Information

Texas Instruments Signal Chain Guide 2013 | 139
Interface
General – I
2
C
Enhanced I
2
C Controlled Keypad Scan IC
TCA8418E
The TCA8418E is an enhanced keypad scan device. It can operate from 1.65 V to
3.6 V and has 18 general-purpose inputs/outputs (GPIO) that can be used to support
up to 80 keys via the I
2
C interface [serial clock [SCL], serial data [SDA]).
The key controller includes an oscillator that debounces at 50 ms and maintains a
10 byte FIFO of key-press and release events that can store up to 10 keys with overflow
wrap capability
. An interrupt (INT) output can be configured to alert key presses and
releases either as they occur or at maximum rate. Also, for the YFP package, a
CAD_INT pin is included to indicate the detection of CTRL-ALT-DEL (i.e., 1, 11, 21)
key-press action.
TCA8418E functional block diagram
Key Features
• Operatingpower-supplyvoltagerange
of 1.65 V to 3.6 V
• SupportsQWERTYkeypadoperation
plus GPIO expansion
• 18GPIOscanbeconfiguredintoeight
inputs and ten outputs to support an
8- to 10- keypad array (80 buttons)
•
15-kVhumanbodymodelESD
protection on GPIO lines
•
Lowstandby(idle)current
consumption: 3 mA
•
Pollingcurrentdrain70mAfor
one key pressed
•
10-byteFIFOtostore10key
presses and releases
•
Verysmallpackage:WCSP(YFP):
2 mm x 2 mm; 0.4 mm pitch
Applications
• Smartphones
• PDAs
• GPSdevices
• MP3players
• Digitalcameras
Get more information: www.ti.com/product/TCA8418E
CPU/MCU
1
2
C Master
V
CC
SDA
P0
P1
P2
P3
P4
P5
P6
P7
P8
P9
P10
P11
P12
P13
General Purpose
I/O for Hot Key
Inputs
SCL
IRQ
RESET