AD7143 datasheet(21/56 Pages) AD

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AD7143

Rev. 0 | Page 21 of 56

NOTES

1. SLOW FILTER EN IS SET AND SW1 IS CLOSED WHEN |STAGE_SF_WORD 0 TO STAGE_SF_WORD 1| EXCEEDS THE VALUE PROGRAMMED IN THE

SLOW_FILTER_UPDATE_LVL REGISTER PROVIDING PROXIMITY IS NOT SET.

2. PROXIMITY 1 IS SET WHEN |STAGE_FF_WORD 0 TO STAGE_FF_WORD 3| EXCEEDS THE VALUE PROGRAMMED IN THE

PROXIMITY_DETECTION_RATE REGISTER.

3. PROXIMITY 2 IS SET WHEN |AVERAGE–AMBIENT| EXCEEDS THE VALUE PROGRAMMED IN THE PROXIMITY_RECAL_LVL REGISTER.

4. DESCRIPTION OF COMPARATOR FUNCTIONS:

COMPARATOR 1: USED TO DETECT WHEN A USER IS APPROACHING OR LEAVING A SENSOR.

COMPARATOR 2: USED TO DETECT WHEN A USER IS HOVERING OVER A SENSOR, OR APPROACHING A SENSOR VERY SLOWLY.

ALSO USED TO DETECT IF THE SENSOR AMBIENT LEVEL HAS CHANGED AS A RESULT OF THE USER INTERACTION.

FOR EXAMPLE, HUMIDITY OR DIRT LEFT BEHIND ON SENSOR.

COMPARATOR 3: USED TO ENABLE THE SLOW FILTER UPDATE RATE. THE SLOW FILTER IS UPDATED WHEN SLOW FILTER EN IS SET AND

PROXIMITY

IS NOT SET.

BANK 3 REGISTERS

SW1

PROXIMITY

SLOW_FILTER_EN

STAGE_SF_WORD0

STAGE_SF_WORD1

STAGE_SF_WORD2

STAGE_SF_WORD3

STAGE_SF_WORD4

STAGE_SF_WORD5

STAGE_SF_WORD6

STAGE_SF_WORD7

STAGE_FF_WORD0

STAGE_FF_WORD1

STAGE_FF_WORD2

STAGE_FF_WORD3

STAGE_FF_WORD4

STAGE_FF_WORD5

STAGE_FF_WORD6

STAGE_FF_WORD7

ΣWORD(N)

= 0

COMPARATOR 3

WORD0 TO WORD1

SLOW_FILTER_UPDATE_LVL

STAGE_SF_AMBIENT

BANK 3 REGISTERS

STAGE_FF_AVG

BANK 3 REGISTERS

CDC

COMPARATOR 1

|WORD0 TO WORD3|

PROXIMITY_DETECTION_RATE

COMPARATOR 2

|AVERAGE–AMBIENT|

PROXIMITY_RECAL_LVL

PROXIMITY 1

PROXIMITY

LP_PROXIMITY_CNT

FP_PROXIMITY_CNT

LP_PROXIMITY_RECAL

FP_PROXIMITY_RECAL

PROXIMITY TIMING

CONTROL LOGIC

TIME

AMBIENT

VALUE

STAGE_SF_WORDx

STAGE_FF_WORDx

SENSOR

CONTACT

Figure 31. AD7143 Proximity Detection and Environmental Calibration

BANK 3 REGISTERS

STAGE_MAX_WORD0

STAGE_MAX_WORD1

STAGE_MAX_WORD2

STAGE_MAX_WORD3

STAGE_MIN_WORD0

STAGE_MIN_WORD1

STAGE_MIN_WORD2

STAGE_MIN_WORD3

STAGE_MAX_AVG

BANK 3 REGISTERS

STAGE_MAX_TEMP

BANK 3 REGISTERS

STAGE_HIGH_THRESHOLD

BANK 3 REGISTERS

STAGE_MIN_AVG

BANK 3 REGISTERS

STAGE_MIN_AVG

BANK 3 REGISTERS

STAGE_LOW_THRESHOLD

BANK 3 REGISTERS

MAX LEVEL

DETECTION

LOGIC

MIN LEVEL

DETECTION

LOGIC

Σ-Δ

16-BIT

CDC

Figure 32. AD7143 Maximum and Minimum Level Detection Logic

AD7143 Datasheet(PDF) 21 Page - Analog Devices

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