AD7142 Analog Devices, AD7142 Datasheet - Page 21

• Manufacturer Part Number: AD7142
• Description: Programmable Controller for Capacitance Touch Sensors
• Manufacturer: Analog Devices

Specifications of AD7142

• Resolution (bits): 16bit
• # Chan: 14
• Sample Rate: 250kSPS
• Interface: I²C/Ser 2-Wire,Ser,SPI
• Analog Input Type: Diff-Uni
• Ain Range: ± 2 pF (Delta C)
• Adc Architecture: Sigma-Delta
• Pkg Type: CSP

SLOW_FILTER_EN
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
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:
PROVIDING PROXIMITY IS NOT SET.
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.
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.
PROXIMITY
SLOW_FILTER_UPDATE_LVL
CDC
WORD0 – WORD3
REGISTER 0x003
COMPARATOR 2
16
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.
STAGE_FF_WORD0
STAGE_FF_WORD1
STAGE_FF_WORD2
STAGE_FF_WORD3
STAGE_FF_WORD4
STAGE_FF_WORD5
STAGE_FF_WORD6
STAGE_FF_WORD7
Σ
N = 0
7
STAGE_SF_WORD0
STAGE_SF_WORD1
STAGE_SF_WORD2
STAGE_SF_WORD3
STAGE_SF_WORD4
STAGE_SF_WORD5
STAGE_SF_WORD6
STAGE_SF_WORD7
WORD(N)
BANK 3 REGISTERS
8
BANK 3 REGISTERS
Figure 32. AD7142 Proximity Detection and Environmental Calibration
SW1
BANK 3 REGISTERS
PROXIMITY_DETECTION_RATE
STAGE_FF_AVG
WORD0 – WORD3
REGISTER 0x003
COMPARATOR 1
STAGE_SF_AMBIENT
BANK 3 REGISTERS
Rev. A | Page 21 of 72
PROXIMITY_RECAL_LVL
AVERAGE – AMBIENT
COMPARATOR 2
REGISTER 0x003
PROXIMITY 1
FP_PROXIMITY_RECAL
FP_PROXIMITY_CNT
PROXIMITY
REGISTER 0x002
REGISTER 0x004
STAGE_SF_WORDX
STAGE_FF_WORDX
PROXIMITY TIMING
CONTROL LOGIC
LP_PROXIMITY_RECAL
LP_PROXIMITY_CNT
CONTACT
SENSOR
REGISTER 0X002
REGISTER 0X004
AMBIENT VALUE
AD7142
TIME