S32M276 questions

[Ted_Qiao]

I am working on A sample which used [S32M276] IC. I set 48pin_VDDE for angle sensor. According to Datasheet, the output max current of VDDE is 30mA, and the supply current of angle sensor is 2.5mA max. the VDDE pin could only output 5V when I set the overcurrent detection not working. If I set the overcurrent detection Enable, the VDDE pin will not output 5V. Could you give me some hints about this question?

The relevant circuit is below for reference. What's the coupling capacitor value from your recommendation > there is no recommendation value in the HW design manual. I use 4u7 MLCC in this design.

[Ted_Qiao]

Hi Leo,

Many thanks for your kindly comments. I confirmed with software engineer that he did the set for VDDE following The 78.4.3 VDDE from reference manual, and confirmed that the overcurrent event happened after start-up. Unfortunately, I could not send the whole project schematic due to confidential, but the circuit for VDDE(48-pin) relevant is quite simple as shown before, one 4.7uF MLCC at 48-pin, and 2*100nF MLCC for power supply of angle sensor(TLE5501).

Our software engineer gives me a test-FW to test the inrush current (with 100ms delay to Enable the overcurrent function).

I confirmed that the inrush current at HW level, the VDDE inrush current is 1.03A lasts for 30us.

The local NXP technical supporter told me that VDDE is derive from VDD, if VDD is already filtered, no need to put more MLCC for VDDE.

I checked the datasheet of angle sensor – TLE5501, the 100nF*2 coupling MLCC is recommended, need to be kept.

So I removed the 4.7uF to test again, the result shows that,

1, the over-current flag still set with 100nF*2 status.

2, the inrush current is around, 21.7mA lasts for 20ns.

Below are my questions,

1, What's the coupling capacitor value from your recommendation? Is it possible to remove 4.7uF capacitor nearby 48-pin, and only keep the 2*100nF capacitor for angle sensor?

2, What’s the inrush current threshold of the VDDE output? Does the 21.7mA when at 2*100nF status will lead to a overcurrent event for VDDE? From HW perspectives, the value is not exceed 30mA maximum output value, should be no harm to MCU.

If anything unclear, keep me informed anytime. Thanks and nice day.

Best Regards, Ted

[Ted_Qiao]

I would like to apologize that part of the inrush current data I submitted were incorrect. The correction of inrush current for VDDE is as following:

1, According to the schematic, when the VDDE with an external 4.7uF+100nF*2, the inrush current is around 1.31A lasts for 20us.

2, Removed the 4.7uF, only keep the 100nF*2 coupling MLCC for angle sensor, the inrush current is around 1.06A lasts for 1us.

3, Removed all external MLCC, then the inrush current is around 21.7mA lasts for 20ns.

The inrush current of 1 and 2 is much greater than 30mA(max output current of VDDE), it will trigger overcurrent event. >> So I tested it with the condition that the overcurrent function is activated after 100ms.

and for 3, it is below 30mA, it will not cause overcurrent.

VDDE is derived from VDD, which already has sufficient MLCCs according to design guidelines, So Could I remove the 4.7uF MLCC?

In addition, according to the datasheet of angle sensor, 100nF*2 coupling MLCC shall be fit to its power pin. So question, If I could choose the status 2(100nF*2), Does the 1.06A 1us  inrush current cause damage to the SOC?  If no damage, I could set the overcurrent function delay to activate VDDE overcurrent function.

I just come up to another solution for this topic, the original purpose of using VDDE for angle sensor is for low power mode. The system is required that the ECU Quiescentcurrent should be lower than 100uA. And I confirmed that the S32M276 IC could achieve it in deepsleep mode as below table. I would like to ask if it is possible to switch the angle sensor power supply from VDDE to VDD_AE10 or VDD_HV-A? I am wondering if it will affect the deepsleep current value after changing, and meet the system requirement of 100uA below.

Looking forward to you reply and thank you in advance.

[_Leo_]

Hi again,

For confidential assistance, such as schematic review, please submit a ticket in the following way: -> Support

Regarding the recommended capacitor value for VDDE, it is not stated in AN14116, but it is recommended <1uF to avoid a high current peak.

The Maximum allowed continuous current on VDDE (@ supply = 5 V) is 30mA.

Regarding the Over-current detect threshold, it is 175mA.

On the other hand, VDD_AE10 or VDD_HV_A should not be used for external loads. Instead you can use VDDE.

If the issue persist, please submit a for schematic review.

We hope this resolves your issue.

[Ted_Qiao]

Hi Leo,

Many thanks for your kindly support. I already sent the schematic to you with submit ticket, did you receive it? kind ask you help to review it.

Come back to 48pin-VDDE topic, as said before, I removed 4.7uF MLCC, only keep 100nF*2, then the test result shows that the inrush current is around 1.06A lasts for 1us. Still over 175mA overcurrent detect threshold, and as a result, it will lead to overcurrent event.

*test FW is that the overcurrent function is activated with 100ms delay after VDDE on command.

Although the inrush current energy is very low, I still want to confirm with you that if it will do damage to internal switch of S32M276-IC?

If no influence, I want to make VDDE with external MLCC 100nF*2 as HW solution,

together with FW solution that the overcurrent function is activated with 100ms delay after VDDE on command in the next version.

[Julián_AragónM]

Hi @Ted_Qiao,

Thank you for your patience. Currently, my colleague Leo is on leave, and I will be taking over this case for now. Please find below internal team's feedback:

Suggestion is to try using two 10nF caps instead of 100nF. It is too large to cause a high inrush current; this may be triggering a shutdown. If the sensor device power supply is stable enough, we can remove caps to avoid such large inrush.

In the other hand, you can try to change PMC voltage to 3.3V and see how the inrush is. Means, pre-charge the caps with 3.3V and then change to 5V.

The VDDE overcurrent max threshold is 175mA according to the datasheet, so the 1A is too large.

Best regards,
Julián

[Ted_Qiao]

Many thanks for your kindly reply. I still insist on using 2*100nF MLCC according to the angle sensor datasheet. So does the 1.06A lasts 1us inrush current into VDDE pin will damage the MCU?

[Julián_AragónM]

Hi @Ted_Qiao,

The VDDE overcurrent max threshold is 175mA according to the datasheet, so the 1A is too large. 

Even though this is a very brief pulse, repeated events may stress the internal switch and affect it over long periods, as well as being prone to triggering overcurrent events.

As I've mentioned, recommendation from internal team is to change PMC voltage to 3.3V and see how the inrush is; by pre-charging the caps with 3.3V and then changing to 5V. The data is needed for evaluation.

Best regards,
Julián

[_Leo_]

Schematic received.

Please give me more time to get internal feedback about your questions so that I can give you a proper answer.

We appreciate your patience and understanding.

[_Leo_]

Thank you for your interest in our products and for contributing to our community.

The 78.4.3 VDDE as power supply section of reference manual provide more details about your issue.

Could you please confirm that you have followed such steps?

If the issue persist, please share your project to test it from our side with the S32M27XEVB.

I hope this information is helpful.