TouchXpress™ Family
CPT212B Data Sheet
The CPT212B device, part of the TouchXpress family, is designed
to quickly add capacitive touch via an I2C interface by eliminating
the firmware complexity and reducing the development time for ca-
pacitive sensing applications.
Supporting up to 12 capacitive sensor inputs in packages as small as a 3 mm x 3 mm
QFN, the CPT212B is a highly-integrated device that interfaces via I2C to the host pro-
cessor to provide a simple solution for adding capacitive touch. The device also comes
with advanced features like moisture immunity, wake-on proximity, and buzzer feedback
for an enhanced user experience. No firmware development is needed, and all the ca-
pacitive touch sense parameters can be configured using a simple GUI-based configura-
tor. By eliminating the need for complex firmware development, the CPT212B device en-
ables rapid user interface designs with minimal development effort.
The CPT212B device is ideal for a wide range of capacitive touch applications including
the following:
KEY FEATURES
• No firmware development required
•Simple GUI-based configurator
• 12 Capacitive Sensor inputs with
programmable sensitivity
• I2C interface to communicate to and
configure from the host
• Lowest power capacitive sense solution
• Active — 200 µA
• Sleep — 1 µA
• Wake on proximity
• Superior noise immunity: SNR up to 270:1
• Moisture immunity
• Mutually-exclusive touch qualifier
• Buzzer output for audible touch feedback
• Home appliances
•Instrument / Control panels
• White goods
• Medical equipment
•Consumer electronics
• Lighting control
Input
Features
Output
Features
Capacitive Touch Sensing
Features
Baselining
Low Power State
Machine
Configuration
Profile for each
Input
Touch
Qualification
Mutually-
Exclusive Touch
Qualifier
Input Engine
with
12 Inputs
Proximity Wake
Input
Optimized Active
Lowest power mode with feature operational:
Active
Optional Buzzer
Output
I2C Output I2C Event Buffer
Interrupt Pin
Low Power Sleep
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1. Feature List and Ordering Information
R
Tape and Reel (Optional)
G M
Temperature Grade — –40 to +85 °C (G)
12
T–2 B A –
Package Type — QFN20 (M)
01
CP
Silicon Labs Xpress Product Line
Firmware Revision
Hardware Revision
Interface Type — GPO (0), I2C (1), Configuration I2C (2)
Number of Capacitive Sense Inputs
TouchXpress Family
Capacitive Sense Features — Button (B)
Figure 1.1. CPT212B Part Numbering
The CPT212B has the following features:
• Capacitive sensing input engine with 12 inputs
• Post-sample touch qualification engine
• Configuration profile space in non-volatile memory
• I2C event buffer with interrupt pin to signal when new touch events have been qualified
• Configuration loading with both the dedicated configuration interface and through the I2C interface
• Low power state machine to minimize current draw in all use cases
• Capacitive proximity sensing input
• Buzzer output
• Mutually-exclusive touch qualifier
Table 1.1. Product Selection Guide
Ordering
Part Number
Configuration over I2C
Pb-free
(RoHS Compliant)
Temperature Range
Package
CPT212B-A01-GM Yes Yes -40 to +85 °C QFN20
See http://www.silabs.com/products/interface/capacitive-touch-controllers for other devices available in the TouchXpress family.
CPT212B Data Sheet
Feature List and Ordering Information
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Table of Contents
1. Feature List and Ordering Information ......................2
2. Typical Connection Diagrams .........................5
2.1 Signal, Analog, and Power Connections .....................5
2.2 Configuration ..............................6
3. Electrical Specifications ...........................7
3.1 Electrical Characteristics ..........................7
3.1.1 Recommended Operating Conditions ....................7
3.1.2 Power Consumption..........................8
3.1.3 Reset and Supply Monitor ........................9
3.1.4 Configuration Memory .........................9
3.1.5 I2C Configuration Interface .......................10
3.1.6 Capacitive Sense...........................11
3.1.7 Buzzer Output............................12
3.2 Thermal Conditions ............................12
3.3 Absolute Maximum Ratings .........................13
3.4 Typical Performance Curves .........................14
4. Functional Description ........................... 17
4.1 Capacitive Sensing Input ..........................17
4.1.1 Introduction ............................17
4.1.2 Touch Qualification Criteria .......................17
4.1.3 Thresholds .............................17
4.1.4 Debounce Counter ..........................18
4.1.5 Touch Deltas ............................18
4.1.6 Auto-Accumulation and Averaging .....................18
4.1.7 Drive Strength............................18
4.1.8 Active Mode Scan Enable ........................18
4.1.9 Active Mode Scan Period ........................18
4.1.10 Active Mode Scan Type ........................19
4.1.11 Sleep Mode Scan Period........................19
4.1.12 Active Mode and Sleep Mode Transitions ..................20
4.2 I2C Event Buffer Interface ..........................20
4.2.1 Introduction ............................20
4.2.2 Startup Behavior ...........................21
4.2.3 Sensing Mode Event Packet Structure ...................21
4.2.4 Packet Retrieval in Sensing Mode .....................22
4.2.5 Defined Event Types .........................23
4.2.6 Description Bytes for Touch Events ....................23
4.2.7 Slave Address............................24
4.2.8 Entering Sensing Mode from Configuration Loading Mode .............24
4.2.9 Determining Configuration Validity .....................24
4.2.10 Configuration Loading Procedure .....................26
4.2.11 CRC Algorithm ...........................28
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4.3 Capacitive Proximity Sensing.........................29
4.3.1 Wake on Proximity ..........................29
4.3.2 Proximity Configuration.........................29
4.4 Buzzer Output ..............................29
4.4.1 Introduction ............................29
4.4.2 Buzzer Configuration .........................30
4.5 Mutually Exclusive Buttons .........................30
4.6 Configuration Profile............................31
5. Pin Definitions ..............................32
5.1 CPT212B QFN20 Pin Definitions .......................32
6. QFN20 Package Specifications........................ 34
6.1 QFN20 Package Dimensions ........................34
6.2 QFN20 PCB Land Pattern .........................36
6.3 QFN20 Package Marking ..........................37
7. Relevant Application Notes .........................38
8. Revision History .............................39
8.1 Revision 1.1 ..............................39
8.2 Revision 1.0 ..............................39
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2. Typical Connection Diagrams
2.1 Signal, Analog, and Power Connections
Figure 2.1 Connection Diagram on page 5 shows a typical connection diagram for the power pins of CPT212B devices.
4.7 µF and 0.1 µF bypass
capacitors required for the power
pins placed as close to the pins as
possible.
Host
Processor
1 kΩ
1-10 kΩ 1-10 kΩ
CPT212B
Device
1.8-3.6 V (in)
1.8-3.6 V (in)
...
1.8-3.6 V (in)
Electrode
Electrode
GND
VDD
EB_SCL
EB_INT
CS10
CS00
Config Data
Config Clk / RSTb
EB_SDA
Figure 2.1. Connection Diagram
Note: The I2C pull-up resistor values will vary depending on the speed requirements of the bus and the host processor requirements.
CPT212B Data Sheet
Typical Connection Diagrams
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2.2 Configuration
There are two ways to configure the CPT212B: through the I2C interface, and through the dedicated configuration interface. The dia-
gram below shows a typical connection diagram for the dedicated configuration interface pins. The ToolStick Base Adapter is available
on the evaluation board.
Note: The USB Debug Adapter does not support configuration for TouchXpress devices. Instead, the ToolStick Base Adapter must be
used to configure these devices.
CPT212B Device
Config Clk
1 k
VDD
Config Data
GND
ToolStick
Figure 2.2. Configuration Connection Diagram
CPT212B Data Sheet
Typical Connection Diagrams
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3. Electrical Specifications
3.1 Electrical Characteristics
All electrical parameters in all tables are specified under the conditions listed in 3.1.1 Recommended Operating Conditions, unless sta-
ted otherwise.
3.1.1 Recommended Operating Conditions
Table 3.1. Recommended Operating Conditions
Parameter Symbol Test Condition Min Typ Max Unit
Operating Supply Voltage on VDD VDD 1.8 2.4 3.6 V
Minimum RAM Data Retention
Voltage on VDD1
VRAM Not in Sleep Mode — 1.4 — V
Sleep Mode — 0.3 0.5 V
Operating Ambient Temperature TA–40 — 85 °C
Note:
1. All voltages with respect to GND.
CPT212B Data Sheet
Electrical Specifications
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3.1.2 Power Consumption
See 3.4 Typical Performance Curves for power consumption plots.
Table 3.2. Power Consumption
Parameter Symbol Test Condition Min Typ Max Unit
Active Mode Supply Current IDD Sensing Mode — 3.1 — mA
Configuration Mode — 3.1 — mA
Optimized Active Mode Supply
Current
IDD — 180 — µA
Sleep Mode Current1, 2 IDD 3 sensors or fewer — 0.78 — µA
4 sensors — 0.79 — µA
5 sensors — 0.81 — µA
6 sensors — 0.82 — µA
7 sensors — 0.84 — µA
10 sensors — 0.88 — µA
12 sensors — 0.95 — µA
System Current with Varying Scan
Time — Base with One Sensor1
IDD Scan period = 10 ms — 154 — µA
Scan period = 20 ms — 77 — µA
Scan period = 50 ms — 31 — µA
Scan period = 75 ms — 21 — µA
Scan period = 100 ms — 16 — µA
System Current with Varying Scan
Time — Each Additional Sensor1
IDD Scan period = 10 ms — 47 — µA
Scan period = 20 ms — 23 — µA
Scan period = 50 ms — 9 — µA
Scan period = 75 ms — 6 — µA
Scan period = 100 ms — 5 — µA
Note:
1. Measured with Free Run Mode disabled and sensors set to 4x accumulation, 8x gain.
2. Measured with scan period set to 250 ms.
CPT212B Data Sheet
Electrical Specifications
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3.1.3 Reset and Supply Monitor
Table 3.3. Reset and Supply Monitor
Parameter Symbol Test Condition Min Typ Max Unit
VDD Supply Monitor Threshold VVDDM Reset Trigger 1.7 1.75 1.8 V
VWARN Early Warning 1.8 1.85 1.9 V
Power-On Reset (POR) Monitor
Threshold
VPOR Rising Voltage on VDD — 1.75 — V
Falling Voltage on VDD 0.75 1.0 1.3 V
VDD Ramp Time tRMP Time to VDD ≥ 1.8 V — — 3 ms
RST Low Time to Generate Reset tRSTL 15 — — µs
Boot Time1tboot 1 sensor — 25 — ms
2 sensors — 40 — ms
3 sensors — 55 — ms
4 sensors — 70 — ms
5 sensors — 85 — ms
6 sensors — 100 — ms
7 sensors — 115 — ms
8 sensors — 130 — ms
9 sensors — 145 — ms
10 sensors — 160 — ms
11 sensors — 175 — ms
12 sensors — 200 — ms
Note:
1. Boot time is defined as the time from when the device enters sensing mode until the first capacitive sensing scan occurs.
3.1.4 Configuration Memory
Table 3.4. Configuration Memory
Parameter Symbol Test Condition Min Typ Max Units
Endurance (Write/Erase Cycles) NWE 20 k 100 k — Cycles
Note:
1. Data Retention Information is published in the Quarterly Quality and Reliability Report.
CPT212B Data Sheet
Electrical Specifications
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3.1.5 I2C Configuration Interface
Table 3.5. I2C Configuration Interface
Parameter Symbol Test Condition Min Typ Max Units
I2C Configuration Interface Boot
Time
tI2C_boot Time after any reset until the I2C
Configuration Interface is ready to
receive commands
— 200 — µs
I2C Configuration Erase Delay terase — 45 — ms
I2C Configuration Write Delay twrite — 1 — ms
I2C Configuration CRC Delay tCRC — 45 — ms
I2C Configuration Validity Check
Delay
tvalid — 200 — µs
Interrupt Pin Low Time After Enter-
ing Sensing Mode
tINT_low — — 5 µs
CPT212B Data Sheet
Electrical Specifications
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3.1.6 Capacitive Sense
Table 3.6. Capacitive Sense
Parameter Symbol Test Condition Min Typ Max Unit
Scan Time Per Sensor1tSCAN Accumulation = 1x — 64 — µs
Accumulation = 4x — 256 — µs
Accumulation = 8x — 512 — µs
Accumulation = 16x — 1.024 — ms
Accumulation = 32x — 2.048 — ms
Accumulation = 64x — 4.096 — ms
Signal to Noise Ratio1, 2 SNR Accumulation = 1x — 90:1 — codes
Accumulation = 4x — 180:1 — codes
Accumulation = 8x — 182:1 — codes
Accumulation = 16x — 210:1 — codes
Accumulation = 32x — 230:1 — codes
Accumulation = 64x — 270:1 — codes
Conversion Time tCONV Gain = 1x — 205 — µs
Gain = 2x — 123 — µs
Gain = 3x — 98 — µs
Gain = 4x — 85 — µs
Gain = 5x — 76 — µs
Gain = 6x — 72 — µs
Gain = 7x — 67 — µs
Gain = 8x — 64 — µs
Total Processing Time3tPROC 1 sensor — 576 — µs
2 sensors — 796 — µs
3 sensors — 1.0 — ms
4 sensors — 1.2 — ms
5 sensors — 1.4 — ms
6 sensors — 1.7 — ms
7 sensors — 1.9 — ms
8 sensors — 2.1 — ms
9 sensors — 2.3 — ms
10 sensors — 2.6 — ms
11 sensors — 2.8 — ms
12 sensors — 3.0 — ms
Maximum External Capacitive
Load
CEXTMAX Gain = 8x — 45 — pF
Gain = 1x — 500 — pF
CPT212B Data Sheet
Electrical Specifications
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Parameter Symbol Test Condition Min Typ Max Unit
Maximum External Series Impe-
dance
REXTMAX Gain = 8x — 50 — kΩ
Note:
1. Measured with gain set to 8x.
2. Measured with an evaluation board with 1/16" overlay using Capacitive Sense Profiler.
3. Sensors configured to 8x gain, 1x accumulation with sensor sampling and system processing time included and mutually-exclu-
sive buttons, buzzer, and touch time-outs disabled.
3.1.7 Buzzer Output
Table 3.7. Buzzer Output
Parameter Symbol Test Condition Min Typ Max Unit
Output High Voltage (High Drive) VOH IOH = –3 mA VDD – 0.7 — — V
Output Low Voltage (High Drive) VOL IOL = 8.5 mA — — 0.6 V
Output High Voltage (Low Drive) VOH IOH = –1 mA VDD – 0.7 — — V
Output Low Voltage (Low Drive) VOL IOL = 1.4 mA — — 0.6 V
Weak Pull-Up Current IPU VDD = 1.8 V
VIN = 0 V
— –4 — µA
VDD = 3.6 V
VIN = 0 V
–35 –20 — µA
3.2 Thermal Conditions
Table 3.8. Thermal Conditions
Parameter Symbol Test Condition Min Typ Max Unit
Thermal Resistance* θJA QFN20 Packages — 60 — °C/W
Note:
1. Thermal resistance assumes a multi-layer PCB with any exposed pad soldered to a PCB pad.
CPT212B Data Sheet
Electrical Specifications
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3.3 Absolute Maximum Ratings
Stresses above those listed in Table 3.9 Absolute Maximum Ratings on page 13 may cause permanent damage to the device. This is
a stress rating only and functional operation of the devices at those or any other conditions above those indicated in the operation list-
ings of this specification is not implied. Exposure to maximum rating conditions for extended periods may affect device reliability. For
more information on the available quality and reliability data, see the Quality and Reliability Monitor Report at http://www.silabs.com/
support/quality/pages/default.aspx.
Table 3.9. Absolute Maximum Ratings
Parameter Symbol Test Condition Min Max Unit
Ambient Temperature Under Bias TBIAS –55 125 °C
Storage Temperature TSTG –65 150 °C
Voltage on VDD VDD GND–0.3 4.0 V
Voltage on I/O pins or RSTb VIN GND–0.3 VDD + 0.3 V
Total Current Sunk into Supply Pin IVDD — 400 mA
Total Current Sourced out of Ground
Pin
IGND 400 — mA
Current Sourced or Sunk by Any I/O
Pin or RSTb
IIO –100 100 mA
Maximum Total Current through all
Port Pins
IIOTOT — 200 mA
Operating Junction Temperature TJ–40 105 °C
Exposure to maximum rating conditions for extended periods may affect device reliability.
CPT212B Data Sheet
Electrical Specifications
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3.4 Typical Performance Curves
Figure 3.1. Active Mode Processing Time Per Sensor
Note: Active mode processing time per sensor measured with sensors configured to 1x accumulation, 8x gain. Sensor sampling and
system processing time is included with mutually-exclusive buttons, the buzzer, and touch time-outs disabled.
Figure 3.2. Current vs. Active Mode Scan Period — Base Current Consumption
CPT212B Data Sheet
Electrical Specifications
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Figure 3.3. Current vs. Active Mode Scan Period — Current Consumption for Each Additional Sensor
Note: Active mode scan period current draw measured with free run mode disabled and all 12 sensors enabled at 4x accumulation, 8x
gain. In addition, the buzzer, and mutually-exclusive button groups were disabled.
Figure 3.4. Typical VOH Curves
CPT212B Data Sheet
Electrical Specifications
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Figure 3.5. Typical VOL Curves
CPT212B Data Sheet
Electrical Specifications
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4. Functional Description
4.1 Capacitive Sensing Input
4.1.1 Introduction
The capacitive to digital converter uses an iterative, charge-timing self-capacitance technique to measure capacitance on an input pin.
Sampling is configured and controlled by settings in the non-volatile configuration profile, which can be changed through the 2-pin con-
figuration interface.
Baseline
Active threshold
Touch delta Inactive threshold
Capacitance
Time
Figure 4.1. Capacitive Sense Data Types
4.1.2 Touch Qualification Criteria
The device detects a touch event when an inactive (untouched) input enabled by the input enable mask detects an sequence of meas-
urements that cross the active threshold.
The device detects a touch release event when an active (touched) input enabled by the input enable mask detects an sequence of
measurements that cross the inactive threshold.
The debounce configuration profile parameter defines how many measurements in a row must cross a threshold before a touch or re-
lease is qualified. In electrically noisy environments more heavily filtered data is used for qualification.
4.1.3 Thresholds
Capacitive sensing inputs use input-specific thresholds for touch qualification. Each input uses two thresholds, one to detect inactive-to-
active transitions on the input, and another to determine active-to-inactive transitions on the input. The inputs use two thresholds to add
hysteresis and prevent active/inactive ringing on inputs. Each threshold can be set through Simplicity Studio tools and all thresholds are
stored in non-volatile memory in the device's configuration profile.
Thresholds are defined as percentages of a capacitive sensing input's touch delta.
CPT212B Data Sheet
Functional Description
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4.1.4 Debounce Counter
Each capacitive sensing input maintains its own debounce counter. For an inactive sensor, this counter tracks the number of succes-
sive samples which have crossed that input's active threshold. For an active sensor, this counter tracks the number of successive sam-
ples which have crossed the inactive threshold. When the counter reaches a terminal value defined in the the configuration profile, the
touch/release event is qualified.
4.1.5 Touch Deltas
Each capacitive sensing input uses a stored touch delta value that describes the expected difference between inactive and active ca-
pacitive sensing output codes. This value is stored in the configuration profile for the system and is used by the touch qualification en-
gine, which defines inactive and active thresholds relative to the touch delta.
The touch deltas are stored in the configuration profile in a touch delta/16 format. For this reason, touch deltas must be configured as
multiples of 16.
4.1.6 Auto-Accumulation and Averaging
Capacitive sensing inputs have an auto-accumulate and average post-sample filter that can be used to improve signal strength if nee-
ded. Settings stored in the configuration profile can configure the engine to accumulate 1, 4, 8, 16, 32, or 64 samples. After the defined
number of samples have been accumulated, the result is divided by either 1, 4, 8, 16, 32, or 64, depending on the accumulation setting.
This auto-accumulated and averaged value is the sample output used for all touch qualification processing. Note that sample time per
sensor increases as the level of accumulation increases. To reduce current consumption, the engine should not be set to auto-accumu-
late unless it is required to achieve acceptable signal strength due to thick overlays or other system-level factors.
4.1.7 Drive Strength
The drive strength of the current source used to charge the electrode being measured by the capacitive sensing input can be adjusted
in integer increments from 1x to 8x (8x is the default). High drive strength gives the best sensitivity and resolution for small capacitors,
such as those typically implemented as touch-sensitive PCB features. To measure larger capacitance values, the drive strength should
be lowered accordingly. The highest drive strength setting that yields capacitive sensing output which does not saturate the sensing
engine when the electrode is active (touched) should always be used to maximize input sensitivity.
4.1.8 Active Mode Scan Enable
Active mode scanning of capacitive sensing inputs is controlled by an enable setting for each capacitive sensing input. This setting is
stored in the configuration profile.
4.1.9 Active Mode Scan Period
The capacitive sensing input engine stays in active mode whenever one or more inputs have qualified as active. During this time, the
sensors scan at a periodicity defined by the active mode scan period, which is stored in the configuration profile. Every active mode
scan pushes new samples through the processing engine, which checks for new touch and release events on all enabled inputs.
If free run mode is enabled, the engine will repeatedly scan all enabled inputs during the active mode scan period. In this mode of
operation, the active mode scan period is used as a timer to determine how much time has passed since the last qualified active sensor
has been seen. When a defined amount of time without a qualified touch event has occurred, the engine switches to a low power mode
using the sleep mode scan period, and conserves current.
If free run mode is disabled, the engine will enter a low power state after completing one scan of all enabled inputs and processing the
resulting samples. The engine will remain in this low power state until it wakes, at a time defined by active mode scan period, to perform
another scan.
CPT212B Data Sheet
Functional Description
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4.1.10 Active Mode Scan Type
The active mode scan type, which is stored in the configuration profile, controls whether the capacitive sensing engine in active mode
will scan only once during the active mode scan period before going to sleep, or whether the engine will continue scanning as quickly
as possible during the active mode scan period, never entering a low power state.
For optimal responsiveness, the engine should be configured to run with free run mode enabled. Setting the scan mode to 'free run'
causes touch qualification on a new touch to occur as quickly as the scanning engine can convert and process samples on all sensors.
In this mode, qualification time is not bounded by active mode scan period, and is only bounded by scanning configuration factors such
as the debounce setting, the number of enabled sensors, the accumulation setting on each sensor, and the timing constraints of any
enabled component.
For optimal current draw when in active mode, the engine should be configured to use the 'one scan per period' mode setting. In this
case, touch qualification is bound by the scan period and the debounce setting of the device.
Touch Event
(t = 0 ms) 10 ms 20 ms 30 ms 40 ms
Optimized
Active sample sample
Active process additional
processing process additional
processing
Sleep sleep sleep
debounce
count = 1
touch
qualified
Figure 4.2. Timing and Current — One Sample Per Period Mode
Touch Event
(t = 0 ms) 10 ms 20 ms 30 ms 40 ms
Optimized
Active sample
Active process additional
processing
Sleep
debounce
count = 1
touch
qualified
sample
process additional
processing
Figure 4.3. Timing and Current — Free Run Mode
4.1.11 Sleep Mode Scan Period
The sleep mode scan period defines the rate at which a scan of the inputs enabled as wake-up sources are sampled. Each enabled
sensor can also be enabled as a wake-up source. After the sleep mode scan completes, the scan is processed for a qualified candidate
touch. If a candidate touch is qualified, the system wakes form sleep mode and enters active mode scanning.
The sleep mode scan period is stored in the configuration profile and is defined in units of ms.
CPT212B Data Sheet
Functional Description
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4.1.12 Active Mode and Sleep Mode Transitions
Capacitive sensing inputs will stay in active mode until no inputs detect qualified touches for a span of time defined by the counts until
sleep parameter stored in the configuration profile. The scan period of enabled inputs is defined by the active mode scan period, also
found in the configuration profile. If free run mode is enabled, the active mode sensing engine will remain awake and scanning the sen-
sors as fast as possible. If free run mode is disabled, the engine will put itself into a low power state for the remainder of the active
mode scan period, after a scan has completed.
When in sleep mode, the sensing engine will wake at a period defined by sleep mode scan period to do a scan on sensors that have
been enabled as wakeup sources. If the engine finds a candidate touch in this state, the system reverts to active mode to continue
scanning.
Note that in systems where a proximity input is selected, the sleep mode scan engine uses conversions on the proximity input instead
of sensors enabled as wakeup sources.
Devices configured to wake on a touch will attempt to qualify the candidate touch that initiated the sleep-to-active transition. If qualifica-
tion completes successfully, the device will signal this qualification to the external system. Touch qualification of this candidate touch
uses the same active mode thresholds, debounce setting, and active mode scan period settings as any touch that occurs during active
mode scanning.
qualified touch
release
Touch Delta
touch release new touch
Device Execution
no touch
counter = 1
no touch
counter = 2
...
no touch counter
= counts before
sleep
device enters
sleep
sleep scan sees
touch, wakes,
qualifies touch
no touch
counter = 0
t
Figure 4.4. Active and Sleep Transitions
4.2 I2C Event Buffer Interface
4.2.1 Introduction
The event buffer I2C interface provides an event-driven, packetized communication system describing newly qualified events generated
by the capacitive sensing input engine. The interface runs in one of two mutually exclusive modes: sensing mode and configuration
loading mode, where a new configuration profile can be downloaded to the device and stored in non-volatile memory.
CPT212B Data Sheet
Functional Description
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In sensing mode, the interface provides access to a first-in-first-out buffer of data packets. When the sensing engine generates these
packets and pushes them onto the buffer, the interface then signals the host to indicate that one or more packets are available in the
buffer by activating the event buffer interrupt pin.
In sensing mode, the interrupt pin is defined as active-low and operates as a push-pull digital output. In configuration loading mode, the
interrupt pin is configured as a digital input and functions as a chip select. I2C transactions will be ignored by the device unless the host
has pulled the interrupt pin low before sending the start condition.
The host reads the packets through an I2C interface, with the host acting as an I2C master. Once all packets have been fully transmit-
ted across the I2C interface, the event buffer interrupt pin is de-activated. The device will remain in active mode until no packets remain
in the buffer, even if no sensors have been qualified as active for the period of time defined by the active mode scan period.
In configuration loading mode, the interface enables an in-system programming initiated by the host. In this mode, the host can update
the performance configuration space.
4.2.2 Startup Behavior
When the device exits a POR or hardware reset, it first enters configuration loading mode, discussed in detail 4.2.10 Configuration
Loading Procedure. A host can command the device to enter sensing mode using the mode selection command discussed in
4.2.8 Entering Sensing Mode from Configuration Loading Mode. If the device has a valid configuration profile stored in non-volatile
memory, the device will then enter sensing mode and remain in this mode until the next power cycle or reset.
4.2.3 Sensing Mode Event Packet Structure
Every qualified event detected by the capacitive sensing input engine generates a single packet that can be retrieved by the host pro-
cessor through the event buffer I2C interface. The packet is an atomic data unit that fully describes the generated event.
Note: The bytes in the packet are transmitted MSB first.
Each packet has a standard structure that can be parsed by the host.
Table 4.1. Standard Packet Structure
Byte # Designator
0 I2C Slave Address + read bit
1 Packet counter and event type
2 Event description (byte 1)
3 Event description (byte 2)
CPT212B Data Sheet
Functional Description
silabs.com | Building a more connected world. Rev. 1.1 | 21
Not Recommended for New Designs
The packet counter is a 4-bit number stored in the upper bits of byte 1. Each new event will be assigned a counter value that is +1 from
the last qualified event. After event 15, the counter wraps back to 0 for the next event. The counter captures the temporal nature of
touch events so that a host can reconstruct a sequence of events over time. Also, the host can use the counter value to determine if a
packet has been lost due to a buffer overflow. The event buffer counter is reset to 0 upon entrance to sensing mode.
The event type is a 4-bit value describes the originator of the event. For instance, the source could be a capacitive sensing button. The
event type is stored in the lower 4 bits of byte 1.
The event description bytes define characteristics of the event that have been qualified. Event descriptions are defined relative to the
event source. An event source that is a capacitive sensing input will have a defined set of valid event description values. Those same
values will mean something different for a different type of event source. Event description values are defined relative to the event type
field of byte 1.
Touch
Event
I2C Slave Address
+ read bit CSxx index 0x00
byte 0 byte 2 byte 3
Touch
Release
Event
I2C Slave Address
+ read bit CSxx index 0x00
byte 0 byte 2 byte 3
packet
counter
xxxx
event
type
0000
packet
counter
xxxx
event
type
0001
byte1
byte1
Proximity
Event
I2C Slave Address
+ read bit
byte 0 byte 2 byte 3
byte1
packet
counter
xxxx
event
type
0011
byte 3
0x00 0x00
Figure 4.5. I2C Event Buffer Packet Structure
The CSxx index transmitted in byte 2 for Touch and Touch Release events enables the host processor to determine the sensor that
caused the event.
4.2.4 Packet Retrieval in Sensing Mode
When the least significant byte of an event packet has been transferred during a master read transaction, that event is popped from the
device's buffer. If only a part of the event is read, the event will stay in the buffer and will be transmitted again by the device during the
next read.
If the host initiates a master read when the device is in sensing mode but the interrupt pin is not active, signifying that the device has no
events in its buffer to transmit, the device will NACK its slave address on the bus.
If the I2C master sends a stop condition on the bus before the entire packet has been read, the device will not pop the packet from its
internal buffer. Instead, the I2C state machine will reset, and the next transaction will begin with the first byte of the same event that
was being read in the previous, prematurely-terminated transaction.
The I2C event buffer has a depth of 22 events. If the host does not read events promptly after seeing the interrupt pin go active, there is
the possibility of a buffer overflow. In the event of an overflow, the I2C engine will discard the oldest events first.
New I2C packets will only be generated at the active mode sample rate, and so the buffer will fill a maximum of 12 packets (in the case
simultaneous touch/releases) per sample period. If the host runs the I2C bus at 400 kHz and reads packets as soon as the interrupt pin
activates, all packets can be read from the buffer in 1 to 2 ms, which is faster than the rate at which a new active mode scan sequence
can complete.
CPT212B Data Sheet
Functional Description
silabs.com | Building a more connected world. Rev. 1.1 | 22
Not Recommended for New Designs
4.2.5 Defined Event Types
The device assigns the following event types:
Table 4.2. Event Type Mapping
Event Type Value Mapping
Sensing Mode
0 (0x0) Sensor activity - touch event
1 (0x1) Sensor activity - release event
3 (0x3) Proximity activity
Configuration Loading Mode
8 (0x8) Mode selection
9 (0x9) Configuration unlock
10 (0xA) Configuration erase
11 (0xB) Write configuration
12 (0xC) Write CRC
Note that this event type value is stored in the lower 4 bits of the first non-address byte of a packet. The upper 4 bits are a packet
counter value.
4.2.6 Description Bytes for Touch Events
A touch or release event uses only one byte of the description field. That field identifies which sensor caused the touch or release event
as shown below.
Table 4.3. Touch or Release Event Sensor Mapping
Value Mapping
0 Capacitive sensing input 0
1 Capacitive sensing input 1
2 Capacitive sensing input 2
3 Capacitive sensing input 3
4 Capacitive sensing input 4
5 Capacitive sensing input 5
6 Capacitive sensing input 6
7 Capacitive sensing input 7
8 Capacitive sensing input 8
9 Capacitive sensing input 9
10 Capacitive sensing input 10
11 Capacitive sensing input 11
CPT212B Data Sheet
Functional Description
silabs.com | Building a more connected world. Rev. 1.1 | 23
Not Recommended for New Designs
4.2.7 Slave Address
When the device comes out of reset and has not been commanded to enter sensing mode, the device responds to the slave address
0xC0. Additionally, the device will only respond to commands with address 0xC0 if the host drives the interrupt pin low, using the pin as
a chip select.
In sensing mode, the device responds to I2C transactions addressed to the slave address stored in the configuration profile.
4.2.8 Entering Sensing Mode from Configuration Loading Mode
Upon exiting reset, the device enters configuration loading mode. During this time, a host can re-write the configuration profile through a
sequence of master write commands. The host can also command the device to enter sensing mode using the mode selection com-
mand. The mode switch command is structured as shown in the following figure.
Mode Selection
byte 1
packet
counter
xxxx
event
type
1000
byte 2
0x010xC0 + write bit
byte 0
Note: The INT pin must be driven low prior to the I2C start and high after the I2C
stop.
Figure 4.6. Mode Selection Command
The device will only enter sensing mode if the configuration profile stored in non-volatile memory is valid. The validity of the configura-
tion profile can be checked using the Configuration Profile Validity Check command.
Note that this mode setting feature must be executed once per device, per reset. Until this command has been received by a device,
the device will remain in its startup state and not performing any touch qualification.
4.2.9 Determining Configuration Validity
At any point when the device is in configuration loading mode, the host can issue a Configuration Profile Validity Check command. This
command is issued when the host starts a master read command. This command is unique in that it does not include a byte containing
the packet counter or event type.
Configuration Profile
Validity Check
byte 1
Configuration
Profile State
0xC0 + read bit
byte 0
Note: The INT pin must be driven low prior to the I2C start and high
after the I2C stop.
Note: This is a read transaction where data is provided from the
CPT device.
Figure 4.7. Configuration Profile Validity Check Command
CPT212B Data Sheet
Functional Description
silabs.com | Building a more connected world. Rev. 1.1 | 24
Not Recommended for New Designs
Table 4.4. Decoding the Configuration Profile State
Value Description
0x80 Configuration profile valid
0x01 Configuration profile invalid
The validity of the configuration profile is determined by comparing a CRC stored in non-volatile memory to a CRC generated at runtime
by the device. The CRC is calculated using the algorithm described in 4.2.11 CRC Algorithm.
Note: The CRC for the configuration profile spans 510 bytes, with 0xFF padding in addresses above any non-0xFF configuration profile
bytes.
CPT212B Data Sheet
Functional Description
silabs.com | Building a more connected world. Rev. 1.1 | 25
Not Recommended for New Designs
4.2.10 Configuration Loading Procedure
Once the device has been configured to configuration bootload mode, the I2C interface can accept and process the bootload command
set. The bootloading procedure executes as follows in the steps below. Valid bootload mode commands are shown below.
1. Host sends the configuration loading unlock sequence.
2. Host sends config erase command, which erases the configuration profile. Packet should be resent until device ACKs reception.
3. Host sends bytes 0-7 of configuration profile in a write config command. Packet resent until device ACKs reception.
4. Host repeats process of the previous step, sending the next 8 bytes of the config profile in a write config command, resending until
packet is ACKed.
5. After all 8-byte packets of the configuration profile have been transmitted to the device and ACKed by the device, host sends write
CRC command. This CRC uses the algorithm described in 4.2.11 CRC Algorithm.
6. Host sends a mode switch command to enter sensing mode.
Once the device has successfully entered sensing mode after a mode switch command, the device will remain in sensing mode until a
hardware reset.
Configuration
Unlock
0xC0 + write bit
byte 0 byte 2
packet
counter
xxxx
event
type
1001
byte 1
0xA5
byte 3
0xF1
Configuration
Erase
Write CRC
Write
Configuration
Configuration
Profile Validity
Check
0xC0 + write bit
byte 0
packet
counter
xxxx
event
type
1010
byte 1
0xC0 + write bit
byte 0
packet
counter
xxxx
event
type
1011
byte 1
... xx
byte 8
xx
byte 9
0xC0 + write bit
byte 0
packet
counter
xxxx
event
type
1100
byte 1
Config
Profile CRC
MSB
byte 3
Config
Profile CRC
LSB
byte 4
byte 0 byte 1
Configuration
Profile State
0xC0 + read bit
byte 2 byte 3
xx xx
Note: The INT pin must be driven low prior to the I2C start and high after the I2C stop for
each of these commands.
Figure 4.8. Configuration Loading Command Sequence
CPT212B Data Sheet
Functional Description
silabs.com | Building a more connected world. Rev. 1.1 | 26
Not Recommended for New Designs
Mode Selection
byte 1
packet
counter
xxxx
event
type
1000
byte 2
0x010xC0 + write bit
byte 0
Note: The INT pin must be driven low prior to the I2C start and high after the I2C
stop.
Figure 4.9. Entering Sensing Mode
See 4.2.5 Defined Event Types for a list of all sensing and configuration mode event types values.
CPT212B Data Sheet
Functional Description
silabs.com | Building a more connected world. Rev. 1.1 | 27
Not Recommended for New Designs
4.2.11 CRC Algorithm
The CRC is generated using the standard CCITT-16 16-bit polynomial (0x1021) with an initial seed of 0xFFFF.
The device generates a 16-bit CRC result equivalent to the following algorithm:
1. XOR the input with the most-significant bits of the current CRC result. If this is the first iteration of the CRC unit, the current CRC
result will be the set initial value (0x0000 or 0xFFFF).
2. If the MSB of the CRC result is set, shift the CRC result and XOR the result with the polynomial.
3. If the MSB of the CRC result is not set, shift the CRC result.
4. Repeat steps 2 and 3 for all 8 bits.
The algorithm is also described in the following example.
unsigned short UpdateCRC (unsigned short CRC_acc, unsigned char CRC_input)
{
unsigned char i; // loop counter
#define POLY 0x1021
// Create the CRC "dividend" for polynomial arithmetic (binary arithmetic
// with no carries)
CRC_acc = CRC_acc ^ (CRC_input << 8);
// "Divide" the poly into the dividend using CRC XOR subtraction
// CRC_acc holds the "remainder" of each divide
//
// Only complete this division for 8 bits since input is 1 byte
for (i = 0; i < 8; i++)
{
// Check if the MSB is set (if MSB is 1, then the POLY can "divide"
// into the "dividend")
if ((CRC_acc & 0x8000) == 0x8000)
{
// if so, shift the CRC value, and XOR "subtract" the poly
CRC_acc = CRC_acc << 1;
CRC_acc ^= POLY;
}
else
{
// if not, just shift the CRC value
CRC_acc = CRC_acc << 1;
}
}
// Return the final remainder (CRC value)
return CRC_acc;
}
The following table lists several input values and the associated outputs using this 16-bit CRC algorithm:
Table 4.5. Example 16-bit CRC Outputs
Input Output
0x63 0xBD35
0x8C 0xB1F4
0x7D 0x4ECA
0xAA, 0xBB, 0xCC 0x6CF6
0x00, 0x00, 0xAA, 0xBB, 0xCC 0xB166
CPT212B Data Sheet
Functional Description
silabs.com | Building a more connected world. Rev. 1.1 | 28
Not Recommended for New Designs
4.3 Capacitive Proximity Sensing
4.3.1 Wake on Proximity
The wake on capacitive proximity detection engine monitors for the presence of a conductive object such as a hand to move within
detectable range of the sensor. When the engine detects an object, the device wakes from sleep and can begin qualifying touch events
on all sensors enabled for active mode sensing.
4.3.2 Proximity Configuration
The proximity sensing feature uses a single sensor input for proximity qualification. The configuration profile stores the pin chosen by
the user. The sensor used for proximity qualification should also have a drive strength setting that is as high as possible without saturat-
ing the input when no conductive object is in proximity to the proximity sensor. The accumulation setting of the input is also configura-
ble.
The proximity threshold controls the sensitivity of the input. A lower threshold setting increases sensitivity and increases the range of
the sensor.
A proximity sensing input cannot be used for touch qualification, and so the active and inactive thresholds are not used for proximity
sensors. Additionally, the proximity input has no effect on other components of the device such as mutually exclusive button groups,
buzzer output, and touch time out timers.
4.4 Buzzer Output
4.4.1 Introduction
The buzzer output engine produces a square wave of a configurable duration and frequency when a capacitive sensing input goes from
inactive to active. The feature can be enabled and disabled through the configuration profile. The configuration profile also includes the
settings for active duration and frequency.
No Touch, Buzzer Inactive
Device Execution
Optimized
Active sample sample
Active process additional
processing process additional
processing
Sleep sleep sleep
Figure 4.10. Effects of the Buzzer on Current Draw — Active Mode, No Touch, Buzzer Inactive
CPT212B Data Sheet
Functional Description
silabs.com | Building a more connected world. Rev. 1.1 | 29
Not Recommended for New Designs
Touch Detected, Buzzer Active
Device Execution
Optimized
Active
Active additional
processing
Sleep
sleep
(stall)
sample
process additional
processing
sleep
(stall)
sample
process
Figure 4.11. Effects of the Buzzer on Current Draw — Active Mode, Touch Detected, Buzzer Active
4.4.2 Buzzer Configuration
When enabled, buzzer output will appear on the CS11/buzzer pin (pin 10) of the device. When buzzer output is enabled, CS11 is not
available for capactive input sensing.
When activated, the buzzer will remain active for either the duration specified in the configuration profile, or until the last active sensor
has qualified a touch release.
The configuration profile supports configuration of output frequencies ranging from 1 kHz to 4 kHz.
The configuration profile can configure the buzzer output pin to either push pull mode or open drain mode.
4.5 Mutually Exclusive Buttons
When enabled through the configuration profile, this system allows one and only one capacitive sensing input to be qualified as active
at a time. The first sensor active will remain the only sensor active until released. The device will internally qualify multiple touch and
release events but will not report them.
CPT212B Data Sheet
Functional Description
silabs.com | Building a more connected world. Rev. 1.1 | 30
Not Recommended for New Designs
If multiple sensors have been internally qualified as active, the first sensor's touch event will be reported. If a touch event occurs simul-
taneously on more than one sensor, the touch with the highest touch delta will be reported.
If two sensors are qualified as active and the sensor being reported as active qualifies a touch release, the device will report that re-
lease and then report a touch qualification on the still-active second sensor.
In the case where a device has simultaneously qualified more than two active sensors and the reported active sensor qualifies and
reports a release, the remaining qualified sensor with the highest sensor name will then be reported. For example, if sensors CS00,
CS01, and CS02 are active with CS00 externally reported as active, after CS00's release, CS02 would be externally reported as an
active sensor unless the device has already qualified a touch release on CS02.
If both the touch timeout feature and the mutually exclusive button group feature are enabled, the timeout timer will only run on the
touch that is externally reported as being active.
CS00
Device Execution
CS01 CS02
physical touch on pad
touch reported by CPT device
release reported by CPT device
Figure 4.12. Mutually-Exclusive Button Operation
4.6 Configuration Profile
The configuration interface is used by the device to configure default values and performance characteristics that effect capacitive
sensing. The configuration data can be programmed through the Configuration interface (Config Clk and Config Data pins) using
[Xpress Configurator] in Simplicity Studio or through the I2C interface from the host processor.
Several configuration profile templates are available in Simplicity Studio to provide a starting point for development.
CPT212B Data Sheet
Functional Description
silabs.com | Building a more connected world. Rev. 1.1 | 31
Not Recommended for New Designs
5. Pin Definitions
5.1 CPT212B QFN20 Pin Definitions
20
19
18
17
2
3
4
5
7
8
9
10
15
14
13
12
20 pin QFN
(Top View)
CS01
CS00
GND
VDD
RSTb /
Config Clk
Config Data
CS06
CS07
CS08
CS09
GND
CS10
CS02
CS03
CS04
CS05
GND
1
6 11
16
EB_INT
EB_SCL
EB_SDA
CS11 /
BUZZER
Figure 5.1. CPT212B QFN20 Pinout
Table 5.1. Pin Definitions for CPT212B QFN20
Pin
Number
Pin Name Description
1 CS01 Analog input
Capactive sensing input 1
2 CS00 Analog input
Capacitive sensing input 0
3 GND Ground
4 VDD Supply power input
5 RSTb /
Config Clk
Active-low reset /
Configuration clock
6 Config Data Configuration data
CPT212B Data Sheet
Pin Definitions
silabs.com | Building a more connected world. Rev. 1.1 | 32
Not Recommended for New Designs
Pin
Number
Pin Name Description
7 EB_INT Push-pull digital output
Event buffer interrupt pin
8 EB_SCL Open drain digital output
Event buffer I2C SCL
9 EB_SDA Open drain digital input
Event buffer I2C SDA
10 CS11 /
Buzzer
Analog input, capacitive sensing input 11
Digital output for buzzer
11 CS10 Analog input
Capacitive sensing input 10
12 GND Ground
13 CS09 Analog input
Capacitive sensing input 9
14 CS08 Analog input
Capacitive sensing input 9
15 CS07 Analog input
Capacitive sensing input 7
16 CS06 Analog input
Capacitive sensing input 6
17 CS05 Analog input
Capacitive sensing input 5
18 CS04 Analog input
Capacitive sensing input 4
19 CS03 Analog input
Capacitive sensing input 3
20 CS02 Analog input
Capacitive sensing input 2
CPT212B Data Sheet
Pin Definitions
silabs.com | Building a more connected world. Rev. 1.1 | 33
Not Recommended for New Designs
6. QFN20 Package Specifications
6.1 QFN20 Package Dimensions
Figure 6.1. QFN20 Package Drawing
Table 6.1. QFN20 Package Dimensions
Dimension Min Typ Max
A 0.50 0.55 0.60
A1 0.00 — 0.05
b 0.20 0.25 0.30
b1 0.275 0.325 0.375
D 3.00 BSC
D2 1.6 1.70 1.80
e 0.50 BSC
e1 0.513 BSC
E 3.00 BSC
E2 1.60 1.70 1.80
L 0.35 0.40 0.45
L1 0.00 — 0.10
CPT212B Data Sheet
QFN20 Package Specifications
silabs.com | Building a more connected world. Rev. 1.1 | 34
Not Recommended for New Designs
Dimension Min Typ Max
aaa — 0.10 —
bbb — 0.10 —
ddd — 0.05 —
eee — — 0.08
Note:
1. All dimensions shown are in millimeters (mm) unless otherwise noted.
2. Dimensioning and Tolerancing per ANSI Y14.5M-1994.
3. This drawing is based upon JEDEC Solid State Product Outline MO-248 but includes custom features which are toleranced per
supplier designation.
4. Recommended card reflow profile is per the JEDEC/IPC J-STD-020 specification for Small Body Components.
CPT212B Data Sheet
QFN20 Package Specifications
silabs.com | Building a more connected world. Rev. 1.1 | 35
Not Recommended for New Designs
6.2 QFN20 PCB Land Pattern
Figure 6.2. QFN20 PCB Land Pattern Drawing
Table 6.2. QFN20 PCB Land Pattern Dimensions
Dimension Min Max
C1 2.70
C2 2.70
C3 2.53
C4 2.53
E 0.50 REF
X1 0.20 0.30
X2 0.24 0.34
X3 1.70 1.80
Y1 0.50 0.60
Y2 0.24 0.34
Y3 1.70 1.80
CPT212B Data Sheet
QFN20 Package Specifications
silabs.com | Building a more connected world. Rev. 1.1 | 36
Not Recommended for New Designs
Dimension Min Max
Note:
1. All dimensions shown are in millimeters (mm) unless otherwise noted.
2. Dimensioning and Tolerancing is per the ANSI Y14.5M-1994 specification.
3. This Land Pattern Design is based on the IPC-7351 guidelines.
4. All metal pads are to be non-solder mask defined (NSMD). Clearance between the solder mask and the metal pad is to be 60 µm
minimum, all the way around the pad.
5. A stainless steel, laser-cut and electro-polished stencil with trapezoidal walls should be used to assure good solder paste release.
6. The stencil thickness should be 0.125 mm (5 mils).
7. The ratio of stencil aperture to land pad size should be 1:1 for the perimeter pads.
8. A 2x2 array of 0.75 mm openings on a 0.95 mm pitch should be used for the center pad to assure proper paste volume.
9. A No-Clean, Type-3 solder paste is recommended.
10. The recommended card reflow profile is per the JEDEC/IPC J-STD-020 specification for Small Body Components.
6.3 QFN20 Package Marking
212B
TTTT
YWW+
Figure 6.3. QFN20 Package Marking
The package marking consists of:
•212B – The part number designation.
• TTTT – A trace or manufacturing code. The first letter of this code is the hardware revision.
• Y – The last digit of the assembly year.
• WW – The 2-digit workweek when the device was assembled.
• + – Indicates the device is RoHS-compliant.
CPT212B Data Sheet
QFN20 Package Specifications
silabs.com | Building a more connected world. Rev. 1.1 | 37
Not Recommended for New Designs
7. Relevant Application Notes
The following Application Notes are applicable to the CPT212B devices:
•AN957: TouchXpress™ Configuration and Profiling Guide — This application note guides developers through the evaluation and
configuration process of TouchXpress devices using Simplicity Studio [Xpress Configurator] and [Capacitive Sense Profiler].
•AN447: Printed Circuit Design Notes for Capacitive Sensing Performance — This document describes hardware design guidelines
specifically for capacitive sensing applications, including button placement and other layout guidelines.
•AN949: TouchXpress™ Programming Guide — This application note discusses the production programming options available for
TouchXpress devices.
Application Notes can be accessed on the Silicon Labs website (www.silabs.com/interface-appnotes) or in Simplicity Studio in the [Doc-
umentation]>[Application Notes] area.
CPT212B Data Sheet
Relevant Application Notes
silabs.com | Building a more connected world. Rev. 1.1 | 38
Not Recommended for New Designs
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Disclaimer
Silicon Labs intends to provide customers with the latest, accurate, and in-depth documentation of all peripherals and modules available for system and software implementers using or
intending to use the Silicon Labs products. Characterization data, available modules and peripherals, memory sizes and memory addresses refer to each specific device, and "Typical"
parameters provided can and do vary in different applications. Application examples described herein are for illustrative purposes only. Silicon Labs reserves the right to make changes
without further notice and limitation to product information, specifications, and descriptions herein, and does not give warranties as to the accuracy or completeness of the included
information. Silicon Labs shall have no liability for the consequences of use of the information supplied herein. This document does not imply or express copyright licenses granted
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