Datasheet

ams Datasheet Page 49
[v1-08] 2020-Jun-29 Document Feedback
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