NXP S32M276CHABMKHSR Structure question

[Ted_Qiao]

Hi NXP technician,

This is Ted from Melecs Wuxi, nice to contact you.

I have one question about the structure of S32M276 IC. ( pls. refer to the attached file: Schematic- S32M276).

I did the design as datasheet recommendation, connect the 9pin-VDD_AE10, 12pin,25pin,37pin-VDD_HV_A together with beads. from my understanding, 9pin-VDD_AE10 P5V output voltage is generated by internal regulator, then supply the MCU-die on VDD_HV_A pin.

But I removed L300, and after that, the PCBA could still working as normal.

So my question is that the VDD_AE10 pin and VDD_HV_A pin are internally connected together?  Otherwise, after removing L300 system still work, which does not make sense..

[danielmartynek]

Hi Ted,

The AE die generates VDD_AE10.
On the AE side, VDD_AE10 is the power supply of the AE ports, all the ports are clamped to VDD_AE10.
On the MCU side, VDD_HV_A is the power supply of the MCU ports, all the ports are clamped to VDD_HV_A.
These two dies are interconnected.

If the input voltage on any MCU port is higher than VDD_HV_A + Vf of the clamp, the VDD_HV_A domain is going to be powered by the injected current. And you should measure VDD_AE10 - Vf on VDD_HV_A - this can damage the device.

Regards,
Daniel

[Ted_Qiao]

Hi Daniel,

Thanks for your reply.

1, So it means that the VDD_AE10 and VDD_HV_A are internally connected?

And I could not understand the meaning of this sentence

[And you should measure VDD_AE10 - Vf on VDD_HV_A - this can damage the device.]

If you could give me some more explanation.

[danielmartynek]

Hi Ted,

When L300 is removed, what voltage do you measure on VDD_HV_A?

The MCU-side power supply domain VDD_HV_A is likely powered through the GPIOs that are shared between the MCU and the AE side, because all GPIOs are clamped to VDD_HV_A. In other words, VDD_HV_A can be powered through any pin if the voltage on that pin is greater than VDD_HV_A. You should therefore measure approximately VDD_HV_A = VDD_AE10 - Vf, not VDD_HV_A = VDD_AE10.

Thank you,

BR, Daniel

[Ted_Qiao]

Hi Daniel,

Thanks for your reply.

When L300 is removed, I measured 4.98V on VDD_HV_A, while VDD_AE10 = 5.02V；

So could I say like that VDD_HV_A and VDD_AE10 are internally connected.

And should connect them together to make low impedance.