sx8643 Semtech Corporation, sx8643 Datasheet - Page 30

• Manufacturer Part Number: sx8643
• Description: Ultra Low Power, Capacitive Button Touch Controller 12 Sensors With Enhanced Led Drivers
• Manufacturer: Semtech Corporation

SX8643
Ultra Low Power, Capacitive Button Touch Controller
(12 sensors) with Enhanced LED Drivers
ADVANCED COMMUNICATIONS & SENSING
DATASHEET
4 P
IN DESCRIPTIONS
4.1 Introduction
This chapter describes briefly the pins of the SX8643, the way the pins are protected, if the pins are analog,
digital, require pull up or pull down resistors and show control signals if these are available.
4.2 ASI pins
CAP0, CAP1, ..., CAP11
The capacitance sensor pins (CAP0, CAP1, ..., CAP11) are connected directly to the ASI circuitry which converts
the sensed capacitance into digital values.
The capacitance sensor pins which are not used should be left open.
The enabled CAP pins need be connected directly to the sensors without significant resistance (typical below
some ohms, connection vias are allowed).
The capacitance sensor pins are protected to VANA and GROUND.
Figure 30 shows the simplified diagram of the CAP0, CAP1, ..., CAP11 pins.
SX8643
VANA
sensor
CAPx
ASI
CAP_INx
Note : x = 0, 1,2,…11
Simplified diagram of CAP0, CAP1, ..., CAP11
Figure 30
CN, CP
The CN and the CP pins are connected to the ASI circuitry. A 1nF sampling capacitor between CP and CN needs
to be placed as close as possible to the SX8643.
The CN and CP are protected to VANA and GROUND.
Figure 31 shows the simplified diagram of the CN and CP pins.
Revision 7_5, February 10
© 2010 Semtech Corp.
www.semtech.com
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