SBAS883A February 2018 – June 2018 OPT3101
PRODUCTION DATA.
In this mode a fixed LED current is used for the Illumination driver. Figure 17 shows the frame timing. Each frame is divided into multiple sub-frames, which can be varied from 1 to 212. Each sub-frame is 10,000 clocks of 40 MHz, which is equal to a 4-kHz sub-frame rate. In each sub-frame, 8192 clocks is the photodiode signal integration time and the remainder of the time is used for processing the signal and computing amplitude and phase. The device can be operated at the highest frame rate of 4 kHz by setting the number of sub-frames to 1 (NUM_SUB_FRAMES = 0) in a frame.
PARAMETER | ADDRESS | DESCRIPTION |
---|---|---|
NUM_SUB_FRAMES | 9Fh[11:0] | Total number of sub-frames in a frame. Each sub-frame is 0.25 ms.
Number of sub frames in a frame = NUM_SUB_FRAMES + 1. This number must be equal or greater than NUM_AVG_SUB_FRAMES. |
NUM_AVG_SUB_FRAMES | 9Fh[23:12] | Specifies the number of sub-frames to be averaged in a frame. Number of averaged sub-frames should be a power of 2
Averaging sub-frames = NUM_AVG_SUB_FRAMES + 1. |
If the number of averaged sub-frames is not a power of 2, the output amplitude AMP_OUT scales according Equation 2. This is only a digital scaling factor and does not affect the distance noise of the measurement. It is recommended to use number of averaged sub-frames as a power of 2.