+184.6M*V(29)) ? 2 : 0 R13 33 24 10K C8 24 0 10P Q1 8 30 25 QSWITCH Q2 1 25 2 QSWITCH R15 25 2 100 D5 2 30 DMC34063 G1 2 30 26 23 5M R16 2 4 10MEG R23 31 28 1M V6 28 0 V7 36 3 B13 29 0 V=I(V6)/(I(V7)+866.8M*I(V6)) ..ENDS -- Thanks, - Win
From: Jim Thompson on 7 Apr 2010 20:03 On 7 Apr 2010 16:56:30 -0700, Winfield Hill <Winfield_member(a)newsguy.com> wrote: >Jim Thompson wrote... >> >> Is the model in text format or is it encrypted? > > The Intusoft version is in plain text. I think this > is it, along with an X1 call. It's not exactly what > I expected to see. E.g., who's Kehinde Omolayo? Hmm, > Magnetico, Inc. Hmm, 2003, "Standex International Corp. > has purchased substantially all of the assets..."; the > trail grows cold. > >X1 7 4 5 0 8 6 7 7 MC34063AX2 { } >.SUBCKT MC34063AX2 1 2 3 4 5 6 7 8 >*exempt 20030227 20395 -30736294 >*BY KEHINDE OMOLAYO 2-20-03 >*TERMINAL ID >*SWITCH COLLECTOR=1 SWITCH EMITTER=2 TIMING CAPACITOR=3 GND=4 >*COMPARATOR INVERTING INPUT=5 VCC=6 IPK SENSE=7 DRIVER COLLECTOR=8 >.MODEL DMC34063 D (CJO=2P N=0.05) >.MODEL QSWITCH NPN BF=75 CJC=2P IS=3E-9 RB=1 RC=0.45 RE=0 >+ VJC=.75 VJE=.75 VJS=.75 >E1 10 0 5 4 1 >R1 4 5 10MEG >V1 20 0 PULSE 0 2 >E2 11 0 3 4 1 >B1 13 0 V=1M/(ABS((27.475-195M*V(12))+(36.002+244M*V(12))*V(9)- >+(302.302+651M*V(12))*V(9)^2)+1F) >E3 12 0 6 4 1 >E4 9 0 6 7 1 >R2 6 7 10MEG >B2 14 0 V=1M*((-10.765-151M*V(12))+(45.344+864M*V(12))*V(9)- >+(35.99+1.378*V(12))*V(9)^2+(8.341+839M*V(12))*V(9)^3) >B4 15 0 V=V(9)>0.32 ? V(14) : V(13) >C1 19 0 10P >B5 16 0 V= V(20)<1 ? 2 : V(24)>1 ? 2 : V(19)>1 ? 0 : 2 >R3 16 17 150 >C2 17 0 10P >B6 18 0 V=V(20)<1 ? 0 : V(24)>1 ? 0 : V(11)<(1.083-1.239*V(29)) ? 2 : >+ V(17)>1 ? 0 : 2 >R4 18 19 150 >D1 4 3 DMC34063 >D2 3 6 DMC34063 >C3 11 31 1N >B7 4 36 I=V(17)>1 ? -(224.4U+2.359U*V(12))*0.77 : V(15)*0.77 >C5 23 0 10P >B9 21 0 V= V(20)<1 ? 2 : V(17)>1 ? 2 : V(26)>1 ? 0 : 2 >R5 27 26 150 >C6 26 0 10P >B10 27 0 V=V(20)<1 ? 0 : V(17)>1 ? 0 : V(10)<1.25 ? 2 : V(23)>1 ? 0 : 2 >R6 21 23 150 >B12 33 0 V=V(11)>(1.148+184.6M*V(29)) ? 2 : 0 >R13 33 24 10K >C8 24 0 10P >Q1 8 30 25 QSWITCH >Q2 1 25 2 QSWITCH >R15 25 2 100 >D5 2 30 DMC34063 >G1 2 30 26 23 5M >R16 2 4 10MEG >R23 31 28 1M >V6 28 0 >V7 36 3 >B13 29 0 V=I(V6)/(I(V7)+866.8M*I(V6)) >.ENDS Thanks, Win! I'll try to pick it apart when I have a free moment. Most of those behavioral games are less than adequate... particularly those IF..THEN..ELSE statements :-( ...Jim Thompson -- | James E.Thompson, CTO | mens | | Analog Innovations, Inc. | et | | Analog/Mixed-Signal ASIC's and Discrete Systems | manus | | Phoenix, Arizona 85048 Skype: Contacts Only | | | Voice:(480)460-2350 Fax: Available upon request | Brass Rat | | E-mail Icon at http://www.analog-innovations.com | 1962 | The only thing bipartisan in this country is hypocrisy
From: Joerg on 7 Apr 2010 20:06
Winfield Hill wrote: > Jim Thompson wrote... >> Is the model in text format or is it encrypted? > > The Intusoft version is in plain text. I think this > is it, along with an X1 call. It's not exactly what > I expected to see. E.g., who's Kehinde Omolayo? Hmm, > Magnetico, Inc. Hmm, 2003, "Standex International Corp. > has purchased substantially all of the assets..."; the > trail grows cold. > > X1 7 4 5 0 8 6 7 7 MC34063AX2 { } > .SUBCKT MC34063AX2 1 2 3 4 5 6 7 8 > *exempt 20030227 20395 -30736294 > *BY KEHINDE OMOLAYO 2-20-03 > *TERMINAL ID > *SWITCH COLLECTOR=1 SWITCH EMITTER=2 TIMING CAPACITOR=3 GND=4 > *COMPARATOR INVERTING INPUT=5 VCC=6 IPK SENSE=7 DRIVER COLLECTOR=8 > .MODEL DMC34063 D (CJO=2P N=0.05) > .MODEL QSWITCH NPN BF=75 CJC=2P IS=3E-9 RB=1 RC=0.45 RE=0 > + VJC=.75 VJE=.75 VJS=.75 > E1 10 0 5 4 1 > R1 4 5 10MEG > V1 20 0 PULSE 0 2 > E2 11 0 3 4 1 > B1 13 0 V=1M/(ABS((27.475-195M*V(12))+(36.002+244M*V(12))*V(9)- > +(302.302+651M*V(12))*V(9)^2)+1F) > E3 12 0 6 4 1 > E4 9 0 6 7 1 > R2 6 7 10MEG > B2 14 0 V=1M*((-10.765-151M*V(12))+(45.344+864M*V(12))*V(9)- > +(35.99+1.378*V(12))*V(9)^2+(8.341+839M*V(12))*V(9)^3) > B4 15 0 V=V(9)>0.32 ? V(14) : V(13) > C1 19 0 10P > B5 16 0 V= V(20)<1 ? 2 : V(24)>1 ? 2 : V(19)>1 ? 0 : 2 > R3 16 17 150 > C2 17 0 10P > B6 18 0 V=V(20)<1 ? 0 : V(24)>1 ? 0 : V(11)<(1.083-1.239*V(29)) ? 2 : > + V(17)>1 ? 0 : 2 > R4 18 19 150 > D1 4 3 DMC34063 > D2 3 6 DMC34063 > C3 11 31 1N > B7 4 36 I=V(17)>1 ? -(224.4U+2.359U*V(12))*0.77 : V(15)*0.77 > C5 23 0 10P > B9 21 0 V= V(20)<1 ? 2 : V(17)>1 ? 2 : V(26)>1 ? 0 : 2 > R5 27 26 150 > C6 26 0 10P > B10 27 0 V=V(20)<1 ? 0 : V(17)>1 ? 0 : V(10)<1.25 ? 2 : V(23)>1 ? 0 : 2 > R6 21 23 150 > B12 33 0 V=V(11)>(1.148+184.6M*V(29)) ? 2 : 0 > R13 33 24 10K > C8 24 0 10P > Q1 8 30 25 QSWITCH > Q2 1 25 2 QSWITCH > R15 25 2 100 > D5 2 30 DMC34063 > G1 2 30 26 23 5M > R16 2 4 10MEG > R23 31 28 1M > V6 28 0 > V7 36 3 > B13 29 0 V=I(V6)/(I(V7)+866.8M*I(V6)) > .ENDS > > There's actually three more models around but they essentially behave similar. Thing is, the chip is not supposed to turn off the switch during the positive ramp because the comparator does not tie into the reset input of the register, only the set input. <scratching_ head> -- Regards, Joerg http://www.analogconsultants.com/ "gmail" domain blocked because of excessive spam. Use another domain or send PM. |