Keyboard Shortcuts
ctrl + shift + ? :
Show all keyboard shortcuts
ctrl + g :
Navigate to a group
ctrl + shift + f :
Find
ctrl + / :
Quick actions
esc to dismiss
Likes
- LTspice
- Messages
Search
|
Re: Wanted Max7405 model or how to model a switched capacitor filter
There is a simulation of a switch capacitor filter in this groups files.
toggle quoted message
Show quoted text
Files > Files sorted by message number > msg 2398 Take a look at this simulation. It may answer some of your questions. Howard On 9/23/2011 4:11 PM, poppletech wrote:
I would like to model a switched capacitor low pass filter, specifically the MAX7405. Is there a model availble? Or what would be the best way to model the frequency controlled cutoff frequency and the switching noise? |
|
Re: Inductor initial conditions
Ganesan
As usual this group is very helpful in helping me find workarounds; but
toggle quoted message
Show quoted text
the basic questions remain unanswered... cheers AG On 9/23/2011 6:07 PM, Rick wrote:
|
|
Re: Inductor initial conditions
--- In LTspice@..., Ganesan <dg1@...> wrote:
AG, Hum, you are correct. I don't know why this is, but it is confusing. Maybe someone else can shed some light on this. Anyway, if I want nonzero ic's I always specify them according to the method I noted earlier. Rick |
|
Re: Inductor initial conditions
Ganesan
I sent it to your email address.. But the netlist is in previous
postings and is below. Just cut and paste it into a .cir file and run LTspice on it... cheers AG * C:\Documents and Settings\ganesan\My Documents\Downloads\Draft1.asc > > R1 out 0 1 > > L2 out 0 1 > > R2 out1 0 1 > > C1 out1 0 1 > > .ic I(L2) =1.0 v(out1) =-1.0 > > .tran 5 uic > > .backanno > > .end On 9/23/2011 5:52 PM, Rick wrote:
|
|
Re: Inductor initial conditions
--- In LTspice@..., Ganesan <dg1@...> wrote:
AG, You should be able to upload the file, but my email address is rsawrey@... Rick |
|
Re: Inductor initial conditions
Ganesan
It is small enough to paste here.
toggle quoted message
Show quoted text
cheers AG IC_test.asc Version 4 SHEET 1 880 680 WIRE 176 64 144 64 WIRE 208 64 176 64 WIRE 368 64 352 64 WIRE 400 64 368 64 WIRE 144 96 144 64 WIRE 208 96 208 64 WIRE 352 96 352 64 WIRE 400 96 400 64 WIRE 144 208 144 160 WIRE 176 208 144 208 WIRE 208 208 208 176 WIRE 208 208 176 208 WIRE 352 208 352 176 WIRE 384 208 352 208 WIRE 400 208 400 176 WIRE 400 208 384 208 WIRE 176 240 176 208 WIRE 384 240 384 208 FLAG 176 240 0 FLAG 384 240 0 FLAG 176 64 out1 FLAG 368 64 out SYMBOL res 192 80 R0 SYMATTR InstName R2 SYMATTR Value 1 SYMBOL res 384 80 R0 SYMATTR InstName R1 SYMATTR Value 1 SYMBOL cap 128 96 R0 SYMATTR InstName C1 SYMATTR Value 1 SYMBOL ind 368 80 M0 SYMATTR InstName L2 SYMATTR Value 1 TEXT 160 8 Left 2 !.ic I(L2) =1.0 v(out1) =-1.0 TEXT -32 40 Left 2 !.tran 5 uic On 9/23/2011 5:47 PM, Ganesan wrote:
|
|
Re: Inductor initial conditions
Ganesan
I have just created such a file IC_test.asc.. For reasons I dont
toggle quoted message
Show quoted text
understand I am unable to Upload it to the temp directory. So I am sending it to you by direct email tosawreyrw@... cheers AG On 9/23/2011 5:26 PM, Rick wrote:
|
|
Re: Inductor initial conditions
--- In LTspice@..., Ganesan <dg1@...> wrote:
AG, No, if .tran UIC is specified the .IC directive is ignored, and any ic's on cap or inductor cards are used. If you don't agree post, a .asc file showing your circuit that doesn't work this way. Rick |
|
Re: Inductor initial conditions
Ganesan
The point is when the .tran statement includes UIC, the node voltages
toggle quoted message
Show quoted text
are read from the .IC card but not the inductor currents from the .IC card. What gives? ( we are not talking about IC= Val on the individual elements) Cheers AG On 9/23/2011 4:51 PM, Rick wrote:
|
|
Re: Wanted Max7405 model or how to model a switched capacitor filter
Ganesan
In message #48936 I showed how to model a first order switched Capacitor
toggle quoted message
Show quoted text
filter and the clock frequency can be varied.. I had problems getting it to work in the time domain . (The Laplace has some quirks).. Helmut in a subsequent message solved it for that particular circuit.. I believe, in the general case the frequency domain answer is exact; but the time domain answer may need to be scrutinized.. Cheers AG On 9/23/2011 4:11 PM, poppletech wrote:
|
|
Re: Inductor initial conditions
--- In LTspice@..., Ganesan <dg1@...> wrote:
AG, There are two different ways to specify initial conditions. 1. If the .tran statement includes UIC, the ic=values from the cap and inductor "cards" are used. You don't need to edit the netlist to add them, just add them as Helmut has told you. 2. If the .tran statement does NOT include UIC, then the value(s) in the .IC directive are applied. Rick |
|
Re: How to Specify Polarity on Capacitor Initial Conditions
When you use an ic=<value> parameter on a capacitor, you have to think
of the SPICE netlist description. The specified voltage is between the first node and the second one, for example: Cnnn n1 n2 470p ic=-2.5V would set node n1 2.5V lower than node n2. You may need to experiment a bit to see how the schematic symbol (with its various orientations) translates to the netlist. Use View > SPICE Netlist to see the netlist. Andy |
|
Wanted Max7405 model or how to model a switched capacitor filter
poppletech
I would like to model a switched capacitor low pass filter, specifically the MAX7405. Is there a model availble? Or what would be the best way to model the frequency controlled cutoff frequency and the switching noise?
So far I have been using an 'e' behavorial voltage source with a laplace transform of the filter transfer function. I have not figured out how to control the cutoff frequency by the frequency of an input signal. Can anyone help with that? Thank you Ken |
|
Re: Inductor initial conditions
Ganesan
Thanks
toggle quoted message
Show quoted text
Ag On 9/23/2011 3:31 PM, Helmut wrote:
|
|
Re: Inductor initial conditions
Hello AG,
toggle quoted message
Show quoted text
Initial conditions can be set in any capacitor or inductor. Instead of 5n use the following to charge the capacitor with 5V. 5n IC=5 Instead of 10u use the following to set the inductor current to 1A. 10u IC=1 Best regards, Helmut --- In LTspice@..., Ganesan <dg1@...> wrote:
|
|
Re: Inductor initial conditions
Ganesan
Helmut,
toggle quoted message
Show quoted text
Are there symbols for inductors and capacitors, where I can put in Initial conditions? Cheers AG ============================= On 9/23/2011 1:58 PM, Ganesan wrote:
|
|
Re: Regarding Monte carlo setup
--- In LTspice@..., "pindsen" <windven@...> wrote:
Hello Carsten, .step param 0 5 1 The 1 is the increment from step to step. Here is an example with increment 0.1 .step param xy 0 10 0.1 xy=0 xy=0.1 xy=0.2 xy=... xy=9.9 xy=10 Best regards, Helmut |
|
Re: Inductor initial conditions
Ganesan
Philip,
toggle quoted message
Show quoted text
Here is a simple netlist. When I include the uic ( userspecified initial condition) option on the tran card, it still accepts the initial voltage for the nodes but not the inductor currents.. * C:\Documents and Settings\ganesan\My Documents\Downloads\Draft1.asc R1 out 0 1 L2 out 0 1 R2 out1 0 1 C1 out1 0 1 .ic I(L2) =1.0 v(out1) =-1.0 .tran 5 uic .backanno .end Now I am totally confused.. Cheers AG On 9/23/2011 2:29 PM, kungfu_phil wrote:
|
|
Re: Inductor initial conditions
Apparently, LTspice uses the initial condition methods differently; whethter specificed by an .IC command or as an ic value of a component.
toggle quoted message
Show quoted text
If you remove the uic from the .TRAN command, the .ic command as you had it works fine, without adding the ic statement to the inductor. The HELP file for the .IC command says, "A DC solution is performed using the initial conditions as constraints." When you specify uic in the .TRAN command, you are telling it to skip the initial operating point solution. Thus, it looks like LTspice does not use the initial condition set by the .IC command when you tell it to skip the initial operating point solution. On the other hand, the HELP for the inductor or a capacitor says that the ic initial current option is , "used only if uic flagged on the .tran card". The same thing seems to happen with voltages. The ic value on a capacitor is used only when you specify uic in the TRAN command. Conversely, the .IC command line appears to be ignored when you specify uic in the TRAN line. - Philip --- In LTspice@..., "Apparajan" <dg1@...> wrote:
|
|
Re: Inductor initial conditions
Ganesan
if I hand edit the net list and put the IC= value manually on the
toggle quoted message
Show quoted text
inductor , it works.. It looks like .IC doesn't work for Inductors... cheers AG On 9/23/2011 1:33 PM, Ganesan wrote:
|
to navigate to use esc to dismiss