Cypress CapSense CY8CMBR2044, Design Manual

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Contents
AN66308 - CY8CMBR2044 CapSense® Design Guide, Doc. No. 001-66308 Rev. *F 4
4.2 ESD Protection .................................................................................................................................................... 31
4.2.1 Prevent ................................................................................................................................................... 31
4.2.2 Redirect .................................................................................................................................................. 31
4.2.3 Clamp ..................................................................................................................................................... 31
4.3 Electromagnetic Compatibility (EMC) Considerations ......................................................................................... 32
4.3.1 Radiated Interference ............................................................................................................................. 32
4.3.2 Conducted Immunity and Emissions ....................................................................................................... 32
4.4 PCB Layout Guidelines ....................................................................................................................................... 32
5. Low-Power Design Considerations ........................................................................................................................... 33
5.1 System Design Recommendations ...................................................................................................................... 33
5.2 Calculating Average Power ................................................................................................................................. 33
5.2.1 Button Scan Rate (T
R
) ............................................................................................................................ 33
5.2.2 Scan Time (T
S
) ....................................................................................................................................... 34
5.2.3 Average Current in NO TOUCH State (I
AVE_NT
) ....................................................................................... 35
5.2.4 Average Current in TOUCH State (I
AVE_T
) ............................................................................................... 35
5.2.5 Average Standalone Current (I
AVE_SA
) ..................................................................................................... 35
5.2.6 Average Current (I
AVE
) ............................................................................................................................ 35
5.2.7 Average Power (P
AVE
) ............................................................................................................................. 36
5.2.8 Example Calculation ............................................................................................................................... 36
5.3 Sleep Modes........................................................................................................................................................ 37
5.3.1 Low-Power Sleep Mode .......................................................................................................................... 37
5.3.2 Deep Sleep Mode ................................................................................................................................... 37
6. Resources .................................................................................................................................................................... 38
6.1 Website ............................................................................................................................................................... 38
6.2 Datasheet ............................................................................................................................................................ 38
6.3 Design Toolbox .................................................................................................................................................... 38
6.4 Multi-Chart ........................................................................................................................................................... 38
6.5 Design Support .................................................................................................................................................... 39
7. Appendix ...................................................................................................................................................................... 40
7.1 Schematic Example ............................................................................................................................................. 40
7.1.1 Schematic 1: Four Buttons with Four GPOs ........................................................................................... 40
7.1.2 Schematic 2: Three Buttons with Advanced Features enabled .............................................................. 42
Acronyms ...................................................................................................................................................................... 43
Glossary ................................................................................................................................................................................ 44
Revision History ................................................................................................................................................................... 50
Document Revision History ........................................................................................................................................... 50