AD7147A Analog Devices, AD7147A Datasheet - Page 37

• Manufacturer Part Number: AD7147A
• Manufacturer: Analog Devices

Specifications of AD7147A

• Resolution (bits): 16bit
• # Chan: 13
• Sample Rate: 111SPS
• Interface: I²C/Ser 2-Wire,Ser,SPI
• Analog Input Type: Capacitive
• Ain Range: ± 8 pF (Delta C)
• Adc Architecture: Sigma-Delta
• Pkg Type: CSP

PCB DESIGN GUIDELINES
CAPACITIVE SENSOR BOARD MECHANICAL SPECIFICATIONS
Table 20.
Parameter
Distance from Edge of Any Sensor to Edge of Grounded Metal Object
Distance Between Sensor Edges
Distance Between Bottom of Sensor Board and Controller Board or Grounded
1
2
The distance is dependent on the application and the position of the switches relative to each other and with respect to the user’s finger position and handling.
Adjacent sensors with no space between them are implemented differentially.
The 1.0 mm specification is intended to prevent direct sensor board contact with any conductive material. This specification, however, does not guarantee an absence
of EMI coupling from the controller board to the sensors. To avoid potential EMI-coupling issues, place a grounded metal shield between the capacitive sensor board
and the main controller board, as shown in Figure 57.
Metal Casing
D
1
Figure 55. Capacitive Sensor Board, Top View
CAPACITIVE SENSOR
PRINTED CIRCUIT
SLIDER
2
METAL OBJECT
D
BUTTONS
2
1
SWITCH
8-WAY
D
D
4
3
Rev. B | Page 37 of 68
WLCSP PACKAGE
Nonsolder mask definer PCB fabrication is recommended to
increase the reliability of the solder joint.
The copper pad on the user’s PCB should be 80% of the diameter
of the WLCSP ball. The solder mask opening should be 50 μm
on either side of the copper pad.
See the AN-617 Application Note, MicroCSP™ Wafer Level Chip
Scale Package, for more information and layout guidelines for
the WLCSP package.
D
D
5
5
Figure 57. Capacitive Sensor Board with Grounded Shield
Symbol
D
D
D
1
2
5
CONTROLLER PRINTED CIRCUIT BOARD OR METAL CASING
CONTROLLER PRINTED CIRCUIT BOARD OR METAL CASING
= D
Figure 56. Capacitive Sensor Board, Side View
3
= D
4
CAPACITIVE SENSOR BOARD
CAPACITIVE SENSOR BOARD
GROUNDED METAL SHIELD
Min
0.1
0
Typ
1.0
Max
AD7147A
Unit
mm
mm
mm