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AN: TL598 Spice Model

You can do that with PSpice: Save Bias Point / Load Bias Point.

Save from a .TRAN, Load to a .AC

I thought LTspice could do that as well ?? ...Jim Thompson

--
| James E.Thompson                                 |    mens     | 
| Analog Innovations                               |     et      | 
| Analog/Mixed-Signal ASIC's and Discrete Systems  |    manus    | 
| San Tan Valley, AZ 85142     Skype: skypeanalog  |             | 
| Voice:(480)460-2350  Fax: Available upon request |  Brass Rat  | 
| E-mail Icon at http://www.analog-innovations.com |    1962     | 
              
I love to cook with wine.     Sometimes I even put it in the food.
Reply to
Jim Thompson
Loading thread data ...

There's .savebias / .loadbias, but they're not the same thing.

It iterates to a bias point (hopefully) and then saves that, not the results of the transient.

Cheers

Phil Hobbs

--
Dr Philip C D Hobbs 
Principal Consultant 
ElectroOptical Innovations LLC 
Optics, Electro-optics, Photonics, Analog Electronics 

160 North State Road #203 
Briarcliff Manor NY 10510 

hobbs at electrooptical dot net 
http://electrooptical.net
Reply to
Phil Hobbs

In PSpice, do a .OP, SaveBias (to a file)

Setup .TRAN, LoadBias (that file you saved), run .TRAN ...Jim Thompson

--
| James E.Thompson                                 |    mens     | 
| Analog Innovations                               |     et      | 
| Analog/Mixed-Signal ASIC's and Discrete Systems  |    manus    | 
| San Tan Valley, AZ 85142     Skype: skypeanalog  |             | 
| Voice:(480)460-2350  Fax: Available upon request |  Brass Rat  | 
| E-mail Icon at http://www.analog-innovations.com |    1962     | 
              
I love to cook with wine.     Sometimes I even put it in the food.
Reply to
Jim Thompson

How do you set the parameters of the SW in LTspice? ...Jim Thompson

--
| James E.Thompson                                 |    mens     | 
| Analog Innovations                               |     et      | 
| Analog/Mixed-Signal ASIC's and Discrete Systems  |    manus    | 
| San Tan Valley, AZ 85142     Skype: skypeanalog  |             | 
| Voice:(480)460-2350  Fax: Available upon request |  Brass Rat  | 
| E-mail Icon at http://www.analog-innovations.com |    1962     | 
              
I love to cook with wine.     Sometimes I even put it in the food.
Reply to
Jim Thompson

RON, ROFF, which do what you'd expect; VT, which is the switching threshold (the switch looks like RON for V > VT, and ROFF for V < VT); and VH, the hysteresis.

If VH is positive, then the upward-going transition occurs at V = VT + VH and the downward-going one at V = VT - VH. (IOW it does what you expect except that VH is the half-width of the deadband, not the full width.)

Negative values of VH cause a smooth transition between RON and ROFF, so that the switching begins at VT + VH (which is less than VT in this case) and is complete at VT - VH (which is more than VT). IIRC the function is some smooth polynomial approximation to the arctan, so at least the first few derivatives are continuous.

Cheers

Phil Hobbs

--
Dr Philip C D Hobbs 
Principal Consultant 
ElectroOptical Innovations LLC 
Optics, Electro-optics, Photonics, Analog Electronics 

160 North State Road #203 
Briarcliff Manor NY 10510 

hobbs at electrooptical dot net 
http://electrooptical.net
Reply to
Phil Hobbs

I'm used to PSpice, click on a symbol and you see a table where you fill in the blanks. I click on SW in LTspice, I see several blank lines... SpiceLine SpicelIne2

Where do I enter Ron, Roff, Von, Voff, etc? ...Jim Thompson

--
| James E.Thompson                                 |    mens     | 
| Analog Innovations                               |     et      | 
| Analog/Mixed-Signal ASIC's and Discrete Systems  |    manus    | 
| San Tan Valley, AZ 85142     Skype: skypeanalog  |             | 
| Voice:(480)460-2350  Fax: Available upon request |  Brass Rat  | 
| E-mail Icon at http://www.analog-innovations.com |    1962     | 
              
I love to cook with wine.     Sometimes I even put it in the food.
Reply to
Jim Thompson

You have to put in a .model statement:

.model simplesw sw(Vt=1 Vh=-.5 Ron=1 Roff=1T)

and put 'simplesw' on the 'value' line in the dialogue box.

To make a NC switch, you can interchange the values of Ron and Roff, i.e.

.model simpleNC sw(Vt=1 Vh=-.5 Ron=1T Roff=1)

Cheers

Phil Hobbs

--
Dr Philip C D Hobbs 
Principal Consultant 
ElectroOptical Innovations LLC 
Optics, Electro-optics, Photonics, Analog Electronics 

160 North State Road #203 
Briarcliff Manor NY 10510 

hobbs at electrooptical dot net 
http://electrooptical.net
Reply to
Phil Hobbs

Checked it out, LTspice switch with negative hysteresis looks exactly same V-I curve as in PSpice... PSpice runs the OPA2140, LTspice will not, so it looks like a major makeover.

If you need only GBW and noise, that can be done simply, otherwise the long winter ;-)

...Jim Thompson

--
| James E.Thompson                                 |    mens     | 
| Analog Innovations                               |     et      | 
| Analog/Mixed-Signal ASIC's and Discrete Systems  |    manus    | 
| San Tan Valley, AZ 85142     Skype: skypeanalog  |             | 
| Voice:(480)460-2350  Fax: Available upon request |  Brass Rat  | 
| E-mail Icon at http://www.analog-innovations.com |    1962     | 
              
I love to cook with wine.     Sometimes I even put it in the food.
Reply to
Jim Thompson

BTW: PSpice won't converge on asymmetric supplies either. So the TI model is crap :-( ...Jim Thompson

--
| James E.Thompson                                 |    mens     | 
| Analog Innovations                               |     et      | 
| Analog/Mixed-Signal ASIC's and Discrete Systems  |    manus    | 
| San Tan Valley, AZ 85142     Skype: skypeanalog  |             | 
| Voice:(480)460-2350  Fax: Available upon request |  Brass Rat  | 
| E-mail Icon at http://www.analog-innovations.com |    1962     | 
              
I love to cook with wine.     Sometimes I even put it in the food.
Reply to
Jim Thompson

If I were more motivated I'd try it on TINA, but given the complexity of the model I'd be surprised if they'd fix it even if it's broken on TINA as well.

Cheers

Phil Hobbs

--
Dr Philip C D Hobbs 
Principal Consultant 
ElectroOptical Innovations LLC 
Optics, Electro-optics, Photonics, Analog Electronics 

160 North State Road #203 
Briarcliff Manor NY 10510 

hobbs at electrooptical dot net 
http://electrooptical.net
Reply to
Phil Hobbs

The SUBCKT looks to be an extremist's attempt at obfuscation. All kinds of voltage sources, indicating either attempts at obfuscation or total ignorance of how to write proper behavioral controlled sources. Also a bunch of unbounded current sources that probably pull to infinity at the slightest provocation >:-}

Maybe you should choose another brand and let TI know?

When I get the time I'll consider writing a model from the datasheet. The TI SUBCKT is grotesque, to put it mildly ;-) ...Jim Thompson

--
| James E.Thompson                                 |    mens     | 
| Analog Innovations                               |     et      | 
| Analog/Mixed-Signal ASIC's and Discrete Systems  |    manus    | 
| San Tan Valley, AZ 85142     Skype: skypeanalog  |             | 
| Voice:(480)460-2350  Fax: Available upon request |  Brass Rat  | 
| E-mail Icon at http://www.analog-innovations.com |    1962     | 
              
I love to cook with wine.     Sometimes I even put it in the food.
Reply to
Jim Thompson

Here's a funny for you, a current flowing FROM V- INTO the chip...

IS3 40 V- -500F

Another... obsolete H controlled source...

HCCVS2 50 11 VCCVS2_in 1K ...Jim Thompson

--
| James E.Thompson                                 |    mens     | 
| Analog Innovations                               |     et      | 
| Analog/Mixed-Signal ASIC's and Discrete Systems  |    manus    | 
| San Tan Valley, AZ 85142     Skype: skypeanalog  |             | 
| Voice:(480)460-2350  Fax: Available upon request |  Brass Rat  | 
| E-mail Icon at http://www.analog-innovations.com |    1962     | 
              
I love to cook with wine.     Sometimes I even put it in the food.
Reply to
Jim Thompson

Well, it's about 10 times longer than your normal op amp model--I was hoping that was a good thing. ;)

The OPA140 is pretty well your perfect low-power TIA part, except for the 10 pF input capacitance, which is on the high side.

Cheers

Phil Hobbs

--
Dr Philip C D Hobbs 
Principal Consultant 
ElectroOptical Innovations LLC 
Optics, Electro-optics, Photonics, Analog Electronics 

160 North State Road #203 
Briarcliff Manor NY 10510 

hobbs at electrooptical dot net 
http://electrooptical.net
Reply to
Phil Hobbs

When they spec 7pF common-mode input capacitance, is that from _each_ input pin, or combined? ...Jim Thompson

--
| James E.Thompson                                 |    mens     | 
| Analog Innovations                               |     et      | 
| Analog/Mixed-Signal ASIC's and Discrete Systems  |    manus    | 
| San Tan Valley, AZ 85142     Skype: skypeanalog  |             | 
| Voice:(480)460-2350  Fax: Available upon request |  Brass Rat  | 
| E-mail Icon at http://www.analog-innovations.com |    1962     | 
              
I love to cook with wine.     Sometimes I even put it in the food.
Reply to
Jim Thompson

I've been trying to get a straight answer to that question from various manufacturers for a long time, so far without success. My guess (after discussion with JL) is that they just hang a 3-terminal capacitance meter from one input to the supply common and call that "common mode", and then do the same between inputs, and call that "differential mode".

Measuring those values in normal circuit operation can be a bit subtle. Normally what I care about is the total capacitive loading on the summing junction of an inverting stage, which might be C_CM, or C_diff + C_CM/2, or something else.

The best method is probably to put a pot between the SJ and the actual inverting input, and measure the phase margin with various values of resistance. I should have bugged Jim Williams for an app note while I had the chance. :(

Cheers

Phil Hobbs

--
Dr Philip C D Hobbs 
Principal Consultant 
ElectroOptical Innovations LLC 
Optics, Electro-optics, Photonics, Analog Electronics 

160 North State Road #203 
Briarcliff Manor NY 10510 

hobbs at electrooptical dot net 
http://electrooptical.net
Reply to
Phil Hobbs

Fit to the AC and slew-rate characteristics...

No swing limits yet, but I'm only up to 35 lines >:-} ...Jim Thompson

--
| James E.Thompson                                 |    mens     | 
| Analog Innovations                               |     et      | 
| Analog/Mixed-Signal ASIC's and Discrete Systems  |    manus    | 
| San Tan Valley, AZ 85142     Skype: skypeanalog  |             | 
| Voice:(480)460-2350  Fax: Available upon request |  Brass Rat  | 
| E-mail Icon at http://www.analog-innovations.com |    1962     | 
              
I love to cook with wine.     Sometimes I even put it in the food.
Reply to
Jim Thompson

Versus 467 lines in TI's model.

And I'm just fitting graphs in the datasheet, so no relation to internal components and no obfuscation needed. ...Jim Thompson

--
| James E.Thompson                                 |    mens     | 
| Analog Innovations                               |     et      | 
| Analog/Mixed-Signal ASIC's and Discrete Systems  |    manus    | 
| San Tan Valley, AZ 85142     Skype: skypeanalog  |             | 
| Voice:(480)460-2350  Fax: Available upon request |  Brass Rat  | 
| E-mail Icon at http://www.analog-innovations.com |    1962     | 
              
I love to cook with wine.     Sometimes I even put it in the food.
Reply to
Jim Thompson

Nice, thanks. I'll have a whack at it when I get out of my current C++ programming blitz.

Cheers

Phil Hobbs

--
Dr Philip C D Hobbs 
Principal Consultant 
ElectroOptical Innovations LLC 
Optics, Electro-optics, Photonics, Analog Electronics 

160 North State Road #203 
Briarcliff Manor NY 10510 

hobbs at electrooptical dot net 
http://electrooptical.net
Reply to
Phil Hobbs

It's fun... as I have a spare time gap I develop another function to add to my toolkit. I'll explain how I did that phase dip later ;-) ...Jim Thompson

--
| James E.Thompson                                 |    mens     | 
| Analog Innovations                               |     et      | 
| Analog/Mixed-Signal ASIC's and Discrete Systems  |    manus    | 
| San Tan Valley, AZ 85142     Skype: skypeanalog  |             | 
| Voice:(480)460-2350  Fax: Available upon request |  Brass Rat  | 
| E-mail Icon at http://www.analog-innovations.com |    1962     | 
              
I love to cook with wine.     Sometimes I even put it in the food.
Reply to
Jim Thompson

Further improvement...

Figured out how to nail 1/f noise... I can even twiddle the exponent ;-)

I miss matching the TI noise model above ~300MHz but, given the rest of the TI model is not well-behaved, I not sure I'm the one in the wrong. ...Jim Thompson

--
| James E.Thompson                                 |    mens     | 
| Analog Innovations                               |     et      | 
| Analog/Mixed-Signal ASIC's and Discrete Systems  |    manus    | 
| San Tan Valley, AZ 85142     Skype: skypeanalog  |             | 
| Voice:(480)460-2350  Fax: Available upon request |  Brass Rat  | 
| E-mail Icon at http://www.analog-innovations.com |    1962     | 
              
I love to cook with wine.     Sometimes I even put it in the food.
Reply to
Jim Thompson

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