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Simulation of chips

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sallehzxc

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Hi,

I am currently a student tasked to implement and test out an Remote 8-Bit I 2C and SMBus Low-Power I/O Expander With Reset and Configuration Registers (http://www.ti.com/lit/ds/symlink/pca9557.pdf) and a synthesizer chip (http://www.analog.com/media/en/technical-documentation/data-sheets/ADF4350.pdf) on LTspice as part of my module requirements. It's my first time dealing with LTspice and i am unable to find the models, or even similar specs models to do the simulations.

Can anybody provide me a suggestion on how i can proceed moving forward if i were to use LTspice? If not, can you provide me alternatives on what I can do to test out the outputs of said chips?

Lastly, is there anything else i should be considering when doing up testing of chips in general on LTspice?

Thank you for your responses in advance !!
 

kubeek

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None of the chips has any model available, so I guess you will have to go by the datasheet. Anyway, what exactly it is that you´re trying to simulate?
 

Ian Rogers

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These are highly complex chips.... I use Proteus ( I has the slightly lesser pca9554a ) Isis can completely simulate I2C devices... I'm not sure of the "free" version but I pay dearly for the software...
 

dknguyen

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Hi,

I am currently a student tasked to implement and test out an Remote 8-Bit I 2C and SMBus Low-Power I/O Expander With Reset and Configuration Registers (http://www.ti.com/lit/ds/symlink/pca9557.pdf) and a synthesizer chip (http://www.analog.com/media/en/technical-documentation/data-sheets/ADF4350.pdf) on LTspice as part of my module requirements. It's my first time dealing with LTspice and i am unable to find the models, or even similar specs models to do the simulations.

Can anybody provide me a suggestion on how i can proceed moving forward if i were to use LTspice? If not, can you provide me alternatives on what I can do to test out the outputs of said chips?

Lastly, is there anything else i should be considering when doing up testing of chips in general on LTspice?

Thank you for your responses in advance !!
You said your task is to implement and test it. Did anyone say that you need to simulate it? Because I doubt they intended for you to simulate it due to the problems you have already encountered. It sounds more like they wanted you to actually build it and test the circuit.
 

alec_t

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In the absence of existing models of ICs you will have to brew your own for a simulation, working from any functional diagrams, schematics and electrical characteristics shown in the datasheets. This involves cobbling together various primitive models, such as the ones in LTspice's Digital folder. You have been set a challenging task. The models would then need validating by comparing their behaviour with that of the real-world ICs.
 

sallehzxc

New Member
yup, my mentor in question has plans in line with what alec_t is mentioning. I'm still stuck with the chip design and her lack of emphasis on the task as well as aid is killing me! I am tasked to just see the behavior with regards to the frequency range they are planning to use as input, to see if they are able to simulate.

Thank you though everyone i really appreciate the help! if anyone has any advice for me, i am all ears and would be more than happy to listen!
 

sallehzxc

New Member
None of the chips has any model available, so I guess you will have to go by the datasheet. Anyway, what exactly it is that you´re trying to simulate?
She has a reference circuit for me! actually if it is possible, i was wondering if anyone could explain the fundamental concept of the chips? so far, i understand that the ADF4350 is basically a form of feedback loop utilising the idea of comparators and flip flops to determine and get other freqs. I sadly do not understand how the other chip works, PCA9557.
 

alec_t

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I am tasked to just see the behavior with regards to the frequency range they are planning to use as input, to see if they are able to simulate.
This leads to a self-fulfilling prophecy. If you design the model based on the rated maximum frequency as per the datasheet then, unsurprisingly, when you test the model by running a sim you will find it behaves perfectly at that frequency.
 

kubeek

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PCA9557 is as it name says, an IO expander. You send it a command over the I2C bus, and it either sets the output pins to some state, or reads back the input pins.
 

sallehzxc

New Member
This leads to a self-fulfilling prophecy. If you design the model based on the rated maximum frequency as per the datasheet then, unsurprisingly, when you test the model by running a sim you will find it behaves perfectly at that frequency.
yup thats the funny part. we know it works but somehow i think in a sense she wants me to work backwards and do a justification on why the model/schematic was chosen in the first place. kind of like a justification document as to why things/chips were chosen in the first place. if it is of any value, this is my final year project for my undergraduate studies and sadly i have reached a stump on simulations amongst all the other experiments going on haha
 

sallehzxc

New Member
PCA9557 is as it name says, an IO expander. You send it a command over the I2C bus, and it either sets the output pins to some state, or reads back the input pins.
hmm, so the fundamental idea around how the circuit works is just dependent on clock and data lines meant for addressing before information is inputted in?
additionallt, i have three more chips if anybody here has time to help! TQP3M9018 , PE4245, HRF- AT4520. is tqp3m9018 basically just a gain amplifier that amplifies signal? hrf1t4520 is just to attenuate the signal to higher levels?(which is the same thing?) and pe4245 is the last on the schematic. sadly the schematic is confidential but i have attached the general block diagram for anybody who is interested.
 

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alec_t

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sallehzxc

New Member
Yes.

It's a programmable attenuator. It doesn't raise the signal to higher levels: rather, it reduces it by a selected amount.
Ahh... Thank you that helps alot! i'll be meeting my mentor in a week and hopefully it goes well! Thank you and everyone else in advance for your help!
Hopefully if there are any better ideas, you can share them and I can effectively do it!
THANKS A MILLION GUYS!
 
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