TDC1000: Clear Explanation of Autozero

FERNANDO HOOD

Intellectual 310 points

Part Number: TDC1000

Can I have a clear explanation of Autozero. I am not sure exactly what is going on when this is set.

over 5 years ago

0 Bharat Aravamudhan over 5 years ago

TI__Genius 11015 points

Fernando,

Please refer to the sections 8.3.6 Comparators for STOP Pulse Generation in the TDC1000 Datasheet.

The STOP pulse generation block of the TDC1000 contains two auto-zeroed comparators (a zero-cross detect and a threshold-detect comparator), a threshold setting DAC, and an event manager. Comparator auto-zero periods occur at the beginning of every TOF receive cycle. During these periods, the comparator’s input offset is stored in an internal 2.5-pF capacitor, and it is subtracted from the input signal during the echo processing phase. The duration of auto-zero period is configured with the AUTOZERO_PERIOD field located in the CLOCK_RATE register.

0 FERNANDO HOOD over 5 years ago in reply to Bharat Aravamudhan

Intellectual 310 points

Perhaps the datasheet is not clear?

0 FERNANDO HOOD over 5 years ago in reply to FERNANDO HOOD

Intellectual 310 points

Still awaiting a proper explanation.

0 Bharat Aravamudhan over 5 years ago in reply to FERNANDO HOOD

TI__Genius 11015 points

Fernando,

Please let me know which aspect of the auto-zero you need help with. Is it its implementation or usage ?

0 FERNANDO HOOD over 5 years ago in reply to Bharat Aravamudhan

Intellectual 310 points

During these periods, the comparator’s input offset is stored in an internal 2.5-pF capacitor, and it is subtracted from the input signal during the echo processing phase.

What is the effect of the above? Reducing the signal? Making the signal zero for the period?

0 Bharat Aravamudhan over 5 years ago in reply to FERNANDO HOOD

TI__Genius 11015 points

Fernando,

I will respond to your question by Friday this week. Sorry about this delay.

0 FERNANDO HOOD over 5 years ago in reply to Bharat Aravamudhan

Intellectual 310 points

Thanks for the response. Also why is the THLD levels so far apart. If the echo and ringing is less than the steps then it will be challenging to discern the two.

0 Bharat Aravamudhan over 5 years ago in reply to FERNANDO HOOD

TI__Genius 11015 points

Fernando,

Please let me know when are the THLD levels far apart? What is the steps that you point out here ?

Please provide me more about the setup that you have & try to measure the ToF, that can help me point you to the correct explanations for the same.

0 FERNANDO HOOD over 5 years ago in reply to Bharat Aravamudhan

Intellectual 310 points

Level were a side note.. The main question was on autozero which up to now has not been properly explained.

0 Bharat Aravamudhan over 5 years ago in reply to FERNANDO HOOD

TI__Genius 11015 points

Fernando,

Please refer to our FAQ on the Auto-Zero under the section "Auto Zero Period" https://e2e.ti.com/support/sensors/f/1023/t/724028. in detail.

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TDC1000: Clear Explanation of Autozero