RC4580-Q1: Schematic Review for stereo audio

Mohit Goel

Part Number: RC4580-Q1
Other Parts Discussed in Thread: TS5A22364-Q1, RC4580, TLV9002, TINA-TI

Hi Team,

Please review the above schematic attached, I need to confirm if it is good for stereo audio out from the audio jack of laptop.

What should be the connection on a non-inverting pin of OPAMP in case of inverting input?

1. I have fed it the same GND_LP as the audio jack.

2. Two channel inputs (LP_AUDIO_L/LP_AUDIO_R) are the outputs of audio mux TS5A22364-Q1.

3. Before this stage, two audio jacks are giving input to the audio mux.

Second, do this OPAMP need a Low pass filter stage on inverting input? also, review the inverting input RC circuit.

over 2 years ago

0 Jerry Madalvanos over 2 years ago

TI__Mastermind 26981 points

Mohit,

The non-inverting pin should be inside the valid common mode range of the amplifier. I do not know what potential GND_LP is, but it would need to be 2.5V above the GND rail to be within the valid common mode range of RC4580. You can add a voltage divider on the input (similar to the thread linked). Additionally to implement a low pass without adding significant phase lag, please see the following circuit.

You would need a low pass if you expect some sort of high frequency noise.

https://www.ti.com/lit/an/sboa293a/sboa293a.pdf

Best,
Jerry

0 Mohit Goel over 2 years ago in reply to Jerry Madalvanos

Prodigy 70 points

Hi Jerry,

Thanks for reviewing the schematics, the circuit you shared is of dual supply voltage but we are using the single supply voltage. So, do I have to use a voltage source/regulator for a dual supply or is there any solution for a single supply? I am sharing the single supply circuit application from TLV9002 datasheet. Please check and confirm if it can be practical for RC4580 design.

0 Jerry Madalvanos over 2 years ago in reply to Mohit Goel

TI__Mastermind 26981 points

Hey Mohit,

The Cpd in the schematic you reference is a capacitor to model the photodiode capacitance, and not part of the filter. You can use single supply with the RC4580, the circuit I linked was to give you the equations to calculate your cutoff for your low-pass filter.

Best,
Jerry

0 Mohit Goel over 2 years ago in reply to Jerry Madalvanos

Prodigy 70 points

Hey jerry,

Please help me to calculate the equations in my circuit, I dont know the following parameters: input voltage in case of laptop audio jack out, pole frequency, R1,C1 values. I have only supply voltage which is 5V.

0 Caro Walter over 2 years ago in reply to Mohit Goel

TI__Mastermind 18927 points

Hey Mohit,

Jerry is out of office so I will take over this thread.

I suggest to use the following circuit design for the calculations: Single-supply, 2nd-order, multiple feedback low-pass filter circuit
It uses a single 5V supply as in your circuit, Vref may be implemented with a separate IC reference or with a voltage divider, as Jerry suggests:

Jerry Madalvanos said:
You can add a voltage divider on the input (similar to the thread linked)

I also recommend adding decoupling capacitors to the circuit.

Additionally, if you would not like to calculate the design values from the table (as the document suggests), there is also the option of the filter designer on ti.com: https://www.ti.com/design-resources/design-tools-simulation/filter-designer.html

All the best,
Carolina

0 Mohit Goel over 1 year ago in reply to Caro Walter

Prodigy 70 points

Hi Carolina,

Could you please suggest online simulation tool and model for RC4580? So that, I can see output results. I have three circuits of different inputs (audio jack of laptop, HDMI audio, USB codec audio). My question is can I use the same circuit for all three inputs for similar output?

Thanks

0 Jerry Madalvanos over 1 year ago in reply to Mohit Goel

TI__Mastermind 26981 points

Hey Mohit,

We have an encrypted HSPICE model but do not have a simulation model for the RC4580 for TINA-TI or PSpice for TI. There many other automotive audio op amps that do have spice models for your application to verify the application.

https://e2e.ti.com/support/amplifiers-group/amplifiers/f/amplifiers-forum/1126127/faq-choosing-the-right-audio-op-amps-in-context

Here is an FAQ on audio op amp selection.

If you would like to use the RC4580, you can order samples and prototype the solution.

Best,
Jerry

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RC4580-Q1: Schematic Review for stereo audio