AS7058 datasheet(39/199 Pages) AMSOSRAM

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AS7058

Functional description

Datasheet • PUBLIC • Document Feedback

DS001077 • v2-00 • 2025-Sep-24

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Figure 33: Tripple measurement mode – simplified timing diagram

7.5.2.3

Advanced automatic offset compensation (AAOC)

The built in AAOC is an advanced ambient light compensation solution which does not require

an external host to adjust the DAC offset current. In conventional approach with Double

Measurement and Tripple Measurement the DAC offset current registers need to be controlled

and adjusted by a host MCU via I²C or SPI interface. This approach might require several

measurement iterations until an appropriate offset value is found. The AAOC function

eliminates the need of MCU interaction to find the correct photodiode offset current. It is based

on a successive approximation approach to determine the upper 4 bits of the photodiode offset

measurements prior to the actual PPG measurement like it is shown in Figure 34. During each

pre-measurement cycle the LED is also switched on and the ADC data read is feed into the

SAR algorithm which adjusts the photodiode current.

Photodiode Selection

Photodiode Offset Current

LED On

ADC Modulator

ADC Reset

SINC Downsampler

Sample Data LED Off

Sample Data LED OFF

Sample Data LED On

Sample Data LED Off

Sample Data LED OFF

Result Sample Difference

DATA LED OFF/2 + DATA LED

ON – DATA LED OFF/2

PPG

Sequencer

PPG

Sample

PPG

Sample

PPG

Sample

PPG Sample Period

Subsample

PPG Sub-Samples

Tripple PPG Measurement

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