MPC5674 Internal temperature sensor gone awary

[ICStedman]

I know there are similar posts but has anyone experienced issues with the internal temperature sensor on the MPC5674 reading too high on recent date codes?

We have experienced issues with devices with dates codes 1634-1707 but the most recent failure was on a date code of 1929. The issue is that the 'calibrated' temperature sensor reads around 15-20C higher than another device, in the same system (at similar ambient). I know it has a +/-10C accuracy but this large a variation has thrown up a few issues here.

[ICStedman]

Hi,

The part number is SPC5674FF3MVV3R and the affected date code is 1929.

Previously we have had issues on part SPC5674FF3MVV3R and date codes, 1634-1707

[davidtosenovjan]

Yes, it is clear to me.

But I wanted to know whether all 3 devices in the presented table are of the SPC5674FF3MVV3R date code 1929?

Could you share the complete part number (all lines printed on the chip)?

[ICStedman]

Awaiting some software expertise to read the calibration constants, then I'll report back. 
Looking at section 33.3 of the MPC5674 reference, for the Temperature formula it has:

Tsens_code(Tlow)=Vtsens(tlow)/Vref0 x 2^14

Below it states, Vref0 is the ADC reference voltage during factory calibration.

Is this a mis-print or is there a Vref0 calibration constant somewhere?

[PetrS]

Hi,

you can refer to below example
https://community.nxp.com/t5/MPC5xxx-Knowledge-Base/Example-MPC5674F-TSENS-Temperature-calc-CW210/ta...

BR, Petr

[PetrS]

Hi,

we have no indication there is similar issue with a recent datecodes, but let me check this.
For that, could you please give summary of the values read from TCCR0/TCCR1 registers and ADC reading of temp sensor and bandgap on "bad" part? And comapring this with some OK part if you have.

Thanks,

BR, Petr

[ICStedman]

Hi,

Sorry for the delay in replying, has taken some time to get the support needed due to current restrictions.

The data requested:

Card	TCCR0	TCCR1	Thigh	Tlow	Vbg	Tsens ADC	Reported value
Good	A3EA9533	CF9EFFFF	145	-45	1.22V	6559	16.78C
Suspect 1	A17192BA	CF9EFFFF	145	-45	1.23V	6296	36.88C
Suspect 2	A3179460	CF9EFFFF	145	-45	1.22V	6582	26.60C

All cards measured on the same rig, within a few minutes of each other. Lab ambient was 23C and 45% humidity. Even the 'good' card is a bit low but I do note the +/-10C accuracy of the sensor.

Any suggestions?

[davidtosenovjan]

Hi, Petr asked me to continue with this thread.

Could you share exact part numbers of this devices including date codes?