AM5706: Internal connection of VSSA_OSC0(AA12) to SoC

O.H

Part Number: AM5706

Hi experts,

Q1:Is it correct to understand that "VSSA_OSC0" is connected to GND inside the SoC since it is marked "TYPE: GND" on the datasheet?

Q2:If an external crystal is used, is it correct to understand that "VSSA_OSC0" should be connected to GND, although it is not specified in the datasheet?

My customer confirmed that the SoC works without any problem even if "VSSA_OSC0" is left unconnected to GND on the board side. (xo_osc0 and vssa_osc0 are connected.) They are not experiencing any problems, but they would like to know the correct status of the SoC internal connections for their design.

Best regards,
O.H

over 3 years ago

+1 Robert Eschler over 3 years ago

TI__Guru 53015 points

Q1: Yes - VSSA_OSC0 is connected to GND inside the package.

Q2: If external crystal is used, no VSSA_OSC0 should NOT be connected to GND. Connect only to load capacitor(s) for crystal.

From data manual:

0 O.H over 3 years ago in reply to Robert Eschler

Mastermind 6480 points

Hi,

Thank you for your prompt response. I understood about Q1.

Please allow me to confirm one additional point.

Does "VSS_OSC" in "AM57x Schematic Checklist (Rev. B)" not apply to "VSSA_OSCx"?

Best regards,
O.H

+1 Robert Eschler over 3 years ago in reply to O.H

TI__Guru 53015 points

The checklist is not correct. The crystal load capacitors should connect to VSS_OSC and not system GND. As previously mention, the GND connection is internal. This topology will help reduce the noise on the crystal inputs. Connecting the VSS_OSC to GND externally may slightly increase the noise - which may or may not affect anything. The recommendation is to NOT connect VSS_OSC to GND.

0 O.H over 3 years ago in reply to Robert Eschler

Mastermind 6480 points

Hi,

I understood. Thank you for your kind support!

Best regards,
O.H

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AM5706: Internal connection of VSSA_OSC0(AA12) to SoC