SX8644I05AWLTRT Semtech, SX8644I05AWLTRT Datasheet - Page 32

• Manufacturer Part Number: SX8644I05AWLTRT
• Description: 12-ch Capacitive Touch Solution (Button & Slider)
• Manufacturer: Semtech

SX8644
Ultra Low Power, Capacitive Button and Slider
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 SX8644, 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 35 shows the simplified diagram of the CAP0, CAP1, ..., CAP11 pins.
SX8644
VANA
sensor
CAPx
ASI
CAP_INx
Note : x = 0, 1,2,…11
Simplified diagram of CAP0, CAP1, ..., CAP11
Figure 35
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 SX8644.
The CN and CP are protected to VANA and GROUND.
Figure 36 shows the simplified diagram of the CN and CP pins.
Revision 7_3, January 10
© 2009 Semtech Corp.
www.semtech.com
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