TPA3251: question about GND Pin

Dr wu

Prodigy 90 points

Part Number: TPA3251

the left side GND pin 12,13 from 12V power source, name the GND to P_GND

the right side GND pin 34,41,42 from 35V power source, name the GND to A_GND

may be has little volts( usually<0.5v, name V1) between P_GND an A_GND when 35V Power source has high loading.

my question is

A: the little V1 will damage the chip?

B: make chip unstable working ?

C: make extra noise?

D: all GND pin is connected in chip internal?

E: will be better sound qulity and better Channel Separation?

any one known it?

thanks!

over 5 years ago

0 Shawn Zheng over 5 years ago

TI__Mastermind 24835 points

Hellp,
We are looking into this and will give you some feedback later. Before that, could you please show us the SCH if possible?
Best regards,
Shawn Zheng

0 Dr wu over 5 years ago in reply to Shawn Zheng

Prodigy 90 points

thanks, I had updated with the simple SCH

0 Dr wu over 5 years ago

Prodigy 90 points

there is nobody know it?

0 Dr wu over 5 years ago in reply to Shawn Zheng

Prodigy 90 points

do you known, all GND Pin is connected together in the chipset ?
or witch is the difference for every GND Pin?

0 Shawn Zheng over 5 years ago in reply to Dr wu

TI__Mastermind 24835 points

Hello,
Justin will help you in this soon later, thanks for your patience!
Best regards,
Shawn Zheng

0 Justin Bohr over 5 years ago in reply to Shawn Zheng

TI__Mastermind 27850 points

Hi Dr Wu,

Sorry about the delay. The GND of the device is one ground, and I would recommend that a single GND plane with well managed return currents for the design. A mismatch in ground potentials could cause decreased performance and if extreme enough the device can shutdown.

We have had a number of cases where the GND pins 12 and 13 did not have a direct enough path to the GND side of the VBG cap, causing the VBG return current to pass through the class D output return currents, causing large noise on the VBG pin. This in turn cause the device to shutdown at high output powers as the analog reference of the entire part was thrown off.

Justin

0 Dr wu over 5 years ago in reply to Justin Bohr

Prodigy 90 points

dear Justin,

thanks for your reply.

I have tested the chip, it has about 4.556Mohms between GND 12,13 and GND 33,34

and GND 25,26,33,34,41,42 had connected together in the chipset internal, because them has near 0 ohms.

it means GND 25,26,33,34,41,42 is one GND, and GND 12,14 is one GND.

the result is, the chip has two real GND.

now, my question is: what's the 4.556Mohms mean? has isolation in the chip between the two GND?

0 Justin Bohr over 5 years ago in reply to Dr wu

TI__Mastermind 27850 points

Hi Dr. Wu,

There is a separation between AGND and PGND with ESD diodes, so the impedance you are seeing is the ESD diodes.

Justin

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TPA3251: question about GND Pin