TMF8701 datasheet(50/66 Pages) AMSCO

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Datasheet, Public

Page 49

[v2-00] 2023-Feb-21

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TMF8701 − Application Information

Reference SPAD, TDC and Histogram

There is an internal reference SPAD with associated TDC and

histogram. This is used to determine the start time of each

pulse. The reference SPAD is processed during calibration. The

reference channel processing occurs internal to the device with

no user interaction required.

All histograms can be processed inside the TMF8701 and/or

readout through the I²C interface. As the readout is constrained

by the I²C speed and the I²C bus utilization (TMF8701 can

support I²C speed up to 1MHz), it is recommended to readout

the histograms only for debugging purposes.

Figure 115 shows a histogram obtained from TMF8701. The

x-axis is scaled in bins, and the nominal bin size is 100ps per bin

and each TDC has 256 bins. The y-axis is scaled in counts

represented by 16 bits values. The green line shows the

reference histogram from TDC0 and its peak marks the

reference or zero distance. The other four lines (blue, cyan, red

and violet) are the histograms obtained from TDC1 to TDC4. A

target at 20cm is used to generate the peak around bin 25.

Figure 115:

Histogram

TMF8701 Datasheet(PDF) 50 Page - ams AG