LDS6200 Family PureTouch(R)* Low Channel Capacitive Touch Sensor IC Family FEATURES o o o o o o o o o o o o DESCRIPTION The LDS6200 Family of capacitive touch controllers enables streamlining of the human-machine interface through the implementation of touch-based user inputs such as touch buttons, sliders, and scroll wheels. Employing a finely tuned sigma-delta capacitance-to-digital converter and proprietary noise-filtering algorithms, each device is able to reliably sense small changes in capacitance, allowing touch-based inputs to replace a side variety of mechanical input types. On-chip automatic calibration accounts for environmental changes such as temperature, humidity, and dust and is executed automatically. Up to 8 touch sensor channels o 2ms update rate per active sensor input** Built-in Slider/Scroll Support Configurable hysteresis and debounce Touch Preference Modes 1.65-5.5v supply voltage Low touch sensor operating power o Full power mode (typ): <125uW*** o Optional low power mode On-chip automatic calibration algorithm 2 I C compatible serial I/F with VDDIO Power on touch detection Configurable for proximity sensing GPIO and interrupt output The LDS6200 Family consists of four products with up to 8 capacitive sensor input pins. 3mm x 3mm 16-pin and 20-pin TQFN packages Part # Touch Sensors Package SOIC packages also available LDS6201 Up to 2 16ld TQFN LDS6202 Up to 4 16ld SOIC LDS6203 Up to 6 20ld TQFN LDS6204 Up to 8 20ld SOIC o APPLICATIONS o o o o o o o o Mobile handsets, personal media players Portable navigation devices Remote controls Office equipment, multi-function printers Set top boxes Home appliances Brown goods Industrial controls The LDS6200 Family supports touch sensor supply 2 voltages from 1.65 to 5.5V. All parts support I C compatible serial interfaces and offer both a General Purpose I/O (GPIO) and VDDIO support, enabling 1.65V to 5.5V voltage interface support. Typical touch sensor operating power for the device is less than 125uW***. Package offerings include thin form factor 3mm x 3mm 16-pin TQFN, 3mm x 3mm 20-pin TQFN, 3.9mm x 9.9mm 16-pin SOIC, 7.5mm x 12.8mm 20-pin SOIC. * PureTouch is a registred trademark of IDT ** Nominal decimation rate (d=1024), per sensor input *** 1.8V, excluding VDDIO current, which varies with VDDIO voltage, I/F type, and communication frequency (c) 2011 IDT Characteristics subject to change without notice 1 Doc. No. 6200DS, Rev. 0.5 LDS6200 Family TYPICAL APPLICATION CIRCUIT FOR DUAL SUPPLY VOLTAGES VDDIO (1.65V~5.5V) VDDIO SHIELD VDD RPU SENSOR PCB RPU C0 C1 C2 SCLK SDA SCLK SDA C3 C2 C4 C5 Host Processor With I2C RPU C6 C7 INTB INTB VDD* (1.65V~1.95V) RESETB RESETB VDD LDOEN GPIO floating TEST1 TEST0 C1 VSS C1, C2 > 1uF *For direct application of 1.8V voltage. 2 Figure 1: Application Circuit with I C I/F using dual voltage sources (c) 2011 IDT Characteristics subject to change without notice 2 Doc. No. 6200 FamilyDS, Rev. 0.5 LDS6200 Family TYPICAL APPLICATION CIRCUIT FOR SINGLE SUPPLY VOLTAGE VDDIO (1.65V~5.5V) VDD VDDIO SHIELD SENSOR PCB RPU C0 RPU C1 C2 SCLK SDA SCLK SDA C3 C2 C4 C5 Host Processor With I2C RPU C6 C7 INTB INTB VDDIO* (1.65V~5.5V) RESETB RESETB VDD C1 LDOEN GPIO floating TEST1 TEST0 VSS C1, C2 > 1uF *For voltages >1.95V, apply voltage to VDDIO and tie VDD to ground through C1 2 Figure 2: Application Circuit with I C I/F using single voltage source (c) 2011 IDT Characteristics subject to change without notice 3 Doc. No. 6200 FamilyDS, Rev. 0.5 LDS6200 Family ABSOLUTE MAXIMUM RATINGS Item Touch Sensor Supply Voltage Serial Interface Operating Voltage Input voltage range (Digital) Input voltage range (Analog) Output voltage range (Digital) Output voltage range (Analog) Operating Temperature Range Storage Temperature Range Symbol VDD VDDIO VIN AVIN VOH AVOH TOPR TSTG Rating -0.3 to +6.0 -0.3 to +6.0 -0.3 to VDDIO +0.3 -0.3 to VDD +0.3 -0.3 to VDDIO +0.3 -0.3 to VDD +0.3 -40 to +85 -55 to +125 Unit V V V V V V C C Test condition C = 100pF, R = 1.5k Charging Resistor = 300M C = 200pF, R = 0 Rating 8000 1500 400 Unit V V V ESD PROTECTION LEVEL Model Human Body Model Charge Device Model Machine Model RECOMMENDED OPERATING CONDITIONS Parameter VDD* VDDIO Ambient Temperature Range * For supply voltages >1.95V, apply to VDDIO pin and Typical application circuit shown on page 3 Condition Unit 1.65 to 1.95 V 1.65 to 5.5 V -40 to +85 C tie VDD pin to GND through C1 (c) 2011 IDT Characteristics subject to change without notice 4 Doc. No. 6200 FamilyDS, Rev. 0.5 LDS6200 Family ELECTRICAL OPERATING CHARACTERISTICS VDD = 1.8V, VDDIO = 1.8V TAMB = -40C to +85C unless otherwise specified Parameter Symbol Power & Operating Voltage Conditions Related Pins Min Typ Max Unit - Operating Voltage(1) : Touch* VDD - VDD 1.65 1.8 1.95 V Operating Voltage(3) : Touch - I/O VDDIO - VDDIO 1.65 - 5.5 V High Level Input Voltage VIH - (*1) 0.7*VDDIO Low Level Input Voltage VIL - (*1) VSS Input Leakage Current IIL VIN= VDDIO or VSS (*1) -1 0.8*VDDIO Logic Inputs V 0.3*VDDIO V uA Logic Outputs High Level Output Voltage VOH IOH= -1mA (*2) Low Level Output Voltage VOL IOL= +1mA (*2) V 0.2*VDDIO V 2.15 ms Capacitance-to-Digital Converter CDC Update Rate per Active Sensor Tcdc (*3) CIN Input Leakage IILcin IOH= -1mA 1.95 Sensor Capacitance Csensor 2.05 C0~Cx nA 25 (*4) pF * For supply voltages >1.95V, apply to VDDIO pin, set LDOEN to logic high, and tie VDD1 pin to GND through C1 Typical application circuits shown on page 2 and 3 NOTE: (*1): SCLK, SDA, GPIO; (*2): SDA, INTB, GPIO; (*3) DECIMATION RATE = 1024, PER UTILIZED SENSOR; (*4): MAXIMUM SENSOR CAPACITANCE MAY BE ALLOWED TO EXCEED 25PF DEPENDING UPON SYSTEM CONDITIONS - CONTACT IDT FOR EXCEPTION CONDITIONS (c) 2011 IDT Characteristics subject to change without notice 5 Doc. No. 6200 FamilyDS, Rev. 0.5 LDS6200 Family ELECTRICAL OPERATING CHARACTERISTICS (CURRENT CONSUMPTION) VDD = 1.8V, VDDIO = 1.8V, TAMB = -40C to 85C unless otherwise specified Parameter Symbol Conditions Related Pins Min Typ Max Unit 55 100 uA Current Consumption Full Power Mode Iddfp Sleep Mode Iddsl Shutdown, TAMB = 25C Iddsd Shutdown Iddsd (c) 2011 IDT Characteristics subject to change without notice 17 TAMB = 25C TAMB = -40C to +85C 6 0.5 uA 5 uA 10 uA Doc. No. 6200 FamilyDS, Rev. 0.5 LDS6200 Family I2C-COMPATIBLE TIMING SPECIFICATIONS For VDD = 1.65-1.95V, VDDIO = 1.65V to 5.5V, over ambient temperature range -40C to +85C. Parameter Tmax Unit Description fSCLK 400 kHz SCLK clock frequency tR 300 ns Clock/data rise time tF 300 ns Clock/data fall time 50 0.9 0.9 s s s ns ns s s s ns s s Start condition hold time Clock low period Clock high period Data setup time Data hold time Stop condition setup time Start condition setup time Bus free time between stop and start conditions Max spike width suppressed by SCLK and SDA inputs Data valid time Data valid acknowledge time tHD:STA tSLW tSHW tSU:DAT tHD:DAT tSU:STO tSU:STA tBUF tSP tVD:DAT tVD:ACK Tmin 0.6 1.3 0.6 100 0 0.6 0.6 1.3 2 Figure 3: I C-Compatible Detailed Timing Diagram (c) 2011 IDT Characteristics subject to change without notice 7 Doc. No. 6200 FamilyDS, Rev. 0.5 LDS6200 Family WRITING AND READING OVER THE I2C-COMPATIBLE INTERFACE 2 The LDS6200 Family is always a slave on the I C interface bus and uses the 7-bit device address of 0101 100. Data transfer utilizes 8-bit bytes, with the master initiating a data transfer (START) by taking SDA from high-to-low while keeping SCLK high, followed by the 7-bit device address plus a read/write bit dictating the direction of data transfer (read=1, write=0). Data is sent over a series of 9 clock pulses made up of 8 bits of data and an acknowledge bit from the LDS6200 Family. The STOP condition occurs when SDA is taken from low-to-high while keeping SCLK high, upon which the LDS6200 Family resets its address pointer to 0x000 and the serial interface pins enter the idle state. Data must be transitioned when the clock signal is low and remain stable when SCLK is high, as a low-to-high transition on SDA when SCLK is high would be interpreted as a STOP signal. WRITING DATA OVER I2C The device address (0101 100) and read/write bit (0 for writing) are sent over the bus, followed by two data bytes containing the 10-bit register address to be written. The upper and lower register address bits are shown below: MSB 7 6 5 4 3 2 X X X X X X MSB 7 6 5 4 3 2 LSB 1 0 Register Register Addr Bit 9 Addr Bit 8 1 LSB 0 Register Register Register Register Register Register Register Register Addr Bit 7 Addr Bit 6 Addr Bit 5 Addr Bit 4 Addr Bit 3 Addr Bit 2 Addr Bit 1 Addr Bit 0 The third and fourth data bytes contain the 8 MSBs and LSBs, respectively, to be written to the internal register pointed to by the 10-bit register address. 2 Figure 4: I C-Compatible Register Write The LDS6200 Family automatically increments the address pointer enabling sequential writes to registers in the same write transaction. Finishing the transaction involves the master generating a stop condition on SDO or repeat 2 start condition if the I C link is to remain active. (c) 2011 IDT Characteristics subject to change without notice 8 Doc. No. 6200 FamilyDS, Rev. 0.5 LDS6200 Family READING DATA OVER I2C To initiate a read operation, the master must first write the read starting address to the LDS6200 Family. The device address (0101 100) and read/write bit (0 for initial write of starting address) is sent over the bus, followed by two data bytes that contain the 10-bit register address to be read. The address format is identical to that used during write operations, with only the 10 lower bits of the 16-bit address word containing address information. The master then either ends the write operation with a STOP signal followed by initiation (START) of a read operation, or more ideally, issues a "REPEAT START" command. In both cases, the read/write bit is set to "1" (see Figure 9 for details of both continuations methods). In either case, the LDS6200 Family provides the MSB eight bits of data first, followed by the LSB eight bits in the next byte. 2 Figure 5: I C-Compatible Detailed Timing Diagram The LDS6200 Family address pointer automatically increments after each read, resulting in a continuous output of read data until the master returns a no acknowledge (ACK signal high) and stop condition to the bus. If the address pointer reaches its maximum value and the master continues to attempt to read from the part, the LDS6200 Family continues to send data from the last register that was addressed. (c) 2011 IDT Characteristics subject to change without notice 9 Doc. No. 6200 FamilyDS, Rev. 0.5 LDS6200 Family DEVICE PINOUTS (QFN) (c) 2011 IDT Characteristics subject to change without notice 10 LDOEN VDDIO INTB VSS TEST1 RESETB TEST0 SHIELD LDS6201NTGI Doc. No. 6200 FamilyDS, Rev. 0.5 LDS6200 Family TEST0 VSS LDOEN VDDIO LDS6202NTGI 16 15 14 13 C2 2 11 GPIO C1 3 10 SCLK C0 4 9 SDA (c) 2011 IDT Characteristics subject to change without notice 5 6 11 7 8 INTB VDD RESETB 12 TEST1 1 SHIELD C3 Doc. No. 6200 FamilyDS, Rev. 0.5 LDS6200 Family LDS6203NTGI 20 19 18 17 16 C5 1 15 VDDIO C4 2 14 VDD C3 3 13 GPIO C2 4 12 SCLK C1 5 11 SDA 6 (c) 2011 IDT Characteristics subject to change without notice 7 8 12 9 10 Doc. No. 6200 FamilyDS, Rev. 0.5 LDS6200 Family C6 C7 TEST0 VSS LDOEN LDS6204NTGI 20 19 18 17 16 2 14 VDD C3 3 13 GPIO C2 4 12 SCLK C1 5 11 SDA (c) 2011 IDT Characteristics subject to change without notice 6 7 8 9 10 INTB C4 RESETB VDDIO TEST1 15 SHIELD 1 C0 C5 13 Doc. No. 6200 FamilyDS, Rev. 0.5 LDS6200 Family DEVICE PINOUTS (SOIC) LDS6201DCGI VSS 1 16 LDOEN TEST0 2 3 15 14 4 5 6 13 12 11 VDDIO VDD GPIO 7 10 INTB 8 9 RESETB N.C. N.C. C1 C0 SHIELD TEST1 (c) 2011 IDT Characteristics subject to change without notice 14 SCLK SDA Doc. No. 6200 FamilyDS, Rev. 0.5 LDS6200 Family LDS6202DCGI VSS 1 16 LDOEN TEST0 2 3 15 14 4 5 6 13 12 11 VDDIO VDD GPIO 7 10 INTB 8 9 RESETB C3 C2 C1 C0 SHIELD TEST1 (c) 2011 IDT Characteristics subject to change without notice 15 SCLK SDA Doc. No. 6200 FamilyDS, Rev. 0.5 LDS6200 Family LDS6203SOGI TEST0 1 20 VSS N.C. 2 3 19 18 4 5 6 17 16 15 LDOEN VDDIO VDD GPIO 7 14 C0 8 9 13 12 RESETB SHIELD 10 11 TEST1 N.C. C5 C4 C3 C2 C1 (c) 2011 IDT Characteristics subject to change without notice 16 SCLK SDA INTB Doc. No. 6200 FamilyDS, Rev. 0.5 LDS6200 Family LDS6204SOGI TEST0 1 20 VSS C7 2 3 19 18 4 5 6 17 16 15 LDOEN VDDIO VDD GPIO 7 14 C0 8 9 13 12 RESETB SHIELD 10 11 TEST1 C6 C5 C4 C3 C2 C1 (c) 2011 IDT Characteristics subject to change without notice 17 SCLK SDA INTB Doc. No. 6200 FamilyDS, Rev. 0.5 LDS6200 Family PIN LIST and FUNCTIONAL DESCRIPTIONS Pin Name Functional Description Cx VDD VSS LDOEN SDA SCLK GPIO Dedicated Capacitance Sensor Input Touch Sensor Supply Voltage (1.8V nominal, LDO Disabled) Touch Sensor Ground LDO Enable ("0" = LDO Disable, 1.8V applied directly to VDD pin) ("1" = LDO Enable, Supply Voltage Applied to VDDIO) Touch Sensor Supply Voltage (>1.95V, LDO Enabled) and/or Serial I/F Operating Voltage 2 I C Data I/O 2 I C Clock Input General Purpose Input Output INTB RESETB SHIELD Interrupt Output (CMOS Output) Hardware Reset pin for device (Active low) CDC Shield. Connect to external shield/plane to reduce stray capacitance. TEST0 TEST1 N.C. Test pin must be connected to ground Test pin must be connected to ground No Connect (must be left floating) VDDIO (c) 2011 IDT Characteristics subject to change without notice 18 Doc. No. 6200 FamilyDS, Rev. 0.5 LDS6200 Family FUNCTIONAL BLOCK DIAGRAM Switch Matrix Figure 6: LDS6200 Family Functional Block Diagram (c) 2011 IDT Characteristics subject to change without notice 19 Doc. No. 6200 FamilyDS, Rev. 0.5 LDS6200 Family THEORY OF OPERATION (R) The LDS6200 Family operates with supply voltages ranging from 1.8V to 5.5V. Available package options vary by device and include two thin form factor 3mm x 3mm 16-pin and 3mm x 3mm 20-pin TQFN packages, and 3.9mm x 9.9mm 16-pin or 7.5mm x 12.8mm 20-pin SOIC packages. The LDS6200 PureTouch Family of capacitive touch controllers feature a highly-accurate capacitance-todigital converter (CDC) for touch button, slider, and scroll applications. Capacitive sensing is accomplished using a sigma-delta converter capable of converting a sensor input signal into a digital output that is compared against a touch/no-touch threshold value to determine if a touch has occurred. The button status and digitized capacitance values are stored in on-chip registers available to a host 2 processor via the I C or SMBus-compatible serial interface options. On-chip self-calibration continously takes environmental effects such as temperature, humidity, and dust into consideration to establish an accurate baseline capacitance for each sensor to ensure maximum responsiveness to true touch events. The LDS6200 Family includes up to 8 sensor input pins, with a programmable switch matrix determining which sensor inputs are connected to the CDC at any given time. The sensor inputs may be connected to external capacitance sensors arranged as buttons, sliders, scroll wheels or other creatively arranged user inputs. Button, slider, and scroll inputs are natively supported using built in logic, with location and direction automatically calculated for slider and scroll inputs. On-chip registers allow adjustment of the sampling (decimation) rate, threshold/sensitivity for each individual sensor, and hysteresis and debounce characteristics, enabling a very high degree of configurability in scan rate, button sensitivity and overall touch characteristics. An interrupt output, INTB, is available to notify the host when a touch event has occurred. A GPIO is also available to act as an input to control the INTB output. The GPIO pin may also be configured as an output low or output high pin to turn on and off an external LED. Due to its ultra-low touch sensor power consumption of <125uW*** (typ), the LDS6200 Family may be operated continuously at full power to achieve the most responsive touch charactersitics and best possible user experience. In this mode, touch sensor detection occurs continuously at very low power levels, eliminating the need for sleep periods between detection cycles that result in touch latency and an inconsistent user experience. (c) 2011 IDT Characteristics subject to change without notice *** 1.8V, excluding VDDIO current, which varies with VDDIO voltage, I/F type, and communication frequency 20 Doc. No. 6200 FamilyDS, Rev. 0.5 LDS6200 Family POWER-UP/INITIALIZATION SEQUENCE OPERATING MODES The power up and initialization sequence involves the following flow: The LDS6200 Family may be programmed to operate in three different modes. Power-Up Cold Reset Command Initialize Configuration Registers Software Reset Command In full power mode, touch detection occurs continuously, without delays between detection cycles. This mode is utilized when the touch inputs need to be fully active and always responsive to touch inputs. Due to its ultra-low touch sensor power consumption of <125uW***, the LDS6200 Family may be operated continuously in full power mode even when battery life is of premium importance. Initialization of the configuration registers is required to define the functionality of each channel, set touch sensitivity levels, and generally specify the desired configuration of the highly flexible LDS6200 Family touch controller. The Cold Reset and Software Reset Commands are required to ensure consistency of operation before and after the initialization process occurs. The device may also be put into a configurable low power mode for situations where a small inserted delay (typically less than 0.3s) between the first touch and touch reporting is acceptable. This optional low power mode can cut power by more than half. AUTOMATIC CALIBRATION MODE The LDS6200 Family integrates on-chip sensor calibration to compensate for uncontrollable environmental factors such as moisture and temperature changes. Without such compensation, the baseline "no-touch" value may drift over time, affecting the ability of the device to measure valid touch events. The calibration algorithm is executed after every conversion cycle, ensuring that even rapidly changing ambient conditions are well compensated. Lastly, the device can be put into Shutdown mode, which disables touch sensing and lowers power consumption to ~1uW (typical). Only the serial interface bus is active during Shutdown mode to receive any commands (such as exit from Shutdown mode). Two methods of device reset are provided. Software Reset (writing any value to register 0x001) executes a soft reset of the device by initiating a new calibration cycle and resetting the state machine, including the Interrupt Status Register. Previously configured control registers, however, are not affected by a Software Reset, so no reconfiguration or re-initialization need occur. *** 1.8V, excluding VDDIO current, which varies with VDDIO voltage, I/F type, and communication frequency Hardware Reset (setting RESETB low or writing any value to register 0x000) resets the state machine and all previously configured registers, requiring a re-initialization by the host to set configuration registers to their proper state. Both Software and Hardware Reset take ~0.5-1s in the typical case to return the device to its fully functioning state. The actual time depends upon the number of active sensors requiring calibration and the relative sensor values. Where start-up time is especially important, fine-tuning of certain configuration registers is possible to expedite initial calibration. Please contact your IDT representative if start-up time optimization is required. (c) 2011 IDT Characteristics subject to change without notice 21 Doc. No. 6200 FamilyDS, Rev. 0.5 LDS6200 Family LOW POWER MODE CONFIGURATION Low power mode may be utilized when extremely low power consumption is desired and a small amount of added delay/latency is acceptable. By setting Bit 1 of the Power Configuration Register (0x002) to "1", low power mode is activated and the touch controller will alternate between full power sensing and a lower power sleep mode where power is conserved but touches are not sensed. The amount of power saved is a function of the sleep period time inserted between full power scan cycles. The full power scan cycle time is equal to ~2ms x the number of active sensors. For example, 10 active sensors would result in a full power scan cycle time of ~20ms. The amount of sleep time inserted occurs in 1ms increments by setting the Sleep Configuration Register (0x056) to the # of milliseconds desired for the sleep cycle. For example, a setting of 50 (decimal) will insert 50ms of sleep time, lowering the average power consumption compared to a continuous full power state. The longer the sleep period added, the lower the average power consumption will be, with the trade-off of longer potential latency between touch and touch recognition The following tables show that low power mode current consumption is a function of not only the inserted sleep period, but also the number of active sensors. It should also be noted that the greatest power savings benefit is realized when adding the first ~250ms of sleep period (less when fewer sensors are active). When adding sleep periods longer than ~250ms, the resulting reduction in current is relatively minor. Accordingly, the system designer should take into consideration the # of active sensors and incremental power savings when deciding upon the sleep period, as it may not be materially beneficial to insert longer sleep periods. *** 1.8V, excluding VDDIO current, which varies with VDDIO voltage, I/F type, and communication frequency In an example scenario of 8 active sensors, current consumption may be lowered to ~24uA*** (>60% current reduction) when introducing a relatively brief 100ms of sleep. Adding an additional 150ms of sleep (for 250ms total) only saves an additional 4uA. Once a touch is detected, the touch controller will remain in full power mode, maximizing touch responsiveness, until a certain amount of time passes without a touch event. The Sleep Wait Register (0x003) specifies the time the controller will remain in full power mode (waiting for a new touch) before going back to low power mode. (c) 2011 IDT Characteristics subject to change without notice 22 Doc. No. 6200 FamilyDS, Rev. 0.5 LDS6200 Family mode (Absolute or Relative) only and is not applicable to Two Strongest Touch modes. SELECTIVE TOUCH MODES The LDS6200 Family touch controller is capable of detecting up to 8 simultaneous touches (on LDS6204). However, in certain situations, the application may want to only allow one or two valid touch events at any given time. RECALIBRATION FOR "STUCK" TOUCHES The LDS6200 Family of products enables an automatic forced recalibration when a touch persists beyond a certain length of time. This optional feature enables recalibration in the case that some material remains on the sensor resulting in a continuous, but unintended, touch signal. To accommodate such application requirements and avoid inadvertent touches, the LDS6200 Family has four selective touch modes: Strongest Absolute Touch and Two Strongest Absolute Touches. As the names indicate, Strongest Absolute Touch mode only registers the single strongest touch event at any given time, as judged by the absolute capacitance value, as long as it is above the touch threshold value. Similarly, Two Strongest Absolute Touches mode only registers the two strongest touch events at any given time, as judged by absolute capacitance values. The Stuck Touch Recalibration Register (0x053) sets the time limit for a continous touch before a recalibration is forced. When a recalibration occurs, all active sensors are recalibrated. To ensure that a lengthy, but real, touch does not result in recalibration, it is generally advisable to set the timer limit for stuck touch recalibration to be well above the expected duration for a valid touch. The actual time limit is a function of the # of configured active sensors. For more detail on how to set a specific stuck touch time limit, please refer to the Detailed Register Document for the particular device being used. New to the LDS6200 Family are Strongest Relative Touch and Strongest Two Relative Touches. Instead of judging strongest touch by absolute capacitance value, the judgments are made looking at the delta between measured capacitance value and touch threshold value. The largest delta (defined as "capacitance value minus threshold level" for each sensor) is considered the strongest relative touch (and largest two deltas considered the two strongest relative touches). Where sensor sizes (and therefore the resulting capacitance values resulting from a touch) are significantly different, these two new modes can help achieve the desired effect of registering the most definitive/intended touch or touches. PROXIMITY SENSOR The LDS6200 Family has built in proximity sesnsor cabability. Each touch sensor can be enabled to act as a proximity sensor by using register 0x039 bits 0-7, but only one touch sensor can be used as a proximity sensor. Register 0x046 bits 0-7 are used to check the status of the proximity sensor. Increasing bits 10 - 15 of register 0x039 will increase the sensitivity of the proximity channel. Sensitivity should be adjusted for each application to achieve solid reliability. For more information please see Application Note 62xxAN1. Bits 8 and 9 of the "Touch Configuration Register" (0x040) control whether selective touch is active (Bit 8/9 = 1/0 for Strongest Touch, 0/1 for Two Strongest Touches). The device defaults to the unrestricted or "all touch" mode (Bits 8 and 9 = 0) upon power up. TOUCH EVENT DURING POWER ON To select between Absolute and Relative touch preference modes, a single bit RELATIVE_EN (bit 15 of Register 0x075) is utilized, with bit status "0" used for the Absolute modes and bit status "1" used for the Relative Modes. When the device is first powered on the device will automatically calibrate to adjust to external conditions such as ambient temperature, humidity and smudges. To indicate a touch event during power on, bit 0 of register 0x038 will need to be enabled by setting to `1'. In order to be able to identify a touch event upon power up SELC values must be predefined for each active touch sensor using registers 0x030 - 0x037. By setting a predefined SELC value a touch event can still be recognized on power up without concern of not having the touch event aknowledged since it has been calibrated into the signal. For more information please see Application Note 62xxAN1. To avoid frequent toggling of the strongest touch with two touches of comparable strength, an additional (optional) time criteria may be added that requires a new and stronger touch to remain stronger for a certain period of time before replacing the current strongest touch. The REPLACEMENT_TIME bits (015 of Strongest Touch Replacement Time Configuration Register 0x028) are used for this purpose. This option is available in Strongest Touch (c) 2011 IDT Characteristics subject to change without notice 23 Doc. No. 6200 FamilyDS, Rev. 0.5 LDS6200 Family TOUCH OPTIMIZATION HYSTERESIS DEBOUNCE Hysteresis is another method of ensuring touch stability. The hysteresis feature enables a "buffer region" to be established within which the capacitive value of an established touch may vary and still be recognized as a continous touch. Hysteresis Configuration Register 0x075 (bits 0-5) sets the amount of capacitance variation (referenced from the Touch Threshold level depicted in the diagram below) that may be tolerated before the current touch is reported as being removed from the sensor. The debounce feature enables a time criteria to be set as an "acceptance" criteria for a touch being recognized as valid. Because capactive touch inputs frequently involve rigid overlays, there is no compression or "give" associated with a touch. As a result, a finger may very lightly "bounce" for a period of time, resulting in a fluctuating capacitive effect on the capacitive sensor. If the fluctuation results in capacitance values varying above and below the touch threshold level, multiple touches may be erroneously reported to the host processor. Debounce: Min Time Criteria for Valid Touch Touch NOT Recognized Debounce: Min Time Criteria for Valid Touch Capacitance Value By setting a time criteria required for the capacitive signal to remain above the threshold value, this type of inadvertant multiple touch event may be eliminated. The Debounce Registers (0x020 to 0x027) are used for this purpose. Bits 0-8 set the # of consecutive scan cycles that the capacitive signal must remain above the touch threshold value before a touch is reported to the host. The LDS62xx family allows each channel to set its debouce criteria independently of the other channels. Once Touched, Remain Touched Until Below The diagram above shows a typical example of hysteresis, which allows a certain amount of capacitance variation to occur without multiple touch events being reported to the host. In the above diagram, the buffer region is defined by the area below the Touch Threshold Level and above the "UnTouch" Threshold level. This size of this region is effectively specified by programming the amount of capacitance variation allowed via the Hysteresis Configuration Register value. Touch Recognized With hysteresis, the weaker capacitive signal depicted by the two intermittent lines falling below the original touch threshold are now considered a continuation of the original touch since they remain above the UnTouch threshold level. The diagram above shows an example of fluctuating capacitive signal and the debounce time that eliminates multiple touch reporting. (c) 2011 IDT Characteristics subject to change without notice 24 Doc. No. 6200 FamilyDS, Rev. 0.5 LDS6200 Family CAPACITANCE-TO-DIGITAL CONVERSION The LDS6200 Family capacitance-to-digital converter (CDC) utilizes a sigma-delta design for capacitive sensing. Up to 8 sensor inputs are available to be connected through a switch matrix to the CDC. The nominal decimation (oversampling) rate is 1024, which designates the number of samples acquired per sensor input for each scan cycle. The decimation process averages multiple samples from the CDC to arrive at one optimized result. The process of averaging multiple samples reduces the effect of spurious noise that can adversely affect touch detection. The decimation rate may be programmed from the nominal value of 1024 to alternate rates of 128, 256, 512, or 2048. Since the update time per sensor is directly affected by the selected decimation rate, care should be taken to assure that the proper balance is achieved between system performance and touch update rates. In the majority of cases, the default decimation rate is optimal. The conversion time per sensor input depends upon the programmed decimation rate and the possible options are shown in the table below: Conversion Time/Input vs Decimation Rate (ms) Conversion Time Decimation Rate (d) 128 256 512 0.256 0.512 1.024 1024 2.048 Table 1: Conversion Time (in ms) per Input vs Decimation Rate The update rate (time between sequential scan cycles) is the product of the single output CDC conversion rate above multiplied by the number of active sensors. For the highest channel LDS6200 offering, if all 8 sensor inputs are utilized, the maximum possible update rate would be ~16ms. (c) 2011 IDT Characteristics subject to change without notice 25 Doc. No. 6200 FamilyDS, Rev. 0.5 LDS6200 Family CDC SEQUENCER Based upon the status of the sensor input configuration above, the on-board sequencer will proceed to sample all sensor-connected inputs and convert the capacitance measurements to digital capacitive value referenced off a baseline value. Those configured as floating will not be connected to the CDC for conversion. CD C The number of sensor inputs required for different input types will depend upon the nature of input type. A simple button input that registers only a touch/notouch situation ("0D") requires only one input. Position-variable inputs with more than just an on/off designation ("1D" inputs such as sliders and scroll wheels) require more than one input, with the required number dependant upon the desired resolution. For example, a coarse scroll wheel may be implemented with only 4 sensor inputs, while a higher resolution version might be implemented with 10 inputs. The LDS6200 Family of products includes built-in 2x interpolation, meaning 2 times the number of touch positions as physical elements can be achieved (2 times # of elements minus 1 in case of sliders). The location ID and direction are available via status registers. Figure 8: Scroll Wheel Connection Example More detail on the configuration and usage of the built-in slider/scroll functionality will be available Application Note 61xxAN1: "LDS61xx Enhanced Functionality Usage and Configuration". SIMPLE RETRIEVAL OF TOUCH RESULTS: BUTTONS Figures 11 and 12 below show connection examples of both a button/slider combination and a scroll wheel implementation. The Interrupt Status Registers (0x043) contains the Interrupt status of every sensor input. When the relative magnitude of touch is not important and only touch or no-touch status is required, the Interrupt Status Register is sufficient for determining touch status of buttons. CD C The INTB pin is designed to drive low when either a valid touch or touch-termination ("untouch") event occurs. In this way, INTB provides notification to the host processor that a touch-relevent event has occurred and the Interrupt Status Registers have been updated. By reading the Interrupt Status Registers and determining which sensor input interrupt bit is high, the system may determine which sensor was touched or untouched. (Note: The polarity of the INTB status pin may be configured at power up to invert to drive high when a touch or touch-termination event occurs). The act of reading the Interrupt Status Register resets the INTB pin back to the high state. When the next touch-relevant event occurs, the process is repeated, with the host processor being notified by INTB driving low and subsequently reading the Interrupt Status Registers to determine which sensor inputs were touched or "untouched". Figure 7: Button/Slider Connection Example (c) 2011 IDT Characteristics subject to change without notice 26 Doc. No. 6200 FamilyDS, Rev. 0.5 LDS6200 Family For "0D" or simple "on/off" (touch/untouch) inputs like buttons, the results of the Interrupt Status Register are sufficient to take action based on which touch button was activated. TOUCH RESULTS: SLIDERS AND SCROLL Position-variable or "1D" inputs with more than an on/off status require the host processor to read back the conversion status results to properly interpret touch location. The LDS6200 Family offers built-in support for slider and scroll wheels, enabling the user to assign which sensor channels are utilized in slider or scroll input types. Slider/Scroll Configuration register 0x074 allows up to 8 channels (C0-C7) to be assigned as slider/scroll wheel elements. A separate slider/scroll interrupt bit is available, as well as a direction bit and 5-bit location ID register, register 0x045 bits 0-4, to directly read the current location being touched as well as the direction of movement. Two times interpolation is available to generate two times (two times minus one for sliders) the number of reported touch positions as actual touch elements to support higher resolution requirements. For more information on configuring slider and scroll wheel setup and interpreting the results registers, please see the Application Note 61xxAN1: "LDS61xx Enhanced Functionality Usage and Configuration". Interpolation to achieve higher than 2x resolution enhancement is possible by using host-side algorithms to read the digital capacitance values and interpolate beyond the 2x level. The degree of interpolation achievable is a function of the sensor size, shape, and overlay thickness. Contact your local IDT contact for more information on >2x interpolated slider and scroll implementations. (c) 2011 IDT Characteristics subject to change without notice 27 Doc. No. 6200 FamilyDS, Rev. 0.5 LDS6200 Family OUTPUTS GPIO OUTPUT The GPIO pin may be disabled, configured as an input to control the INTB output (details on usage of GPIO as an input follow on page 38), or configured as either a low or high output. The "GPIO Configuration Register" (0x009) bits [1:0] are used for this purpose. The default state for GPIO is the output low state. Figure 9: Sensor Activation Interrupt Example Use of the GPIO as an output can used to turn on and off an LED if used with as the gate control of an external transistor which supplies the LED drive current. The second interrupt notifies the host that the touch stimulus is no longer in contact with the sensor. In order for the second interrupt to be properly differentiated from the first, the host should read back the Interrupt Status Registers when INTB is first pulled low to enable the INTB pin to return to its high state and be re-triggered when the untouch event occurs. INTERRUPT (INTB) The INTB output notifies the host processor of an interrupt event. Interrupt events are classified into two categories: a sensor touch or untouch interrupt or a GPIO input generated interrupt. SHIELD By default, the INTB pin is configured as an activelow CMOS output, with no pull-up resistor necessary. When an interrupt event occurs, the LDS6200 Family pulls the INTB pin low to signal the host processor that a touch-relevant event has occurred. In the default device configuration, the SHIELD pin outputs the identical excitation waveform as that used on the actively read sensor input. In this configuration, SHIELD may effectively be utilized to reduce stray capacitance to ground that has the potential to affect the capacitance-to-digital conversion process. Once the interrupt signal is triggered, the host processor may read the Interrupt Status Registers (0x043) to determine which type of interrupt has occurred (Bit 15 of 0x043 for GPIO input generated interrupt, other bits for touch generated interrupts). In the case of a touch or untouch event, a touch (finger down) will result in a "1" in the associated sensor register bit, while an untouch (finger up) will result in a "0". By shielding both a) the connection traces between sensor array and LDS6200 Family sensor inputs and b) the shield plane around the sensor array elements themselves, stray capacitance is significantly reduced. Interactions between adjacent connection traces and between closely spaced sensor array elements are also reduced and longer distances between sensor array and LDS6200 Family may be supported while still achieving a high level of touch performance. The Interrupt Status Registers and the INTB pin itself are reset once the host completes a read operation, enabling the next interrupt event to be sensed and communicated. Please refer to AN5: Preliminary Use of SHIELD application note for more guidance on use of the SHIELD pin. Touch and Untouch Interrupts As mentioned in the above section, two interrupt events will be registered once a touch occurs: the first when contact is made with the capacitive sensor (finger down or "touch"), and again when contact is terminated (finger up or "untouch"). The figure below illustrates this. (c) 2011 IDT Characteristics subject to change without notice 28 Doc. No. 6200 FamilyDS, Rev. 0.5 LDS6200 Family GPIO AS INPUT TO INTERRUPT SIGNAL The GPIO pin may also be configured as an input to control the interrupt output INTB by programming the bits [1:0] in the "GPIO Configuration Register" (0x009) to [0,1]. When using GPIO as an input, INTB can be triggered on a low level, high level, falling edge, rising edge, or on both falling and rising edges of the GPIO pin. The GPIO Input Configuration bits (bits [4:2] of register 0x009) determine which stimuli type will trigger INTB. Figures 14-18 illustrate the various types of input triggers. Figure 11: GPIO High Level Trigger (GPIO Input Cfg = "010") The GPIO status bit in the second Interrupt Status Register (Bit 15 of register 0x043) indicates that the GPIO trigger condition occurred. After a host reads this status register, the GPIO status bit and INTB signal are cleared (assuming the original triggering condition is no longer present) and no touch events are otherwise causing INTB to remain low. Register 0x009 Bits [4:2] Input Stimuli Type 000 001 010 011/100 101 110 111 Not used (Default) Low level trigger High level trigger Not used Falling edge trigger Rising edge trigger Both edge trigger Figure 12: GPIO Falling Edge Trigger (GPIO Input Cfg = "101") Figure 13: GPIO Rising Edge Trigger (GPIO Input Cfg = "110") Table 3: GPIO Interrupt Configuration Figure 10: GPIO Low Level Trigger (GPIO Input Cfg = "001") (c) 2011 IDT Characteristics subject to change without notice Figure 14: GPIO Both (Falling/Rising) Edge Trigger (GPIO Input Cfg = "111") 29 Doc. No. 6200 FamilyDS, Rev. 0.5 LDS6200 Family PACKAGE DRAWING AND DIMENSIONS 16-PIN TQFN, 3mm x 3mm, 0.5mm PITCH (c) 2011 IDT Characteristics subject to change without notice 30 Doc. No. 6200 FamilyDS, Rev. 0.5 LDS6200 Family PACKAGE DRAWING AND DIMENSIONS 16-PIN SOIC, 3.9mm x 9.9mm, 1.27mm PITCH (c) 2011 IDT Characteristics subject to change without notice 31 Doc. No. 6200 FamilyDS, Rev. 0.5 LDS6200 Family PACKAGE DRAWING AND DIMENSIONS 20-PIN TQFN, 3mm x 3mm, 0.4mm PITCH PACKAGE DRAWING AND DIMENSIONS (c) 2011 IDT Characteristics subject to change without notice 32 Doc. No. 6200 FamilyDS, Rev. 0.5 LDS6200 Family 20-PIN SOIC, 7.5mm x 12.8mm, 1.27mm PITCH (c) 2011 IDT Characteristics subject to change without notice 33 Doc. No. 6200 FamilyDS, Rev. 0.5 LDS6200 Family ORDERING INFORMATION Part Number* Package LDS6201NTGI8 Package Marking TQFN-16 3mm x 3mm (1) LDS6201DCGI8 SOIC-16 3.9mm X 9.9mm LDS6202NTGI8 (1) TQFN-16 3mm x 3mm SOIC-16 3.9mm X 9.9mm LDS6203NTGI8 (1) LDS6203SOGI8 SOIC-20 7.5mm X 12.8mm LDS6204NTGI8 (1) LDS6204SOGI8 TQFN-20 3mm x 3mm DCG NTG (1) LDS6202DCGI8 TQFN-20 3mm x 3mm NTG (1) DCG NTG (1) SOIC-20 7.5mm X 12.8mm SOG NTG (1) SOG Notes (*Remove the "8" at the end of the part number for non-T/R option): 1. Matte-Tin Plated Finish (RoHS-compliant) 2. Quantity per reel is 2500 for TQFN package and 1500 for SOIC package EXAMPLE OF ORDERING INFORMATION Prefix LDS Device # Suffix 620x NTG I8 Temperature Range and Packing Option Temperature Range: I = Industrial (-40C to 80C) Packing Option: 8 = Tape & Reel Product Number (see Product Family Guide on Page 1) PL Indicator Package Code NTG = TQFN DCG = SOIC SOG = SOIC (c) 2011 IDT Characteristics subject to change without notice 34 Doc. No. 6200 FamilyDS, Rev. 0.5 LDS6200 Family REVISION LOG Date 01/13/10 04/09/10 05/06/10 06/25/10 11/10/10 6/1/11 Rev. 0.0 0.1 0.2 0.3 0.4 0.5 Reason Initial Draft Block diagram correction Figure 11 and 12 update Removed SSOP package and included SOIC package Updated pinout diagrams to indicate TEST0 and TEST1 pins. Clarify connection requirements for TEST0 and TEST1 pins. Updated 16ld TQFN package dimenions on page 30. Updated I2C read timing diagram DISCLAIMER Integrated Device Technology , Inc. (IDT) and its subsidiaries reserve the right to modify the products and/or specifications described herein at any time and at IDT's sole discretion. All information in this document, including descriptions of product features and performance, is subject to change without notice. Performance specifications and the operating parameters of the described products are determined in the independent state and are not guaranteed to perform the same way when installed in customer products. The information contained herein is provided without representation or warranty of any kind, whether express or implied, including, but not limited to, the suitability of IDT's products for any particular purpose, an implied warranty of merchantability, or non-infringement of the intellectual property rights of others. This document is presented only as a guide and does not convey any license under intellectual property rights of IDT or any third parties. IDT's products are not intended for use in life support systems or similar devices where the failure or malfunction of an IDT product can be reasonably expected to significantly affect the health or safety of users. Anyone using an IDT product in such a manner does so at their own risk, absent an express, written agreement by IDT. Integrated Device Technology, IDT and the IDT logo are registered trademarks of IDT. Other trademarks and service marks used herein, including protected names, logos and designs, are the property of IDT or their respective third party owners. 6024 Silver Creek Valley Road San Jose, California 95138 http://www.idt.com (c) 2011 IDT Characteristics subject to change without notice Document No: 6200 Family DS Revision: 0.5 Issue date: 6/30/11 35 Doc. No. 6200 FamilyDS, Rev. 0.5 LDS6100 Family