VCNL4000
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Vishay Semiconductors
Rev. 1.8, 10-May-12
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Document Number: 83798
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3.3 Continuous Conversion Mode in Ambient Light Measurement
In the following is a detail description of the function “continuous conversion” (bit 7 of register #4)
Standard mode (bit 7 of reg #4 = 0):
In standard mode the ambient light measurement is done during a fixed time frame of 100 ms. The single measurement itself
takes actually only appr. 300 μs.
The following figures show examples of this measurement timing in standard mode using averaging function 2 and 8 as
examples for illustration (possible values up to 128).
Fig. 15 - Ambient Light Measurement with Averaging = 2;
Final Measurement Result = Average of these 2 Measurements
Fig. 16 - Ambient Light Measurement with Averaging = 8;
Final Measurement Result = Average of these 8 Measurements
Note
• ≥ Independent of setting of averaging the result is available only after 100 ms.
Continuous conversion mode (bit7 of reg #4 = 1):
In continuous conversion mode the single measurements are done directly subsequent after each other.
See following examples in figure 17 and 18
Fig. 17 - Ambient Light Measurement with Averaging = 2;
using Continuous Conversion Mode
Fig. 18 - Ambient Light Measurement with Averaging = 8;
using Continuous Conversion Mode
12.5 ms
Start
100 ms
22316
460 μs
Start
1.5 ms
22317
460 μs
Start
4.2 ms
22318
