IQS231A-00004000-TSR 数据手册
Azoteq
IQ Switch®
ProxSense® Series
IQS231A/B DATASHEET
Single Channel Capacitive Proximity/Touch Controller for SAR Applications
1
Device Overview
The IQS231A/B ProxSense® IC is a self-capacitance controller designed for applications where an
awake/activate on proximity function is required. The IQS231A/B is an ultra-low power solution that
uses unique release and/or movement detection for applications that require long- term detection.
The IQS231A/B operates standalone or I2C and features configuration via OTP (One Time
Programmable) bits. Switching from I2C to standalone during runtime is also possible in order to
access all settings while offering the simplicity of a standalone output.
IQS231B offers alternate hardware with identical firmware to the IQS231A. IQS231B hardware offers
improved temperature response and low temperature range.
1.1
>
Integrated SAR user interface offering a
simple GPIO output
>
Extended controls in I2C mode (setup in I2C,
runtime with standalone output)
>
Quick release detection – effectively
prevent false triggers from remaining
>
>
Quick release sensitivity options
Optional
input
for
synchronized
implementations (input to instruct IC when to
sense)
>
Wide range of control for sensing in high
power RF environments
>
Pin compatible with devices of same
package type (All ProxSense TSOT23-6
devices1,IQS211A WLCSP-8 device)
>
1.8V (-2%) to 3.6V Input voltage
>
Capacitive resolution down to 0.02fF
>
Capacitive load capability up to 120pF
>
External threshold adjustment pin
(minimize need for pre-empted OTP
adjustments)
>
Minimal external components (direct
input strap)
>
Standalone failsafe mode (backwards
compatible failsafe output, short pulses
on output to indicate operational device)
>
>
1
Main Features
Default OTP options focus on safety and
passing SAR lab qualification, OTP
changes offer performance advantages
I2C
interface
compatibility)
option
6 pin TSOT23-6
RoHS2
Compliant
8 pin WLCSP-8
6 pin DFN6
Representations only, not
actual markings
>
Synchronization output – failsafe pulses may
be used by the master to synchronize on.
Sensing is done after each pulse
>
Synchronization input – Sensing is only done
while Sync input is low
>
Low power sensing: 30Hz (default), 100Hz,
8Hz, 4Hz (sub 6uA mode)
>
Constant sampling rates during all power
modes with rapidly debounced output
changes
>
Advanced temperature
compensation option
&
interference
(improved
Input voltage level and pin functions may differ
Copyright © Azoteq (Pty) Ltd 2020
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IQS231A/B Datasheet
Revision 2.5
Page 1 of 47
October 2021
Azoteq
IQ Switch®
ProxSense® Series
1.2
Applications
>
SAR sensor
>
Hold detection for screen activation
>
Integrated hybrid designs (RF and
capacitive sensing combined)
>
On-ear detection
>
Movement sensing applications (user
interaction detection, anti-theft)
TA
DFN6
-20ºC to 85 ºC
-40ºC to 85 ºC
1.3
IQS231B
TSOT23-6
WLCSP-8 (1.5 x 0.9 x 0.4mm)
IQS231A
IQS231A (NRFND)
IQS231B
IQS231B
Block Diagram
VDDHI
VDDHI
VREG
BOD
POR
circuit
Internal
regulator
Digital - μP, RAM, ROM
Nonvolatile
memory
VSS
SDA / IO2
Analog
ProxSense Engine (ADC)
I2C
HW
or
GPIO
SCL / IO1
MCU
(Master)
Analog - Capacitive
offset calibration
Cx
Reference GND
(battery, metal frame,
copper pad)
Sensing Pad
∆E-field = ∆Capacitance
Figure 1.1 Functional Block Diagram for IQS231A/B
The IQS231A/B supports relative capacitance measurements for detecting capacitance changes.
Basic features of the IQS231A/B include:
>
Charge-transfer capacitance measurement technology (Analog ProxSense® Engine)
>
Finite state machine to automate detection and environmental compensation without MCU
interaction (integrated microprocessor)
>
Self-capacitance measurements
>
Signal conditioning to provide signal gain (Analog – Capacitive offset calibration)
>
Signal conditioning to provide offset compensation for parasitic capacitance (Analog – Capacitive
offset calibration)
>
Integrated calibration capacitors (Analog – Capacitive offset calibration)
>
Integrated timer for timer triggered conversions
>
Integrated LDO regulator for increased immunity to power supply noise
Copyright © Azoteq (Pty) Ltd 2020
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IQS231A/B Datasheet
Revision 2.5
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October 2021
IQ Switch®
ProxSense® Series
Azoteq
>
Integrated oscillator
>
Processing logic to perform measurement filtering, environmental compensation, threshold
detection and movement detection
Copyright © Azoteq (Pty) Ltd 2020
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IQS231A/B Datasheet
Revision 2.5
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IQ Switch®
ProxSense® Series
Azoteq
TABLE OF CONTENTS
IQS231A/B DATASHEET .................................................................................................................................. 1
1
DEVICE OVERVIEW .................................................................................................................................. 1
1.1
1.2
1.3
2
MAIN FEATURES ........................................................................................................................... 1
APPLICATIONS .............................................................................................................................. 2
BLOCK DIAGRAM ........................................................................................................................... 2
PACKAGING AND PIN-OUT ..................................................................................................................... 8
2.1
2.2
3
TSOT23-6 & DFN6 ..................................................................................................................... 8
WLCSP ....................................................................................................................................... 9
REFERENCE SCHEMATICS: ................................................................................................................. 10
3.1
3.2
RECOMMENDED CAPACITOR VALUES ........................................................................................... 12
EXCEPTION TO RECOMMENDED CAPACITOR VALUES ..................................................................... 12
4
SUMMARY: ONE-TIME-PROGRAMMABLE (OTP) OPTIONS .............................................................. 13
5
SUMMARY: PROGRAMMING REFERENCE (I2C MEMORY MAP) ...................................................... 14
6
SUMMARY: FEATURES ......................................................................................................................... 15
7
FEATURES: EXTENDED DETAILS ........................................................................................................ 18
7.1
7.2
AUTOMATIC TUNING IMPLEMENTATION (ATI) ................................................................................ 18
SENSITIVITY ADJUSTMENT ........................................................................................................... 18
I2C PROGRAMMING GUIDE (SUMMARY) ............................................................................................. 19
8
8.1
8.2
8.3
8.4
8.5
8.6
8.7
8.8
8.9
9
ADD I2C CONNECTION................................................................................................................. 19
I2C COMMAND STRUCTURE ......................................................................................................... 19
CONTROL BYTE .......................................................................................................................... 20
TEST MODE (ADDRESS 0X45) ...................................................................................................... 20
I2C TYPICAL SETUP..................................................................................................................... 20
I2C READ (EVENT REGISTER) ...................................................................................................... 20
I2C POLLING AND SENSING TIMING .............................................................................................. 21
MOVEMENT TIME-OUT ACCURACY ............................................................................................... 21
SAMPLING FREQUENCY VS SENSING FREQUENCY ........................................................................ 21
CONFIGURATION OPTIONS .................................................................................................................. 23
9.1
9.2
9.3
9.4
OTP DETAILS: BANK 0 ................................................................................................................ 23
OTP DETAILS: BANK 1 ................................................................................................................ 24
OTP DETAILS: BANK 2 ................................................................................................................ 25
OTP DETAILS: BANK 3 ................................................................................................................ 28
10
FULL PROGRAMMING REFERENCE .................................................................................................... 30
11
SPECIFICATIONS ................................................................................................................................... 34
11.1
11.2
12
PACKAGE INFORMATION ..................................................................................................................... 39
12.1
12.2
12.3
13
ABSOLUTE MAXIMUM RATINGS .................................................................................................... 34
I2C TIMING SPECIFICATIONS ........................................................................................................ 38
TSOT23-6 ................................................................................................................................. 39
DFN-6 ....................................................................................................................................... 40
WLCSP-8 .................................................................................................................................. 41
ORDERING AND PART-NUMBER INFORMATION ............................................................................... 42
13.1
13.2
ORDERING INFORMATION ............................................................................................................ 42
DEVICE NUMBERING CONVENTION – TSOT23-6 .......................................................................... 42
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IQ Switch®
ProxSense® Series
13.3
13.4
Azoteq
DEVICE NUMBERING CONVENTION: 8-PIN WLCSP ........................................................................ 43
DEVICE NUMBERING CONVENTION – DFN6.................................................................................. 44
14
TAPE AND REEL INFORMATION .......................................................................................................... 45
15
REVISION HISTORY ............................................................................................................................... 46
Copyright © Azoteq (Pty) Ltd 2020
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Revision 2.5
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IQ Switch®
ProxSense® Series
Azoteq
List of Abbreviations
AC
Alternating Current
ATI
Automatic Tuning Implementation
CH
Channel
ESD
Electrostatic Discharge
GPIO
General Purpose Input/Output
GUI
Graphic User Interface
GND
Ground
IIR
Infinite Impulse Response
IO
Input/Output
I2C
Inter Integrated Circuit
LTA
Long Term Average
LDO
Low-Dropout Regulator
MCU
Microcontroller Unit
NC
Not Connected
OTP
One Time Programmable
POR
Power on Reset
PGM
Programming Pin
Prox
Proximity level trigger
RF
Radio Frequency
SAR
Self Absorption Rate
SCL
Serial Clock
SDA
Serial Data
SNR
Signal to Noise Ratio
UI
User Interface
Vss
Ground
VREG
Regulator Output
VDDHI
Supply Input
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IQ Switch®
ProxSense® Series
Azoteq
List of Symbols
A
Ampère
ᵒC
Degrees Celsius
Hz
Hertz
Kbits/s
kilobits per second
kHz
kilohertz
kΩ
kilo-ohm
kV
kilovolt
μA
micro- Ampère
μF
micro-Farad
μs
microseconds
mA
milli-Ampère
mm
milli-meter
ms
milliseconds
mV
millivolt
min
minute
nA
nano-Ampère
ns
nanoseconds
Ω
Ohm
pF
pico-Farad
s
seconds
V
Volt
V/s
Volts per second
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Azoteq
IQ Switch®
ProxSense® Series
2
Packaging and Pin-Out
2.1
TSOT23-6 & DFN6
VSS 2
IQS
231A/B
VSS
2
5 VDDHI
IQS231
IO1/SCL 1
6 Cx
IO1 / SCL 1
IO2/SDA 3
6
Cx
5
VDDHI
4
VREG
4 VREG
IO2 / SDA 3
Figure 2.1 IQS231A/B TSOT23-6 Pin-out
Figure 2.2 IQS231B DFN6 Pin-out
Table 2.1 TSOT23-6 and DFN-6-Pin-out Description
IQS231A/B TSOT23-6/ IQS231B DFN-6
Pin
Name
Type
Function
1
PRIMARY I/O
Digital Input/ Output
Multifunction IO1 / SCL (I2C Clock signal)
2
VSS
Signal GND
3
SECONDARY I/O
Digital Input/ Output
Multifunction IO2 / SDA (I2C Data output)
4
VREG
Regulator output
Requires external capacitor
5
VDDHI
Supply Input
Supply:1.764V – 3.6V
6
Cx
Sense electrode
Connect to conductive area intended for sensor
Table 2.2 Multifunction Pin Descriptions
Multifunction
name
2
pin
22-Dxx
Multifunction pin option
IC NAME
Output type
Batch code
IO1
Proximity output / Proximity output with heartbeat
Open-drain2
IO2
Sensitivity input / Synchronization input / Movement
output / Touch output
Open-drain2
Requires pull-up resistor
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Revision 2.5
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Azoteq
IQ Switch®
ProxSense® Series
2.2
WLCSP
1
2
3
4
IQS231A/B
8
7
6
5
Figure 2.3 IQS231A/B 8-pin WLCSP (top view)
Table 2.3 8-pin WLCSP Pin-out description
IQS231A 8-pin WLCSP
Pin
Name
Type
Function
1
Cx
Sense electrode
Connect to conductive area intended for sensor
2
PRIMARY I/O
Digital Input/ Output
Multifunction IO1 / SCL (I2C Clock signal)
3
VREG
Regulator output
Requires external capacitor
4
VSS
Signal GND
5
FLOATING IO
Digital Input/Output
Not used. Floating input during runtime.
Recommended: Connect to GND
6
SECONDARY I/O
Digital Input/Output
Multifunction IO2 / SDA (I2C Data output)
7
VDDHI
Supply Input
Supply:1.764V – 3.6V
Configuration pin
Connection for OTP programming. Floating input
during runtime.
Recommended: Connect to GND. Connect separate
pad/pin for in-circuit programming (separate modules
only)
8
PGM
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Revision 2.5
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IQ Switch®
ProxSense® Series
3
Azoteq
Reference Schematics:
Figure 3.1 IQS231A/B TSOT23-6 and DFN-6 Reference Schematic
Footnotes:
* R5: Place a 47Ω resistor in the VDDHI supply line to prevent a potential ESD induced latch -up.
Maximum supply current should be limited to 80mA on the IQS231A/B VDDHI pin to prevent latchup.
** C1 & C3: See Section 3.1 for recommended values. The target is to prevent the VREG voltage to
drop more than 40mV from its regulated value during a sleep cycle (see Figure 9.1).
***C5: Example load of 2.2pF. This value may vary to adjust sensitivity. 1pF for higher sensitivity and
up to 60pF for proximity detection use. A total load of 120pF is allowed by the sensing system.
****R1: Vary this value to control the RC slope of the capacitance measurement signal. Use for
harmonic suppression and to enable a high impedance sensing path in a low impedance system.
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IQS231A/B Datasheet
Revision 2.5
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IQ Switch®
ProxSense® Series
Azoteq
Figure 3.2 IQS231B WLCSP-8 Reference Schematic
Footnotes:
* R5: Place a 47Ω resistor in the VDDHI supply line to prevent a potential ESD induced latch-up.
Maximum supply current should be limited to 80mA on the IQS231A/B VDDHI pin to prevent latchup.
** C1 & C3: See Section 3.1 for recommended values. The target is to prevent the VREG voltage to
drop more than 40mV from its regulated value during a sleep cycle (see Figure 9.1).
***C5: Example load of 2.2pF. This value may vary to adjust sensitivity. 1pF for higher sensitivity and
up to 60pF for proximity detection use. A total load of 120pF is allowed by the sensing system.
****R1: Vary this value to control the RC slope of the capacitance measurement signal. Use for
harmonic suppression and to enable a high impedance sensing path in a low impedance system.
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IQS231A/B Datasheet
Revision 2.5
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October 2021
IQ Switch®
ProxSense® Series
3.1
Azoteq
Recommended Capacitor Values
The VREG capacitor value (C1) is chosen to ensure VREG remains above the maximum BOD
specification stated in Table 11.3. The combination of C1 (VREG) and C3 (VDDHI) is chosen to
prevent a potential ESD issue.
Known issue: In some cases, the IQS231A/B will not recover from ESD events. In cases where a
high current source or regulator with low impedance path is present (a source that keeps VDDHI
above the BOD level), the ESD event drains the VREG capacitor, but VDDHI voltage remains above
BOD. When the ESD event is timed with the “sleep” power mode it causes a firmware run-time failure
that only recovers when forcing a POR on VDDHI.
Recommended values to prevent this is shown in Table 3.1.
Table 3.1 VDDHI and VREG capacitor size recommendation to prevent ESD issues with typical hardware
combinations
Low power scan time
Capacitor
recommendation
3.2
8ms (default) 128ms
32ms
C1 = 1µF
C1 = 4.7µF
C3 = 1µF
C3 = 2.2µF
256ms
C1 = 10µF
C3 = 2.2µF
Exception to recommended capacitor values
In applications where the VDDHI source has high internal resistance or a high resistance path, it will
be required to ensure C3 > C1 to prevent a VDDHI BOD after the IC sleep cycle (see Table 11.3)
Table 3.2 Capacitor Values for VDDHI (C3) and VREG (C1) under certain supply voltage conditions
Low power scan time
Capacitor
recommendation
Copyright © Azoteq (Pty) Ltd 2020
All Rights Reserved
8ms (default) 128ms
32ms
C1 = 1µF
C1 = 4.7µF
C3 = 1µF
C3 = 10µF
IQS231A/B Datasheet
Revision 2.5
256ms
C1 = 10µF
C3 = 10µF
Page 12 of 47
October 2021
Azoteq
IQ Switch®
ProxSense® Series
4
Summary: One-Time-Programmable (OTP) Options
OTP bank 0
Bit7
IQS231A/B 000000xx TSR
6
5
4
3
Movement time-out
Reserved
Movement
threshold
Quick
threshold
2
release
1
Quick release beta
Prox no mov UI
00 – 2s
01 – 5s
10 – 10s
11 – Disabled (0s)
n/a
0 – 4 counts
1 – 6 counts
00 – moderate
counts
01 – strict
10 – relaxed
11 – very strict
100
00 – 2 (fast following)
01 – 3
10 – 4
11 – 5 (slow following)
150
50
250
Bit 0
Prox&Mov Uis
00 – 10s
01 – 30s
10 – 60s
11 – 10min
*See time-out accuracy section
OTP Bank 1
Bit7
6
IQS231A/B 0000xx00 TSR
5
4
3
I2C address
Proximity Threshold
(low/high)
00 – standalone
01 – 44H
10 – 46H
11 – 47H
Sensitivity input low / Sync input
active / Mov output / Touch output/
Ignore input, no output
00 – 4 counts (1Warning)
01 – 6
10 – 8
11 – 10
Sensitivity input high (internal
20kΩ pull-up)
00 – 8 counts
01 – 10
10 – 12
11 – 14
*See time-out accuracy section
OTP Bank 2
2
1
Bit 0
AC Filter
Touch threshold
00 – 1
01 – 2
10 – 3
11 – 0
00 – 32 counts
01 – 64
10 – 256
11 – 320
IQS231A/B 00xx0000 TSR
Bit7
6
5
3
2
1
Increase
debounce
Target
Base value
Failsafe
Quick
release
User interface
0 – 6in, 4out
1 – 12in, 8out
0 = 1200 /
1096
(movement)
1 = 768
00 – 100 counts
01 – 75
10 – 150
11 – 200
0 – Disabled
1 – Enabled
0 – Enabled
1 – Disabled
00 – Prox / No movement
01 – Prox with movement
10 – Prox with movement /
Touch with no movement
11 – Same as ‘10’, touch output
forced on IO2
OTP Bank 3
Bit7
6
4
Bit 0
IQS231A/B xx000000 TSR
5
4
2
1
Charge transfer
frequency
Temperature
& interference
compensation
IO2 function
3
ATI
events on
IO1
Sample rate
Bit 0
00 – 500kHz
01 – 125 kHz
10 – 64 kHz
11 – 16.5kHz
0 – Disabled
1 – Enabled
00 – Sensitivity input
(proximity threshold adjust)
01 – Synchronize input
10 – Movement output
11 – Ignore input, no output
0 – Enabled
1 – Disabled
Sample-to-sample time
(Response time) Includes 6
sample debounce burst of 24ms
00 – 30 Hz
(57ms)
01 – 100 Hz
(34ms)
10 – 8 Hz
(154ms)
11 – 4 Hz
(280ms)
*See time-out accuracy section
8.8 & 8.9
1
Careful design is key when using a threshold of 4 combined with a base value of 100 / 75 and a target of 1200. Contact Azoteq.
Copyright © Azoteq (Pty) Ltd 2020
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Azoteq
IQ Switch®
ProxSense® Series
5
Summary: Programming Reference (I2C Memory Map)
I2C Communications Layout
Address/
Register name/s
Command/
Byte
R/W
Default
Value
Bit 7
Bit 6
Bit 5
Bit 4
DEFAULT
MAIN_EVENTS
R
n/a
DEBUG
SENSING
WARM
COMMS
DISABLED
BOOT
POINTER
Each read instruction returns ‘MAIN_EVENTS’ byte as first byte, followed by the data at the specified address
00H
PRODUCT_NUMBER
R
0x40
0x40
01H
SOFTWARE_VERSION
R
0x06
0x06 (IQS231A), 0x07 (IQS231B – Identical to 0x06 software)
02H
DEBUG_EVENTS
R
n/a
RESERVED
ATI_ERROR
CH0_ATI
RESERVED
03H
04H
Reserved
COMMANDS
R/W
R/W
n/a
0x00
05H
OTP Bank 1
R/W
0x00
06H
OTP Bank 2
R/W
0x00
07H
OTP Bank 3
R/W
0x00
08H
QUICK RELEASE
R/W
0x00
09H
MOVEMENT
R/W
0x34
(2s, 8)
RESERVED
ATI_CH0
DISABLE
SENSING
Standalone / I2C address
Increase
Target
debounce
Charge transfer frequency
ENABLE
TOGGLE
SENSING
AC FILTER
Proximity threshold
Read only
Base value
Temperature
& interference
compensation
Bit 3
0x8 = 75
0x9 = 200
0xA = 300
0xB = 400
0xC = 10min
0xD = 30min
0xE = 60min
0xF = 90min
0x8 = 30s
0x9 = 1min
0xA = 2min
0xB = 5min
0x4 =
0x5 =
0x6 =
0x7 =
Bit 1
Bit 0
COLD
BOOT
RELEASE
TOUCH
PROX
QUICK
RELEASE
EXIT MOV
DETECT
ENTER
MOV
DETECT
MOVEMENT
RESERVED
TOGGLE
MODE
RESERVED
WARM
BOOT
ULP
AC Filter
Failsafe
pulses IO1
IO2 Function
Quick release
ATI events on
IO1
Quick release threshold LUT
0xC = 500
0xD = 750
0xE = 850
0xF = 1000
Bit 2
Touch threshold
Read only
User interface selection
Sample rate
Quick release beta
10
20
25
30
0x0 = 100
0x1 = 150
0x2 = 50
0x3 = 250
0x4 = 4s
0x5 = 5s
0x6 = 10s
0x7 = 20s
0x0 = 0s
0x1 = 0.5s
0x2 = 1s
0x3 = 2s
Filter halt time
Movement threshold = (Value × 2)
Available range: 0 – 30
0 = always movement trigger
0AH
TOUCH THRESHOLD
R/W
PROXIMITY
THRESHOLD
R/W
0x07
(32)
0x00
Touch threshold = (Value × 4) + 4
0BH
0CH
R/W
0x03
Temperature tracking threshold when not in touch / prox detect
0DH
Temperature &
interference threshold
CH0 Multipliers
R/W
n/a
Reserved
Reserved
CH0 Sensitivity Multiplier
0–3
CH0 Compensation multiplier
0 – 15
0EH
0FH
CH0 Compensation
CH1 Multipliers
R/W
R/W
n/a
n/a
0 – 255
Reserved
Reserved
CH1 Sensitivity Multiplier
0–3
CH1 Compensation multiplier
0 – 15
10H
11H
12H
CH1 Compensation
System flags
UI flags
R/W
R
R
n/a
n/a
n/a
0 – 255
I2C
TEMP
CH1_ACTIVE
CURRENT_CH
NO SYNC
CH0_LTA_HALTED
ATI_MODE
ZOOM MODE
TEMPERATURE
RESEED
Reserved
UI AUTO ATI
OFF
UI SENSING
DISABLED
QUICK_RELEASE
Reserved
OUTPUT
ACTIVE
13H
14H
ATI flags
Event flags
R
R
n/a
n/a
TEMP
CHANNEL ATI
Reserved
CH1
MOVEMENT
CH0_ATI
ERROR
CH0
UNDEBOUNCED
CH0_ TOUCH
CH0_PROX
15H
16H
17H
CH0 ACF_H
CH0 ACF_L
CH0 LTA_H
R
R
R
n/a
n/a
n/a
18H
19H
1AH
1BH
1CH
1DH
1EH
1FH
20H
21H
22H
23H
24H
25H
26H
27H
CH0 LTA_L
CH0 QRD_H
CH0 QRD_L
CH1 ACF_H
CH1 ACF_L
CH1 UMOV_H
CH1 UMOV_L
CH1 LMOV_H
CH1 LMOV_L
CH1_RAW_H
CH1_RAW_L
TEMPERATURE_H
TEMPERATURE_L
LTA_HALT_TIMER_H
LTA_HALT_TIMER_L
FILTER_HALT_TIMER
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
n/a
n/a
n/a
n/a
n/a
n/a
n/a
n/a
n/a
n/a
n/a
n/a
n/a
n/a
n/a
n/a
28H
TIMER_READ_INPUT
R
n/a
29H
TIMER_REDO_ATI
R
n/a
Available range: 4 – 1024
Reserved
Reserved
CH1_ATI
ERROR
Reserved
00 – 4 counts
01 – 6
10 – 8
11 – 10
Proximity channel: Filtered count value
0 – 2000
Proximity channel: Reference count value (Long term average)
0 – 2000
Proximity channel: Quick release detect reference value
0 – 2000
Movement channel: Filtered count value
0 – 2000
Movement channel: Upper reference count value
0 – 2000
Movement channel: Lower reference count value
0 – 2000
Temperature channel: Unfiltered count value (if temperature feature enabled)
0 – 2000
Movement channel temperature reference (a previous value of temperature channel)
0 – 2000
Countdown timer to give active feedback on the time-out. Movement events will reset this timer
(0 – 255) × 100ms | Timer range: 0 – 90min
Countdown timer to give active feedback on the fixed 5sec time-out when in filter halt mode (before entering Proximity detect)
0 – 50 x 100ms | Timer range: 0 – 5 seconds
Countdown timer to signal when a read operation is done on IO2
(0 – 10) x 100ms | Timer range: 0 – 1 seconds
Countdown timer to give active feedback on the time until re-calibration is attempted after ATI-error
(0 – 255) × 100ms | Timer range: 0 – 25s
Copyright © Azoteq (Pty) Ltd 2020
All Rights Reserved
IQS231A/B Datasheet
Revision 2.5
Page 14 of 47
October 2021
IQ Switch®
ProxSense® Series
6
Azoteq
Summary: Features
Pin compatibility
DYCAL / Quick release
Control in RF
environments
Advanced temperature
& interference
compensation
User interface selection
Copyright © Azoteq (Pty) Ltd 2020
All Rights Reserved
Designs using the IQS229 or IQS128 will benefit from a “drop-in”
replacement on a production device for evaluation.
Using the added I2C capability on the IQS231A/B will require an
added connection to the master device.
A DYCAL-type implementation (referring to dynamic threshold
calibration) is recommended as main stability feature for the latest
SAR user interface. Passing the device SAR qualification with this
type of interface has been proven successful.
“Quick release” detection is the improved “DYCAL”-type
implementation and focusses on a release characteristic within a
time window.
Movement features add a second level of protection against stuck
conditions with the quick release detection.
The quick release will be detected on the proximity channel (not the
secondary movement channel) and the signal slope will be
monitored to enable the quick release. A single action from a
touch/proximity state will trigger the quick release event and the
event will only remain as long the proximity state holds.
Several features are offered to ensure operation in various designs
where high power RF signals may influence the sensing signal:
• Increased low frequency sensing options to allow for high
impedance filter circuits
• Increased debounce option to prevent RF noise triggers
• Advanced temperature compensation for fast temperature
variations caused by high power RF circuits
• Interference compensation for false triggers caused by
conducted/radiated noise.
An improved compensation feature is offered to prevent false
triggers due to quickly varying temperature & high interference
environments. This feature effectively tracks temperature changes &
compensates for interference only when no proximity trigger is
present.
The device offers 3 main UI’s intended for SAR use. These are:
• Proximity UI, no continuous movement sensing
• Proximity UI, continuous movement sensing
• Proximity & touch UI, continuous movement sensing during
proximity, no movement sensing during touch (No time-out
during long duration stationary SAR tests)
In all cases the use of the quick release feature is recommended to
prevent typical non-human activations from remaining.
In all cases “no movement” and “movement sensing” refers to the
capacitive movement sensing during normal activation. “Handheld
detection” and “quick release” features will enable movement sensing
with a no-movement time-out, irrespective of which UI is selected.
IQS231A/B Datasheet
Revision 2.5
Page 15 of 47
October 2021
IQ Switch®
ProxSense® Series
Azoteq
Summary: Features (Continued 1)
Movement detection is designed to function as human presence
detection in a localized area. This device can’t be used to fulfil an
accelerometer function (“G-sensor” function).
Human presence detection requires an exception in SAR testing
because the qualification testing only uses stationary “phantom
bodies”. Optimized human detection is offered through an integrated
Movement detection separate channel, dedicated towards human detection.
Default input use: internal pull-up (20kΩ) by default, tie directly to
GND for more sensitive option.
Apart from the simple external adjustment, an external capacitor is
Sensitivity adjustment recommended for sensitivity adjustments. 1pF is considered a small
change in sensitivity, while 10pF changes are considered large. A
maximum of 60pF load is recommended for effective proximity
sensing.
A single pulse of 500µs is integrated on IO1. This pulse is the failsafe
heartbeat, sent on each sensing event. This pulse will be sent during
the “stabilize time” as shown in Figure 9.1.
Cx
The failsafe indicator signal will precede the conversions (sampling).
The failsafe signal will be repeated during burst mode in order to offer
synchronization output to the master, indicating exactly when
IO1
sensitive measurements are done. Measurement times have a fixed
maximum which the user can implement.
Failsafe heartbeat
The failsafe signal is disabled by default and may be enabled via OTP
option or I2C initialize with standalone setup.
High
configurability
Through I2C the IQS231A/B can be used in many ways and the
configuration can be updated during later stages of development than
with the OTP route.
Configure the device via a dedicated I 2C type connection and switch
to any standalone mode for runtime operation. This minimizes the
processor load and spurious content from communication signals.
Switch I2C to standalone Unexpected reset conditions should be managed via the failsafe pulse
OTP option or by polling the device periodically. When the heartbeat
disappears or I2C responds to the polling, default state applies, and
the master should reconfigure the device through I 2C.
Copyright © Azoteq (Pty) Ltd 2020
All Rights Reserved
IQS231A/B Datasheet
Revision 2.5
Page 16 of 47
October 2021
IQ Switch®
ProxSense® Series
Azoteq
Summary: Features (Continued 2)
Synchronize input In order to ensure a stable sensing environment, sensing may be
done in strategic time windows controlled by a master device.
The ATI ensures optimal sensitivity during runtime for various sensor
environments.
Two channels are calibrated (proximity channel and movement
Automatic tuning (ATI) channel). Both run on the same Cx pin in different time slots.
An ATI-block time is defined to prevent re-ATI loops during touch
release events. The ATI-block is fixed for the movement channel, and
fixed for the standard touch/proximity channel
LTA: signal reference behavior is optimized for SAR where trigger
Reference signal tests are important in product qualification. The LTA will therefore be
behavior slow while still able to prevent typical temperature drift from causing
activations.
Standard I2C polling for:
• Debugging & normal use
• Device polling optimized for guaranteed response (within
Improved I2C interface
tCLK_stretch – clock stretching will be applied to the bus SCL line)
Copyright © Azoteq (Pty) Ltd 2020
All Rights Reserved
IQS231A/B Datasheet
Revision 2.5
Page 17 of 47
October 2021
IQ Switch®
ProxSense® Series
7
7.1
Azoteq
Features: Extended Details
Automatic Tuning Implementation (ATI)
External sensor connections are calibrated in the following ways:
>
Power On Reset (proximity channel is calibrated at each POR)
>
Movement channel is only calibrated with POR when hand-held detection is enabled
>
Proximity & movement channel is calibrated when the reference is out of bounds (1/8 of target
counts). The reference of the proximity channel is rapidly adapted when capacitance moves
away from the trigger threshold OR when an automatic “reseed” is done (Reseed: reference =
actual sensor value). The reference of the movement channel is rapidly adapted in any direction
of capacitive changes.
>
Redo-ATI of the proximity channel can be initiated by the user in I 2C mode using an I2C
command.
During each proximity channel ATI event, the proximity output is activated to indicate the event and
ensure a safe output during the event and in the case of an ATI-error.
7.2
Sensitivity Adjustment
Apart from the simple external adjustment, an external capacitor is recommended for sensitivity
adjustments. 1pF is considered a small change in sensitivity, while 10pF changes are considered
large. A maximum of 60pF load is recommended for effective proximity sensing.
Copyright © Azoteq (Pty) Ltd 2020
All Rights Reserved
IQS231A/B Datasheet
Revision 2.5
Page 18 of 47
October 2021
Azoteq
IQ Switch®
ProxSense® Series
8
I2C Programming Guide (Summary)
The IQS231A/B device interfaces to a master controller via a 2-wire (SDA and SCL) serial interface
bus that is I2CTM compatible, with a maximum communication speed of 400kbit/s.
The protocol acknowledges an address request independently. The I 2C hardware module is awake
for address recognition while the IQS231A/B is in sleep mode, giving the ability to wake the device
at any time and effectively communicate via serial interface. This is different compared to other ultralow power Azoteq solutions where the communications module also sleeps during standard IC sleep
times. Repeated polling requests where required in such case.
8.1
Add I2C Connection
When using I2C mode, ensure the connections as shown in Figure 2.2. Internal pull-up resistors are
sufficient for communication speeds up to 100kbits/s with low capacitance on the lines (