TLV320AIC3100: TLV320AIC3100

Bruce Doan

Part Number: TLV320AIC3100
Other Parts Discussed in Thread: TLV9162,

Tool/software:

The datasheet for the AIC3100 suggests sending differenmtial audio to the device.

Without increasing component count, would it be better to use 1/2 of the TLC9162 as a buffer for Vcc/2 or as an inverter to be able to send differential audio?

The distance from the analog preamp to the AIC3100 is only 3 inches and the (single ended) audio is being routed near the board edge, surrounded by ground plane.

Also, I am looking for recommendations on improving the pcb layout of this device.

I am using 4 layers with a ground plane on layer 2 and power planes on layer 3

Is it really necessary to split the ground plane?

11 months ago

0 Garret Godfrey 11 months ago

TI__Mastermind 22146 points

Hi Bruce,

It's likely better to use the TLV9162 as an inverter for the differential audio.

It's also not really necessary to split the ground plane, as this is not the recommended method anymore. See the following thread for suggestions on routing these signals to achieve separation without separate ground planes: https://e2e.ti.com/support/audio-group/audio/f/audio-forum/887125/tlv320aic3106-tlv320aic3106-digital-ground-vs-analog-ground/3280115

Best,

Garret

0 Bruce Doan 11 months ago in reply to Garret Godfrey

Prodigy 210 points

Thanks for the rapid response.

my design is committed to the following layer stack:

top- signal

layer2 - ground plane

layer3 - power plane (several power bus pours)

bottom layer- signal

I have made every effort to physically distance digital and analog circuits.

The entire design works well (no noise) with the old AIC24 codec and a separate class D power amp.

The AIC3100 design has no audible noise but an unexceptionable level of (some signal) noise visible on the input of the I2S DSP

The layout example shown here

https://www.ti.com/lit/ug/slau209a/slau209a.pdf

is confusing

0 Garret Godfrey 11 months ago in reply to Bruce Doan

TI__Mastermind 22146 points

Hi Bruce,

Unfortunately that is the only layout reference we have. Here is an app note for Common Noise Issues in Audio Codecs, although it does suggest separate ground planes.

Best,

Garret

0 Bruce Doan 11 months ago in reply to Garret Godfrey

Prodigy 210 points

Regarding my input buffer, it is just a high impedance input (1 medium) unity gain buffer.

So the impedance feeding the codec input is low (maybe 100ohms).

if my voltage divider (vcc/2) is not buffered, will I see a lot more noise ?

The buffer was providing a low impedance reference to the 1.8meg biasing resistor for (+) input.

0 Jeff McPherson 11 months ago in reply to Bruce Doan

TI__Guru 51170 points

Hi Bruce,

I think the extra fidelity you get with a differential signal is a bigger benefit than any noise introduced by a non-buffered bias. As long as the bias supply is relatively clean (good decoupling, low noise regulator, etc)

Best regards,
Jeff McPherson

0 Bruce Doan 11 months ago in reply to Jeff McPherson

Prodigy 210 points

The supply is a buck regulator that is isolated from the input amp by a ferrite bead and decoupled. My Vcc/2 would be just resistive divider again decoupled but I would be loosing the unity gain buffer on that vcc/2 node.

0 Garret Godfrey 11 months ago in reply to Bruce Doan

TI__Mastermind 22146 points

Hi Bruce,

It would be fine to keep the buffer and just send single-ended audio to the device if that is your preference. However, the differential signals are better at common noise rejection and should be a viable solution given a clean supply as Jeff mentioned.

Best,

Garret

0 Bruce Doan 10 months ago in reply to Garret Godfrey

Prodigy 210 points

Would this be the proper configuration for differential input?

0 Garret Godfrey 10 months ago in reply to Bruce Doan

TI__Mastermind 22146 points

Hi Bruce,

Yes looks good.

Best,

Garret

0 Bruce Doan 10 months ago in reply to Garret Godfrey

Prodigy 210 points

I am at the point of revising the pcb layout for this device.

You previously mentioned that the guidelines in the datasheet and evaluation board guide are the only layout information that you have.

Is there any possibility to glean "sucessful" layout examples from some users of this device?

0 Garret Godfrey 10 months ago in reply to Bruce Doan

TI__Mastermind 22146 points

Hi Bruce,

Unfortunately most, if not all, of these layouts are restricted so I am unable to share. My best suggestion would be to look up "TLV320AIC3100 layout" (or even just "layout") in the E2E search bar to find general recommendations our engineers have made on this device and others from the same family over the years.

Best,

Garret