TMD37253 datasheet(13/56 Pages) OSRAM

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[v2-00] 2023-Mar-21

TMD3725 − Detailed Description

Proximity

Proximity results are affected by three fundamental factors: the

integrated IR LED emission, IR reception, and environmental

factors, including target distance and surface reflectivity.

The IR reception signal path begins with IR detection from a

photodiode and ends with the 8-bit proximity result in PDATA

adjusted to optimize performance. Offset correction or

cross-talk compensation is accomplished by adjustment to the

POFFSET register.

The analog circuitry of the device applies the offset value as a

subtraction to the signal accumulation; therefore a positive

offset value has the effect of decreasing the results.

Color and Ambient Light Sense

The color and ALS reception signal path begins as photodiodes

receive filtered light and ends with 16-bit results. The IR

photodiode primarily used for proximity sense, is multiplexed

with the green channel’s ADC to measure the IR content of

ambient light. The color photodiodes are filtered with a UV and

IR filters. The IR photodiode is filtered to receive only IR. Signal

from the RGBC photodiodes simultaneously accumulate for a

period of time set by the value in ATIME before the results are

available. Measurement of IR must be done in a separate

integration because it shares the ADC with the green

photodiode. Gain is adjustable from 1x to 128x to facilitate

operation over a wide range of lighting conditions. Custom LUX

equations are used to calculate the amount of ambient light,

color temperature, as well as, determine the light type (e.g. LED,

fluorescent, incandescent, etc.) using the ALS results.

I²C Characteristics

The device uses I²C serial communication protocol for

communication. The device supports 7-bit chip addressing and

both standard and fast clock frequency modes with a chip

address of 0x39. Read and Write transactions comply with the

standard set by Philips (now NXP).

Internal to the device, an 8-bit buffer stores the register address

location of the desired byte to read or write. This buffer

auto-increments upon each byte transfer and is retained

between transaction events (i.e. valid even after the master

issues a STOP command and the I²C bus is released).

During consecutive Read transactions, the future/repeated I²C

Read transaction may omit the memory address byte normally

following the chip address byte; the buffer retains the last

Detailed Description

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