Datasheet CAP1296 Datasheet
6-Channel Capacitive Touch Sensor with
SMBus
Protocol
VDD
GND
Capacitive Touch Sensing
Algorithm
CS1 CS2 CS4 CS5
SMCLK
SMDATA
ALERT#
CS6
CS3 /
SG
Proximity Detection & Signal Guard
CAP1296
PRODUCT FEATURES
General Description
The CAP1296 which incorporates RightTouch® technology,
is a multiple channel capacitive touch sensor. It contains six
(6) individual capacitive touch sensor inputs with
programmable sensitivity for use in touch sensor
applications. Each sensor input is calibrated to compensate
for system parasitic capacitance and automatically
recalibrated to compensate for gradual environmental
changes.
In addition, the CAP1296 can be configured to detect
proximity on one or more channels with an optional signal
guard to reduce noise sensitivity and to isolate the proximity
antenna from nearby conductive surfaces that would
otherwise attenuate the e-field.
The CAP1296 includes Multiple Pattern Touch recognition
that allows the user to select a specific set of buttons to be
touched simultaneously. If this pattern is detected, a status
bit is set and an interrupt is generated.
The CAP1296 has Active and Standby states, each with its
own sensor input configuration controls. The Combo state
allows a combination of sensor input controls to be used
which enables one or more sensor inputs to operate as
buttons while another sensor input is operating as a
proximity detector. Power consumption in the Standby and
Combo states is dependent on the number of sensor inputs
enabled as well as averaging, sampling time, and cycle
time. Deep Sleep is the lowest power state available,
drawing 5µA (typical) of current. In this state, no sensor
inputs are active, and communications will wake the device.
Datasheet
Applications
Desktop and Notebook PCs
LCD Monitors
Consumer Electronics
Appliances
Features
Six (6) Capacitive Touch Sensor Inputs
— Programmable sensitivity
— Automatic recalibration
— Calibrates for parasitic capacitance
— Individual thresholds for each button
Proximity Detection
Signal Guard
— Isolates the proximity antenna from attenuation
— Reduces system noise sensitivity effects on inputs
Mu ltiple Button Pattern Detection
Power Button Support
Press and Hold Feature for Volume-like Applications
3.3V or 5V Supply
Analog Filtering for System Noise Sources
RF Detection and Avoidance Filters
Digital EMI Blocker
8kV ESD Rating on All Pins (HBM)
Low Power Operation
— 5µA quiescent current in Deep Sleep
— 50µA quiescent current in Standby (1 sensor input
monitored)
— Samples one or more channels in Standby
SMBus / I
Available in a 10-pin 3mm x 3mm DFN RoHS compliant
package
2
C Compliant Communication Interface
Block Diagram
2013 Microchip Technology Inc. DS01569A-page 1
6-Channel Capacitive Touch Sensor with Proximity Detection & Signal Guard
Ordering Information:
ORDERING
NUMBER PACKAGE FEATURES
Datasheet
CAP1296-1-AIA-TR 10-pin DFN 3mm x 3mm
(RoHS compliant)
Reel size is 4,000 pieces for 10-pin DFN
This product meets the halogen maximum concentration values per IEC 61249-2-21
Six capacitive touch sensor inputs, SMBus interface,
SMBus address 0101_000(r/w). Proximity and signal
guard.
DS01569A-page 2 2013 Microchip Technology Inc.
6-Channel Capacitive Touch Sensor with Proximity Detection & Signal Guard
Datasheet
Table of Contents
Chapter 1 Pin Description. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
Chapter 2 Electrical Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
Chapter 3 Communications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
3.1 Communications. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
3.2 System Management Bus. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
3.2.1 SMBus Start Bit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
3.2.2 SMBus Address and RD / WR
3.2.3 SMBus Data Bytes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
3.2.4 SMBus ACK and NACK Bits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
3.2.5 SMBus Stop Bit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
3.2.6 SMBus Timeout. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
3.2.7 SMBus and I
3.3 SMBus Protocols . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
3.3.1 SMBus Write Byte . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
3.3.2 SMBus Read Byte . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
3.3.3 SMBus Send Byte . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
3.3.4 SMBus Receive Byte. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
3.4 I
2
C Protocols. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
3.4.1 Block Read . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
3.4.2 Block Write . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
2
C Compatibility . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
Bit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
Chapter 4 General Description. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
4.1 Power States . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
4.2 Reset . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
4.3 Capacitive Touch Sensing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
4.3.1 Capacitive Touch Sensing Settings. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
4.3.1.1 Active State Sensing Settings........................................................................................20
4.3.1.2 Standby State Sensing Settings .......................................... ... .... ... ................................20
4.3.1.3 Combo State Sensing Settings......................................................................................21
4.3.2 Sensing Cycle . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
4.4 Sensor Input Calibration. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
4.4.1 Automatic Recalibration. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
4.4.2 Negative Delta Count Recalibration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
4.4.3 Delayed Recalibration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
4.5 Proximity Detection. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
4.5.1 Signal Guard . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
4.6 Power Button . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
4.7 Multiple Touch Pattern Detection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
4.8 Noise Controls . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
4.8.1 Low Frequency Noise Detection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
4.8.2 RF Noise Detection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
4.8.3 Noise Status and Configuration. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
4.9 Interrupts. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
4.9.1 ALERT# Pin. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
4.9.2 Capacitive Sensor Input Interrupt Behavior. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
4.9.3 Interrupts for the Power Button . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
4.9.4 Interrupts for Multiple Touch Pattern Detection. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
4.9.5 Interrupts for Sensor Input Calibration Failures. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
2013 Microchip Technology Inc. DS01569A-page 3
6-Channel Capacitive Touch Sensor with Proximity Detection & Signal Guard
Datasheet
Chapter 5 Register Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
5.1 Main Control Register. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
5.2 Status Registers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
5.2.1 General Status - 02h . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
5.2.2 Sensor Input Status - 03h . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
5.3 Noise Flag Status Registers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
5.4 Sensor Input Delta Count Registers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
5.5 Sensitivity Control Register. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
5.6 Configuration Registers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36
5.6.1 Configuration - 20h . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36
5.6.2 Configuration 2 - 44h. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37
5.7 Sensor Input Enable Register. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38
5.8 Sensor Input Configuration Register. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38
5.9 Sensor Input Configuration 2 Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40
5.10 Averaging and Sampling Configuration Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41
5.11 Calibration Activate and Status Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42
5.12 Interrupt Enable Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43
5.13 Repeat Rate Enable Register. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44
5.14 Signal Guard Enable Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45
5.15 Multiple Touch Configuration Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45
5.16 Multiple Touch Pattern Configuration Register. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46
5.17 Multiple Touch Pattern Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47
5.18 Base Count Out of Limit Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48
5.19 Recalibration Configuration Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48
5.20 Sensor Input Threshold Registers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50
5.21 Sensor Input Noise Threshold Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51
5.22 Standby Channel Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51
5.23 Standby Configuration Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52
5.24 Standby Sensitivity Register. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54
5.25 Standby Threshold Register. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54
5.26 Sensor Input Base Count Registers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55
5.27 Power Button Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55
5.28 Power Button Configuration Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56
5.29 Sensor Input Calibration Registers. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57
5.30 Calibration Sensitivity Configuration Registers. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58
5.31 Product ID Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58
5.32 Manufacturer ID Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58
5.33 Revision Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59
Chapter 6 Package Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 60
6.1 CAP1296 Package Drawings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 60
6.2 Package Marking . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 64
Appendix ADevice Delta . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 65
A.1 Delta from CAP1106-1 to CAP1296-1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 65
Revision History. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 67
DS01569A-page 4 2013 Microchip Technology Inc.
6-Channel Capacitive Touch Sensor with Proximity Detection & Signal Guard
Datasheet
List of Figures
Figure 1.1 CAP1296-1 Pin Diagram (10-Pin 3 x 3 mm DFN) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
Figure 3.1 SMBus Timing Diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
Figure 4.1 System Diagram for CAP1296 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
Figure 4.2 POR and PORR With Slow Rising V
Figure 4.3 Signal Guard. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
Figure 4.4 Sensor Interrupt Behavior - Repeat Rate Enabled. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
Figure 4.5 Sensor Interrupt Behavior - No Repeat Rate Enabled . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
Figure 6.1 CAP1296 Package Drawing - 10-Pin DFN 3mm x 3mm . . . . . . . . . . . . . . . . . . . . . . . . . . 60
Figure 6.2 CAP1296 Package Dimensions - 10-Pin DFN 3mm x 3mm. . . . . . . . . . . . . . . . . . . . . . . . 61
Figure 6.3 CAP1296 PCB Land Pattern and Stencil - 10-Pin DFN 3mm x 3mm. . . . . . . . . . . . . . . . . 61
Figure 6.4 CAP1296 PCB Detail A - 10-Pin DFN 3mm x 3mm . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 62
Figure 6.5 CAP1296 PCB Detail B - 10-Pin DFN 3mm x 3mm . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 63
Figure 6.6 CAP1296 Land Dimensions - 10-Pin DFN 3mm x 3mm. . . . . . . . . . . . . . . . . . . . . . . . . . . 63
Figure 6.7 CAP1296-1 Package Marking . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 64
and BOR with Falling V
DD
DD . . . . . . . . . . . . . . . . . . . . . . . 20
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6-Channel Capacitive Touch Sensor with Proximity Detection & Signal Guard
Datasheet
List of Tables
Table 1.1 Pin Description for CAP1296 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
Table 1.2 Pin Types . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
Table 2.1 Absolute Maximum Ratings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
Table 2.2 Electrical Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
Table 3.1 Protocol Format . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
Table 3.2 Write Byte Protocol. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
Table 3.3 Read Byte Protocol. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
Table 3.4 Send Byte Protocol. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
Table 3.5 Receive Byte Protocol. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
Table 3.6 Block Read Protocol . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
Table 3.7 Block Write Protocol . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
Table 4.1 Ideal Base Counts. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
Table 5.1 Register Set in Hexadecimal Order . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
Table 5.2 Main Control Register. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
Table 5.3 Power State Bit Overrides. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
Table 5.4 GAIN and C_GAIN Bit Decode. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
Table 5.5 Status Registers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
Table 5.6 Noise Flag Status Registers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
Table 5.7 Sensor Input Delta Count Registers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
Table 5.8 Sensitivity Control Register. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
Table 5.9 DELTA_SENSE Bit Decode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
Table 5.10 BASE_SHIFT Bit Decode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
Table 5.11 Configuration Registers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36
Table 5.12 Sensor Input Enable Register. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38
Table 5.13 Sensor Input Configuration Register. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38
Table 5.14 MAX_DUR Bit Decode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38
Table 5.15 RPT_RATE Bit Decode. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39
Table 5.16 Sensor Input Configuration 2 Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40
Table 5.17 M_PRESS Bit Decode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40
Table 5.18 Averaging and Sampling Configuration Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41
Table 5.19 AVG Bit Decode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41
Table 5.20 SAMP_TIME Bit Decode. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42
Table 5.21 CYCLE_TIME Bit Decode. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42
Table 5.22 Calibration Activate and Status Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42
Table 5.23 Interrupt Enable Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43
Table 5.24 Repeat Rate Enable Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44
Table 5.25 Signal Guard Enable Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45
Table 5.26 Multiple Touch Configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45
Table 5.27 B_MULT_T Bit Decode. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46
Table 5.28 Multiple Touch Pattern Configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46
Table 5.29 MTP_TH Bit Decode. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47
Table 5.30 Multiple Touch Pattern Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47
Table 5.31 Base Count Out of Limit Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48
Table 5.32 Recalibration Configuration Registers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48
Table 5.33 NEG_DELTA_CNT Bit Decode. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49
Table 5.34 CAL_CFG Bit Decode. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50
Table 5.35 Sensor Input Threshold Registers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50
Table 5.36 Sensor Input Noise Threshold Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51
Table 5.37 CSx_BN_TH Bit Decode. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51
Table 5.38 Standby Channel Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51
Table 5.39 Standby Configuration Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52
Table 5.40 STBY_AVG Bit Decode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52
DS01569A-page 6 2013 Microchip Technology Inc.
6-Channel Capacitive Touch Sensor with Proximity Detection & Signal Guard
Datasheet
Table 5.41 STBY_SAMP_TIME Bit Decode. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53
Table 5.42 STBY_CY_TIME Bit Decode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53
Table 5.43 Standby Sensitivity Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54
Table 5.44 STBY_SENSE Bit Decode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54
Table 5.45 Standby Threshold Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54
Table 5.46 Sensor Input Base Count Registers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55
Table 5.47 Power Button Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55
Table 5.48 PWR_BTN Bit Decode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56
Table 5.49 Power Button Configuration Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56
Table 5.50 Power Button Time Bits Decode. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57
Table 5.51 Sensor Input Calibration Registers. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57
Table 5.52 Calibration Sensitivity Configuration Registers. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58
Table 5.53 CALSENX Bit Decode. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58
Table 5.54 Product ID Register. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58
Table 5.55 Vendor ID Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58
Table 5.56 Revision Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59
Table A.1 Register Delta. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 65
Table 6.1 Revision History . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 67
2013 Microchip Technology Inc. DS01569A-page 7
6-Channel Capacitive Touch Sensor with Proximity Detection & Signal Guard
CS3 / SG
CS2
1
2
3
4
5
CS4
CS1
ALERT#
SMDATA
VDD
SMCLK CS5
CS6
GND
10
9
8
7
6
Chapter 1 Pin Description
Figure 1.1 CAP1296-1 Pin Diagram (10-Pin 3 x 3 mm DFN)
Datasheet
Table 1.1 Pin Description for CAP1296
PIN # PIN NAME PIN FUNCTION PIN TYPE
1 CS1 Capacitive Touch Sensor Input 1 AIO
2ALERT#
3SMDATA
4SMCLK
5 VDD Positive Power supply Power n/a
6 CS6 Capacitive Touch Sensor Input 6 AIO
7 CS5 Capacitive Touch Sensor Input 5 AIO
8 CS4 Capacitive Touch Sensor Input 4 AIO
9 CS3 / SG
ALERT# - Active low alert / interrupt output for
SMBus alert - requires pull-up resistor (default)
SMDATA - Bi-directional, open-dra in SMBus or
2
C data - requires pull-up resistor
I
2
SMCLK - SMBus or I
CS3 - Capacitive Touch Sensor Input 3 AIO
SG - Signal guard output AIO Leave Open
C clock input - requires
pull-up resistor
OD
DIOD n/a
DI n/a
CONNECTION
Connect to
Connect to
Connect to
Connect to
Connect to
Connect to
UNUSED
Ground
Ground
Ground
Ground
Ground
Ground
10 CS2 Capacitive Touch Sensor Input 2 AIO
Bottom
Pad
DS01569A-page 8 2013 Microchip Technology Inc.
GND Ground Power n/a
Connect to
Ground
6-Channel Capacitive Touch Sensor with Proximity Detection & Signal Guard
Datasheet
APPLICATION NOTE: All digital pins are 5V tolerant pins.
The pin types are described in Table1.2.
Table 1.2 Pin Types
PIN TYPE DESCRIPTION
Power This pin is used to supply power or ground to th e device.
DI Digital Input - This pin is used as a digital input. This pin is 5V tolerant.
AIO Analog Input / Output - This pin is used as an I/O for analog signals.
DIOD
OD
Digital Input / Open Drain Output - This pin is used as a digital I/O. When it is used as an
output, it is open drain and requires a pull-up resistor. This pin is 5V tolerant.
Open Drain Digital Output - This pin is used as a digital output. It is open drain and requires
a pull-up resistor. This pin is 5V tolerant.
2013 Microchip Technology Inc. DS01569A-page 9
6-Channel Capacitive Touch Sensor with Proximity Detection & Signal Guard
Chapter 2 Electrical Specifications
Table 2.1 Absolute Maximum Ratings
Voltage on VDD pin -0.3 to 6.5 V
Voltage on CS pins to GND -0.3 to 4.0 V
Datasheet
Voltage on 5V tolerant pins (V
Voltage on 5V tolerant pins (|V
Input current to any pin except VDD +
) -0.3 to 5.5 V
5VT_PIN
- VDD|) (see Note 2.2)0 to 3.6 V
5VT_PIN
10 mA
Output short circuit current Continuous N/A
Package Power Dissipation up to TA = 85°C for 10-pin DFN
0.5 W
(see Note 2.3)
Junction to Ambient (θ
) (see Note 2.4)78 °C/W
JA
Operating Ambient Temperature Range -40 to 125 °C
Storage Temperature Range -55 to 150 °C
ESD Rating, All Pins, HBM 8000 V
Note 2.1 Stresses above those listed could cause permanent damage to the device. This is a stress
rating only and functional operation of the device at any other condition above those
indicated in the operation sections of this specification is not implied.
Note 2.2 For the 5V tolerant pins that have a pull-up resistor, the voltage difference between
V
and VDD must never exceed 3.6V.
5VT_PIN
Note 2.3 The Package Power Dissipation specification assumes a recommended thermal via design
consisting of a 2x3 matrix of 0.3mm (12mil) vias at 0.9mm pitch conn ected to the ground
plane with a 1.6 x 2.3mm thermal landing.
Note 2.4 Junction to Ambient (θ
) is dependent on the design of the thermal vias. Without thermal
JA
vias and a thermal landing, the θJA will be higher.
DS01569A-page 10 2013 Microchip Technology Inc.
6-Channel Capacitive Touch Sensor with Proximity Detection & Signal Guard
Datasheet
Table 2.2 Electrical Specifications
VDD = 3V to 5.5V, TA = 0°C to 85°C, all Typical values at TA = 25°C unless otherwise noted.
CHARACTERISTIC SYMBOL MIN TYP MAX UNIT CONDITIONS
DC POWER
Supply Voltage V
Supply Current
Maximum Base
Capacitance
Minimum Detectable
Capacitive Shift
DD
I
STBY_DEF
I
STBY_LP
I
DSLEEP_3V
I
DSLEEP_5V
I
DD
C
BASE
ΔC
TOUCH
3.0 5.5 V
Standby state active
120 170 µA
1 sensor input monitored
Default conditions (8 avg, 70ms
cycle time)
Standby state active
50 µA
1 sensor input monitored
1 avg, 140ms cycle time
Deep Sleep state active
5TBDµA
No communications
T
< 40°C
A
3.135 < V
< 3.465V
DD
Deep Sleep state active
TBD TBD µA
500 750 µA
No communications
T
< 40°C
A
V
= 5V
DD
Capacitive Sensing Active
signal guard disabled
CAPACITIVE TOUCH SENSOR INPUTS
50 pF Pad untouched
20 fF Pad touched - defaul t conditions
Recommended Cap
Shift
ΔC
TOUCH
0.1 2 pF Pad touched - Not tested
Untouched Current Counts
Power Supply
Rejection
PSR ±3 ±10
counts
/ V
Base Capacitance 5pF - 50pF
Negative Delta Counts disabled
Maximum sensitivity
All other parameters default
POWER-ON AND BROWN-OUT RESET (SEE Section 4.2, "Reset")
Power-On Reset
Voltage
Power-On Reset
Release Voltage
Brown-Out Reset V
V
V
PORR
POR
BOR
1 1.3 V Pin States Defined
2.85 V
Rising V
Ensured by design
2.8 V Falling V
DD
DD
VDD Rise Rate
(ensures internal
POR signal)
2013 Microchip Technology Inc. DS01569A-page 11
SV
DD
0.05 V/ms 0 to 3V in 60ms
6-Channel Capacitive Touch Sensor with Proximity Detection & Signal Guard
Table 2.2 Electrical Specifications (continued)
V
= 3V to 5.5V, TA = 0°C to 85°C, all Typical values at TA = 25°C unless otherwise noted.
DD
CHARACTERISTIC SYMBOL MIN TYP MAX UNIT CONDITIONS
Datasheet
Power-Up Timer
Period
Brown-Out Reset
Voltage Delay
t
t
BORDC
Time to
Communications
Ready
Time to First
Conversion Ready
t
COMM_DLY
t
CONV_DLY
Output Low Voltage V
Output High Voltage V
Input High Voltage V
Input Low Voltage V
Leakage Current I
PWRT
OL
OH
IH
IL
LEAK
10 ms
1µsV
DD
= V
BOR
- 1
TIMING
15 ms
170 200 ms
I/O PINS
VDD -
0.4
0.4 V I
VI
SOURCE_IO
SINK_IO
= 8mA
= 8mA
2.0 V
0.8 V
powered or unpowered
T
< 85°C
±5 µA
pull-up voltage <
A
3.6V if
unpowered
SG PIN
Capacitive Drive
Capability
C
BASE_SG
20 200 pF capacitance to ground
SMBUS TIMING
Input Capacitance C
Clock Frequency f
Spike Suppression t
Bus Free Time Stop
to Start
Start Setup Time t
Sta rt Ho ld Ti me t
Stop Setup Time t
Data Hold Time t
Data Hold Time t
Data Setup Time t
DS01569A-page 12 2013 Microchip Technology Inc.
IN
SMB
SP
t
BUF
SU:STA
HD:STA
SU:STO
HD:DAT
HD:DAT
SU:DAT
10 400 kHz
1.3 µs
0.6 µs
0.6 µs
0.6 µs
0 µs When transmitting to the master
0.3 µs When receiving from the master
0.6 µs
5pF
50 ns
6-Channel Capacitive Touch Sensor with Proximity Detection & Signal Guard
Datasheet
Table 2.2 Electrical Specifications (continued)
VDD = 3V to 5.5V, TA = 0°C to 85°C, all Typical values at TA = 25°C unless otherwise noted.
CHARACTERISTIC SYMBOL MIN TYP MAX UNIT CONDITIONS
Clock Low Period t
Clock High Period t
Clock / Data Fall
Time
Clock / Data Rise
Time
Capacitive Load C
LOW
HIGH
t
FALL
t
RISE
LOAD
1.3 µs
0.6 µs
300 ns Min = 20+0.1C
300 ns Min = 20+0.1C
400 pF per bus line
LOAD
LOAD
ns
ns
2013 Microchip Technology Inc. DS01569A-page 13
6-Channel Capacitive Touch Sensor with Proximity Detection & Signal Guard
SMDATA
SMCLK
T
BUF
P
S
S - Start Condition
P - Stop Condition
PS
T
HIGH
T
LOW
T
HD:STA
T
SU:STO
T
HD:STA
T
HD:DAT
T
SU:DAT
T
SU:STA
T
FALL
T
RISE
Chapter 3 Communications
3.1 Communications
The CAP1296 communicates using the SMBus or I2C protocol.
3.2 System Management Bus
The CAP1296 communicates with a host controller, such as an MCHP SIO, through the SMBus. The
SMBus is a two-wire serial communication protocol between a computer host and its peripheral
devices. A detailed timing diagram is shown in Figure 3.1. Stretching of the SMCLK signal is supported;
however, the CAP1296 will not stretch the clock signal.
Datasheet
Figure 3.1 SMBus Timing Diagram
3.2.1 SMBus Start Bit
The SMBus Start bit is defined as a transition of the SMBus Data line from a logic ‘1’ state to a logic
‘0’ state while the SMBus Clock line is in a logic ‘1’ state.
3.2.2 SMBus Address and RD / WR Bit
The SMBus Address Byte consists of the 7-bit client address followed by the RD / WR indicator bit. If
this RD / WR bit is a logic ‘0’, then the SMBus Host is writing data to the client device. If this RD / WR
bit is a logic ‘1’, then the SMBus Host is reading data from the client device.
The CAP1296 responds to SMBus address 0101_000(r/w).
3.2.3 SMBus Data Bytes
All SMBus Data bytes are sent most significant bit first and composed of 8-bits of information.
3.2.4 SMBus ACK and NACK Bits
The SMBus client will acknowledge all data bytes that it receives. This is done by the cl ient device
DS01569A-page 14 2013 Microchip Technology Inc.
pulling the SMBus Data line low after the 8th bit of each byte that is transmitted. This applies to both
the Write Byte and Block Write protocols.
The Host will NACK (not acknowledge) the last data byte to be received from the client by holding the
SMBus data line high after the 8th data bit has been sent. For the Block Read protocol, the Host will
ACK each data byte that it receives except the last data byte.
6-Channel Capacitive Touch Sensor with Proximity Detection & Signal Guard
Datasheet
3.2.5 SMBus Stop Bit
The SMBus Stop bit is defined as a transition of the SMBus Data line from a logic ‘0’ state to a logic
‘1’ state while the SMBus clock line is in a logic ‘1’ state. When the CAP1296 detects an SMBus Stop
bit and it has been communicating with the SMBus protocol, it will reset its client interface and prepare
to receive further communications.
3.2.6 SMBus Timeout
The CAP1296 includes an SMBus timeout feature. Following a 30ms period of inactivity on the SMBus
where the SMCLK pin is held low, the device will timeout and reset the SMBus interface.
The timeout function defaults to disabled. It can be enabled by setting the TIMEOUT bit in the
Configuration register (see Section 5.6, "Configuration Registers").
3.2.7 SMBus and I2C Compatibility
The major differences between SMBus and I2C devices are highlighted here. For more information,
refer to the SMBus 2.0 specification.
1. CAP1296 supports I
2. Minimum frequency for SMBus communications is 10kHz.
2
C fast mode at 400kHz. This covers the SMBus max time of 100kHz.
3. The SMBus client protocol will reset if the clock is held low longer than 30ms (timeout condition).
This can be enabled in the CAP1296 by setting the TIMEOUT bit in the Configuration register. I2C
does not have a timeout.
4. The SMBus client protocol will reset if both the clock and the data line are high for longer than
200us (idle condition). This can be enabled in the CAP1296 by setting the TIMEOUT bit in the
Configuration register. I
2
5. I
C devices do not support the Alert Response Address functionality (which is op tional for SMBus).
2
C devices support block read and write differently. I2C protocol allows for unlimited number of
6. I
bytes to be sent in either direction. The SMBus protocol requires that an additional data byte
indicating number of bytes to read / write is transmitted. The CAP1296 supports I
2
C does not have an idle condition.
3.3 SMBus Protocols
The CAP1296 is SMBus 2.0 compatible and supports Write Byte, Read Byte, Send Byte, and Receive
Byte as valid protocols as shown below.
All of the below protocols use the convention in Table 3.1.
DATA SENT
TO DEVICE
Data sent Data sent
Table 3.1 Protocol Format
DATA SENT TO
THE HOST
2
C formatting only .
2013 Microchip Technology Inc. DS01569A-page 15
3.3.1 SMBus Write Byte
The Write Byte is used to write one byte of data to a specific register as shown in Table 3.2.
6-Channel Capacitive Touch Sensor with Proximity Detection & Signal Guard
Datasheet
Table 3.2 Write Byte Protocol
START
SLAVE
ADDRESS WR
ACK
REGISTER
ADDRESS ACK
REGISTER
DATA ACK STOP
1 ->0 0101 _000 0 0 XXh 0 XXh 0 0 -> 1
3.3.2 SMBus Read Byte
The Read Byte protocol is used to read one byte of data from the registers as show n in Table 3.3.
Table 3.3 Read Byte Protocol
START SLAVE
ADDRESS
WR ACK REGISTER
ADDRESS
ACK START CLIENT
ADDRESS
RD ACK REGISTER
DATA
NACK STOP
1->0 0101_000 0 0 XXh 0 1 ->0 0 101_000 1 0 XXh 1 0 -> 1
3.3.3 SMBus Send Byte
The Send Byte protocol is used to set the internal address register pointer to the correct address
location. No data is transferred during the Send Byte protocol as shown in Table 3.4.
APPLICATION NOTE: The Send Byte protocol is not functional in Deep Sleep (i.e., DSLEEP bit is set).
Table 3.4 Send Byte Protocol
START
SLAVE
ADDRESS WR ACK
REGISTER
ADDRESS ACK STOP
1 -> 0 0101_000 0 0 XXh 0 0 -> 1
3.3.4 SMBus Receive Byte
The Receive Byte protocol is used to read data from a register when the internal register address
pointer is known to be at the right location (e.g. set via Send Byte). This is used for consecutive reads
of the same register as shown in Table 3.5.
APPLICATION NOTE: The Receive Byte protocol is not functional in Deep Sleep (i.e., DSLEEP bit is set).
Table 3.5 Receive Byte Protocol
SLAVE
START
1 -> 0 0101_000 1 0 XXh 1 0 -> 1
DS01569A-page 16 2013 Microchip Technology Inc.
ADDRESS RD
ACK REGISTER DATA NACK STOP
6-Channel Capacitive Touch Sensor with Proximity Detection & Signal Guard
Datasheet
3.4 I2C Protocols
The CAP1296 supports I2C Block Read and Block Write.
The protocols listed below use the convention in Table 3.1.
3.4.1 Block Read
The Block Read is used to read multiple data bytes from a group of contiguous registers as sh own in
Table 3.6.
APPLICATION NOTE: When using the Block Read protocol, the internal address pointer will be automatically
incremented after every data byte is received. It will wrap from FFh to 00h.
Table 3.6 Block Read Protocol
START SLAVE
ADDRESS
WR ACK REGISTER
ADDRESS
ACK START SLAVE
ADDRESS
RD ACK REGISTER
DATA
1->0 0101_000 0 0 XXh 0 1 ->0 0101_000 1 0 XXh
ACK REGISTER
DATA
ACK REGISTER
DATA
ACK REGISTER
DATA
ACK . . . REGISTER
DATA
NACK STOP
0 XXh 0 XXh 0 XXh 0 . . . XXh 1 0 -> 1
3.4.2 Block Write
The Block Write is used to write multiple data bytes to a group of contiguous registers as shown in
Table 3.7.
APPLICATION NOTE: When using the Block Write protocol, the internal address pointer will be automatically
incremented after every data byte is received. It will wrap from FFh to 00h.
Table 3.7 Block Write Protocol
REGISTER
ADDRESS ACK
START
SLAVE
ADDRESS WR
ACK
1 ->0 0101_000 0 0 XXh 0 XXh 0
REGISTER
DATA
ACK
REGISTER
DATA ACK . . .
REGISTER
DATA ACK STOP
REGISTER
DATA ACK
XXh 0 XXh 0 . . . XXh 0 0 -> 1
2013 Microchip Technology Inc. DS01569A-page 17
6-Channel Capacitive Touch Sensor with Proximity Detection & Signal Guard
Chapter 4 General Description
The CAP1296 is a multiple channel capacitive touch sensor. It contains six (6) individual capacitive
touch sensor inputs with programmable sensitivity for use in touch sensor applications. Each sensor
input is calibrated to compensate for system parasitic capacitance and automatically recalibrated to
compensate for gradual environmental changes.
In addition, the CAP1296 can be configured to detect proximity on one or more channels with an
optional signal guard to reduce noise sensitivity.
The CAP1296 includes Multiple Pattern Touch recognition that allows the user to select a specific set
of buttons to be touched simultaneously. If this pattern is detected, a status bit is set and an interrupt
is generated.
The CAP1296 has Active and Standby states, each with its own sensor input configuration controls.
The Combo state allows a combination of sensor input controls to be used which enab les one or more
sensor inputs to operate as buttons while another sensor input is operating as a proximity detector.
Power consumption in the Standby and Combo states is dependent on the number of sensor inputs
enabled as well as averaging, sampling time, and cycle time. Deep Sleep is the lowest power state
available, drawing 5µA (typical) of current. In this state, no sensor inputs are active, and
communications will wake the device.
The device communicates with a host controller using SMBus / I
device for updated information at any time or it may configure the device to flag an in terrupt whenever
a touch is detected on any sensor pad.
Datasheet
2
C. The host controller may poll the
A typical system diagram is shown in Figure 4.1.
DS01569A-page 18 2013 Microchip Technology Inc.
6-Channel Capacitive Touch Sensor with Proximity Detection & Signal Guard
CAP1296
CS4
SMDATA
SMCLK
Embedded
Controller
3.0V to 5.5V
ALERT#
CS5
CS6
CS2
CS1
Touch
Button
Touch
Button
Touch
Button
Proximity
Sensor
Touch
Button
SG*
VDDGND
* CS3 / SG is a multi-function pin. If not
using the signal guard sh own here, CS3
can be another touch button.
10kOhm
resistors
3.0V to 5.5V
1.0uF0.1uF
Datasheet
Figure 4.1 System Diagram for CAP1296
4.1 Power States
The CAP1296 has 4 power states depending on the status of the STBY, COMBO, and DSLEEP bits
(see Section 5.1, "Main Control Register"). When the device transitions between power states,
previously detected touches (for channels that are being de-activated) a re cleared a nd the sensor i nput
status bits are reset.
1. Active - The normal mode of operation. The device is monitoring capacitive sensor inputs enabled
in the Active state (see Section 5.7, "Sensor Input Enable Register").
2. Standby - When the STBY bit is set, the device is monitoring the capacitive sensor in puts enabled
in the Standby state (see Section 5.22, "Standby Channel Register"). Interrupts can still be
generated based on the enabled channels. The device will still respond to communications
normally and can be returned to the Active state of operation by clearing the STBY bit. Power
consumption in this state is dependent on the number of sensor inputs enabled as well as
averaging, sampling time, and cycle time.
3. Combo - When the COMBO bit is set, the device is monitoring capacitive sensor inputs enabled
in the Active state as well as inputs enabled in the Standby state (hence the name “Combo”).
Interrupts can still be generated based on the enabled channels. The device wi ll still respond to
communications normally and can be returned to the Active state of operation by clearing the
COMBO bit. Power consumption in this state is dependent on the number of sensor inputs enabled
as well as averaging, sampling time, and cycle time.
2013 Microchip Technology Inc. DS01569A-page 19
4. Deep Sleep - When the DSLEEP bit is set, the device is in its lowest power state. It is not
V
DD
V
BOR
T
PWRT
GND
Undefined
SYSRST
V
POR
V
PORR
T
BORDCTPWRT
monitoring any capacitive sensor inputs. While in Deep Sleep, the CAP1296 can be awakened by
SMBus communications targeting the device. This will not cause the DSLEEP to be cleared so the
device will return to Deep Sleep once all communications have stopped. The device can be
returned to the Active state of operation by clearing the DSLEEP bit.
4.2 Reset
The Power-On Reset (POR) circuit holds the device in reset until VDD has reached an acceptable level,
Power-on Reset Release Voltage (V
used to extend the start-up period until all device operation conditions have been met. Th e power-up
timer starts after V
The Brown-Out Reset (BOR) circuit holds the device in reset when V
for longer than the BOR reset delay (t
up timer is started again and must finish before reset is released, as shown in Figure 4.2.
reaches V
DD
6-Channel Capacitive Touch Sensor with Proximity Detection & Signal Guard
Datasheet
), for minimum operation. The power-up timer (PWRT) is
PORR
. POR and PORR with slow rising VDD is shown in Figure 4.2.
PORR
falls to a minimum level, V
). After a BOR, when VDD rises above V
BORDC
DD
PORR
, the power-
BOR
Figure 4.2 POR and PORR With Slow Rising V
and BOR with Falling V
DD
DD
4.3 Capacitive Touch Sensing
The CAP1296 contains six (6) independent capacitive touch sensor inputs. Each sensor input has
dynamic range to detect a change of capacitance due to a touch. Additionally, each sensor input can
be configured to be automatically and routinely recalibrated.
4.3.1 Capacitive Touch Sensing Settings
Controls for managing capacitive touch sensor inp uts are determined by the power state.
4.3.1.1 Active State Sensing Settings
The Active state is used for normal operation. Sensor inputs being monitored are determined by the
Sensor Input Enable Register (see Section 5.7, "Sensor Input Enable Register"). Sensitivity is
controlled by the Sensitivity Control Register (see Section 5.5, "Sensitivity Control Register").
Averaging, sample time, and cycle time are controlled by the Averaging and Sampling Configuration
Register (see Section 5.10, "Averaging and Sampling Configuration Register"). Each channel can have
a separate touch detection threshold, as defined in the Sensor Input Threshold registers (see Section
5.20, "Sensor Input Threshold Registers").
4.3.1.2 Standby State Sensing Settings
The Standby state is used for standby operation. In general, fewer sensor inputs are enabled, and they
are programmed to have more sensitivity. Sensor inputs being monitored are determined by the
Standby Channel Register (see Section 5.22, "Standby Channel Register"). Sensitivity is controlled by
DS01569A-page 20 2013 Microchip Technology Inc.
6-Channel Capacitive Touch Sensor with Proximity Detection & Signal Guard
Datasheet
the Standby Sensitivity Register (see Section 5.24, "Standby Sensitivity Register"). Averaging, sample
time, and cycle time are controlled by the Averaging and Sampling Configuration Register (see Section
5.23, "Standby Configuration Register"). There is one touch detection threshold, which applies to all
sensors enabled in Standby, as defined in the Standby Threshold Register (see Section 5.25, "Standby
Threshold Register").
4.3.1.3 Combo State Sensing Settings
The Combo state is used when a combination of proximity detection and norm al button operation is
required. When the COMBO bit is set, the sensing cycle includes sensor inputs enabled in the Active
state as well as sensor inputs enabled in the Standby state. Sensor inputs enabled in the Active state
will use the Active settings described in Section 4.3.1.1, "Active State Sensing Settings". Sensor inputs
enabled in the Standby state will use the Standby settings described in Section 4.3.1.2, "Standby State
Sensing Settings". If a sensor input is enabled in both th e Active state and in the Standby state, the
Active state settings will be used in Combo state. The programmed cycle time is determined by
STBY_CY_TIME[1:0].
The Combo state also has two gain settings. When the COMBO bit is set, the GAIN[1:0] control only
applies to the sensors enabled in the Active state, and the C_GAIN[1:0] control applies to the sensors
enabled in the Standby state.
4.3.2 Sensing Cycle
Except when in Deep Sleep, the device automatically initiates a sensing cycle and repeats the cycle
every time it finishes. The cycle polls through each enabled sensor input starting with CS1 and
extending through CS6. As each capacitive touch sensor i nput is polled, its measurement is compared
against a baseline “not touched” measurement. If the delta measurement is large enou gh to exceed
the applicable threshold, a touch is detected and an interrupt can be generated (see Section 4.9.2,
"Capacitive Sensor Input Interrupt Behavior").
The sensing cycle time is programmable (see Section 5.10, "Averaging and Sampling Configuration
Register" and Section 5.23, "Standby Configuration Register"). If all enabled inputs can be sampled in
less than the cycle time, the device is placed into a lower power state for the remainder of the sensi ng
cycle. If the number of active sensor inputs cannot be sampled within the specified cycle time, the
cycle time is extended and the device is not placed in a lower power state.
4.4 Sensor Input Calibration
Calibration sets the Base Count Registers (Section 5.26, "Sensor Input Base Count Registers") which
contain the “not touched” values used for touch detection comparisons. Calibration automatically
occurs after a power-on reset (POR), when sample time is changed, when the gain is changed, when
the calibration sensitivity is changed, and whenever a sensor input is newly enabled (for example,
when transitioning from a power state in which it was disabled to a power state in which it is enab led).
During calibration, the analog sensing circuits are tuned to the capacitance of the untouched pad.
Then, samples are taken from each sensor input so that a base count can be established. After
calibration, the untouched delta counts are zero.
APPLICATION NOTE: During the calibration routine, the sensor inputs will not detect a press for up to 200ms and
the Sensor Base Count Register values will be invalid. In addition, any press on the
corresponding sensor pads will invalidate the calibration.
The host controller can force a calibration for selected sensor inputs at any time using the Calibrati on
Activate and Status Register (Section 5.11, "Calibration Activate and Status Register"). When a bit is
set, the corresponding capacitive touch sensor input will be calibrated (both analog and digital). The
bit is automatically cleared once the calibration routine has successfully finished.
If analog calibration fails for a sensor input, the corresponding bit is not cleared in the Calibration
Activate and Status Register, and the ACAL_FAIL bit is set in the General Status Register (Section 5.2,
"Status Registers"). An interrupt can be generated. Analog calibration will fail if a noise bit is set or if
2013 Microchip Technology Inc. DS01569A-page 21
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