IQS228AS-00000000-TSR

Azoteq IQ Switch® ProxSense® Series IQS228AS/B DATASHEET Single channel capacitive proximity and touch controller The ProxSense® IQS228AS/B is a single channel self-capacitive sensor with Dynamic Calibration (DYCAL™) to allow for sensor drift during prolonged activation. Features > > > > > > > > > > > > > > > > 1 Self capacitive channel DYCAL™: Intelligent Hysteresis Proximity and Touch outputs Automatic Tuning Internal Reference Capacitor Minimum external components 1-Wire data streaming I2C Debug option User selectable options (OTP): Ext sync control or Ext filter control I/O Sink or Source selection Time-out for stuck key Proximity and Touch sensitivity selections Low Power modes Low power mode 2.5A Supply voltage: 1.8V to 3.6V RoHS2 Compliant Applications > > > > > > > > Proximity sensors SAR detection for Tablets On-ear detection for mobile phones 3D glasses Personal Media Players White goods and appliances Human Interface Devices Proximity activated backlighting Available Options TA TSOT23-6 WLCSP-8 DFN-6 -20°C to 85°C IQS228AS - - -40°C to 85°C IQS228B IQS228B IQS228B Copyright © Azoteq (Pty) Ltd 2021 All rights reserved IQS228AS/B Datasheet Revision 1.41 Page 1 of 41 March 2022 IQ Switch® ProxSense® Series Azoteq Contents IQS228AS/B DATASHEET ..................................................................................................................................................... 1 1 OVERVIEW ........................................................................................................................................................................ 5 1.1 DEVICE ...................................................................................................................................................... 5 1.2 OPERATION................................................................................................................................................ 5 1.3 APPLICABILITY ............................................................................................................................................ 5 2 PACKAGING AND PIN-OUT ............................................................................................................................................... 6 2.1 IQS228AS/B ............................................................................................................................................. 6 2.1.1 Pin-out TSOT23-6 .............................................................................................................................6 2.1.2 Pin-out WLCSP-8 ..............................................................................................................................7 2.1.3 Pin-out DFN-6 ....................................................................................................................................8 2.2 SCHEMATIC ................................................................................................................................................ 9 2.2.1 TSOT23-6 ..........................................................................................................................................9 2.2.2 WLCSP-8 .........................................................................................................................................10 2.2.3 DFN-6 ..............................................................................................................................................11 3 USER CONFIGURABLE OPTIONS ..................................................................................................................................... 12 3.1 CONFIGURING DEVICES ............................................................................................................................ 12 3.1.1 IQS228AS/B User Selectable Options ............................................................................................12 4 MEASURING CAPACITANCE USING THE CHARGE TRANSFER METHOD .......................................................................... 15 5 DYCAL™ OPERATION ...................................................................................................................................................... 16 6 OPERATING PRINCIPLE ................................................................................................................................................... 17 7 CONFIGURABLE SETTINGS .............................................................................................................................................. 17 7.1 CTRL: EXTERNAL CONTROL ..................................................................................................................... 17 7.1.1 Charge Halt......................................................................................................................................17 7.1.2 Halt LTA Filter ..................................................................................................................................17 7.1.3 Pulse on CTRL: ...............................................................................................................................17 7.2 LOGIC .................................................................................................................................................... 18 7.3 RF NOISE ON IQS228AS/B...................................................................................................................... 18 7.3.1 ND: RF Noise Detection ..................................................................................................................18 7.3.2 IQS228AS/B RF Noise Immunity.....................................................................................................18 7.4 PROXIMITY THRESHOLD ............................................................................................................................ 19 7.5 TOUCH THRESHOLD ................................................................................................................................. 19 7.6 MULTIPLIERS ............................................................................................................................................ 19 7.7 CHARGE TRANSFER ................................................................................................................................. 19 7.8 TARGET COUNTS ..................................................................................................................................... 19 7.9 ENABLE PARTIAL ATI................................................................................................................................ 19 7.10 DYCAL TURBO .................................................................................................................................... 20 7.11 FILTER HALT .......................................................................................................................................... 20 7.12 LOW POWER MODES .............................................................................................................................. 20 7.13 ZOOM .................................................................................................................................................... 20 8 STREAMING MODE......................................................................................................................................................... 21 8.1 EVENT MODE ........................................................................................................................................... 22 8.2 I2C .......................................................................................................................................................... 22 9 AUTO TUNING IMPLEMENTATION (ATI) ......................................................................................................................... 23 9.1 FULL ATI ................................................................................................................................................. 23 9.2 ATI TARGET............................................................................................................................................. 23 9.3 ATIBASE: SIGNIFICANCE OF ATI BASE ........................................................................................................ 23 Copyright © Azoteq (Pty) Ltd 2021 All rights reserved IQS228AS/B Datasheet Revision 1.41 Page 2 of 41 March 2022 IQ Switch® ProxSense® Series Azoteq 9.4 SENSITIVITY DUE TO ATI .......................................................................................................................... 23 9.5 ATI PROCEDURE ...................................................................................................................................... 23 10 DYCAL SPECIFIC SETTINGS ............................................................................................................................................ 25 10.1 RELEASE THRESHOLD ............................................................................................................................ 25 10.2 INPUT ENABLE........................................................................................................................................ 25 11 ELECTRICAL SPECIFICATIONS ........................................................................................................................................ 26 11.1 ABSOLUTE MAXIMUM SPECIFICATIONS .................................................................................................... 26 11.2 GENERAL CHARACTERISTICS .................................................................................................................. 26 11.3 OUTPUT CHARACTERISTICS .................................................................................................................... 27 11.4 PACKAGING INFORMATION ...................................................................................................................... 28 11.4.1 TSOT23-6 ......................................................................................................................................28 11.4.2 WLCSP-8 .......................................................................................................................................29 11.4.3 DFN-6 ............................................................................................................................................30 11.4.4 MSL Level ......................................................................................................................................31 12 DATASHEET AND PART-NUMBER INFORMATION ......................................................................................................... 32 12.1 ORDERING INFORMATION ........................................................................................................................ 32 12.2 DEVICE MARKING – TOP ......................................................................................................................... 33 12.2.1 TSOT23-6 Package Markings .......................................................................................................33 12.2.2 WLCSP-8 Package Markings ........................................................................................................34 12.2.3 DFN-6 Package Markings .............................................................................................................34 12.3 TAPE AND REEL SPECIFICATION .............................................................................................................. 35 APPENDIX A. MEMORY MAP ............................................................................................................................................. 36 APPENDIX B. ERRATA ........................................................................................................................................................ 40 FILTER HALT TIMES ........................................................................................................................................ 40 APPENDIX C. CONTACT INFORMATION ............................................................................................................................. 41 Copyright © Azoteq (Pty) Ltd 2021 All rights reserved IQS228AS/B Datasheet Revision 1.41 Page 3 of 41 March 2022 IQ Switch® ProxSense® Series Azoteq List of Abbreviations ATI Automatic Tuning Implementation BP Boost Power Mode CS Counts (Number of Charge Transfers) Cs DYCAL Internal Reference Capacitor TM Dynamic Calibration EMI Electromagnetic Interference ESD Electro-Static Discharge FTB/EFT (Electrical) Fast Transient Bursts GND Ground HC Halt Charge LP Low Power Mode LTA Long Term Average ND Noise Detect THR Threshold TM Touch Mode Copyright © Azoteq (Pty) Ltd 2021 All rights reserved IQS228AS/B Datasheet Revision 1.41 Page 4 of 41 March 2022 IQ Switch® ProxSense® Series charge transfer principle is thoroughly described in the application note: “AZD004 Azoteq Capacitive Sensing”.) 1 Overview 1.1 Device The IQS228AS/B is a single channel capacitive proximity and touch device which employs an internal voltage regulator and reference capacitor (Cs). The IQS228AS/B device has a dedicated pin(s) for the connection of a sense electrode(s) (Cx) and output pin(s) for proximity and touch events on OUT. The polarity of the output pins can be configured. A 1-wire open drain data streaming protocol OR I2C interface is implemented for debugging purposes. Special device configuration can be done by setting one time programmable (OTP) options. The device automatically tracks slow varying environmental changes via various signal processing algorithms and has an Automatic Tuning Implementation (ATI) algorithm to calibrate the device to the sense electrode. DYCAL™ (Dynamic Calibration) is a special form of hysteresis that can track slow varying environmental change even while the sensor is in a touch state. This is ideal for portable applications. The charge transfer method of capacitive sensing is employed on the IQS228AS/B. (The Copyright © Azoteq (Pty) Ltd 2021 All rights reserved Azoteq 1.2 Operation The device has been designed to be used in applications where proximity is required and touch conditions can prevail for an extended period of time which may result in uncompensated drift in conventional capacitive sensors. A low threshold is used to detect the proximity of an object, with a higher threshold for touch detection. Dynamic Calibration is performed when a TOUCH condition is detected for longer than tDYCAL. The hysteresis algorithm will now check for the release condition of the touch, while still tracking environmental changes 1.3 Applicability All specifications, except where specifically mentioned otherwise, provided by this datasheet are applicable to the following ranges: > Temperature: • IQS228AS: -20°C to +85°C • IQS228B: -40°C to +85°C > Supply voltage (VDDHI): 1.8V to 3.6V IQS228AS/B Datasheet Revision 1.41 Page 5 of 41 March 2022 Azoteq IQ Switch® ProxSense® Series 2 Packaging and Pin-Out The IQS228AS/B is available in a TSOT23-6 package. the IQS228B is available in TSOT23-6, DFN6 or WLCSP-8 package 2.1 IQS228AS/B 2.1.1 Pin-out TSOT23-6 TOUT 1 228AS/B GND 2 POUT 3 6 Cx 5 VDDHI 4 VREG Figure 2.1:Pin-out of IQS228AS/B in the TSOT23-6 package. 22-Bxx Table 2.1: Pin-out description IC NAME IQS228AS/B in TSOT23-6 Batch code 228BxxFunction Pin Name Type 1 OUT Digital Out Output 2 GND Ground GND Reference 3 CTRL / ND Digital Input/Output Control input or proximity output / ND pin 4 VREG Analogue Output Internal Regulator Pin (Connect 1µF bypass capacitor) 5 VDDHI Supply Input 6 CX Analogue IC NAME Batch code Supply Voltage Input 228Axx Sense Electrode IC NAME Batch code 22-Axx IC NAME Batch code IQS228AS XX zzz zzz zz ppb IC NAME Copyright © Azoteq (Pty) Ltd 2021 All rights reserved IQS228AS/B Datasheet Revision 1.41 CONFIGURATION BULK PACAKAGIN Page 6 of 41 March 2022 PACKAGE TYPE Azoteq IQ Switch® ProxSense® Series 2.1.2 Pin-out WLCSP-8 1 2 3 4 IQS228 8 7 6 5 Figure 2.2 IQS228B 8-pin WLCSP Table 2.2 8 -pin WLCSP Pin-out Description IQS228B 8-pin WLCSP Pin Name Type Function 1 Cx Sense electrode Connect to conductive area intended for sensor 2 OUT Digital Out Output 3 VREG Regulator output Requires external capacitor 4 VSS Signal GND 5 INPUT Digital Input Floating input during runtime. Recommended: Connect to POUT 6 POUT / ND Digital Input/Output Control input or proximity output / ND pin 7 VDDHI Supply Input Supply Voltage Input Configuration pin Connection for OTP programming. Floating input during runtime. Recommended: Connect to OUT pin. Programming can still be performed using this pin, provided a diode is used. (See AZD026 – Configuration Tools Overview) 8 PGM Copyright © Azoteq (Pty) Ltd 2021 All rights reserved IQS228AS/B Datasheet Revision 1.41 Page 7 of 41 March 2022 Azoteq IQ Switch® ProxSense® Series 2.1.3 Pin-out DFN-6 POUT 3 6 Cx TOUT 1 5 VDDHI GND 2 4 VREG POUT 3 IQS228 GND 2 IQS227 TOUT 1 6 Cx 5 VDDHI 4 VREG Figure 2.3: Pin-out of IQS228B in DFN-6 package. Table 2.3:Pin-out description. 22-Bxx IQS228B 6-pin DFN Pin Name Type Function 1 OUT Digital Out Output GND Ground GND Reference CTRL / ND Digital Input/Output Control input or proximity output / ND pin 227Bxx 2 3 Batch code 4 Batch VREG 5 VDDHI Supply Input Supply Voltage Input 6 CX Analogue Sense Electrode 227Dxx codeAnalogue Output Internal Regulator Pin (Connect 1µF bypass capacitor) Batch code 22-Dxx Batch code Copyright © Azoteq (Pty) Ltd 2021 All rights reserved IQS228AS/B Datasheet Revision 1.41 Page 8 of 41 March 2022 IQ Switch® ProxSense® Series Azoteq 2.2 Schematic 2.2.1 TSOT23-6 Refer to AZD008 for touch key design Figure 2.4: Typical application reference schematic of IQS228AS/B. C2 &C3 are optional for added RF immunity. Figure 2.5: IQS228AS/B output pin configuration for I2C debug operation, or driving LEDs (active high or low option available). Where a system level ESD strike is found to cause the IC to go into ESD induced latch-up, it is suggested that the supply current to the IQS228 IC is limited by means of a series resistor that could limit the maximum supply current to the IC to A ground plane should be placed under the IC, except under the Cx line. > All the tracks on the PCB must be kept as short as possible. > The capacitor between VDDHI and GND as well as between VREG and GND, must be placed as close as possible to the IC. > A 100 pF capacitor should 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 GND. > If the device is too sensitive for a specific order option, a parasitic capacitor (typically 20pF) can be added between the Cx line and ground. > Proper sense electrode and button design principles must be followed. > Unintentional coupling of sense electrode to ground and other circuitry must be limited by increasing the distance to these sources. In some instances a ground plane some distance from the device and sense electrode may provide significant shielding from undesired interference. IQS228AS/B Datasheet Revision 1.41 Page 18 of 41 March 2022 IQ Switch® ProxSense® Series When the capacitance between the sense electrode and ground becomes too large the sensitivity of the device may be influenced. 7.4 Proximity Threshold The IQS228AS/B has 4 proximity threshold settings indicated in counts. The proximity threshold is selected by the designer to obtain the desired sensitivity and noise immunity. A proximity event is triggered if the Counts (CS) diverges more than the selected threshold from the LTA for 6 consecutive cycles. When using partial ATI, the base value is set up using the multipliers. Compensation will still be added automatically to reach the target. 7.7 Charge Transfer 7.5 Touch Threshold The IQS228AS/B has 8 touch threshold settings indicated in counts. The touch threshold is selected by the designer to obtain the desired touch sensitivity. A touch event is triggered if the Counts (CS) diverges more than the selected threshold from the LTA for 2 consecutive cycles. In the NO-TOUCH state the Counts (CS) must diverge more than the touch threshold value below the LTA. Operating in the TOUCH STATE, the CS must diverge more than REL_TTHR of the touch threshold value above the LTA. The following equation is used to determine if a touch or release event occurred. TOUCH STATE: Configuration: Bank0 bit 4-2 TTHR2:TTHR0 Touch Thresholds TTHR2:TTHR0: Touch Thresholds Bit Selection 000 72/256 001 4/256 (Most sensitive) 010 8/256 011 24/256 100 48/256 101 96/256 110 128/256 111 160/256 (Least sensitive) 7.6 Multipliers Configuration: Bank0 bit 1-0 PTHR1:PTHR0:Proximity Thresholds Bit Selection 00 4 01 2 (Most sensitive) 10 8 11 16 (Least sensitive) NO TOUCH STATE: Azoteq LTA – CS = REL_TTHR The charge transfer frequency of the IQS228AS/B is adjustable. Changing the transfer frequency will affect sensitivity and response rate. Two options are available: Configuration: Bank2 bit6 TRANS: Charge Transfer Frequency Bit Selection 0 512kHz 1 250kHz 7.8 Target Counts The target of the ATI algorithm can be adjusted between 1200 (default) and 1024 counts. When less sensitivity is required, the lower counts will also increase response rate: Configuration: Bank2 bit3 Target: ATI target counts Bit Selection 0 1200 1 1024 7.9 Enable Partial ATI In some applications the startup time of the IQS228AS/B may be required to be decreased. This is possible by enabling partial ATI, if the multipliers required can be determined, and the compensation alone is adequate to account for environmental change. Copyright © Azoteq (Pty) Ltd 2021 All rights reserved IQS228AS/B Datasheet Revision 1.41 Page 19 of 41 March 2022 IQ Switch® ProxSense® Series Configuration: Bank2 bit2 ATI: Partial ATI Bit Selection 0 Disabled 1 Enabled Azoteq Configuration: Bank2 bit 1-0 Bit Selection 00 9.1ms (BP) 64ms if Zoom disabled 01 128ms (Normal Power Mode) 10 256ms (Low Power Mode 1) 11 512ms (Low Power Mode 2) 7.10 DYCAL TURBO In some applications, it may be required to improve the entry and exit speed of Touch Mode by removing the entry reseed delay, as well as turning off the AC-filters. This can be done by enabling the DYCAL TURBO mode. Configuration: Bank1 bit3 TURBO: DYCAL TURBO Bit Selection 0 Disabled 1 Enabled Note that if Dycal Turbo is enabled, the LTA will halt at the reseed point for tHALT if Touch Mode is entered before a proximity event is registered. 7.13 Zoom The IQS228AS/B has the option to disable the zoom function. This means that the sample time will stay fixed, even when proximity and touch events are made. When this is activated, boost power mode will change from a 9ms sample time, to 64ms. Configuration: Bank3 bit3 Zoom: Zoom Disable Bit Selection 0 Enabled 1 Disabled 7.11 Filter Halt The LTA filter only executes while no proximity events are detected to ensure compensation only for environmental changes. Once a touch event is detected the filter will resume operation and will no longer be halted. The halt timing configuration settings determine how long the filter is halted. Configuration: Bank1 bit 7-6 Bit Selection 00 20 seconds 01 40 seconds 10 Never 11 3 seconds The presence of a proximity condition for a time exceeding the halt time will be deemed as a fault state which would trigger a reseed event where after the output state on the OUT pin will be reset to its original condition. 7.12 Low Power Modes There exist 4 LP modes. The LP modes will decrease the sampling frequency of CS which will reduce the power consumption of the device. However, this will also increase the response time of the device. Copyright © Azoteq (Pty) Ltd 2021 All rights reserved IQS228AS/B Datasheet Revision 1.41 Page 20 of 41 March 2022 Azoteq IQ Switch® ProxSense® Series 1. Communications initiated by a START bit. Bit defined as a low condition for TSTART. 2. Following the START bit, is a synchronisation byte (TINIT = 0xAA). This byte is used by the MCU for clock synchronisation. 3. Following TINIT the data bytes will be sent. 8 Bytes will be sent after each charge cycle. 4. Each byte sent will be preceded by a START bit and a STOP bit will follow every byte. 5. STOP bit indicated by taking pin 1 high. The STOP bit does not have a defined period. 8 Streaming Mode For a more complete description of the data streaming protocol, please refer to Application Note AZD017 on the Azoteq website. The IQS228AS/B has the capability to stream data to a MCU. This provides the designer the ability to obtain the parameters and sensor data within the device in order to aid design into applications. Data streaming is performed as a 1-wire data protocol on the OUT pin OR I2C interface. The output function of this pin is therefore lost when the device is configured in streaming mode. Data Streaming can be enabled as indicated below: Configuration: Bank2 bit5: Streaming Mode Bit Selection 0 Disabled 1 Enabled Figure 8.1 illustrates the communication protocol for initialising and sending data with the 1 wire communication protocol. TOUT /OUT B1 tINIT tDATA B2 B3 B4 B5 B6 B7 B8 tSTOP Stop – Start Start Stop – Start Figure 8.1: Debug: 1-wire streaming Debug Mode. The following table defines the bit definitions for the IQS228AS/B devices during Streaming Mode. Copyright © Azoteq (Pty) Ltd 2021 All rights reserved IQS228AS/B Datasheet Revision 1.41 Page 21 of 41 March 2022 IQ Switch® ProxSense® Series Table 8.1: Byte Definitions for Streaming Mode Byte (B) Bit 0 The IQS228AS/B can communicate on an I2C compatible bus structure. Note that 4.7kΩ pullup resistors should be placed on SDA and SCL. Value The Control byte indicates the 7-bit device address (0x44H) and the Read/Write indicator bit. AA 1 7:0 CS High byte 2 15:8 CS Low byte 3 23:16 LTA High byte 4 31:24 LTA Low byte 5 Sys Flags 39 38 37 36 35 34 33 32 ~ ~ Active High Filter Halt LP active ATI Busy Noise Found In Zoom 6 47 46 45 44 43 42 41 40 Touch Proximity Multipliers Multipliers Multipliers Multipliers Multipliers Multipliers 7 55:48 Compensation 8 63:56 Counter Azoteq 8.1 Event Mode The IQS228AS/B has Event Mode implemented during 1-wire communication. This allows the MCU to monitor the POUT pin for status changes (proximity or touch made or released events) instead of capturing data continuously. Upon a status change, the IQS228AS/B will pull the POUT pin for low to indicate to the MCU to read data. The POUT pin will stay low for 1.6ms. 8.2 I2C The IQS228AS/B also allow for I2C streaming for debugging. Data Streaming can be changed from 1-wire protocol to I2C as shown below: Configuration: Bank2 bit7: Streaming Mode Bit Selection 0 1-Wire Protocol 1 I2C Streaming The Memory Map for the IQS228AS/B can be found in Appendix A. Copyright © Azoteq (Pty) Ltd 2021 All rights reserved IQS228AS/B Datasheet Revision 1.41 Page 22 of 41 March 2022 IQ Switch® ProxSense® Series 9 Auto Tuning Implementation (ATI) ATI is a sophisticated technology implemented in the latest generation ProxSense® devices that optimises the performance of the sensor in a wide range of applications and environmental conditions (refer to application note AZD0027 Auto Tuning Implementation). ATI makes adjustments through external reference capacitors unnecessary (as required by most other solutions) to obtain optimum performance. 9.1 Full ATI The IQS228AS/B implements an automatic ATI algorithm. This algorithm automatically adjusts the ATI parameters to optimise the sensing electrodes connection to the device. The device will execute the ATI algorithm whenever the device starts-up and or when the counts are not within a predetermined range. There are 2 important definitions to understand for ATI: 9.2 ATI Target ATI adjusts internal circuitry according to two parameters, the ATI multiplier and the ATI compensation. > > The ATI multiplier can be viewed as a course adjustment of the Counts (CS), used to achieve the ATI BASE value. The ATI compensation is a fine adjustment used to reach the ATI TARGET value. With these two parameters the Counts (CS) of the IQS228AS/B is tuned until an ATI target value of 1200 is achieved. 9.3 ATIBASE: Significance of ATI Base As mentioned above, the ATI multiplier is used to select a base value for the ATI. The ATI BASE value is important, as this determines the sensitivity of the device. The sensitivity can be defined as: Sensitivity = ATI TARGET / ATI BASE The ATI Target remains fixed at 1200 and it can thus be seen from this that a larger base value will result in a less sensitive device. The designer has the option to increase/reduce the sensitivity of the system through the ATI BASE Copyright © Azoteq (Pty) Ltd 2021 All rights reserved Azoteq value. For most applications the ATI BASE should be kept default. The options for the ATI BASE values are as follows: Configuration: Bank1 bit 2-0 Bit Selection 000 200 001 50 010 75 011 100 100 150 101 250 110 300 111 500 9.4 Sensitivity Due to ATI The adjustment of the ATI parameters will result in variations in the count and sensitivity. Sensitivity can be observed as the change in count as the result of a fixed change in sensed capacitance. The ATI parameters have been chosen to provide significant overlap. It may therefore be possible to select various combinations of ATI multiplier and ATI compensation settings to obtain the same count. The sensitivity of the various options may however be different for the same count. 9.5 ATI Procedure While the Automatic ATI algorithm is in progress this condition will be indicated in the streaming data and proximity and touch events cannot be detected. The device will only briefly remain in this condition and it will be entered only when relatively large shifts in the count has been detected. The automatic ATI function aims to maintain a constant count, regardless of the capacitance of the sense electrode (within the maximum range of the device). The effects of auto-ATI on the application are the following: > Automatic adjustment of the device configuration and processing parameters for a wide range of PCB and application designs to maintain a optimal configuration for proximity and touch detection. > Automatic tuning of the sense electrode at start-up to optimise the sensitivity of the application. IQS228AS/B Datasheet Revision 1.41 Page 23 of 41 March 2022 IQ Switch® ProxSense® Series Azoteq > Automatic re-tuning when the device detects changes in the sensing electrodes capacitance to accommodate a large range of changes in the environment of the application that influences the sensing electrode. > Re-tuning only occurs during device operation when a relatively large sensitivity reduction is detected. This is to ensure smooth operation of the device during operation. > Re-tuning may temporarily influences the normal functioning of the device, but in most instances the effect will be hardly noticeable. > Shortly after the completion of the re-tuning process the sensitivity of a Proximity detection may be reduced slightly for a few seconds as internal filters stabilises. Automatic ATI can effectively due to: be implemented so > Excellent system signal to noise ratio (SNR). > Effective digital signal processing to remove AC and other noise. > The very stable core of the devices. > The built-in capability to accommodate a large range of sensing electrode capacitances. Copyright © Azoteq (Pty) Ltd 2021 All rights reserved IQS228AS/B Datasheet Revision 1.41 Page 24 of 41 March 2022 IQ Switch® ProxSense® Series Azoteq 10 DYCAL Specific settings 10.1 Release Threshold The IQS228AS/B has the option to increase the release threshold when in TM. This helps that small variations caused by moving a finger/hand on a touch pad will not cause the IC to exit TM, making the solution more robust. The options available are shown below: Configuration: Bank0 bit6 Bit Selection 0 75% of Entry Delta 1 87.5% of Entry Delta After entering TM, as soon as the LTA follows to within 16 counts, a Entry Delta value is calculated as: > Entry Delta =LTAentry - LTAcurrent This calculated Entry Delta value is used for the Release Threshold as shown above. If upon entry, the LTA value is already within 16 Counts, the Entry Delta is taken as the calculated touch threshold value. 10.2 Input Enable The IQS228AS/B can be configured to have the CTRL pin function as an output on a Proximity event. Choosing the CTRL pin as output removes the Filter Halt and Halt Charge options of the pin as an input. Using a touch event to activate OUT will make the system less sensitive which is needed in some applications. The LTA will still halt with the detection of a proximity but will not have an influence on the OUT pin. The LTA will still re-calibrate once a touch condition is detected. Configuration: Bank0 bit7 Bit Selection 0 Output 1 Input Copyright © Azoteq (Pty) Ltd 2021 All rights reserved IQS228AS/B Datasheet Revision 1.41 Page 25 of 41 March 2022 Azoteq IQ Switch® ProxSense® Series 11 Electrical Specifications 11.1 Absolute Maximum Specifications Exceeding these maximum specifications may cause damage to the device. Operating temperature: IQS228AS IQS228B Supply Voltage (VDDHI – VSS) Maximum pin voltage (OUT, CTRL) Pin voltage (Cx) Minimum pin voltage (VDDHI, VREG, OUT, CTRL, Cx) Minimum power-on slope ESD protection (VDDHI, VREG, VSS, OUT, CTRL, Cx) -20°C to 85°C -40°C to 85°C 3.6V VDDHI + 0.3V 1.7V VSS - 0.3V 100V/s 8kV 11.2 General Characteristics IQS228AS/B devices are rated for supply voltages between 1.8V and 3.6V. Table 11.1: IQS228AS/B General Operating Conditions DESCRIPTION Conditions Supply voltage PARAMETER MIN TYP MAX UNIT VDDHI 1.8 3.3 3.6 V Internal regulator output 1.8 ≤ VDDHI ≤ 3.6 VREG 1.64 1.7 1.75 V Boost Power operating current 1.8 ≤ VDDHI ≤ 3.6 IIQS228AS/B_BP 120 129 135 μA Normal Power operating current 1.8 ≤ VDDHI ≤ 3.6 IIQS228AS/B_NP 4.9 6.45 8.1 μA Low power 1 operating current 1.8 ≤ VDDHI ≤ 3.6 IIQS228AS/B LP1 2.95 3.8 4.85 μA Low power 2 operating current 1.8 ≤ VDDHI ≤ 3.6 IIQS228AS/B_LP2 1.88