at42qt1481 ATMEL Corporation, at42qt1481 Datasheet - Page 69

• Manufacturer Part Number: at42qt1481
• Description: 48-key Qmatrix Ic
• Manufacturer: ATMEL Corporation

Contents
9621B–AT42–06/11
1
2
3
Features ..................................................................................................... 1
Pinout and Schematic ............................................................................. 2
Hardware and Functional ........................................................................ 6
Serial Communications ......................................................................... 20
1.1
1.2
1.3
2.1
2.2
2.3
2.4
2.5
2.6
2.7
2.8
2.9
2.10
2.11
2.12
2.13
2.14
2.15
2.16
2.17
2.18
2.19
3.1
3.2
3.3
3.4
3.5
Pinout Configuration .........................................................................................2
Pin Descriptions ................................................................................................2
Schematic ..........................................................................................................5
Introduction ........................................................................................................6
Matrix Scan Sequence ......................................................................................7
Enabling/Disabling Keys – Burst Paring ............................................................7
Response Time .................................................................................................8
Oscillator ............................................................................................................9
Sample Capacitor; Saturation Effects ................................................................9
Sample Resistors ............................................................................................10
Signal Levels ...................................................................................................11
Matrix Series Resistors ....................................................................................11
Key Design ......................................................................................................13
PCB Layout, Construction ...............................................................................13
Power Supply Considerations .........................................................................14
Startup/Calibration Times ................................................................................14
Reset Input ......................................................................................................15
Detection Integrators .......................................................................................15
Sleep ...............................................................................................................16
FMEA Tests .....................................................................................................16
EN60730 Compliance ......................................................................................17
Frequency Hopping .........................................................................................18
Introduction ......................................................................................................20
DRDY Pin ........................................................................................................20
SPI Communications .......................................................................................21
UART Communications ...................................................................................23
Debug Output Interface ...................................................................................25
2.11.1
2.11.2
2.11.3
Overview .....................................................................................13
LED Traces and Other Switching Signals ...................................13
PCB Cleanliness .........................................................................13
AT42QT1481
69