ETC2 IQS253 Configurable 3 channel dycal capacitive sensor with automatic compensation Datasheet

IQ Switch®
ProxSense® Series
IQS253 Datasheet - Configurable 3 Channel DYCALTM
Capacitive Sensor with Automatic Compensation for
Sensitivity Reducing Objects
Unparallelled Features:
o DYCALTM : Intelligent Hysteresis
o Internal Capacitor Implementation (ICI) - Reference capacitor on-chip
o Automatic Tuning Implementation (ATI) - Automatic adjustment for optimal sensor performance
The IQS253 ProxSense® IC is a fully integrated capacitive sensor implementing Dynamic Calibration (DYCALTM ) technology: intelligent hysteresis to allow for sensor drift even during sensor
activation.
Main features:
o Self or Projected Technology sensors
o 3 Channels configurable as DYCALTM /Normal output
o Self: Boolean direct output configurable through I2 C
o Supply voltage: 1.8 V to 3.6 V
o Internal voltage regulator
o Advanced on-chip digital signal processing
o I2 C adjustable settings
• DYCALTM settings
• Control over filter operation
• Time-out for stuck key
• Proximity and Touch sensitivity selections
• Low Power options
• Event Mode possible (only communicates if an event is detected)
o Any applications where a touch and proxim-
Applications:
ity condition can exist for a extended period of time
o Occupancy sensors
o SAR complient sensors for Tablet PC’s
Advantages:
o On-ear detection for mobile phones
and non-activation
o 3D glasses
o Improved digital filtering to reduce external
o Personal Media Players
noise
o Remote Control Sleep implementation
o Gaming Controllers
o Allows for sensor drift in periods of activation
o Highly adjustable I2 C device which only interrupts (Event Mode) when an event is
detected
o Proximity activated backlighting
Copyright ©
Azoteq
IQS253 Datasheet V1.04
1of 53
IQ Switch®
ProxSense® Series
Contents
List of Figures
4
List of Tables
4
Revision History
4
List of Symbols
5
1 Functional Overview
1.1 Applicability . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
6
6
2 Analogue Functionality
6
3 Digital Functionality
7
4 Packaging and Pin-Out
4.1 IQS253 Self Capacitance . . . . . . . . . .
4.2 IQS253 Projected . . . . . . . . . . . . . .
4.3 Power Supply and PCB Layout . . . . . . .
4.4 Design Rules for Harsh EMC Environments
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8
. 8
. 9
. 10
. 11
5 DYCAL
12
5.1 Operating Principle . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
6 ProxSense Module
14
6.1 Charge Transfer Concepts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
7 Prox Module Setup
7.1 Self or Projected Capacitance . .
7.2 Rate of Charge Cycles . . . . . .
7.3 Report Rate . . . . . . . . . . . .
7.4 Active Channels . . . . . . . . . .
7.5 DYCALTM or Direct Output . . . .
7.6 Report Order (Channel Numbers)
7.7 Transfer Frequency (fcx ) . . . . . .
7.8 Counts . . . . . . . . . . . . . . .
7.9 Long Term Average (LTA) . . . . .
7.10 Determine Touch or Prox . . . . .
7.11 ATI . . . . . . . . . . . . . . . . .
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14
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8 DYCALTM
8.1 DYCALTM channels enable . . . .
8.2 DYCALTM on TOUCH/PROX . . .
8.3 LTA Adapt rates (IN and OUT) . .
8.4 Block Channel . . . . . . . . . . .
8.5 DYCALTM Release Threshold . . .
8.6 DYCALTM dynamic touch threshold
8.7 10s_ATI_BLOCK . . . . . . . . .
8.8 250ms_DELAY_TM (tDYCAL ) . . .
8.9 Turbo Mode . . . . . . . . . . . .
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19
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21
Copyright ©
Azoteq
IQS253 Datasheet V1.04
2of 53
IQ Switch®
ProxSense® Series
9 Communication
9.1 IC Setup Window . . . . . .
9.2 Event Mode . . . . . . . . .
9.3 I2 C Specific Commands . . .
9.4 I2 C Read and Write specifics
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10 Boolean Output
10.1 Channels for Boolean operation
10.2 Boolean NOT . . . . . . . . . .
10.3 Boolean AND/OR . . . . . . . .
10.4 Order of Boolean operation: . .
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22
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11 RF Noise
24
11.1 Noise Immunity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
12 Electrical Specifications
26
12.1 General Characteristics (Measured at 25 °C) . . . . . . . . . . . . . . . . . . . . . . 26
12.2 Timing Characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
13 Mechanical Dimensions
29
14 Device Marking
31
15 Ordering Information
31
16 Device Revision History
32
17 Errata
32
18 Contact Information
33
A Appendix A
34
B Appendix B
B.1 IQS253 Memory Map . . . . .
B.2 General Implementation Hints
B.3 Startup Procedure . . . . . . .
B.4 General I2 C Hints . . . . . . .
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References
36
36
52
52
52
53
List of Figures
4.1
4.2
4.3
4.4
5.1
7.1
7.2
9.1
13.1
13.2
13.3
IQS253 Pin Out. . . . . . . . . . . . . .
Self Reference Design. . . . . . . . . .
Projected Reference Design. . . . . . .
EMC Design Choices. . . . . . . . . . .
DYCAL Overview. . . . . . . . . . . . .
Boost power as on CX/CRXx. . . . . . .
Charge cycles as charged in LP modes.
IC Setup Window. . . . . . . . . . . . .
MSOP10 Package . . . . . . . . . . . .
MSOP10 Footprint. . . . . . . . . . . .
MSOP10 Silk Screen. . . . . . . . . . .
Copyright ©
Azoteq
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IQS253 Datasheet V1.04
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3of 53
IQ Switch®
ProxSense® Series
13.4
13.5
13.6
A.1
A.2
A.3
DFN-10 Package. . . . . . . . . . .
DFN Side View. . . . . . . . . . . .
DFN Footprint. . . . . . . . . . . . .
DYCAL output selected on proximity.
DYCAL output selected on touch. . .
Filter halt upon Touch Mode Entry. .
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29
30
30
34
34
35
IQS253 Self Capacitive Pin-out . . . . . . . . . . . . . . . . . . . . . . .
IQS253 Projected Capacitive Pin-out . . . . . . . . . . . . . . . . . . . .
LTA halting in non-TM. . . . . . . . . . . . . . . . . . . . . . . . . . . . .
IQS253 General Operating Conditions - Projected Capacitive Sensor. . .
IQS253 General Operating Conditions - Self Capacitive Sensor. . . . . .
Start-up and shut-down slope Characteristics . . . . . . . . . . . . . . .
Debounce employed on IQS253. . . . . . . . . . . . . . . . . . . . . . .
General Timing Characteristics for 1.80V ≤ VDDHI ≤ 3.60V . . . . . . .
IQS253 charging times . . . . . . . . . . . . . . . . . . . . . . . . . . .
IQS253 DYCAL (OUTPUT_ON_TOUCH = 0) /Proximity Response Times
MSOP10 Package Dimensions. . . . . . . . . . . . . . . . . . . . . . .
MSOP-10 Footprint Dimensions . . . . . . . . . . . . . . . . . . . . . .
MSOP-10 Silk Screen Dimensions . . . . . . . . . . . . . . . . . . . . .
DFN-10 Package Dimensions. . . . . . . . . . . . . . . . . . . . . . . .
DFN-10 Side View Dimensions. . . . . . . . . . . . . . . . . . . . . . .
DFN-10 Footprint Dimensions . . . . . . . . . . . . . . . . . . . . . . .
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8
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18
26
26
27
27
27
28
28
29
29
29
30
30
30
List of Tables
4.1
4.2
7.1
12.1
12.2
12.3
12.4
12.5
12.6
12.7
13.1
13.2
13.3
13.4
13.5
13.6
Revision History
Rev
1.0.1
1.00
1.01
1.02
1.03
1.04
Copyright ©
Azoteq
Description
Preliminary
First Release
Update HC description
Update DFN-10 Footprint
Include the Memory Map in the Datasheet
Update Self Reference Schematic with pull-up on Boolean Output
IQS253 Datasheet V1.04
Date
Sept 2011
Jan 2012
March 2012
April 2012
April 2012
June 2012
4of 53
IQ Switch®
ProxSense® Series
List of Symbols
ATI
BP
CS
CX
EMI
ESD
FTB/EFT
GND
HC
LP
LTA
ND
NTM
P
RDY
SCL
SDA
t
T
THR
TM
TVS
VDDHI
VREG
WDT
Copyright ©
Azoteq
Automatic Tuning Implementation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
Boost Power Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
Count(s) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .13
Sensor Electrode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
Electromagnetic Interference . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
Electro-Static Discharge . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
(Electrical) Fast Transient Bursts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
Ground . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
Halt Charge . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
Low Power Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
Long Term Average . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .13
Noise Detect . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
Non Touch Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
Proximity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
Ready . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
I2 C Clock . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
I2 C Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
Time . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
Touch . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
Threshold . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
Touch Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
Transient VoltageSuppression diode - ESD protection . . . . . . . . . . . . . . . . . . . . . . . 6
Supply (input) Voltage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
Internal Regulator Output . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
Watch-dog Timer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
IQS253 Datasheet V1.04
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ProxSense® Series
1
Functional Overview
o Noise detection activation
The IQS253 is a fully integrated three channel
capacitive sensor implementing the DYCALTM
functionality. Dynamic Calibration (DYCALTM )
is an intelligent hysteresis to allow for sensor
drift even during sensor activation. All channels
can be either configured as a DYCALTM channel or as a normal direct output channel. The
device has an internal voltage regulator and reference capacitor. The regulator is used as reference for the charge transfer circuitry. Both
circuits reduce the external component count
needed. The device automatically tracks slow
varying environmental changes via various signal processing algorithms and has an Automatic Tuning (ATI) algorithm to calibrate the device to the sense electrode. The charge transfer method of capacitive sensing is employed
on the IQS253. (The charge transfer principle
is thoroughly described in the application note:
"AZD004 - Azoteq Capacitive Sensing".) The
IQS253 can be configured as either a self capacitance sensor, where it has a Boolean output pin available. With the sensor configured as
a projected capacitance sensor, this pin is configured as the transmitter electrode. DYCALTM
settings are highly configurable via I2 C. These
settings include:
o DYCALTM activation with either Touch or
o ATI setup (control over sensitivity and when
ATI should occur)
o Redo ATI
o Control over the LTA filters
o WDT enable / disable
o AC Filter enable / disable
o Proximity debounce
o Charge transfer frequency
o Block channel
o Event mode enable / disable
o Setup to wake communication with a particular event
1.1
All
Applicability
specifications,
except
where
specifi-
cally mentioned otherwise, provided by this
datasheet are applicable to the following
ranges:
o Temperature −40 °C to +85 °C
o Supply voltage (VDDHI) 1.8 V to 3.3 V
Proximity detection
o Release threshold
2
o Touch mode (TM) entry speed
The analogue circuitry measures the capaci-
o Downward filter adaptation rate when in TM
tance of the sense electrodes attached to the Cx
o Upward filter adaptation rate when in TM
Analogue Functionality
pins through a charge transfer process that is
periodically initiated by the digital circuitry. The
o ATI block after exiting activation
measuring process is referred to as a conver-
o Boolean output configuration
sion and consists of the discharging of Cs and
Cx, the charging of Cx and then a series of
The above mentioned configuration settings
charge transfers from Cx to Cs until a trip volt-
do not include regular ProxSense® settings ad-
age is reached. The number of charge transfers
justable via I2 C. Regular settings include:
required to reach the trip voltage is referred to
o Proximity / Touch Thresholds
as counts (Cs). The capacitance measurement
circuitry makes use of an internal reference ca-
o Power Modes
pacitor and voltage reference (VREG). The ana-
o Adaptation rate when not in TM
logue circuitry further provides functionality for:
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IQS253 Datasheet V1.04
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IQ Switch®
ProxSense® Series
o Power on reset (POR) detection.
o Brown out detection (BOD).
3
Digital Functionality
The digital processing functionality is responsible for:
o Management of BOD and WDT events.
o Initiation of conversions at the selected rate.
o Processing of CS and execution of algorithms.
o Monitoring and automatic execution of the
ATI algorithm.
o Signal processing and digital filtering.
o Detection of PROX and TOUCH events.
o Managing outputs of the device.
o Managing serial communications.
o Manage programming of OTP options.
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IQS253 Datasheet V1.04
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IQ Switch®
ProxSense® Series
4
Packaging and Pin-Out
The IQS253 IC is available in the MSOP-10 and DFN-10 package. The pin-outs of the self and
projected setup differ with the transmitter (CTX) on the projected configuration being configured as
a Boolean output (B_OUT) on the self configuration.
B Out/
CTX
GND
CX0
CX2
CX1
SCL
VDDHI
SDA
VREG
RDY/
ND
Figure 4.1: IQS253 Pin Out.
4.1
4.1.1
IQS253 Self Capacitance
Pin-out
Table 4.1: IQS253 Self Capacitive Pin-out
Pin
Name
Type
Function
1
GND
Supply Input
Ground Reference
2
CX0
Analogue
Sense Electrode 0
3
CX1
Analogue
Sense Electrode 1
4
VDDHI
Supply Input
Supply Voltage Input
5
VREG
Analogue Output
Internal Regulator Pin (Connect 1 µF bypass capacitor)
6
RDY/ND
Digital Out / Analogue In
I2 C: RDY Data indication Output / ND pin
7
SDA
Digital I/O
I2 C: Data Input / Output
8
SCL
Digital Input
I2 C: Clock Input
9
CX2
Analogue
Sense Electrode 2
10
B_OUT
Digital Output
Boolean Output (Open Drain - Requires pull-up resistor)
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IQS253 Datasheet V1.04
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IQ Switch®
ProxSense® Series
4.1.2
Schematic
VDDHI
IQS253
4
5
C3
C1
100pF
1uF
VDDHI
CX0/CRX0
VREG
CX1/CRX1
CX2/CRX2
C4
C2
100pF
1uF
2
R1
470R
3
R2
470R
9
R3
470R
VDDHI
SDA
SCL
GND
RDY/ND
1
GND
B_OUT/CTX
7
8
6
SDA
SCL
R8
RDY/ND
10
10K
BO
GND
VDDHI
SDA
R5
R6
R7
10K
10K
10K
SDA to MCU
SCL
SCL to MCU
RDY/ND
RDY to MCU
Figure 4.2: Typical application schematic of IQS253 self capacitive configuration.
4.2
IQS253 Projected
Table 4.2: IQS253 Projected Capacitive Pin-out
Pin
Name
Type
Function
1
GND
Supply Input
Ground Reference
2
CX0
Analogue
Projected Charge Receiver 0
3
CX1
Analogue
Projected Charge Receiver 1
4
VDDHI
Supply Input
Supply Voltage Input
5
VREG
Analogue Output
Internal Regulator Pin (Connect 1 µF bypass capacitor)
6
RDY/ND
Digital Out / Analogue In
I2 C: RDY Data indication Output / ND pin
7
SDA
Digital I/O
I2 C: Data Input / Output
8
SCL
Digital Input
I2 C: Clock Input
9
CX2
Analogue
Projected Charge Receiver 2
10
CTX
Analogue
Charge Transmitter
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IQS253 Datasheet V1.04
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IQ Switch®
ProxSense® Series
VDDHI
IQS253
4
5
C3
C1
100pF
1uF
VDDHI
CX0/CRX0
VREG
CX1/CRX1
CX2/CRX2
C4
C2
100pF
1uF
R1
470R
3
R2
470R
9
R3
470R
SDA
SCL
GND
RDY/ND
1
2
GND
B_OUT/CTX
7
8
6
SDA
SCL
RDY/ND
10
R4
470R
GND
VDDHI
R5
R6
R7
10K
10K
10K
SDA
SDA to MCU
SCL
SCL to MCU
RDY/ND
RDY to MCU
Figure 4.3: Typical application schematic of IQS253 projected capacitive configuration. Refer
to the application note for layout guideline [1]
4.3
Power Supply and PCB Layout
Azoteq IC’s provide a high level of on-chip hardware and software noise filtering and ESD protection
(refer to Section 12). Designing PCB’s with better noise immunity against EMI, FTB and ESD in
mind, it is always advisable to keep the critical noise suppression components like the de-coupling
capacitors and series resistors in Figure 4.2 as close as possible to the IC. Always maintain a good
ground connection and ground pour underneath the IC. For more guidelines please refer to the
relevant application notes as mentioned in Section 4.4.
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IQS253 Datasheet V1.04
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IQ Switch®
ProxSense® Series
4.4
Design Rules for Harsh EMC Environments
START
Radiated RF
AZD015
• Rx > 1k may be required
• Long Cx traces not ok
• Use RF detection as last
resort
1) Determine Prox,
Touch & Data
requirements
2) Choose Device
Conducted RF
AZD052
• Preferably use Rx of 470
• Filtering and grounding of
supply very NB
• Traces < 200mm ok
What is the
biggest EMC
threat?
Electro-Static Discharge
Fast Transient Bursts
•
•
•
•
AZD013
• Preferably use Rx of 470
• Rather use TVS than higher
Rx to protect
• Grounding of TVS NB
AZD051
Rx > 1k may be required
Long Cx traces ok
Careful with Cx pad size
Grounding very NB
Figure 4.4: EMC Design Choices. Applicable application notes: [2], [3], [4], [5]
Copyright ©
Azoteq
IQS253 Datasheet V1.04
11of 53
Copyright ©
Azoteq
5 DYCAL
Non-TM
LTA & CS
PTHR
TM
Recallibrate LTA
TTHR
LTARATE = LTA_ADAPT_IN
LTARATE = LTA_ADAPT_OUT
Non-TM: Non-Touch Mode
TM: Touch Mode
1
0
1
TO
0
1
DYCAL
0
12of 53
Figure 5.1: DYCAL Overview.
IQ Switch®
CS
LTA – Long Term Average of CS
PTHR - derived from LTA
TTHR - derived from LTA
2. If touchpad is released in TM:
LTA will track CS as long as CS is below PTHR
CS goes above LTA
if CS goes above PTHR, LTA will halt,
if CS goes above REL_TTHR, OUT will go
LOW & LTA will recalibrate
LTA is allowed to track CS
ProxSense® Series
IQS253 Datasheet V1.04
1. If touchpad is approached in Non-TM:
CS goes below LTA,
if CS goes below PTH, OUT = HIGH & LTA
will halt (not allowed to track CS),
if CS goes below TTH, OUT will stay HIGH
& LTA will recalibrate
Device will enter TM (Touch Mode) & OUT
will stay HIGH
PO
Non-TM
LTARATE = LTA_ADAPT
IQ Switch®
ProxSense® Series
5.1
Operating Principle
Figure 5.1 is a visual representation of the
DYCALTM functionality. The DYCAL output is
used to indicate the status of a DYCALTM event
(both a proximity and a touch event). The
DYCALTM functionality is summarised below.
Non-Touch Mode
The DYCAL output is activated on the successful detection of a proximity event and will remain
activated for the duration of the proximity event,
permitting that this event is not longer than the
filter halt timings. The LTA will be halted in this
time. As soon as a touch condition is detected
(CS below TTHR ), the controller will dynamically
re-calibrate its LTA to the halted LTA - TTHR . The
IC is now in Touch Mode (TM).
Touch Mode
After the re-calibration of the LTA, it will follow
the CS and be allowed to track slow varying environmental changes. If the CS were to exceed
the LTA by a release threshold (REL_TTHR ) the
touch detection will stop and the DYCAL output
will return to its original state.
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IQS253 Datasheet V1.04
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IQ Switch®
ProxSense® Series
6
ProxSense Module
CX/CTX/CRX pin will influence the capacitance of the sense electrodes and therefore
The IQS253 contains a ProxSense® module
that uses patented technology to provide detection of PROX/TOUCH on numerous sensing
lines. The ProxSense® module is a combination
of hardware and software, based on the principles of charge transfer. A measurement is taken
and used for calculating appropriate outputs.
CS. This will have an immediate influence on
CS.
7
Prox Module Setup
7.1
6.1
Charge Transfer Concepts
Capacitance measurements are taken with a
charge transfer process that is periodically initiated. Self capacitive sensing measures the
capacitance between the sense electrode (Cx)
relative to ground. Projected capacitance sensing measures the capacitance between 2 electrodes referred to as the transmitter (CTX) and
receiver (CRX). The measuring process is referred to as a charge transfer cycle and consists
of the following:
o Discharging of an internal sampling capacitor (Cs) and the electrode capacitors (self:
Cx or projected: CTX & CRX) on a channel.
o charging of Cx’s / CTX’s connected to the
channel
Self or Projected Capacitance
The IC can be used in either self or projected
capacitance mode. The IC is default in self capacitance mode. This can be changed to projected capacitance mode through either a FG
(one time programmable option) bit or in the
first communication window with start-up (use
the setup window to set the IC to Projected
mode). The user should set the PROJ bit (bit
7) in the PROX_SETTINGS1 [0xD2H] register
(refer to the Device Settings the Memory Map,
available in Appendix B) to enable projected capacitance technology. The technology enabled
on the IC will be reported in the SYSFLAGS
[0x10H] register. Refer to the IQS253 communication interface application note for more details
o and then a series of charge transfers from
the Cx’s / CRX’s to the internal sampling
capacitors (Cs), until the trip voltage is
reached.
on the ’Setup Window’. This setting can only be
sent to the IQS253 in the setup-communicationwindow. Please see the Section 9.1 for more
information regarding this. Note that this Setup-
The number of charge transfers required to
Window is only available once after power-ON.
reach the trip voltage on a channel is referred
The IQS253 will always start-up in Event
to as Counts (CS). The device continuously re-
Mode (default after POR). Thus, after the initial
peats charge transfers on the sense electrode
Setup-Window, there will only be communica-
connected to the Cx pin.
For each channel
tion windows available upon Events (ATI, prox-
a Long Term Average (LTA) is calculated (12
imity, etc. Refer to the Event_Mask [0xD9H]
bit unsigned integer values). The counts (12
register).
bit unsigned integer values) are processed and
to continuous streaming mode (bit 2 in the
compared to the LTA to detect DYCAL, TOUCH
PROX_SETTINGS2 [0xD3H] register) during
and PROX events. For more information re-
the Setup-Window, the master controller will
garding capacitive sensing, refer to the appli-
have to pull the RDY line low to force a com-
cation note "AZD004 - Azoteq Capacitive Sens-
munication window to setup additional settings.
Therefore, if the device is not set
Please refer to application note [6] for guidelines
ing". Please note: Attaching a probe to the
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IQS253 Datasheet V1.04
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Azoteq
IQ Switch®
ProxSense® Series
on setting up the IQS253.
The value written into this register multiplied by
When using more than one IQS253 device
I2 C
16ms will yield the LP time (t LP ). Please note
bus (especially when sharing a
that this time is only applicable from value 03 H
input pin on the master for the RDY lines), it is
and higher loaded into the LOW_POWER reg-
recommended to use the FG options to set the
ister.
sensing technology (Self OR Projected) and the
different time. See Table 12.6 for all timings.
individual sub-addresses.
With the detection of an undebounced proxim-
on the same
The values 01 H and 02 H will have a
ity event the IC will zoom to BP mode, allow-
7.2
Rate of Charge Cycles
7.2.1
ing a very fast reaction time for further possible DYCAL /touch /proximity events. All active channels will be consecutively charged ev-
Boost Power rate
ery T LP . This succession of charge cycles are
With all 3 channels active and the IQS253
succeeded by the charging of CX2 /CRX2 as a
in Boost Power (BP) mode, the Counts (CS)
dummy charge cycle. If a LP rate is selected
are charged at a fixed sampling frequency
through register LOW_POWER and charging is
(fSAMPLE ) per channel.
not in the zoomed in state (BP mode), the LP bit
This is done to en-
sure regular samples for processing of results.
(SYSFLAGS register) will be set.
It is calculated as each channel having a time
(tCH ANNEL = charge period (tCH ARGE ) + computation time) of 9 ms, thus the time between con-
7.2.3
Halt Charge (HC)
secutive samples on a channel (tSAMPLE ) will
Setting the HC bit will immediately cause the IC
optimally be 27 ms (or 37 Hz).
to stop doing conversions (stop measuring catSAMPLE
pacitance), set the RDY line as an input and
tCHANNEL
tCHARGE
CX0 /
CRX0
enter a sleep mode. To wake up the IQS253,
0
0
and let it continue with conversions, the RDY
tSAMPLE
CX1 /
CRX1
line should be pulled low for at least 1.6ms. The
1
RDY line should thereafter be monitored again
1
tSAMPLE
CX2 /
CRX2
for communication windows. The HC bit in the
2
2
Figure 7.1: Boost power as on CX / CRXx.
memory map will automatically be cleared.
CX0 /
CRX0
0
0
0
Succession of
Charge Cycles
every tLP
For every channel disabled, the sampling rate
CX0 /
CRX0
1
1
1
on a channel will reduce with approximately
tLP
9ms.
CX0 /
CRX0
2
Dummy
Charge
Cycle
7.2.2
2
tLP
2
Dummy
Charge
Cycle
2
2
2
Dummy
Charge
Cycle
Low Power Rates
Low current consumption charging modes are
available. In any Low Power (LP) mode, there
Figure 7.2: Charge cycles as charged in LP
modes.
will be a t LP low power time applicable. This
is determined by the LOW_POWER register.
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IQS253 Datasheet V1.04
Azoteq
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IQ Switch®
ProxSense® Series
7.3
7.8
Report Rate
Counts
The report rate of the device depends on the
Capacitive measurements are available in these
charge transfer frequency, the number of chan-
registers. The data has an AC noise filter ap-
nels enabled and the length of communications
plied, which helps the device to work in very
performed by the master device.
noisy environments.
The filter is default en-
abled.
7.4
Active Channels
7.8.1
Disabling AC Noise Filter
The user has the option to disable channels.
This can be done in the ACTIVE_CHAN regis-
The AC noise filter can be disabled by setting bit
ter. All 3 channels are enabled by default.
ACF_DISABLE in the PROX_SETTINGS2 register. This will increase response times, at the
7.5
DYCALTM or Direct Output
Each channel can be configured to either give
a DYCALTM (default) or a direct-output through
expense of noise immunity.
7.9
Long Term Average (LTA)
Configuring a
The LTA filter can be seen as the baseline or
channel as a direct-output channel will yield that
reference value. The LTA is calculated to con-
the touch and prox indication bits will actively in-
tinuously adapt to any environmental drift. The
dicate whether a channel detects either of these
LTA filter is calculated from the CS value for
events. The DYCALTM function will not be ap-
each channel. The LTA filter allows the device to
plied to direct-channels and any combination
adapt to environmental (slow moving) drift. Ac-
of DYCALTM or direct-output channels can be
tuation (DYCAL, Touch or Prox) decisions are
used.
made by comparing the CS value with the LTA
the DYCAL_CHANS register.
reference value. The 12bit LTA value is contained in the LTA_H and LTA_L registers.
7.6
Report Order (Channel Numbers)
7.9.1
The data is reported in the sequence; Ch0, Ch1,
Ch2, Ch0, Ch1, Ch2, Ch0, etc.
The chan-
nel number (CHAN_NUM) is used to indicate to
which channel the rest of the data in the dataset
belongs.
Filter Adaptation Rates
The LTA will adapt with different rates depending in which state the IC is in. Calculating a
new LTA value is a function of the old LTA and
the newly measured CS. The percentage of CS
used in this LTA calculation is specified as the
filter adaptation rate. 100% specifies that there
7.7
Transfer Frequency (fcx )
are no filtering and LTA = CS. A lower percentage value for the adaptation rate will yield a
The frequency of the charge transfers can be
slower adaptation rate. The IQS253 contains
selected adjusting the XFER_FREQx bits. An
3 user adjustable adaptation rates.
optimal transfer frequency must be selected for
a specific application.
Copyright ©
Azoteq
Filter adaptation rate in non-TM
The LTA filter will adapt according to the
LTA_ADAPT rate if the IQS253 is in non-TM and
IQS253 Datasheet V1.04
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IQ Switch®
ProxSense® Series
no proximity event is detected. See Figure 5.1
for a visual representation.
Self: CS > LTA + 16 Projected: CS < LTA
- 16 Force halt
Setting the FORCE_HALT bit will cause all LTA
Filter adaptation rate in TM
the
values to stop adapting to CS. This bit should be
LTA_ADAPT_IN rate if IC is IN Touch Mode
cleared for the IC to start adapting to the envi-
(TM) and the LTA is adjusting towards CS. This
ronment again. If the FORCE_HALT command
rate will apply until LTA has reached CS. See
was issued while a channel was in non-TM and
Figure 5.1 for a visual representation.
a touch is made on that channel, it will cause the
The
LTA
will
adapt
according
to
LTA to stay halted but decrease with the Touch
Filter Halt in non-TM if |LTA-CS| > 16
The
LTA
will
adapt
according
to
the
LTA_ADAPT_OUT rate if IC is in Touch Mode
Threshold for that channel.
Automatic LTA halting in non-TM
With the IC in non-TM, a proximity event will
(TM), has reached the CS and
cause halting of the LTA. The halting options
o Self: CS < LTA + 16
are:
o Projected: CS > LTA - 16
This is the rate at which LTA adapts before CS
is on its way OUT of TM. See Figure 5.1 for a
visual representation.
7.9.2
Filter Reseed
Setting the RESEED bit in the PROX_SETTINGS0
register, will reseed LTA to:
o Self: 8 above CS
o Projected: 8 below CS
The IC will stay in the state in which it was
before the command was issued.
Thus, ei-
ther non-TM or TM. The bit will automatically be
cleared by the IC as soon as the command has
been executed.
7.9.3
Filter Halting
LTA halt status The status of currently halted
channels is displayed in this byte. With the IC in
non-TM, it will only show that a channel is halted
if it detected a proximity condition. Once a touch
is detected the halting bit for that channel will be
cleared. With the IC in TM, it will show halting
bits of channels where:
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IQS253 Datasheet V1.04
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IQ Switch®
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Table 7.1: LTA halting in non-TM.
HALT1:HALT0
t H ALT
Filter
0
Short (default)
During PROX, filter halts for 20s, then reseeds
1
Long
During PROX, filter halts for 40s, then reseeds
10
Never
Filter NEVER halts
11
Always
Filter is ALWAYS halted during a PROX detection
The halt times given in Table 7.1 will be extended when disabling channels. If the halt
times in Table 7.1 are requried while using less
than 3 channels, the reseed command should
be used from the master device.
Automatic LTA halting in TM
With the IC in TM and LTA within 16 counts
of CS, no halting will occur. Halting will occur
once:
o Self: LTA + Release threshold < CS > LTA +
16
oProjected: LTA - Release Threshold < CS <
LTA - 16
ALWAYS_HALT_DYCAL = 0: The LTA will
halt with the same conditions as stated in Table
7.1.
ALWAYS_HALT_DYCAL = 1: The LTA will
always halt if above conditions apply.
The ALWAYS_HALT_DYCAL bit gives the
designer more freedom, allowing different halting conditions for when the IC is in non-TM and
in TM.
7.10.1
Proximity
Thresholds:
Proximity thresholds can be adjusted individually for each channel and can be any integer
values between 1 and 254.
Status:
The proximity status of the channels are indicated in the PROX register. The indication bits
in this register should only be used if the applicable channel is configured into direct mode,
otherwise the DYCAL status bits should be considered.
Debouncing:
By default, 6 consecutive samples should
satisfy a proximity detection condition.
This debounce can be adjusted to 4
through the PROX_DEBOUNCE bit in the
PROX_SETTINGS3 register.
7.10.2
Touch Threshold and Status
Touch thresholds can be adjusted individually
for each channel and are calculated as a function of the LTA.
TouchThreshold = (value/256 ∗ LTA) (7.1)
7.10
Determine Touch or Prox
An event is determined by comparing the CS
with the LTA. Since the CS reacts differently
when comparing the self with the projected capacitance technology, the user should consider
only the conditions for the technology used.
oSelf: CS < LTA - Threshold
oProjected: CS > LTA + Threshold
where value can be any integer value between
1 and 254.
The proximity status of the channels are indicated in the TOUCH register. (The indication
bits in this register should only be used if the applicable channel is configured into direct mode,
otherwise the DYCAL status bits should be considered)
7.11
ATI
Threshold can be either a Proximity or Touch
The Auto Tuning Implementation (ATI) is
a sophisticated technology implemented in
threshold.
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IQS253 Datasheet V1.04
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IQ Switch®
ProxSense® Series
ProxSense® devices. It allows optimal performance of the devices for a wide range of sensing electrode capacitances, without modification or addition of external components. The
ATI allows the tuning of two parameters, an ATI
Multiplier and an ATI Compensation, to adjust
the sample value for an attached sensing electrode. ATI allows the designer to optimise a specific design by adjusting the sensitivity and stability of each channel through the adjustment of
the ATI parameters. Partial ATI lets the designer
specify the MULTPLIER parameters instead of
an actual base value.See Section 7.11.3. The
IQS253 has an automated ATI function. The
auto-ATI function is by default enabled, but can
be disabled by setting the ATI_OFF bit. The ATI
bit in the SYSFLAGS register will be set while
an ATI event is busy.
jected IC. (Only applicable in projected
mode.)
o MULTIPLIER bits.
The base value used for the ATI function can be
implemented in 2 ways:
1. ATI_PARTIAL = 0. ATI automatically adjusts MULTIPLIER bits to reach a selected
base value . Base values are available
in the CHx_ATI_BASE registers. By using the ALT_BASE bit, an extended list of
base values are available.
2. ATI_PARTIAL = 1.
The designer can
specify the multiplier settings. These settings will give a custom base value from
7.11.1
ATI Sensitivity
where the compensation bits will be automatically implemented to reach the re-
The designer can specify the BASE values for
each channel and a global TARGET value for
all channels. A rough estimation of sensitivity
can be calculated as:
quired target value. The base value is
determined by two sets of multiplier bits.
Sensitivity Multipliers which will also
scale the compensation to normalise the
Sensitivity = TARGET/BASE
sensitivity and Compensation Multipli-
(7.2)
ers to adjust the gain. Refer to the MemAs can be seen from this equation, the sensitivity can be increased by either increasing
the TARGET or decreasing the BASE value. It
should, however, be noted that a higher sensitivity will yield a higher noise susceptibility.
7.11.2
ATI Target
ory Map were the multipliers bits can be
set in registers CH0_ATI_BASE (0xC8) to
CH2_ATI_BASE (0xCA).
7.11.4
Re-ATI
An automatic re-ATI event will occur if the CS is
The target is reached by adjusting the COMPENSATION bits for each channel. The target
value is written into the ATI_TARGET register.
The value written into this register (0 to 255)
multiplied by 8 will yield the new target value.
outside its re-ATI limits. The re-ATI limit is calculated as the target value divided by 8. For example: Target = 1024 Re-ATI will occur if CS is
outside 1024 ±128. A re-ATI event can also be
issued by the master by setting the REDO_ATI
7.11.3
ATI Base (MULTIPLIER)
The following parameters will influence the base
value:
o CS_SIZE : Size of sampling capacitor.
o PROJ_BIAS bits: Adjusts the biasing of
bit. It will clear automatically after the ATI event
was started.
8
DYCALTM
The DYCALTM technique is explained in Section
5. DYCALTM detections are displayed in the DYsome analogue parameters in the proCopyright ©
IQS253 Datasheet V1.04
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IQ Switch®
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CAL_OUT register. The IQS253 will also dis-
threshold and the setting chosen with bits
play whether each channel is in TM in the DY-
REL_THR1:REL_THR0.
CAL_TM register. Important factors to consider
threshold can either be the user selected
TM
when designing the DYCAL
functionality are:
(NOTE: the touch
touch threshold or the dynamic touch threshold, whichever is larger)
8.1
Example:
DYCALTM channels enable
Technology: Self Capacitive
Explained in Section 7.5.
LTA NTM = 1024 (IC in NTM, before detection)
LTATM = 850 (IC in TM, after detection)
8.2
TM
DYCAL
on TOUCH/PROX
TouchTHR = LTA NTM *30/256
The DYCALTM output bits can either be
indicated
when
a
proximity
(default)
RelTHR = 75% * TouchTHR
Answer:
or
touch is detected by configuring the OUT-
o The IQS253 detects a touch condition if: CS
< LTA NTM - TouchTHR , where TouchTHR
= 1024*30/256 = 120. Thus if CS goes
below 1024 - 120 = 904. Channel is in
TM.
PUT_ON_TOUCH bit.
8.3
LTA Adapt rates (IN and
OUT)
oThe IC will exit TM and clear the DYCAL_OUT bit if:
CS > LTATM + 0.75*120 Thus if CS exceeds 850 + 90 = 940 IC will exit TM and
clear DYCAL_OUT.
Explained in Section 7.9.1.
8.4
Block Channel
A Touch on channel 1 can be used to block (and
clear) the other channels’ outputs. This is useful
8.6
on CH1.
touch
The IQS253 calculates a dynamic touch threshold.
o DYCAL_OUT if a channel is in DYCALTM
dynamic
threshold
in Event Mode as the MCU can remain uninterrupted from the IQS253 while a touch is present
DYCALTM
This dynamic threshold enables the IC
to calculate more accurately when a user releases a button. The LTA will reseed to [LTA -
mode
o TOUCH if a channel is in direct-output mode
TouchTHR ] once a touch is made. Using self
capacitance as example; the CS will probably
by setting bit BLOCK_ON_CH1_ENABLE. It
go much lower than the value to which the LTA
should be noted that, if another channel had
reseeded. The IQS253 will only calculate the
a DYCAL
TM
detection and channel 1 detects
a touch event, it will clear the other channels’
dynamic touch threshold once the LTA is within
16 counts of the CS.
DYCALTM outputs.
8.7
8.5
TM
DYCAL
Release Threshold
10s_ATI_BLOCK
After a touch is released and the LTA is re-
The release threshold is relevant for when
seeded towards the CS, it is highly probable
a channel is released after it was in TM.
that the LTA will be outside the re-ATI bound-
It is dependent
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on
the
aries of the IC. This feature helps the channels
selected touch
IQS253 Datasheet V1.04
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IQ Switch®
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to block the re-ATI function for 10 seconds after an actuation has been released. It is also
applicable if a channel is configured in directoutput mode. The 10seconds block of re-ATI
after an actuation can be disabled by setting the
10s_ATI_BLOCK bit.
8.8
250ms_DELAY_TM (tDYCAL )
By default, the LTA will only reseed to [LTA TouchTHR ] after tDYCAL , when entering TM. An
option exists to disable this delay, thus the LTA
will reseed to [LTA - TouchThr] immediately with
the detection of a touch.
8.9
Turbo Mode
The channels are charged in sequence and
have a fixed period. By setting the Turbo_Mode
bit, this period will be shortened to the fastest
possible period, negating any dead-time. The
AC filter will also be disabled for transfers to
complete as fast as possible. If DYCAL is enabled, the Turbo_Mode bit will also allow the IC
to enter Touch Mode as fast as possible upon
an event.
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IQS253 Datasheet V1.04
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IQ Switch®
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9
Communication
between Self or Projected capacitance.
The IQS253 can communicate on the I2 C compatible bus structure. It uses the 2 wire serial
interface bus which is I2 C compatible and an
optional RDY pin is available which indicates
the communication window. The IQS253 has
four available sub addresses, 44H (default) to
47H that is selected upon purchase of the IC.
The maximum I2 C compatible communication
speed for the IQS253 is 400kbit/s. Please refer
to AZD062 - IQS253 Communication Interface
Guidelines [6] and the Memory Map in Appendix
B for more details.
9.1
IC Setup Window
The IQS253 has a ’Setup Window’ in which the
user has the option to write some start-up settings before any conversions are done. For
example, the ’Setup Window’ can be used to
change the IC from Self (default) to Projected
sensing mode.
RDY
VDDHI
tSTART_UP
tCOMMS
9.2
Event Mode
IQS253 will in default be configured to only
communicate with the master if a change in
an event occurs (except for the Setup Window after POR). For this reason, it would be
highly recommended to use the RDY line when
communicating with the IQS253. These communication requests are referred to as EVENT
Mode (only change of events are reported).
Event mode can be disabled by setting the
EVENT_MODE_DISABLE bit. The events responsible for resuming communication can be
chosen through the EVENT_MASK register. By
default all events are enabled. The master has
the capability to force a communication window
at any time, by pulling the RDY line low. The
communication window will open directly following the current conversion.
9.3
9.3.1
I2 C Specific Commands
Reset Indication
SHOW_RESET can be read to determine
whether a reset occurred on the device. This
bit will be a ’1’ after a reset. The value of
SHOW_RESET can be cleared to ’0’ by writing
a ’1’ in the ACK_RESET bit.
Figure 9.1: IC Setup Window.
9.3.2
WDT
TSTART_UP after VDDHI was powered, RDY will
The WDT is used to reset the IC if a problem
go low for this ’Setup Window’. After address(for example a voltage spike) occur during coming the IC, the required settings should be upmunication. The WDT will time-out after TWDT
dated and only thereafter should a STOP bit
if no valid communication occur for this time.
be issued. The IC will then start with its conversions. If the ’Setup Window’ is not serviced
9.3.3 Time-out
within tCOMMS , the RDY will go HIGH again (according to Section 9.3.3). Most settings can be
If no communication is initiated from the masupdated at any time on the IC, except switching
ter within the first tCOMMS of the RDY line
between Self and Projected capacitance techindicating that data is ready, the IC will renology, which can only be done in the ’Setup
sume with the next channel’s charge transfers.
Window’. This setting can also be configured
This time-out can be disabled by setting the
with a FG which would then not require setTIME_OUT_DISABLE bit.
ting up this function via I2 C commands. As the
Setup Window is only available once after POR,
9.4 I2 C Read and Write specifics
applications which do not have control over the
Please refer to the Memory Map and SamIQS253 supply, or have more than one IQS253
ple Code Document for the I2 C read and write
on the bus should use the FG option to select
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IQS253 Datasheet V1.04
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IQ Switch®
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specifics as implemented on most ProxSense®
devices.
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IQS253 Datasheet V1.04
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IQ Switch®
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10
Boolean Output
3. AND/OR operation?
Boolean arithmetic can be applied to one or a
combination of channels to get a result. This
result is available in the BOOLEAN_OUTPUT
bit in the TOUCH register. For the self capacitive IQS253 version, a digital signal output
pin (B_OUT) exists, which corresponds to the
Boolean output bit. This output pin is to be used
for level detection on a master controller, or to
be used with a FET for LED driving. The pin
is not rated to sink or source current. In both
the self and projected configuration, the "Event
Mode" communication could be triggered on a
Boolean based result. The Boolean output will
be calculated using:
11
RF Noise
11.1
Noise Immunity
The IQS253 has advanced immunity to RF
noise sources such as GSM cellular telephones, DECT, Bluetooth and WIFI devices.
Design guidelines should however be followed
to ensure the best noise immunity. The design
of capacitive sensing applications can encompass a large range of situations but as a summary the following should be noted to improve a
TM
o DYCAL_OUT if channel is in DYCAL
design:
mode
o TOUCH output if channel is in direct-output
mode
o A ground plane should be placed under the
IC, except under the Cx line.
o All the tracks on the PCB must be kept as
10.1
Channels for Boolean oper-
o The capacitor between VDDHI and VSS as
ation
The channels that should be used to compute the Boolean output bit is chosen in the
BOOLEAN_SETTINGS register.
10.2
short as possible.
well as between VREG and VSS, must be
placed as close as possible to the IC.
o A 100 pF capacitor can be placed in parallel with the 1uF capacitor between VDDHI
and VSS. Another 100 pF capacitor can
be placed in parallel with the 1uF capacitor between VREG and VSS.
Boolean NOT
A Boolean NOT can be applied to any or all
o When the device is too sensitive for a spe-
channels.
10.3
Boolean AND/OR
The Boolean AND operation will be applied
to the chosen channels.
The OR op-
eration can alternatively be applied if the
BOOLEAN_AND_OR bit is set.
10.4
Order of Boolean operation:
cific application a parasitic capacitor (max
5pF) can be added between the Cx line
and ground.
o Proper sense electrode and button design
principles must be followed.
o Unintentional coupling of sense electrode to
ground and other circuitry must be limited by increasing the distance to these
sources or making use of the driven
shield.
o In some instances a ground plane some
distance from the device and sense electrode may provide significant shielding
from undesired interference.
2. Should NOT be applied to a channel?
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IQS253 Datasheet V1.04
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1. Choose channels for Boolean operation
IQ Switch®
ProxSense® Series
When the capacitance between the sense electrode and ground becomes too large the sensitivity of the device may be influenced.
11.1.1
RF Detection
In cases of extreme RF interference, the onchip RF detection is suggested. This detector can be enabled by setting the ND bit in the
PROX_SETTINGS1 register. By connecting a
suitable antenna to the RF pin, it allows the device to detect RF noise and notify the master
of possible corrupt data. Noise affected samples are not allowed to influence the LTA filter,
and also do not contribute to DYCAL, PROX or
TOUCH detection. With the detection of noise,
the NOISE bit in SYSFLAGS will be set.
11.1.2
RF detector sensitivity
The sensitivity of the RF detector can be selected by setting an appropriate RF detection
voltage through the ND_TRIM bits. Please see
AZD015 for further details regarding this.
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IQS253 Datasheet V1.04
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IQ Switch®
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12
Electrical Specifications
Absolute Maximum Specifications
The following absolute maximum parameters are specified for the device: Exceeding these maximum specifications may cause damage to the device.
o
o
o
o
o
o
o
o
o
12.1
Operating temperature
Supply Voltage (VDDHI - GND)
Maximum pin voltage
Maximum continuous current (for specific Pins)
Minimum pin voltage
Minimum power-on slope
ESD protection (HBM)
Moisture Sensitivity Level MSOP-10
Moisture Sensitivity Level DFN-10
−40 °C to +85 °C
3.6 V
VDDHI + 0.5 V
2 mA
GND - 0.5 V
100 V /s
±4 kV
MSL 1
MSL 3
General Characteristics (Measured at 25 °C)
Table 12.1: IQS253 General Operating Conditions - Projected Capacitive Sensor.
DESCRIPTION
Conditions
PARAMETER
MIN
TYP
MAX
UNIT
VDDHI
1.8
3.3
3.6
V
1.62
1.7
1.79
V
Supply voltage
Internal regulator output
1.8 ≤ VDDHI ≤ 3.3
VREG
Boost Power operating current
1.8 ≤ VDDHI ≤ 3.3
LOW_POWER = 00h
IBP
180
<250
µA
Low power 32 operating current
1.8 ≤ VDDHI ≤ 3.3
LOW_POWER = 20h
I LP32
13
<20
µA
Low power 255 operating current
1.8 ≤ VDDHI ≤ 3.3
LOW_POWER = FFh
I LP255
4.5
<8
µA
Table 12.2: IQS253 General Operating Conditions - Self Capacitive Sensor.
DESCRIPTION
Conditions
PARAMETER
MIN
TYP
MAX
UNIT
VDDHI
1.8
3.3
3.6
V
1.62
1.7
1.79
V
Supply voltage
Internal regulator output
1.8 ≤ VDDHI ≤ 3.3
VREG
Boost Power operating current
1.8 ≤ VDDHI ≤ 3.3
LOW_POWER = 00h
IBP
150
<200
µA
Low power 32 operating current
1.8 ≤ VDDHI ≤ 3.3
LOW_POWER = 20h
I LP32
11
<15
µA
Low power 255 operating current
1.8 ≤ VDDHI ≤ 3.3
LOW_POWER = FFh
I LP255
3.5
<6
µA
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IQS253 Datasheet V1.04
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IQ Switch®
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Table 12.3: Start-up and shut-down slope Characteristics
Description
Condition
Parameter MIN MAX
POR
VDDHI Slope ≥ 100 V/s
POR
1.2
1.6
BOD
BOD
1.15 1.55
Unit
V
V
Table 12.4: Debounce employed on IQS253.
DESCRIPTION
Proximity debounce value
Conditions
Value
PROX_DEBOUNCE = 0
6
PROX_DEBOUNCE = 1
4
-
2
Touch debounce value
12.2
Timing Characteristics
Table 12.5: General Timing Characteristics for 1.80V ≤ VDDHI ≤ 3.60V
SYMBOL
DESCRIPTION
TYP
tSTART −UP
Start-up time before the Setup Window is iniatiated by the IQS253
15
ms
tCOMMS
Time after which communication
window will terminate, if not addressed
22
ms
IC transfer frequency
See XFER_FREQ in IQS253 Memory Map
Charge time of channel
CS * (1/fCX)
Charge time interval
9.01ms
Sample time of channel
Active channels * tCH ANNEL
ms
tBP
Channel sampling period in BP and
Turbo_Mode = OFF
tSAMPLE
ms
tBP_TURBO
Channel sampling period in BP and
Turbo_Mode = OFF
Active channels * tCH ARGE
ms
Low Power Charging time
CS*(1/FCX) + tCH ARGE
tWDT
WDT time-out while communicating
160
ms
tDYCAL
Time before switching to TM in
DYCALTM operation
225≤ 250 ≤275
ms
fCX
tCH ARGE
tCH ANNEL
tSAMPLE
t LP
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IQS253 Datasheet V1.04
UNIT
MHz
ms
27of 53
IQ Switch®
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Table 12.6: IQS253 charging times
Power Mode
Typical (ms)
Boost Power Mode with Turbo_Mode ON 4
Boost Power Mode
9
Low Power Mode 4
64
Low Power Mode 8
128
Low Power Mode 16
256
Low Power Mode 32
512
Low Power Mode 64
1024
Low Power Mode 255
4080
Table 12.7: IQS253 DYCAL (OUTPUT_ON_TOUCH = 0) /Proximity Response Times
Power Mode
Conditions
Boost Power Mode with Turbo_Mode ON1
Boost Power Mode2
Power Modes3
Min**
Unit
Detection with small CS
change (prox) and ACF OFF
135
ms
Detection with large CS
change (touch) and ACF
OFF
81
Release time with ACF OFF
81
ms
Detection with large CS
change (touch) and ACF
OFF
331
ms
Release time with ACF OFF
81
ms
See example
See example (take 250ms
off total time)
See example
ms
ms
**Note: Minimum bit set times are dependent on the size of the change in CS caused by the user
actuation because the minimum time is a function of the debounce of either the touch / proximity
caused. The setting of indication bits are delayed by a charge transfer cycle. With ACF = ON,
detection and release times will dramatically increase due to the CS having to go through a filtering
process adding a delay
LP Response time Example:
LOW_POWER = 34h (52D): t LP = 16ms x 52 = 832ms
Channels active = 2: tSAMPLE = 18ms + 9ms for extra Channel 2 sampling
ACF = OFF: Fast respose on CS
Large CS change: Touch debounce = 2
DetectionTimeLP52 = 27 + 832 + (2 + 1)*27 + 250 = 1.19seconds
1 Minimum
Detection and Release times = (debounce +1) x tSAMPLE
Power Detection and Release times = (debounce +1) x tSAMPLE + 250ms
3 LP Modes = t
SAMPLE + t LP + (debounce + 1) x tSAMPLE + 250m
2 Boost
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IQS253 Datasheet V1.04
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IQ Switch®
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13
Mechanical Dimensions
Table 13.2: MSOP-10 Footprint Dimensions
Dimension
Pitch
C
Y
X
/
:
%
3
)LJ
+
mm
0.50
4.40
1.45
0.30
$
.
7
Figure 13.1: MSOP10 Package.
Table 13.1: MSOP10 Package Dimensions.
Dimension
[mm]
Amin
2.90
Amax
3.10
Bmin
2.90
Bmax
3.10
Hmax
1.1
Lmin
4.75
Lmax
5.05
Tmin
0.40
Tmax
0.80
Pitch
0.50
Wmin
0.17
Wmax
0.27
Figure 13.3: MSOP10 Silk Screen.
Table 13.3: MSOP-10 Silk Screen Dimensions
Dimension
R1
R2
mm
2.30
3.00
<
;
)LJ
&
Figure 13.2: MSOP10 Footprint.
Copyright ©
Azoteq
Figure 13.4: DFN-10 Package Dimensions.
IQS253 Datasheet V1.04
29of 53
IQ Switch®
ProxSense® Series
C
Package Outline
E
Table 13.4: DFN-10 Package Dimensions.
Dimension
[mm]
A
3 ± 0.1
B
0.5
C
0.25
A
D
D
F
3 ± 0.1
L
0.4
P
2.4
Q
1.65
B
F
Figure 13.6: DFN-10 Footprint.
Table 13.6: DFN-10 Footprint Dimensions
Dimension
A
B
C
D
E
F
mm
2.38
1.64
0.60
0.50
0.25
2.80
Figure 13.5: DFN-10 package Side View.
Table 13.5: DFN-10 Side View Dimensions.
Dimension
G
H
I
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Azoteq
mm
0.05
0.65
0.7 - 0.8
IQS253 Datasheet V1.04
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IQ Switch®
ProxSense® Series
14
Device Marking
IQS253 x t z PWWYY
REVISION
DATE CODE
SUB ADDRESS
CONFIGURATION
TEMPERATURE
Pin1 mark on package - Bottom Left.
REVISION
TEMPERATURE RANGE
x
t
IC CONFIGURATION
z
=
=
=
=
P
WW
YY
=
=
=
DATE CODE
15
IC Revision Number
I −40 °C to 85 °C (Industrial)
C 0 °C to 70 °C (Commercial)
Configuration (Hexadecimal)
0 = 44H (Self Capacitance)
1 = 45H (Self Capacitance)
2 = 46H (Self Capacitance)
3 = 47H (Self Capacitance)
4 = 44H (Projected Capacitance)
5 = 45H (Projected Capacitance)
6 = 46H (Projected Capacitance)
7 = 47H (Projected Capacitance)
Package House
WEEK
YEAR
Ordering Information
Orders will be subject to a MOQ (Minimum Order Quantity) of a full reel. Contact the official distributor for sample quantities. A list of the distributors can be found under the "Distributors" section of
www.azoteq.com. The IQS253 has 4 I2 C sub-addresses available. The default address is 0x44H.
For further enquiries regarding this, please contact Azoteq or a local distributor.
IQS253
z
pp
BULK PACKAGING
IC NAME
SUB ADDRESS
CONFIGURATION
Copyright ©
Azoteq
b
PACKAGE TYPE
IQS253 Datasheet V1.04
31of 53
IQ Switch®
ProxSense® Series
IC NAME
BOTTOM MARKING
PACKAGE TYPE
BULK PACKAGING
16
IQS253
z
MS
DN
R
R
T
=
=
=
=
=
=
=
IQS253
I2 C Sub Address (hexadecimal)
MSOP-10
DFN-10
Reel (MSR 4000pcs/reel) - MOQ = 4000pcs
Reel (DNR 3000pcs/reel) - MOQ = 3000pcs
Tube (96pcs/tube, Special Order, MS Only)
Device Revision History
Revision
0
Device ID
3114
Package Markings
x3911
1
4100
x0112 or later
17
Comments
Projected Bias current default 10uA
Unable to float CX/CRX
No Event mode with Boolean Output enabled
Projected Bias current default 5uA
Errata
The ’z’ field is omitted on the package marking on batch code 21512. The configuration is ’0’ on this
lot.
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IQS253 Datasheet V1.04
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IQ Switch®
ProxSense® Series
18
Contact Information
PRETORIA OFFICE
Physical Address
160 Witch Hazel Avenue
Hazel Court 1, 1st Floor
Highveld Techno Park
Centurion, Gauteng
Republic of South Africa
Tel: +27 12 665 2880
Fax: +27 12 665 2883
Postal Address
PO Box 16767
Lyttelton
0140
Republic of South Africa
PAARL OFFICE
Physical Address
109 Main Street
Paarl
7646
Western Cape
Republic of South Africa
Tel: +27 21 863 0033
Fax: +27 21 863 1512
Postal Address
PO Box 3534
Paarl
7620
Republic of South Africa
The following patents relate to the device or usage of the device: US 6,249,089 B1, US 6,621,225
B2, US 6,650,066 B2, US 6,952,084 B2, US 6,984,900 B1, US 7,084,526 B2, US 7,084,531 B2,
US 7,119,459 B2, US 7,265,494 B2, US 7,291,940 B2, US 7,329,970 B2, US 7,336,037 B2, US
7,443,101 B2, US 7,466,040 B2, US 7,498,749 B2, US 7,528,508 B2, US 7,755,219 B2, US
7,772,781, US 7,781,980 B2, US 7,915,765 B2, EP 1 120 018 B1, EP 1 206 168 B1, EP 1 308
913 B1, EP 1 530 178 B1, ZL 99 8 14357.X, AUS 761094
IQ Switch® , ProxSense® , LightSenseTM , AirButton® and the
logo are trademarks of Azoteq.
The information appearing in this Datasheet is believed to be accurate at the time of publication. Azoteq
assumes no liability arising from the use of the information or the product. The applications mentioned
herein are used solely for the purpose of illustration and Azoteq makes no warranty or representation that
such applications will be suitable without further modification, nor recommends the use of its products for
application that may present a risk to human life due to malfunction or otherwise. Azoteq products are not
authorised for use as critical components in life support devices or systems. No licenses to patents are
granted, implicitly or otherwise, under any intellectual property rights. Azoteq reserves the right to alter its
products without prior notification. For the most up-to-date information, please refer to www.azoteq.com.
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IQS253 Datasheet V1.04
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IQ Switch®
ProxSense® Series
A
Appendix A
DycalTM Illustrations
To view the illustrations in Appendix A, the document requires to be opened with Adobe Reader Version 6 or
later. Note that all illustrations are supplementary, and are not required to use with the datasheet.
Figure A.1: DYCAL output selected on proximity, for a projected capacitive IC. Note that the IC still
only enters TM (Touch Mode) when the counts exceed the touch threshold, but the DYCAL output
is active after exceeding the proximity threshold.
Figure A.2: DYCAL output selected on touch, for a projected capacitive IC. Note that the DYCAL
output is only active when the IC enters TM (Touch Mode) when the counts exceed the touch
threshold.
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IQS253 Datasheet V1.04
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Figure A.3: Filter halt upon Touch Mode Entry, for a self capacitive IC. The LTA will halt upon
proximity detection (regardless on which output DYCAL was selected). However, when a touch
condition is registered, the filter will stop halting, to allow the LTA to follow the counts.
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IQS253 Datasheet V1.04
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IQ Switch®
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B
Appendix B
IQS253 Memory Map
The Memory Map of the IQS253 is provided in this section, along with a description of each register and
instruction. The IQS253 communicates via I2 C. For an example implementation that provides example code,
refer to [6].
The general ProxSense® Memory Map is shown below.
Address
Access
Size(Bytes)
00H-0FH
R
16
Address
Access
Size(Bytes)
10H-30H
R
32
Address
Access
Size(Bytes)
31H-34H
R
4
Address
Access
Size(Bytes)
35H-38H
R
4
Address
Access
Size(Bytes)
39H-3CH
R
4
Address
Access
Size(Bytes)
3DH-41H
R
4
Address
Access
Size(Bytes)
42H-82H
R
64
Address
Access
Size(Bytes)
83H-C3H
R/W
64
Address
Access
Size(Bytes)
C4h-FDh
R/W
64
Device Information
Device Specific Data
Proximity Status Bytes
Touch Status Bytes
Halt Bytes
Active Bytes (indicate cycle)
Counts
LTAs
Device Settings
Note: FE and FF are reserved for other functions in communication.
B.1
IQS253 Memory Map
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IQS253 Datasheet V1.04
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IQ Switch®
ProxSense® Series
B.1.1
Device Information
00H
Product Number (PROD_NR)
Access
Bit
R
Value
7
6
5
4
3
2
1
0
41 (Decimal)
01H
Software Number (SW_NR)
Access
Bit
R
Value
7
6
5
4
3
2
1
0
SW_NR
[00H] PROD_NR
The product number for the IQS253 is 41 (decimal).
[01H] SW_NR
The software version number of the device ROM can be read in this byte. Production version IC’s SW
numbers are 0 for Self and Projectd. The Engineering version numbers are shown below.
B.1.2
IQS253 sw nr
Description
13 (decimal)
IQS253 - 3 Channel Self Capacitive Sensor version 1
14 (decimal)
IQS253 - 3 Channel Projected Sensor version 1
Device Specific Data
10H
System Flags (SYSFLAGS)
Access
R
Bit
7
6
5
4
3
2
1
0
Name
System_
Use
SYSTEM_
Use
SHOW_
Reset
PROJ_
Mode
LP
ATI_
Busy
Noise
Zoom
[10H] SYSFLAGS
bit 7: SYSTEM_USE
bit 6: SYSTEM_USE
bit 5: SHOW_RESET: This bit can be read to determine whether a reset occurred on the device since the
ACK_RESET bit has been set. The value of SHOW_RESET can be set to 0 by writing a 1 in the
ACK_RESET bit in the PROX_SETTINGS_2 byte.
bit 4: PROJ_MODE: Capacitive Sensing Technology used
0 = Self Capacitive sensing
1 = Projected Capacitive sensing
bit 3: LP: If a LP mode is enabled, this bit indicates that charging is currently occurring in a LP rate.
0 = Full-speed charging
1 = Charging currently occur at a lower rate
bit 2: ATI_BUSY: Status of automated ATI routine
0 = Auto ATI is not busy
1 = Auto ATI in progress
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IQS253 Datasheet V1.04
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bit 1: NOISE: This bit indicates the presence of noise interference.
0 = IC has not detected the presence of noise
1 = IC has detected the presence of noise
bit 0: ZOOM: Zoom will indicate full-speed charging once an undebounced proximity is detected. In NP
mode, this will not change the charging frequency.
0 = IC not zoomed in
1 = IC detected undebounced proximity and IC is charging at full-speed
B.1.3
Proximity Status Bytes
The proximity status of all the channels on the device are shown here. These bits should not be monitored if
the IC is in DYCAL mode.
31H
Proximity Status (PROX)
Access
Bit
7
R
Name
6
5
4
3
2
1
0
CH2
CH1
CH0
[31H] PROX
The proximity status of the channels is indicated in this byte. The PROX bit of a channel should not be used
if a channel is set as a DYCAL channel.
bit 7-3: SYSTEM_USE
bit 2: CH2: Indicate that a proximity event has been detected on CH2
0 = No proximity event detected
1 = Proximity event detected
bit 1: CH1: Indicate that a proximity event has been detected on CH1
0 = No proximity event detected
1 = Proximity event detected
bit 0: CH0: Indicate that a proximity event has been detected on CH0
0 = No proximity event detected
1 = Proximity event detected
B.1.4
Touch Status Bytes
The touch status of all the channels on the device are shown here. These bits should not be monitored if the
IC is in DYCAL mode.
35H
Touch Status (TOUCH)
Access
Bit
7
R
Name
Boolean_Output
6
5
4
3
2
1
0
CH2
CH1
CH0
[35H] TOUCH
The touch status of the channels is indicated in this byte. The TOUCH bit of a channel should not be used if
a channel is set as a DYCAL channel.
bit 7: BOOLEAN_OUTPUT: A Boolean combination can be outputted to this bit. The Boolean combination
can be configured through bytes BOOLEAN_SETTINGS and BOOLEAN_NOT. This bit will correspond
with the output status of the B_OUT pin of the IQS253 Self capacitive IC.
0 = Boolean Output not active
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IQS253 Datasheet V1.04
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1 = Boolean Output active
bit 6-3: Unused
bit 2: CH2: Indicate that a touch event has been detected on CH2
0 = No touch event detected
1 = Touch event detected
bit 1: CH1: Indicate that a touch event has been detected on CH1
0 = No touch event detected
1 = Touch event detected
bit 0: CH0: Indicate that a touch event has been detected on CH0
0 = No touch event detected
1 = Touch event detected
B.1.5
DYCAL Touch Mode indication
36H
DYCAL TM Indication (DYCAL_TM)
Bit
7
Access
Name
R
Note
6
5
4
3
2
1
0
CH2
CH1
CH0
Indicates if Channel is in TM
[36H] DYCAL_TM
If a channel is configured as a DYCAL channel, these bits will indicate whether TM has been entered. TM is
entered once the touch threshold of a channel has been exceeded.
Bit 7-3: Unused
Bit 2: CH2: CH2 TM indication
0 = Channel not in TM
1 = Channel in TM
Bit 1: CH1: CH1 TM indication
0 = Channel not in TM
1 = Channel in TM
Bit 0: CH0: CH0 TM indication
0 = Channel not in TM
1 = Channel in TM
B.1.6
DYCAL Output indication
37H
Access
R
DYCAL Output Indication (DYCAL_OUT)
Bit
Name
7
6
5
4
3
2
1
0
CH2
CH1
CH0
Indicates a DYCAL detection on a channel
[37H] DYCAL_OUT
If a channel is configured as a DYCAL channel, these bits will indicate whether the DYCAL output is set.
It will default be set with the detection of a proximity, but can be set by a touch by configuring bit DYCAL_SETTINGS:OUTPUT_ON_TOUCH.
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IQS253 Datasheet V1.04
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IQ Switch®
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Bit 7-3: Unused
Bit 2: CH2: CH2 DYCAL output
0 = DYCAL not detected
1 = DYCAL detected
Bit 1: CH1: CH1 DYCAL output
0 = DYCAL not detected
1 = DYCAL detected
Bit 0: CH0: CH0 DYCAL output
0 = DYCAL not detected
1 = DYCAL detected
B.1.7
Halt Bytes
The LTA filter halt status of all the channels are shown here.
39H
LTA Halt Status (HALT)
Access
Bit
7
R
Name
6
5
4
3
2
1
0
CH2
CH1
CH0
[39H] HALT
Indicate the halting state of each channels Long Term Average (LTA). If in non-TM, the halt bit of a channel
will be set once proximity is detected. Once a touch is detected, the IC will enter TM and the halt bit will be
cleared. The halting bit will now only be set again if the CS exceeds the LTA by 16 in Self or if the CS is less
than the LTA by more than 16 in Projected mode.
Bit 7-3: Unused
Bit 2: CH2: CH2 LTA halting state
0 = Channels LTA adapts to the environment
1 = Channels LTA halted
Bit 1: CH1: CH1 halting state
0 = Channels LTA adapts to the environment
1 = Channels LTA halted
Bit 0: CH0: CH0 halting state
0 = Channels LTA adapts to the environment
1 = Channels LTA halted
B.1.8
Channel Number
3DH
Channel Number
Bit
7
6
5
4
3
2
1
0
Access
Value
Variable (0-2)
R
Note
Indicates which channels data is currently available
[3DH] CHAN_NUM
The channel number that can be read in this byte indicates which channels data is currently available.
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IQS253 Datasheet V1.04
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IQ Switch®
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B.1.9
Counts
The Counts of the current channel is available here.
42H
Counts (CS_H)
Bit
7
6
5
4
3
2
1
0
Access
Value
Variable (HIGH byte)
R
Note
Counts of active channel (see Channel Number)
43H
Counts (CS_H)
Bit
7
6
5
4
3
2
1
0
Access
Value
Variable (LOW byte)
R
Note
Counts of active channel (see Channel Number)
[42H & 43H] CS_H & CS_L
The counts for the current channel can be read in this byte. The HIGH byte and LOW byte are found in
consecutive addresses.
B.1.10
Long-Term Averages
The Long-Term average of the current channel is available here to read.
83H
Long-Term Average (LTA_H)
Bit
7
6
5
4
3
2
1
0
Access
Value
Variable (HIGH byte)
R
Note
LTA of active channel (see Channel Number)
84H
Long-Term Average (LTA_L)
Bit
7
6
5
4
3
2
1
0
Access
Value
Variable (LOW byte)
R
Note
LTA of active channel (see Channel Number)
[83H & 84H] LTA_H & LTA_L
The LTA value for the current channel can be read in this byte. The HIGH byte and LOW byte are found in
consecutive addresses.
B.1.11
Device Settings
It is attempted that the commonly used settings are situated closer to the top of the memory block. Settings
that are regarded as more once-off are placed further down.
C4H
ATI Target Value (ATI_TARGET)
Bit
Access
Value
R/W
Default
Note
Copyright ©
Azoteq
7
6
5
4
3
2
1
0
ATI Target value (x8 to get real target)
1
0
0
0
0
0
0
0
128 Decimal (x8 gives Target value = 1024)
IQS253 Datasheet V1.04
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IQ Switch®
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[C4H] ATI_TARGET
The automated ATI target can be set in this byte. The value written to this byte multiplied by 8 will be the
target value of all 3 channels. If a new target value is required, the required target (divided by 8) should be
written to this byte, where-after a re-ATI event should be sent. All 3 channels will now be at the target value
once the SYSFLAGS_ATI_BUSY flag is cleared. ATI Multiplier and Compensation
The ATI Multiplier and ATI Compensation bits allow the controller to be compatible with a large range
of sensors, and in many applications with different environments. ATI allows the user to maintain a specific
sample value on all channels. The ATI Multiplier parameters would produce the largest changes in sample
values and can be thought of as the high bits of ATI. The ATI Compensation bits are used to influence the
sample values on a smaller scale to provide precision when balancing all channels as close as possible
to the target. The ATI Multiplier parameters are further grouped into two parameters namely ATI MultiplierCompensation and ATI Multiplier-Sensitivity. ATI multiplier-Compensation consists of 2 bits and has the
biggest effect on the sample value and can be considered as the highest bit of the ATI parameters. The
ATI Multiplier-Sensitivity can be adjusted with 4 bits for each channel. The value of 1111 would provide the
highest CS value and the value of 0000 would provide the lowest.
CH0 Compensation (COMP0)
C5H
Bit
7
6
5
4
3
2
1
0
Access
Value
Automatically adjusted when ATI enabled
R/W
Default
0
CH1 Compensation (COMP1)
C6H
Bit
7
6
5
4
3
2
1
0
Access
Value
Automatically adjusted when ATI enabled
R/W
Default
0
CH2 Compensation (COMP2)
C7H
Bit
Access
7
Value
6
5
4
3
1
0
Automatically adjusted when ATI enabled
Default
R/W
2
0
[C5H, C6H, C7H] Compensation Settings (CH0_COMP, CH1_COMP, CH2_COMP)
The compensation settings for each channel are contained in these bytes. The values in these bytes are automatically determined if the Auto ATI function was used. If PROX_SETTINGS0:ATI_OFF is set, the Automatic
ATI setting is disabled and this byte can be altered to achieve a custom target value. The ATI Compensation
parameter can be configured for each channel in a range between 0-255 (decimal). The ATI compensation
bits can be used to make small adjustments of the sample values of the individual channels.
C8H
Access
R/W
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CH0 ATI BASE and Multipliers (CH0_ATI_BASE)
Bit
7
6
5
4
3
2
1
0
Value
CH0_
BASE1
CH0_
BASE0
MULT_
COMP1
MULT_
COMP0
MULT_
SENSE3
MULT_
SENSE2
MULT_
SENSE1
MULT_
SENSE0
gain
IQS253 Datasheet V1.04
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IQ Switch®
ProxSense® Series
C9H
CH1 ATI BASE and Multipliers (CH1_ATI_BASE)
Bit
Access
R/W
7
6
5
4
3
2
1
0
CH1_
BASE1
CH1_
BASE0
MULT_
COMP1
MULT_
COMP0
MULT_
SENSE3
MULT_
SENSE2
MULT_
SENSE1
MULT_
SENSE0
CAH
CH2 ATI BASE and Multipliers (CH2_ATI_BASE)
Bit
Access
R/W
7
6
5
4
3
2
1
0
CH2_
BASE1
CH2_
BASE0
MULT_
COMP1
MULT_
COMP0
MULT_
SENSE3
MULT_
SENSE2
MULT_
SENSE1
MULT_
SENSE0
[C8H, C9H, CAH] Base values and Multiplier settings (CH0_BASE, CH1_BASE, CH2_BASE)
The base value or Multiplier settings of each channel can be set in these bytes.
Bit 7-6: CHx_BASE1:CHx_BASE0: Channel base values ALT_BASE = 0; ALT_BASE = 1
00 = 200; 00 = 150
01 = 50; 01 = 350
10 = 100; 10 = 500
11 = 250; 11 = 700
Bit 5-4: MULT_COMP1:MULT_COMP0: Multiplier Compensation setting.
00 = 1:1 (smallest)
01 = 3:1
10 = 1:3
11 = 1:9
Bit 3-0: MULT_SENSE3:MULT_SENSE0: Multiplier Sensitivity setting
0000 = 1 (smallest)
0001 = 2
0010 = 3
0011 = 4
0100 = 5
0101 = 6
0110 = 7
0111 = 8
1000 = 9
1001 = 10
1010 = 11
1011 = 12
1100 = 14
1101 = 14
1110 = 16
1111 = 18
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IQS253 Datasheet V1.04
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IQ Switch®
ProxSense® Series
CBH
Proximity Sensitivity Threshold (PROX_THR_CH0)
Bit
7
6
5
4
3
2
1
0
Access
Name
PT_7
PT_6
PT_5
PT_4
PT_3
PT_2
PT_1
PT_0
R/W
Default
0
0
0
0
0
1
0
0
CCH
Proximity Sensitivity Threshold (PROX_THR_CH1)
Bit
7
6
5
4
3
2
1
0
Access
Name
PT_7
PT_6
PT_5
PT_4
PT_3
PT_2
PT_1
PT_0
R/W
Default
0
0
0
1
0
0
CDH
Proximity Sensitivity Threshold (PROX_THR_CH2)
Bit
7
6
5
4
3
2
1
0
Access
Name
PT_7
PT_6
PT_5
PT_4
PT_3
PT_2
PT_1
PT_0
R/W
Default
0
0
0
1
0
0
[CBH, CCH & CDH] Proximity Sensitivity Settings (PROX_TH_CHx)
Proximity sensitivity thresholds can be anything from 1 to 64.
CEH
Touch Sensitivity Threshold (TOUCH_THR_CH0)
Bit
7
6
5
4
3
2
1
0
Access
Name
TT_5
TT_5
TT_5
TT_4
TT_3
TT_2
TT_1
TT_0
R/W
Default
0
0
1
0
0
0
0
0
Note
CFH
TouchTHR = (value / 256 * LTA)
Touch Sensitivity Threshold (TOUCH_THR_CH1)
Bit
7
6
5
4
3
2
1
0
Access
Name
TT_5
TT_5
TT_5
TT_4
TT_3
TT_2
TT_1
TT_0
R/W
Default
0
0
1
0
0
0
0
0
Note
D0H
TouchTHR = (value / 256 * LTA)
Touch Sensitivity Threshold (TOUCH_THR_CH2)
Bit
7
6
5
4
3
2
1
0
Access
Name
TT_5
TT_5
TT_5
TT_4
TT_3
TT_2
TT_1
TT_0
R/W
Default
0
0
1
0
0
0
0
0
Note
TouchTHR = (value / 256 * LTA)
[CEH, CFH & D0H]Touch Sensitivity Settings (TOUCH_TH_CHx)
Touch sensitivity thresholds are calculated as a fraction of the LTA: TouchTHR = (TOUCH_THR_CHx / 256 *
LTA). There are 256 possible touch threshold values.
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IQS253 Datasheet V1.04
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IQ Switch®
ProxSense® Series
ProxSense Module Settings 0 (PROX_SETTINGS0)
D1H
Bit
Access
R/W
Value
7
6
5
4
3
2
1
0
ATI_
OFF
ATI_
PARTIAL
10s_ATI_
BLOCK
REDO_
ATI
RESEED
CS_
SIZE
PROJ_
BIAS1
PROJ_
BIAS0
0
0
1
0
0
1
1
1
Default
[D1H] PROX_SETTINGS0
Bit 7: AUTO_ATI: Disables the automated ATI routine. By enabling this bit, the device will not be able to
redo ATI if the counts are outside their boundaries.
0 = Auto ATI routine active
1 = ATI disabled
Bit 6: ATI_PARTIAL: Enable Partial ATI.
0 = If ATI occur, it will use the base values as reference
1 = If ATI occur, it will use the MULTIPLIER_COMPx and MULTIPLIER_SENSx as reference
Bit 5: ATI_BLOCK: Enable the 10 second block of ATI after an actuation.
0 = Channels will always redo ATI if LTA is outside boundaries if no actuation is detected
1 = ATI will be blocked for 10 seconds after an actuation has occurred.
Bit 4: REDO_AUTO_ATI: Force the ATI routine to perform. The last written ATI_TARGET value will be used
as target.
0 = No action
1 = Force ATI routine to perform.
Bit 3: RESEED: Reseed the LTA filter. This can be used to adapt to an abrupt environment change,
where the filter is too slow to track this change. Note that with the Short and Long Halt selections, an
automatic Reseed will be performed when the halt time has expired, thus automatically adjusting to
the new surroundings.
0 = Do not reseed
1 = Reseed (this is a global reseed)
Bit 2: CS: Set the size of the internal sampling capacitor. A larger CS capacitor requires more transfers
(higher counts) to be charged.
0 = 29.9pF
1 = 59.8pF
Bit 1-0: PROJ_BIAS1:PROJ_BIAS0: Projected Bias Current
00 = 1.25uA (smallest)
01 = 2.5uA
10 = 5uA
11 = 10uA
D2H
ProxSense Module Settings 1 (PROX_SETTINGS1)
Bit
7
6
5
4
3
2
1
0
Access
Value
PROJ
ALT_
BASE
Turbo_
Mode
HC
ND
ND_
TRIM0
ND_
TRIM0
ND_
TRIM0
R/W
Default
0
0
0
0
0
0
0
0
[D2] PROX_SETTINGS1
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IQS253 Datasheet V1.04
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IQ Switch®
ProxSense® Series
Bit 7: PROJ: Use the IQS253 in projected mode. This setting can only be enabled in the SETUP communications window. Alternatively, us the FG option.
0 = IQS253 in Self Capacitive sensing mode
1 = IQS253 in Projected Capacitive sensing mode
Bit 6: ALT_BASE: Set this bit to choose the alternative base values
0 = Normal base values
1 = Alternative base values
Bit 5: Turbo_Mode: Enable the DYCAL Turbo functionality (If DYCAL is enabled). By enabling this bit, the
device will drastically decrease the time to detect users proximity and touch events.
0 = Normal
1 = Enable Turbo Mode
Bit 4: HC: Halt charges. The device will not perform capacitive sensing charge transfers and thus not be
able to detect any user events.
0 = Charge transfers occur normally
1 = No charge transfers occur
Bit 3: ND: Noise Detection Enable. This setting is used to enable the on-chip noise detection circuitry. With
noise detected, the noise affected samples will be ignored, and have no effect on the Prox, touch or
LTA calculations. The NOISE bit will appropriately be set as indication of the noise status.
0 = Disable noise detection
1 = Enable noise detection
Bit 2-0: ND_TRIM2:ND_TRIM0: ND Trim values
000 = 19.1mV
001 = 9.65mV
010 = 0mV
011 = -10mV
100 = -19.1mV
101 = -29.8mV
110 = -40.9mV
111 = -57.4mV
D3H
ProxSense Module Settings 2 (PROX_SETTINGS2)
Bit
7
6
5
4
3
2
1
0
Access
Value
ACK_
RESET
COMMS_
WDT_
DISABLE
FORCE_
HALT
ACF_
DISABLE
TIME_
OUT_
DISABLE
EVENT_
MODE _
DISABLE
HALT1
HALT0
R/W
Default
0 (W)
0
0
0
0
0
0
0
[D3H] PROX_SETTINGS2
Bit 7: ACK_RESET: Acknowledge SHOW_RESET.
0 = Nothing
1 = Clear the SHOW_RESET flag (send only once)
Bit 6: WDT_DISABLE: Device watchdog timer (WDT) disable.
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0 = Enabled
1 = Disabled
Bit 5: FORCE_HALT: The LTA is halted by setting this bit. It will only be allowed to adapt to the environment
once it is cleared.
0 = LTA adapts to environment until actuation detected.
1 = Halt LTA.
Bit 4: ACF_DISABLE: Disable the AC Filter employed on the Counts (CS).
0 = Enable AC filter.
1 = Disable AC filter.
Bit 3: TIME_OUT_DISABLE: Enable I2 C communication timeout. This bit will enable the IC to resume
charge transfers if communication does not commence within 20ms of the RDY indicating that data is
ready.
0 = Disable time-out.
1 = Enable time-out.
Bit 2: EVENT_MODE_DISABLE: Enable the IC to stream data continuously.
0 = I2 C Communication will only occur if an event occur (events defined in EVENT_MODE_MASK byte)
1 = Continuous streaming mode
Bit 1-0: HALT1:HALT0: LTA halt timings.
00 = 20s
01 = 40s
10 = Never
11 = Always
D4H
Access
R/W
ProxSense Module Settings 3 (PROX_SETTINGS3)
Bit
Value
7
6
5
4
LTA_
ADAPT1
LTA_
ADAPT0
3
2
1
PROX_
DEBOUNCE
XFER_
FREQ1
Default
0
0
XFER_
FREQ0
1
[D4H] PROX_SETTINGS3
Bit 7-6: Unused
Bit 5-4: LTA_ADAPT: Rate at which LTA adapts to CS when no actuation is detected (non- TM mode).
00 = 3.13% (fastest)
01 = 1.56%
10 = 0.78%
11 = 0.39% (slowest)
Bit 3: Unused
Bit 2: PROX_DEBOUNCE: Number of consecutive CS samples required exceeding proximity threshold to
detect a proximity event.
0=6
1=4
Bit 1-0: XFER_FREQ1:XFER_FREQ0: Charge transfer frequency.
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00 = 1MHz
01 = 500kHz
10 = 250kHz
11 = 125kHz
The charge transfer frequency is a very important parameter. Dependant on the design application, the
device frequency must be optimised. For example, if keys are to be used in an environment where steam
or water droplets could form on the keys, a higher transfer frequency improves immunity. Also, if a sensor
electrode is a very large object/size, then a slower frequency must be selected since the capacitance of the
sensor is large, and a slower frequency is required to allow effective capacitive sensing on the sensor.
Active Channels (ACTIVE_CHAN)
D5H
Bit
7
6
5
4
3
2
1
0
Access
Value
CH2
CH1
CH0
R/W
Default
1
1
1
[D5H] ACTIVE_CHAN
Each channel can be individually disabled in this register.
Bit 7-3: Unused
Bit 2: CH2: Setting this bit will disable the channel
0 = Active / Charging
1 = Inactive / Not charging
Bit 1: CH1: Setting this bit will disable the channel
0 = Active / Charging
1 = Inactive / Not charging
Bit 0: CH0: Setting this bit will disable the channel
0 = Active / Charging
1 = Inactive / Not charging
Low Power Settings (LOW_POWER)
D6H
Bit
7
6
5
4
3
2
1
0
Access
Value
LP7
LP6
LP5
LP4
LP3
LP2
LP1
LP0
R/W
Default
Normal Power default (00H). See Note below.
Note
Custom value between 1 and 256 value x 16ms LP time
[D6H] LP_PERIOD
Byte indicates the sleep time between a burst of conversions. Default (00H), a channel is charged every
27ms. The LP time can be set to any custom value between 1 and 256. The time between the conversions
will then be the value x 16ms. (NOTE: CX2 does a dummy conversion before the burst of the active channels
are executed.)
D7H
Access
R/W
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DYCAL Specific Settings (DYCAL_SETTINGS)
Bit
7
6
5
4
3
2
1
0
Value
250ms_
ALWAYS_
BETA_
BETA_
BETA_
OUTPUT_
REL_
REL_
DELAY_
HALT_
TM_
TM_
TM_IN
ON_
THR1
THR0
TM
DYCAL
OUT1
OUT0
0
0
0
0
0
0
Default
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[D7H] DYCAL_SETTINGS
Byte indicates which channels are actively charged.
Bit 7: 250ms_DELAY_TM: A 250ms delay is applied on the LTA when a touch is detected, before the LTA
is reseeded to the LTA-TOUCH_THR
0 = Enabled
1 = Disabled
Bit 6: ALWAYS_HALT_DYCAL: Always halt LTA in TM if CS exceeds LTA by 16 (Self) or if CS is lower than
LTA by 16 (projected)
0 = Halting of LTA in TM according to HALT1:HALT0 settings
1 = Always halt LTA if above condition is met
Bit 5-4: LTA_ADAPT_IN: Rate at which LTA adapts after reseed when heading towards the CS in TM
00 = 1.56%
01 = 6.25% (fastest)
10 = 3.13%
11 = 0.78% (slowest)
Bit 3: LTA_ADAPT_OUT: Rate at which LTA adapts after its reached CS, when CS is heading out of TM.
0 = 0.10% (fastest)
1 = 0.01% (slowest)
Bit 2: OUTPUT_ON_TOUCH: Setting this bit will enable the DYCAL output to change with touch actuation.
0 = DYCAL on Proximity
1 = DYCAL on Touch
Bit 1-0: RELEASE_THR1:RELEASE_THR0: Release threshold with which CS should exceed LTA for LTA
to reseed back to non-TM.
00 = 75%
01 = 50%
10 = 87.5%
11 = 100%
D8H
DYCAL Channels Enable (DYCAL_CHANS)
Bit
7
6
5
4
3
2
1
0
Access
Name
BLOCK_ON_CH1_ENABLE
CH2
CH1
CH0
R/W
Default
0
1
1
1
[D8H] DYCAL enable and Block channel enable (DYCAL_CHANS)
Channels are default configured as DYCAL channels. Clearing a channel bit, will make it a direct output
channel.
Bit 7-4: Unused
Bit 3: CH1_BLOCK: Setting this bit will make channel 1 a block channel
0 = Normal output
1 = CH1 will block the output of the other channels if actuated
Bit 2: CH2: Clearing this bit, will make the channel a direct output channel
0 = Direct Output channel
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1 = DYCAL channel
Bit 1: CH1: Clearing this bit, will make the channel a direct output channel
0 = Direct Output channel
1 = DYCAL channel
Bit 0: CH0: Clearing this bit, will make the channel a direct output channel
0 = Direct Output channel
1 = DYCAL channel
EVENT MODE MASK (EVENT_MASK)
D9H
Bit
7
6
5
4
3
2
1
0
Access
Name
ATI
DYCAL
BOOLEAN
NOISE
TOUCH
PROX
R/W
Default
1
1
1
1
1
1
[D9H] Event Mode mask (EVENT_MASK)
Bit 7-6: Unused
Bit 5: ATI: A communication event will occur if an ATI or re-ATI occurs.
0 = Communication event will not occur
1 = Communication event will occur
Bit 4: DYCAL: A communication event will occur if a DYCAL state change occurs.
0 = Communication event will not occur
1 = Communication event will occur
Bit 3: BOOLEAN: A communication event will occur if a Boolean state change occurs.
0 = Communication event will not occur
1 = Communication event will occur
Bit 2: NOISE: A communication event will occur if noise is detected.
0 = Communication event will not occur
1 = Communication event will occur
Bit 1: TOUCH: A communication event will occur if a proximity state change occurs. Should only be used if
a channel is in direct mode.
0 = Communication event will not occur
1 = Communication event will occur
Bit 0: PROXIMITY: A communication event will occur if a proximity state change occurs. Should only be
used if a channel is in direct mode.
0 = Communication event will not occur
1 = Communication event will occur
DAH
Boolean Settings (BOOLEAN_SETTINGS)
Bit
7
6
5
4
3
2
1
0
Access
Value
BOOL_ AND_OR
MASK_ CH2
MASK_ CH1
MASK_ CH0
R/W
Default
0
0
0
0
[DAH] BOOLEAN_SETTINGS
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Bit 7-4: Unused
Bit 3: BOOLEAN_AND_OR: Boolean AND operation on the channels chosen to perform this action on
0 = Boolean AND operation
1 = Boolean OR operation
Bit 2: CH2: Use this channel in the Boolean operation
0 = No
1 = Yes
Bit 1: CH1: Use this channel in the Boolean operation
0 = No
1 = Yes
Bit 0: CH0: Use this channel in the Boolean operation
0 = No
1 = Yes
Boolean NOT Mask (BOOLEAN_NOT)
DBH
Bit
7
6
5
4
3
2
1
0
Access
Name
NOT_ CH2
NOT_ CH1
NOT_ CH0
R/W
Default
0
0
0
[DBH] BOOLEAN_NOT
Bit 7-3: Unused
Bit 2: CH2: Invert this channels polarity (NOT operation)
0 = No action
1 = NOT Channel (Invert channel polarity)
Bit 1: CH1: Invert this channels polarity (NOT operation)
0 = No action
1 = NOT Channel (Invert channel polarity)
Bit 0: CH0: Invert this channels polarity (NOT operation)
0 = No action
1 = NOT Channel (Invert channel polarity)
DDH
DEFAULT_COMMS_POINTER
Access
Bit
7
R/W
Default
6
5
4
3
2
1
0
10H (Beginning of Device Specific Data)
[DDH] Default Comms Pointer
The value stored in this register will be loaded into the Comms Pointer at the start of a communication window.
For example, if the design only requires the Proximity Status information each cycle, then the Default Comms
Pointer can be set to ADDRESS 31H. This would mean that at the start of each communication window, the
comms pointer would already be set to the Proximity Status register, simply allowing a READ to retrieve the
data, without the need of setting up the address.
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B.2
General Implementation Hints
When implementing the communication interface with the IQS253, please refer to the IQS253 datasheet for
a detailed description of the I2 C communication. This section contains some general guidelines and hints
regarding the communication interface.
B.2.1
I2 C Communication window
When communicating via I2 C, the communication window will automatically close when a STOP bit is received
by the IQS253. The IQS253 will then proceed to start with a new conversion and the READY line will be pulled
low until the new conversion is complete. Note that there is no command via I2 C to initiate a new conversion.
To perform multiple read and write commands, the repeated start function of the I2 C must be used to stack
the commands together.
B.3
Startup Procedure
After sending initial settings to the IQS253, it is important to execute a reseed. It is suggested to execute an
estimated 24 conversions after initial settings before calling for a reseed, to allow the system to stabilise.
B.4
B.4.1
General I2 C Hints
I2 C Pull-up resistors
When implementing I2 C it is important to remember the pull-up resistors on the data and clock lines. 4.7k is
recommended, but for lower clock speeds bigger pull-ups will reduce power consumption. The RDY line is
SW OD and also requires a pull up resistor (typical 10k).
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References
[1] AZD008 - Design Guidelines for Touch Pads. Azoteq, 2011.
[2] AZD013 - Calculating Rx for improving ESD ratings. Azoteq, 2008.
[3] AZD015 - RF Immunity Guidelines. Azoteq, 2011.
[4] AZD051 - Electrical Fast Transient Burst Guidelines. Azoteq, 2011.
[5] AZD052 - Conducted RF Immunity Guidelines. Azoteq, 2011.
[6] AZD062 - IQS253 Communication Interface Guideline. Azoteq, 2012.
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