TMD3721 datasheet(53/89 Pages) OSRAM

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[v3-00] 2023-May-26

TMD3721 − Register O ver view

CALIB Register (Address 0xD7)

Figure 73:

CALIB Register

Proximity response in systems with electrical and optical

crosstalk may be improved by using the calibration feature.

Optical crosstalk is caused when the photodiode receives a

portion of the VCSEL IR, which was unintentionally reflected by

a surface other than the target. Electrical offset is caused by

electrical disturbance in the sensor AFE, and influences the

proximity result as well. Before starting the calibration, it is

required to set PEN, AEN and PON to 0 to bring the state

machine idle, and set DISABLE_APC to 1 to disable the auto

pulse control. The calibration target, BINSRCH_TARGET, needs

to be configured to a desired value, the calibration routine

adjusts the value in POFFSET /POFFSET_SIGN until the

proximity result is as close to the BINSRCH_TARGET as possible.

The calibration needs to run with the same settings as regular

proximity measurement, such as PPULSE, PPULSE_LEN, PGAIN,

PGAIN2, PLDRIVE0. If PTIME_IN_CALIB is enabled, the same

PTIME used for regular proximity measurement is also enabled

during the calibration. If OFFCAL_ENAB_AVG is enabled, the

hardware averaging as selected with PROX_DATA_AVG is

enabled as well during the calibration. The calibration needs to

run 9 proximity measurement cycles. If every cycle of the 9

cycles needs to be synchronized to the VSYNC signal with PSD

delay, PROX_CAL_VSYNC_EN has to be enabled. After all the

settings properly configured, PON needs to be enabled again

Addr: 0xD7

CALIB

Bit

Bit Name

Default

Access

Bit Description

OFFCAL_ENAB_AVG

Enables proximity hardware averaging as

selected with PROX_DATA_AVG during

calibration.

0 = No hardware averaging

1 = Hardware averaging enabled

Reserved

Reserved. Must be set to default value.

ELECTRICAL_

CALIBRATION

0RW

Selects proximity calibration type.

0 = Electrical and optical crosstalk.

1 = Electrical crosstalk only.

4PTIME_IN_CALIB

Enables PTIME during calibration. Useful when

averaging is enabled.

0 = PTIME ignored during calibration

1 = PTIME enabled during calibration

3:1

Reserved

000

Reserved. Must be set to default value.

START_OFFSET_CAL

Set to 1 to start a calibration sequence.

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