TMF8801 datasheet(61/73 Pages) OSRAM

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TMF8801

Application Information

Datasheet

• PUBLIC

DS000648

• v10-00 • 2022-Dec-20

│ 60

9.2

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 TMF8801 and/or readout through the I²C interface. As the

readout is constrained by the I²C speed and the I²C bus utilization (TMF8801 can support I²C speed

up to 1 MHz), it is recommended to readout the histograms only for debugging purposes.

Figure 119 shows a histogram obtained from TMF8801. The x-axis is scaled in bins, where the

nominal bin size is 200 ps per bin and each TDC channel has 128 bins.

Each TDC has two channels: The first channel is shown in bins 0…127, the second channel is shown

in bins 128…255.

The y-axis is scaled in counts represented by 16-bit 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 20 cm is used to

generate the peak around bin 20 respectively bin 148.

Figure 119:

Histogram

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