Datasheet

AD7142
Rev. A | Page 21 of 72
8
7
N = 0
PROXIMITY_DETECTION_RATE
REGISTER 0x003
PROXIMITY_RECAL_LVL
REGISTER 0x003
BANK 3 REGISTERS
PROXIMITY 2
SLOW_FILTER_UPDATE_LVL
REGISTER 0x003
BANK 3 REGISTERS
SW1
16
NOTES
1. SLOW FILTER EN IS SET AND SW1 IS CLOSED WHEN
|STAGE_SF_
WORD 0–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– 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.
FP_PROXIMITY_RECAL
REGISTER 0x004
LP_PROXIMITY_RECAL
REGISTER 0X004
PROXIMITY
AMBIENT VALUE
STAGE_SF_WORDX
CDC OUTPUT CODE
TIME
SENSOR
CONTACT
STAGE_SF_AMBIENT
BANK 3 REGISTERS
STAGE_FF_AVG
BANK 3 REGISTERS
FP_PROXIMITY_CNT
REGISTER 0x002
LP_PROXIMITY_CNT
REGISTER 0X002
PROXIMITY 1
PROXIMITY TIMING
CONTROL LOGIC
WORD(N)
Σ
05702-021
STAGE_SF_WORD7
STAGE_SF_WORD6
STAGE_SF_WORD5
STAGE_SF_WORD4
STAGE_SF_WORD3
STAGE_SF_WORD2
STAGE_SF_WORD1
STAGE_SF_WORD0
STAGE_FF_WORDX
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.
WORD0 – WORD3
CDC
STAGE_FF_WORD0
STAGE_FF_WORD1
STAGE_FF_WORD2
STAGE_FF_WORD3
STAGE_FF_WORD4
STAGE_FF_WORD5
STAGE_FF_WORD6
STAGE_FF_WORD7
AVERAGE – AMBIENT
PROXIMITY
COMPARATOR 1
COMPARATOR 2
COMPARATOR 2
SLOW_FILTER_EN
WORD0 – WORD3
Figure 32. AD7142 Proximity Detection and Environmental Calibration