QT113 lQ QProx™ QT113 CHARGE-TRANSFER TOUCH SENSOR � Projects a proximity field through air or any insulator � Less expensive than many mechanical switches � Sensitivity easily adjusted Vdd 1 8 Vss � Consensus filter for noise immunity � 100% autocal for life - no adjustments required Out 2 7 Sns2 � 2.5 to 5V, 600µA single supply operation Opt1 3 6 Sns1 � Toggle mode for on/off control (strap option) � 10s, 60s, infinite auto-recal timeouts (strap options) Opt2 45 Gain � HeartBeat™ health indicator on output � Only one external part required - a 1¢ capacitor � Lead-Free package APPLICATIONS - �Light switches �Appliance control �Access systems �Elevator buttons �Prox sensors �Security systems �Pointing devices �Consumer devices The QT113 charge-transfer (“QT’”) touch sensor is a self-contained digital IC capable of detecting near-proximity or touch. It will project a proximity sense field through air, and any dielectric like glass, plastic, stone, ceramic, and most kinds of wood. It can also turn small metal-bearing objects into intrinsic sensors, making them responsive to proximity or touch. This capability coupled with its ability to self calibrate continuously can lead to entirely new product concepts. It is designed specifically for human interfaces, like control panels, appliances, toys, lighting controls, or anywhere a mechanical switch or button may be found; it may also be used for some material sensing and control applications provided that the presence duration of objects does not exceed the recalibration timeout interval. Power consumption is only 600µA in most applications. In most cases the power supply need only be minimally regulated, for example by Zener diodes or an inexpensive 3-terminal regulator. The QT113 requires only a common inexpensive capacitor in order to function. The QT113’s RISC core employs signal processing techniques pioneered by Quantum; these are specifically designed to make the device survive real-world challenges, such as ‘stuck sensor’ conditions and signal drift. The option-selectable toggle mode permits on/off touch control, for example for light switch replacement. The Quantum-pioneered HeartBeat™ signal is also included, allowing a microcontroller to monitor the health of the QT113 continuously if desired. By using the charge transfer principle, the IC delivers a level of performance clearly superior to older technologies in a highly cost-effective package. AVAILABLE OPTIONS TA SOIC 8-PIN DIP 0 0 - 0 C to +70 C QT113-DG 0 0 -40 C to +85 C QT113-ISG - Copyright 1999-2004 QRG Ltd R1.05/0405 Figure 1-1 Basic Circuit Configuration 1 - OVERVIEW The QT113 is a digital burst mode charge-transfer (QT) +2.5 to5 sensor designed specifically for touch controls; it includes all hardware and signal processing functions necessary to SENSING provide stable sensing under a wide variety of changing ELECTRODE conditions. Only a single low cost, non-critical capacitor is 1 required for operation. RSERIES Vdd 2 7 OUT SNS2 Figure 1-1 shows a basic circuit using the device. C s 3 5 1.1 BASIC OPERATION OPT1 GAIN 10nF The QT113 employs bursts of charge-transfer cycles to C x acquire its signal. Burst mode permits power consumption in 46 the microamp range, dramatically reduces RF emissions, OPT2 SNS1 lowers susceptibility to EMI, and yet permits excellent Vss OUTPUT=DC response time. Internally the signals are digitally processed TIMEOUT=10 Secs 8 TOGGLE=OFF to reject impulse noise, using a 'consensus' filter which GAIN=HIGH requires three consecutive confirmations of a detection before the output is activated. 1.2 ELECTRODE DRIVE The QT switches and charge measurement hardware The internal ADC treats Cs as a floating transfer capacitor; as functions are all internal to the QT113 (Figure 1-2). A 14-bit a result, the sense electrode can in theory be connected to single-slope switched capacitor ADC includes both the either SNS1 or SNS2 with no performance difference. required QT charge and transfer switches in a configuration However the electrode should only be connected to pin SNS2 that provides direct ADC conversion. The ADC is designed to for optimum noise immunity. dynamically optimize the QT burst length according to the In all cases the rule Cs >> Cx must be observed for proper rate of charge buildup on Cs, which in turn depends on the operation; a typical load capacitance (Cx) ranges from values of Cs, Cx, and Vdd. Vdd is used as the charge 10-20pF while Cs is usually around 10-50nF. reference voltage. Larger values of Cx cause the charge transferred into Cs to rise more rapidly, reducing available Increasing amounts of Cx destroy gain; therefore it is resolution; as a minimum resolution is required for proper important to limit the amount of stray capacitance on both operation, this can result in dramatically reduced apparent SNS terminals, for example by minimizing trace lengths and gain. Conversely, larger values of Cs reduce the rise of widths and keeping these traces away from power or ground differential voltage across it, increasing available resolution traces or copper pours. by permitting longer QT bursts. The value of Cs can thus be The traces and any components associated with SNS1 and increased to allow larger values of Cx to be tolerated (Figures SNS2 will become touch sensitive and should be treated with 4-1, 4-2, 4-3 in Specifications, rear). caution to limit the touch area to the desired location. The IC is responsive to both Cx and Cs, and changes in Cs A series resistor, Rseries, should be placed inline with the can result in substantial changes in sensor gain. SNS2 pin to the electrode to suppress ESD and EMC effects. Option pins allow the selection or alteration of several special features and sensitivity. 1.3 ELECTRODE DESIGN 1.3.1 ELECTRODE GEOMETRY AND SIZE There is no restriction on the shape of Figure 1-2 Internal Switching & Timing the electrode; in most cases common sense and a little experimentation can ELECTRODE result in a good electrode design. The Result SNS2 QT113 will operate equally well with long, thin electrodes as with round or square ones; even random shapes are acceptable. The electrode can also be a 3-dimensional surface or object. C s Sensitivity is related to electrode surface area, orientation with respect Start C to the object being sensed, object Done x composition, and the ground coupling SNS1 quality of both the sensor circuit and the sensed object. If a relatively large electrode surface is desired, and if tests show that the Charge electrode has more capacitance than Amp the QT113 can tolerate, the electrode can be made into a sparse mesh (Figure 1-3) having lower Cx than a lQ 2 R1.05/0405 Burst Controller Single-Slope 14-bit Switched Capacitor ADC solid plane. Sensitivity may even remain the same, as the equally well. Shielding in the form of a metal sheet or foil sensor will be operating in a lower region of the gain curves. connected to circuit ground will prevent walk-by; putting a small air gap between the grounded shield and the electrode 1.3.2 KIRCHOFF’S CURRENT LAW will keep the value of Cx lower to reduce loading and keep Like all capacitance sensors, the QT113 relies on Kirchoff’s gain high. Current Law (Figure 1-3) to detect the change in capacitance of the electrode. This law as applied to capacitive sensing 1.3.5 SENSITIVITY requires that the sensor’s field current must complete a loop, The QT113 can be set for one of 2 gain levels using option returning back to its source in order for capacitance to be pin 5 (Table 1-1). This sensitivity change is made by altering sensed. Although most designers relate to Kirchoff’s law with the internal numerical threshold level required for a detection. regard to hardwired circuits, it applies equally to capacitive Note that sensitivity is also a function of other things: like the field flows. By implication it requires that the signal ground value of Cs, electrode size and capacitance, electrode shape and the target object must both be coupled together in some and orientation, the composition and aspect of the object to manner for a capacitive sensor to operate properly. Note that be sensed, the thickness and composition of any overlaying there is no need to provide actual hardwired ground panel material, and the degree of ground coupling of both connections; capacitive coupling to ground (Cx1) is always sensor and object. sufficient, even if the coupling might seem very tenuous. For 1.3.5.1 Increasing Sensitivity example, powering the sensor via an isolated transformer will In some cases it may be desirable to increase sensitivity provide ample ground coupling, since there is capacitance further, for example when using the sensor with very thick between the windings and/or the transformer core, and from panels having a low dielectric constant. the power wiring itself directly to 'local earth'. Even when battery powered, just the physical size of the PCB and the Sensitivity can often be increased by using a bigger object into which the electronics is embedded will generally electrode, reducing panel thickness, or altering panel be enough to couple a few picofarads back to local earth. composition. Increasing electrode size can have diminishing returns, as high values of Cx will reduce sensor gain (Figures 1.3.3 VIRTUAL CAPACITIVE GROUNDS 4-1 to 4-3). The value of Cs also has a dramatic effect on When detecting human contact (e.g. a fingertip), grounding sensitivity, and this can be increased in value with the of the person is never required. The human body naturally tradeoff of reduced response time. Increasing the electrode's has several hundred picofarads of ‘free space’ capacitance to surface area will not substantially increase touch sensitivity if the local environment (Cx3 in Figure 1-3), which is more than its diameter is already much larger in surface area than the two orders of magnitude greater than that required to create object being detected. Panel material can also be changed to a return path to the QT113 via earth. The QT113's PCB one having a higher dielectric constant, which will help however can be physically quite small, so there may be little propagate the field. Metal areas near the electrode will ‘free space’ coupling (Cx1 in Figure 1-3) between it and the reduce the field strength and increase Cx loading. environment to complete the return path. If the QT113 circuit Ground planes around and under the electrode and its SNS ground cannot be earth grounded by wire, for example via trace will cause high Cx loading and destroy gain. The the supply connections, then a ‘virtual capacitive ground’ may possible signal-to-noise ratio benefits of ground area are be required to increase return coupling. more than negated by the decreased gain from the circuit, A ‘virtual capacitive ground’ can be created by connecting the and so ground areas around electrodes are discouraged. QT113’s own circuit ground to: Keep ground away from the electrodes and traces. - A nearby piece of metal or metallized housing; 1.3.5.2 Decreasing Sensitivity - A floating conductive ground plane; In some cases the QT113 may be too sensitive, even on low - Another electronic device (to which its output might be gain. In this case gain can be lowered further by decreasing connected anyway). Cs. Free-floating ground planes such as metal foils should maximize exposed surface area in a flat plane if possible. A square of metal foil will have little effect if it is rolled up or Figure 1-3 Kirchoff's Current Law crumpled into a ball. Virtual ground planes are more effective and can be made smaller if they are physically bonded to other surfaces, for example a wall or floor. C X2 1.3.4 FIELD SHAPING The electrode can be prevented from sensing in undesired directions with the assistance of metal shielding connected to circuit ground (Figure 1-4). For example, on flat surfaces, the Sense E lectrode field can spread laterally and create a larger touch area than desired. To stop field spreading, it is only necessary to surround the touch electrode on all sides with a ring of metal SENSOR connected to circuit ground; the ring can be on the same or opposite side from the electrode. The ring will kill field C X1 spreading from that point outwards. If one side of the panel to which the electrode is fixed has moving traffic near it, these objects can cause inadvertent C X3 detections. This is called ‘walk-by’ and is caused by the fact Surrounding environm ent that the fields radiate from either surface of the electrode lQ 3 R1.05/0405 become insensitive to touch. In this latter case, the sensor Figure 1-4 Shielding Against Fringe Fields will compensate for the object's removal very quickly, usually in only a few seconds. With large values of Cs and small values of Cx, drift compensation will appear to operate more slowly than with the converse. Note that the positive and negative drift compensation rates are different. 2.1.2 THRESHOLD CALCULATION The internal threshold level is fixed at one of two setting as determined by Table 1-1. These settings are fixed with respect to the internal reference level, which in turn will move Sense Sense in accordance with the drift compensation mechanism. wire wire The QT113 employs a hysteresis dropout below the threshold level of 17% of the delta between the reference and threshold levels. 2.1.3 MAX ON-DURATION If an object or material obstructs the sense pad the signal may rise enough to create a detection, preventing further operation. To prevent this, the sensor includes a timer which monitors detections. If a detection exceeds the timer setting, the timer causes the sensor to perform a full recalibration Unshielded Shielded (when not set to infinite). This is known as the Max Electrode Electrode On-Duration feature. Table 1-1 Gain Setting Strap Options 2 - QT113 SPECIFICS Gain Tie Pin 5 to: 2.1 SIGNAL PROCESSING High - 6 counts Vdd The QT113 processes all signals using 16 bit math, using a Low - 12 counts Vss (Gnd) number of algorithms pioneered by Quantum. The algorithms are specifically designed to provide for high 'survivability' in After the Max On-Duration interval, the sensor will once again the face of numerous adverse environmental changes. function normally to the best of its ability given electrode conditions. There are two finite timeout durations available 2.1.1 DRIFT COMPENSATION ALGORITHM via strap option: 10 and 60 seconds (Table 2-1). Signal drift can occur because of changes in Cx and Cs over time. It is crucial that drift be compensated for, otherwise 2.1.4 DETECTION INTEGRATOR false detections, non-detections, and sensitivity shifts will It is desirable to suppress detections generated by electrical follow. noise or from quick brushes with an object. To accomplish this, the QT113 incorporates a detect integration counter that Drift compensation (Figure 2-1) is performed by making the increments with each detection until a limit is reached, after reference level track the raw signal at a slow rate, but only which the output is activated. If no detection is sensed prior while there is no detection in effect. The rate of adjustment to the final count, the counter is reset immediately to zero. In must be performed slowly, otherwise legitimate detections the QT113, the required count is 3. could be ignored. The QT113 drift compensates using a slew-rate limited change to the reference level; the threshold The Detection Integrator can also be viewed as a 'consensus' and hysteresis values are slaved to this reference. filter, that requires three successive detections to create an output. Once an object is sensed, the drift compensation mechanism ceases since the signal is legitimately high, and therefore should not cause the reference level to change. Figure 2-1 Drift Compensation The QT113's drift compensation is 'asymmetric': the reference level drift-compensates in one Signal direction faster than it does in the other. Hysteresis Specifically, it compensates faster for decreasing signals than for increasing signals. Increasing Threshold signals should not be compensated for quickly, Reference since an approaching finger could be compensated for partially or entirely before even approaching the sense electrode. However, an obstruction over the sense pad, for which the sensor has already made full allowance for, could suddenly be removed leaving the sensor with an Output artificially elevated reference level and thus lQ 4 R1.05/0405 Vdd do not cause the device to ‘stick on’ inadvertently even 2.1.5 FORCED SENSOR RECALIBRATION when the target object is removed from the sense field. The QT113 has no recalibration pin; a forced recalibration is accomplished only when the device is powered up. However, 2.2.2 TOGGLE MODE OUTPUT supply drain is low so it is a simple matter to treat the entire This makes the sensor respond in an on/off mode like a flip IC as a controllable load; simply driving the QT113's Vdd pin flop. It is most useful for controlling power loads, for example directly from another logic gate or a microcontroller port in kitchen appliances, power tools, light switches, etc. (Figure 2-2) will serve as both power and 'forced recal'. The source resistance of most CMOS gates and microcontrollers Max On-Duration in Toggle mode is fixed at 10 seconds. are low enough to provide direct power without problem. Note When a timeout occurs, the sensor recalibrates but leaves that many 8051-based micros have only a weak pullup drive the output toggle state unchanged. capability and will require CMOS buffering. 74HC or 74AC 2.2.3 HEARTBEAT™ OUTPUT series gates can directly power the QT113, as can most other The QT113 output has a full-time HeartBeat™ ‘health’ microcontrollers. indicator superimposed on it. This operates by taking 'Out' Option strap configurations are read by the QT113 only on into a 3-state mode for 300µs once after every QT burst. This powerup. Configurations can only be changed by powering output state can be used to determine that the sensor is the QT113 down and back up again; again, a microcontroller operating properly, or, it can be ignored using one of several can directly alter most of the configurations and cycle power simple methods. to put them in effect. Table 2-1 Output Mode Strap Options 2.1.6 RESPONSE TIME The QT113's response time is highly dependent on burst Tie Tie Max On- length, which in turn is dependent on Cs and Cx (see Figures Pin 3 to: Pin 4 to: Duration 4-1, 4-2). With increasing Cs, response time slows, while DC Out Vdd Vdd 10s increasing levels of Cs reduce response time. Figure 4-3 shows the typical effects of Cs and Cx on response time. DC Out Vdd Gnd 60s Gnd Gnd 10s Toggle 2.2 OUTPUT FEATURES Gnd Vdd infinite DC Out The QT113 is designed for maximum flexibility and can accommodate most popular sensing requirements. These The HeartBeat indicator can be sampled by using a pulldown are selectable using strap options on pins OPT1 and OPT2. resistor on Out, and feeding the resulting negative-going All options are shown in Table 2-1. pulse into a counter, flip flop, one-shot, or other circuit. Since Out is normally high, a pulldown resistor will create negative 2.2.1 DC MODE OUTPUT HeartBeat pulses (Figure 2-3) when the sensor is not The output of the QT113 can respond in a DC mode, where detecting an object; when detecting an object, the output will the output is active-low upon detection. The output will remain low for the duration of the detection, and no remain active-low for the duration of the detection, or until the HeartBeat pulse will be evident. Max On-Duration expires (if not infinite), whichever occurs first. If a max on-duration timeout occurs first, the sensor If the sensor is wired to a microcontroller as shown in Figure performs a full recalibration and the output becomes inactive 2-4, the microcontroller can reconfigure the load resistor to until the next detection. either ground or Vcc depending on the output state of the QT113, so that the pulses are evident in either state. In this mode, three Max On-Duration timeouts are available: 10 seconds, 60 seconds, and infinite. Electromechanical devices like relays will usually ignore this short pulse. The pulse also has too low a duty cycle to visibly Infinite timeout is useful in applications where a prolonged affect LED’s. It can be filtered completely if desired, by detection can occur and where the output must reflect the adding an RC timeconstant to filter the output, or if interfacing detection no matter how long. In infinite timeout mode, the directly and only to a high-impedance CMOS input, by doing designer should take care to be sure that drift in Cs, Cx, and nothing or at most adding a small non-critical capacitor from Out to ground (Figure 2-5). 2.2.4 OUTPUT DRIVE Figure 2-2 Powering From a CMOS Port Pin The QT113’s `output is active low and can sink up to 5mA of non-inductive current. If an inductive load is used, such as a small relay, the load should be diode clamped to prevent PORT X.m damage. When set to operate in a proximity mode (at high gain) the current should be limited to 1mA to prevent gain 0.01µF shifting side effects from occurring, which happens when the CMOS load current creates voltage drops on the die and bonding microcontroller wires; these small shifts can materially influence the signal Vdd level to cause detection instability as described below. PORT X.n OUT QT113 Care should be taken when the QT113 and the load are both powered from the same supply, and the supply is minimally regulated. The QT113 derives its internal references from the Vss power supply, and sensitivity shifts can occur with changes in Vdd, as happens when loads are switched on. This can lQ 5 R1.05/0405 Figure 2-3 Figure 2-4 Getting HearBeat pulses with a pull-down resistor Using a micro to obtain HB pulses in either output state +2.5 to 5 HeartBeat™ P u lses 1 PORT_M.x 2 7 OUT SNS2 Vdd 2 7 R o OUT SNS2 Ro 3 5 Microcontroller OPT1 GAIN 3 5 OPT1 GAIN PORT_M.y 46 46 OPT2 SNS1 OPT2 SNS1 Vss 8 induce detection ‘cycling’, whereby an object is detected, the there are no pullup resistors on these lines, since pullup load is turned on, the supply sags, the detection is no longer resistors add to power drain if tied low. sensed, the load is turned off, the supply rises and the object The Gain input should be connected to either Vdd or Gnd. is reacquired, ad infinitum. To prevent this occurrence, the output should only be lightly loaded if the device is operated Tables 1-1 and 2-1 show the option strap configurations from an unregulated supply, e.g. batteries. Detection available. ‘stiction’, the opposite effect, can occur if a load is shed when Out is active. 3.4 POWER SUPPLY, PCB LAYOUT The power supply can range from 2.5 to 5.0 volts. At 3 volts The output of the QT113 can directly drive a resistively limited LED. The LED should be connected with its cathode current drain averages less than 600µA in most cases, but to the output and its anode towards Vcc, so that it lights when can be higher if Cs is large. Increasing Cx values will actually the sensor is active. If desired the LED can be connected decrease power drain. Operation can be from batteries, but from Out to ground, and driven on when the sensor is be cautious about loads causing supply droop (see Output inactive. Drive, Section 2.2.4). As battery voltage sags with use or fluctuates slowly with temperature, the QT113 will track and compensate for these 3 - CIRCUIT GUIDELINES changes automatically with only minor changes in sensitivity. 3.1 SAMPLE CAPACITOR If the power supply is shared with another electronic system, Charge sampler Cs can be virtually any plastic film or care should be taken to assure that the supply is free of medium-K ceramic capacitor. The acceptable Cs range is digital spikes, sags, and surges which can adversely affect from 10nF to 500nF depending on the sensitivity required; the QT113. The QT113 will track slow changes in Vdd, but it larger values of Cs demand higher stability to ensure reliable can be affected by rapid voltage steps. sensing. Acceptable capacitor types include PPS film, if desired, the supply can be regulated using a conventional polypropylene film, NPO/C0G ceramic, and X7R ceramic. low current regulator, for example CMOS regulators that have low quiescent currents. Bear in mind that such regulators 3.2 OPTION STRAPPING generally have very poor transient line and load stability; in The option pins Opt1 and Opt2 should never be left floating. some cases, shunting Vdd to Vss with a 4.7K resistor to If they are floated, the device will draw excess power and the induce a continuous current drain can have a very positive options will not be properly read on powerup. Intentionally, effect on regulator performance. Parts placement: The chip should be placed to minimize the SNS2 trace length to reduce low frequency pickup, and to Figure 2-5 Eliminating HB Pulses reduce stray Cx which degrades gain. The Cs and Rseries resistors (see Figure 1-1) should be placed as close to the GATE OR body of the chip as possible so that the SNS2 trace between MICRO INPU T Rseries and the SNS2 pin is very short, thereby reducing the 2 7 antenna-like ability of this trace to pick up high frequency CMOS OUT SNS2 signals and feed them directly into the chip. C o For best EMC performance the circuit should be made 100pF 3 5 OPT1 GAIN entirely with SMT components. SNS trace routing: Keep the SNS2 electrode trace (and the 46 electrode itself) away from other signal, power, and ground OPT2 SNS1 traces including over or next to ground planes. Adjacent switching signals can induce noise onto the sensing signal; lQ 6 R1.05/0405 any adjacent trace or ground plane next to or under either The use of semiconductor transient protection devices, SNS trace will cause an increase in Cx load and desensitize Zeners, or MOV's on the sense lead is not advised; these the device. devices have extremely large amounts of parasitic capacitance which will swamp the QT113 and render it For proper operation a 100nF (0.1uF) ceramic bypass unstable or diminish gain. capacitor must be used directly between Vdd and Vss; the bypass cap should be placed very close to the 3.6 EMC ISSUES device’s power pins. External AC fields (EMI) due to RF transmitters or electrical noise sources can cause false detections or unexplained 3.5 ESD PROTECTION shifts in sensitivity. The QT113 includes internal diode protection on its pins to The influence of external fields on the sensor is reduced by absorb and protect the device from most induced discharges, means of the Rseries described above in Section 3.5. The Cs up to 20mA. The electrode should always be insulated capacitor and Rseries (see Figure 1-1) form a natural against direct ESD; a glass or plastic panel is usually enough low-pass filter for incoming RF signals; the roll-off frequency as a barrier to ESD. Glass breakdown voltages are typically of this network is defined by - over 10kV per mm thickness. 1 ESD protection can be enhanced by adding a series resistor F = R 2✜R C series s Rseries (see Figure 1-1) in line with the electrode, of value between 1K and 50K ohms. The optimal value depends on If for example Cs = 22nF, and Rseries = 10K ohms, the rolloff the amount of load capacitance Cx; a high value of Cx means frequency to EMI is 723Hz, vastly lower than any credible Rseries has to be low. The pulse waveform on the electrode external noise source (except for mains frequencies). should be observed on an oscilloscope, and the pulse should However, Rseries and Cs must both be placed very close to look very flat just before the falling edge. If the pulse voltage the body of the IC so that the lead lengths between them and never flattens, the gain of the sensor is reduced and there the IC do not form an unfiltered antenna at very high can be sensing instabilties. frequencies. Rseries and Cs should both be placed very close to the chip. lQ 7 R1.05/0405 4.1 ABSOLUTE MAXIMUM SPECIFICATIONS Operating temp.............................................................. as designated by suffix O O C to +125 C Storage temp..................................................................... -55 VDD................................................................................. -0.5 to +6.5V Max continuous pin current, any control or drive pin.............................................. ±20mA Short circuit duration to ground, any pin........................................................ infinite Short circuit duration to VDD, any pin........................................................... infinite Voltage forced onto any pin.................................................. -0.6V to (Vdd + 0.6) Volts 4.2 RECOMMENDED OPERATING CONDITIONS VDD................................................................................. +2.5 to 5.5V Short-term supply ripple+noise................................................................ ±5mV Long-term supply stability.................................................................. ±100mV Cs value........................................................................... 10nF to 500nF Cx value.............................................................................. 0 to 100pF 4.3 AC SPECIFICATIONS Vdd = 3.0, Ta = recommended operating range, Cs=100nF unless noted Parameter Description Min Typ Max Units Notes TRC Recalibration time 550 ms Cs, Cx dependent TPC Charge duration 2 µs TPT Transfer duration 2 µs TBS Burst spacing interval 2.1 80 ms Cs = 10nF to 500nF; Cx = 0 TBL Burst length 0.5 75 ms Cs = 10nF to 500nF; Cx = 0 TR Response time 30 ms Cx = 10pF; See Figure 4-3 THB Heartbeat pulse width 300 µs 4.4 SIGNAL PROCESSING Description Min Typ Max Units Notes Threshold differential 6 or 12 counts Option pin selected Hysteresis 17 % Note 1 Consensus filter length 3 samples Positive drift compensation rate 1,000 ms/level Negative drift compensation rate 100 ms/level Post-detection recalibration timer duration 10, 60, infinite secs Option pin selected Note 1: Percentage of signal threshold lQ 8 R1.05/0405 4.5 DC SPECIFICATIONS Vdd = 3.0V, Cs = 10nF, Cx = 5pF, TA = recommended range, unless otherwise noted Parameter Description Min Typ Max Units Notes VDD Supply voltage 2.45 5.25 V IDD Supply current 600 1,500 µA VDDS Supply turn-on slope 100 V/s Required for proper startup VIL Low input logic level 0.8 V OPT1, OPT2 VHL High input logic level 2.2 V OPT1, OPT2 VOL Low output voltage 0.6 V OUT, 4mA sink VOH High output voltage Vdd-0.7 V OUT, 1mA source IIL Input leakage current ±1 µA OPT1, OPT2 CX Load capacitance range 0 100 pF AR Acquisition resolution 9 14 bits S Sensitivity range 1,000 28 fF Note 2 Note 2: Sensitivity depends on value of Cx and Cs. Refer to Figures 4-1, 4-2. Figure 4-2 - Typical Threshold Sensitivity vs. Cx, Figure 4-1 - Typical Threshold Sensitivity vs. Cx, Low Gain, at Selected Values of Cs; Vdd = 3.0 High Gain, at Selected Values of Cs; Vdd = 3.0 10.00 10.00 1.00 1.00 10nF 10nF 20nF 20nF 50nF 50nF 100nF 100nF 200nF 200nF 0.10 500nF 500nF 0.10 0.01 0.01 0 102030 40 0 1020 3040 Cx Load, pF Cx Load, pF Chart 4-3 - Typical Response Time vs. Cx; Vdd = 3.0 1000.00 10nF 100.00 20nF 50nF 100nF 200nF 10.00 500nF 1.00 0 10203040 Cx Load, pF lQ 9 R1.05/0405 Detection Threshold, pF Response Time, ms Detection Threshold, pF 4.6 MECHANICAL 8-pin Dual-In-Line Millimeters Inches SYMBOL Min Max Notes Min Max Notes a 6.096 7.112 0.24 0.28 A 7.62 8.255 0.3 0.325 M 9.017 10.922 Typical 0.355 0.43 Typical m 7.62 7.62 BSC 0.3 0.3 BSC Q 0.889 - 0.035 - P 0.254 - 0.01 - L 0.355 0.559 0.014 0.022 L1 1.397 1.651 0.055 0.065 F 2.489 2.591 Typical 0.098 0.102 Typical R 3.048 3.81 0.12 0.15 r 0.381 - 0.015 - S 3.048 3.556 0.12 0.14 S1 - 4.064 - 0.16 Aa 7.62 7.062 BSC 0.3 0.3 BSC x 8.128 9.906 0.32 0.39 Y 0.203 0.381 0.008 0.015 8-pin SOIC Millimeters Inches SYMBOL Min Max Notes Min Max Notes M 4.800 4.979 0.189 0.196 W 5.816 6.198 0.229 0.244 Aa 3.81 3.988 0.15 0.157 H 1.371 1.728 0.054 0.068 h 0.101 0.762 0.004 0.01 D 1.27 1.27 BSC 0.050 0.05 BSC L 0.355 0.483 0.014 0.019 E 0.508 1.016 0.02 0.04 e 0.19 0.249 0.007 0.01 ß 0.381 0.762 0.229 0.03 Ø 0º 8º 0º 8º lQ 10 R1.05/0405 5 - ORDERING INFORMATION PART TEMP RANGE PACKAGE MARKING QT113-DG 0 - 70C PDIP QT113-G Lead-Free QT113-ISG -40 - 85C SOIC-8 QT1 + FG or QT113-IG Lead-Free lQ 11 R1.05/0405 lQ Copyright © 2001-2004 QRG Ltd. All rights reserved Patented and patents pending worldwide Corporate Headquarters 1 Mitchell Point Ensign Way, Hamble SO31 4RF Great Britain Tel: +44 (0)23 8056 5600 Fax: +44 (0)23 80565600 www.qprox.com North America 651 Holiday Drive Bldg. 5 / 300 Pittsburgh, PA 15220 USA Tel: 412-391-7367 Fax: 412-291-1015 This device covered under one or more of the following United States and international patents: 5,730,165, 6,288,707, 6,377,009, 6,452,514, 6,457,355, 6,466,036, 6,535,200. Numerous further patents are pending which may apply to this device or the applications thereof. The specifications set out in this document are subject to change without notice. All products sold and services supplied by QRG are subject to our Terms and Conditions of sale and supply of services which are available online at www.qprox.com and are supplied with every order acknowledgement. QProx, QTouch, QMatrix, QLevel, and QSlide are trademarks of QRG. QRG products are not suitable for medical (including lifesaving equipment), safety or mission critical applications or other similar purposes. Except as expressly set out in QRG's Terms and Conditions, no licenses to patents or other intellectual property of QRG (express or implied) are granted by QRG in connection with the sale of QRG products or provision of QRG services. QRG will not be liable for customer product design and customers are entirely responsible for their products and applications which incorporate QRG's products.