What is the TLE9879QTW40 maximum count frequency for all the counters/timers? Also, what happens at 177C?

[InfiCat]

Hello,

From the datasheet, Timers 12, 13: " maximum count frequency = peripheral clock"

About other timers I only find some "resolution" also expressed as a fraction of "Fpclk" which I don't understand.

Also, I couldn't find what the possible "Fpclk" range is.

I need to count 3 external frequencies (in fact two, gated or clocked by third) up to 8MHz.  I can't tell from the datasheet.

The other question is about 177C: Some places 350F is the "rounded" number to aim for, which is 177C. Will this shut-down at 175?

Thanks,

Cat

[RupakC]

Hi @InfiCat 

Thank you for posting on Infineon Community.

The TLE9879 has several timers:
GPT1: it has a maximum resolution of fGPT/4.   GPT2 : Maximum resolution of fGPT/2
where fGPT is derived from PCLK
Timer 2 and Timer 21: As timers they count with an input clock of fPCLK/12
How to set the prescalers for the different timers is already present in the document.
For example, T2PRE bits in T2MOD can be used to configure timer2.
000=fPCLK
001=fPCLK/2
010=fPCLK/4
011=fPCLK/8
100=fPCLK/16
101=fPCLK/32
110=fPCLK/64
111=fPCLK/128
fPCLK is the input clock frequency and it can be maximum 40MHz.
you may look into the document to know how to set the remaining timers.

In the datasheet below, in page 87, under absolute maximum ratings, it is mentioned that the
maximum junction temperature is 175 degrees, while storage temperature maximum is 150 degrees.

https://www.infineon.com/dgdl/Infineon-TLE9879QTW40-DataSheet-v01_00-EN.pdf?fileId=5546d46274dd77260...

please note that these are absolute maximum ratings only. For functional range,
you should look at page 89 of the document. Beyond 150 degrees, the device runs in extended temperature range.
It should be noted that the device is not subjected to production test in extended temperature region and is specified by design.
Many parameters change their values when the device is run in extended temperature region and this is provided in datasheet.

I hope the above information will help you to resolve your doubts.

Thanks and Regards

[InfiCat]

Thank you @RupakC

Maybe I don't know how to ask, but I feel like I am very little closer to the answers, so I'll try again:

1. I need to measure EXTERNAL frequencies so internal prescalers have no relevance, only Max External frequency that can be counted.

2. I wish you'd point me to the lines/page that state that Max fPCLK = 40MHz; I tried to find it and I'm not sure it's that.

3. I explained that I don't understand the meaning of "resolution" when we talk about a counter (and it's not the number of bits). What is it and how does it limit counting frequency.

4. About temperature, I would like to know how accurate the Overtemperature detector is, and what is the  actual trip temperature (seems it goes to sleep?) if it's supposed to work up to 175C? Is it 176C? 180C?

[RupakC]

Hello @InfiCat 

1. For external frequencies, you may set a GPIO in input mode and read its status to know of the external frequency. The speed of this operation is limited by the internal clock speed of the device. 

2. Page 103 of the following document mentions that PCLK has a maximum frequency of 40MHz
https://www.infineon.com/dgdl/Infineon-TLE987x-UserManual-v01_60-EN.pdf?fileId=5546d4624e24005f014e5...

3. If you have a 16 bit counter, it can count from 0 to 65535. You can count any magnitude of time with these many counts. Resolution is a measure of how much is the time value of each of the counts of the counter.  Therefore, it is clear that for counting larger values of time, a counter with more bits will be preferable since more bits means more total counts. Hence, the resolution of the counter will improve. 
If you have a counter with low (or poor) resolution,  you will have larger steps in which you can measure the time. Hence you cannot count very small magnitudes of time in that case.
I hope I was able to provide you with some idea about the resolution of a counter.

4. The maximum junction temperature Tj_max of the device is 175 degrees. In case of overtemperature (Tj > Tj_max ) the system will be set to Sleep Mode. In the Sleep Mode, the supply to the whole MCU subsystem including the ADC, PLL and NVM is removed. The wake-up detection circuitry remains supplied. Only contents of non-volatile memory are retained.
The user can also activate the system overtemperature power stage disable. In activated, in case of overtemperature, the charge pump and bridge driver is automatically shutdown. 

I hope the above discussion will help to clear some of your doubts.  In case of any further queries, I will be happy to help you. 

Thanks and Regards

[InfiCat · Accepted solution]

Although I'm still waiting for some answers, I got some clarifications from support, so I thought I'd clarify some things here:

1. I know HOW to measure external frequency, what I was asking is what is the maximum external frequency that can be measured by this device.  Now I know it is 10MHz (Table 103, TLE987x User Manual).  I don't know why nobody would just state that, pointing to the table.

2. Thank you for pointing to that document; it's much better than the datasheet I was looking at.

3. It is not correct to state the resolution of a counter is a frequency. It is a mistake. Counter resolution can be expressed in Time, as 1ms if a counter runs at 1KHz. You could also make a case for the number of bits together with the frequency, but NOT a frequency alone. 10MHz is NOT resolution.

4. It seems you don't understand that I'm interested in the REAL temperature that will trigger the overtemperature sleep.  The support gentleman that helped, pointed me to Table 36 of the datasheet that somehow resulted in "overtemperature threshold is nominally 203°C" but it's not clear to me how.  I see that value in Table 175 of the User Manual but it's still not quite clear to me what it means ("post-processing default settings").  But it is pretty clear to me that the chip will NOT go to sleep at 175C or 177C because of overtemperature.