QT113A-ISG - Atmel - Product.Network

APPLICATIONS -

Elevator buttons

Consumer devices

Access systems

Pointing devices

Appliance control

Security systems

Light switches

Prox sensors

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.

QProx™ QT113

HARGE

-T

RANSFER

OUCH

ENSOR

Sns2

Vss

Sns1

GainOpt2

Opt1

Out

Vdd 1

QT113

QT113-ISG-40

C to +85

QT113-DG

C to +70

8-PIN DIPSOICT

AVAILABLE OPTIONS

Projects a proximity field through air or any insulator

Less expensive than many mechanical switches

Sensitivity easily adjusted

Consensus filter for noise immunity

100% autocal for life - no adjustments required

2.5 to 5V, 600µA single supply operation

Toggle mode for on/off control (strap option)

10s, 60s, infinite auto-recal timeouts (strap options)

HeartBeat™ health indicator on output

Only one external part required - a 1¢ capacitor

Lead-Free package

1 - OVERVIEW

The QT113 is a digital burst mode charge-transfer (QT)

sensor designed specifically for touch controls; it includes all

hardware and signal processing functions necessary to

provide stable sensing under a wide variety of changing

conditions. Only a single low cost, non-critical capacitor is

required for operation.

Figure 1-1 shows a basic circuit using the device.

1.1 BASIC OPERATION

The QT113 employs bursts of charge-transfer cycles to

acquire its signal. Burst mode permits power consumption in

the microamp range, dramatically reduces RF emissions,

lowers susceptibility to EMI, and yet permits excellent

response time. Internally the signals are digitally processed

to reject impulse noise, using a 'consensus' filter which

requires three consecutive confirmations of a detection

before the output is activated.

The QT switches and charge measurement hardware

functions are all internal to the QT113 (Figure 1-2). A 14-bit

single-slope switched capacitor ADC includes both the

required QT charge and transfer switches in a configuration

that provides direct ADC conversion. The ADC is designed to

dynamically optimize the QT burst length according to the

rate of charge buildup on Cs, which in turn depends on the

values of Cs, Cx, and Vdd. Vdd is used as the charge

reference voltage. Larger values of Cx cause the charge

transferred into Cs to rise more rapidly, reducing available

resolution; as a minimum resolution is required for proper

operation, this can result in dramatically reduced apparent

gain. Conversely, larger values of Cs reduce the rise of

differential voltage across it, increasing available resolution

by permitting longer QT bursts. The value of Cs can thus be

increased to allow larger values of Cx to be tolerated (Figures

4-1, 4-2, 4-3 in Specifications, rear).

The IC is responsive to both Cx and Cs, and changes in Cs

can result in substantial changes in sensor gain.

Option pins allow the selection or alteration of several special

features and sensitivity.

1.2 ELECTRODE DRIVE

The internal ADC treats Cs as a floating transfer capacitor; as

a result, the sense electrode can in theory be connected to

either SNS1 or SNS2 with no performance difference.

However the electrode should only be connected to pin SNS2

for optimum noise immunity.

In all cases the rule Cs >> Cx must be observed for proper

operation; a typical load capacitance (Cx) ranges from

10-20pF while Cs is usually around 10-50nF.

Increasing amounts of Cx destroy gain; therefore it is

important to limit the amount of stray capacitance on both

SNS terminals, for example by minimizing trace lengths and

widths and keeping these traces away from power or ground

traces or copper pours.

The traces and any components associated with SNS1 and

SNS2 will become touch sensitive and should be treated with

caution to limit the touch area to the desired location.

A series resistor, Rseries, should be placed inline with the

SNS2 pin to the electrode to suppress ESD and EMC effects.

1.3 ELECTRODE DESIGN

1.3.1 E

LECTRODE

EOMETRY

AND

IZE

There is no restriction on the shape of

the electrode; in most cases common

sense and a little experimentation can

result in a good electrode design. The

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.

Sensitivity is related to electrode

surface area, orientation with respect

to the object being sensed, object

composition, and the ground coupling

quality of both the sensor circuit and

the sensed object.

If a relatively large electrode surface is

desired, and if tests show that the

electrode has more capacitance than

the QT113 can tolerate, the electrode

can be made into a sparse mesh

(Figure 1-3) having lower Cx than a

2 R1.05/0405

Figure 1-1 Basic Circuit Configuration

SENSING

ELECTRODE

SERIES

10nF

+2.5

OUT

OPT1

OPT2

GAIN

SNS1

SNS2

Vss

Vdd

OUTPUT=DC

TIMEOUT=10 Secs

TOGGLE=OFF

GAIN=HIGH

Figure 1-2 Internal Switching & Timing

SNS2

SNS1

ELECTRODE

Single-Slope 14-bit

Switched Capacitor ADC

Charge

Amp

Burst Controller

Result

Do ne

Start

solid plane. Sensitivity may even remain the same, as the

sensor will be operating in a lower region of the gain curves.

1.3.2 K

IRCHOFF

’

URRENT

Like all capacitance sensors, the QT113 relies on Kirchoff’s

Current Law (Figure 1-3) to detect the change in capacitance

of the electrode. This law as applied to capacitive sensing

requires that the sensor’s field current must complete a loop,

returning back to its source in order for capacitance to be

sensed. Although most designers relate to Kirchoff’s law with

regard to hardwired circuits, it applies equally to capacitive

field flows. By implication it requires that the signal ground

and the target object must both be coupled together in some

manner for a capacitive sensor to operate properly. Note that

there is no need to provide actual hardwired ground

connections; capacitive coupling to ground (Cx1) is always

sufficient, even if the coupling might seem very tenuous. For

example, powering the sensor via an isolated transformer will

provide ample ground coupling, since there is capacitance

between the windings and/or the transformer core, and from

the power wiring itself directly to 'local earth'. Even when

battery powered, just the physical size of the PCB and the

object into which the electronics is embedded will generally

be enough to couple a few picofarads back to local earth.

1.3.3 V

IRTUAL

APACITIVE

ROUNDS

When detecting human contact (e.g. a fingertip), grounding

of the person is never required. The human body naturally

has several hundred picofarads of ‘free space’ capacitance to

the local environment (Cx3 in Figure 1-3), which is more than

two orders of magnitude greater than that required to create

a return path to the QT113 via earth. The QT113's PCB

however can be physically quite small, so there may be little

‘free space’ coupling (Cx1 in Figure 1-3) between it and the

environment to complete the return path. If the QT113 circuit

ground cannot be earth grounded by wire, for example via

the supply connections, then a ‘virtual capacitive ground’ may

be required to increase return coupling.

A ‘virtual capacitive ground’ can be created by connecting the

QT113’s own circuit ground to:

- A nearby piece of metal or metallized housing;

- A floating conductive ground plane;

- Another electronic device (to which its output might be

connected anyway).

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

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.

1.3.4 F

IELD

HAPING

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

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

connected to circuit ground; the ring can be on the same or

opposite side from the electrode. The ring will kill field

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

detections. This is called ‘walk-by’ and is caused by the fact

that the fields radiate from either surface of the electrode

equally well. Shielding in the form of a metal sheet or foil

connected to circuit ground will prevent walk-by; putting a

small air gap between the grounded shield and the electrode

will keep the value of Cx lower to reduce loading and keep

gain high.

1.3.5 S

ENSITIVITY

The QT113 can be set for one of 2 gain levels using option

pin 5 (Table 1-1). This sensitivity change is made by altering

the internal numerical threshold level required for a detection.

Note that sensitivity is also a function of other things: like the

value of Cs, electrode size and capacitance, electrode shape

and orientation, the composition and aspect of the object to

be sensed, the thickness and composition of any overlaying

panel material, and the degree of ground coupling of both

sensor and object.

1.3.5.1 Increasing Sensitivity

In some cases it may be desirable to increase sensitivity

further, for example when using the sensor with very thick

panels having a low dielectric constant.

Sensitivity can often be increased by using a bigger

electrode, reducing panel thickness, or altering panel

composition. Increasing electrode size can have diminishing

returns, as high values of Cx will reduce sensor gain (Figures

4-1 to 4-3). The value of Cs also has a dramatic effect on

sensitivity, and this can be increased in value with the

tradeoff of reduced response time. Increasing the electrode's

surface area will not substantially increase touch sensitivity if

its diameter is already much larger in surface area than the

object being detected. Panel material can also be changed to

one having a higher dielectric constant, which will help

propagate the field. Metal areas near the electrode will

reduce the field strength and increase Cx loading.

Ground planes around and under the electrode and its SNS

trace will cause high Cx loading and destroy gain. The

possible signal-to-noise ratio benefits of ground area are

more than negated by the decreased gain from the circuit,

and so ground areas around electrodes are discouraged.

Keep ground away from the electrodes and traces.

1.3.5.2 Decreasing Sensitivity

In some cases the QT113 may be too sensitive, even on low

gain. In this case gain can be lowered further by decreasing

Cs.

3 R1.05/0405

Figure 1-3 Kirchoff's Current Law

Sense Electrode

Surrounding environment

SENSOR

2 - QT113 SPECIFICS

2.1 SIGNAL PROCESSING

The QT113 processes all signals using 16 bit math, using a

number of algorithms pioneered by Quantum. The algorithms

are specifically designed to provide for high 'survivability' in

the face of numerous adverse environmental changes.

2.1.1 D

RIFT

OMPENSATION

LGORITHM

Signal drift can occur because of changes in Cx and Cs over

time. It is crucial that drift be compensated for, otherwise

false detections, non-detections, and sensitivity shifts will

follow.

Drift compensation (Figure 2-1) is performed by making the

reference level track the raw signal at a slow rate, but only

while there is no detection in effect. The rate of adjustment

must be performed slowly, otherwise legitimate detections

could be ignored. The QT113 drift compensates using a

slew-rate limited change to the reference level; the threshold

and hysteresis values are slaved to this reference.

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.

The QT113's drift compensation is 'asymmetric':

the reference level drift-compensates in one

direction faster than it does in the other.

Specifically, it compensates faster for decreasing

signals than for increasing signals. Increasing

signals should not be compensated for quickly,

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

artificially elevated reference level and thus

become insensitive to touch. In this latter case, the sensor

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 T

HRESHOLD

ALCULATION

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

in accordance with the drift compensation mechanism.

The QT113 employs a hysteresis dropout below the

threshold level of 17% of the delta between the reference and

threshold levels.

2.1.3 M

-D

URATION

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

(when not set to infinite). This is known as the Max

On-Duration feature.

After the Max On-Duration interval, the sensor will once again

function normally to the best of its ability given electrode

conditions. There are two finite timeout durations available

via strap option: 10 and 60 seconds (Table 2-1).

2.1.4 D

ETECTION

NTEGRATOR

It is desirable to suppress detections generated by electrical

noise or from quick brushes with an object. To accomplish

this, the QT113 incorporates a detect integration counter that

increments with each detection until a limit is reached, after

which the output is activated. If no detection is sensed prior

to the final count, the counter is reset immediately to zero. In

the QT113, the required count is 3.

The Detection Integrator can also be viewed as a 'consensus'

filter, that requires three successive detections to create an

output.

4 R1.05/0405

Figure 1-4 Shielding Against Fringe Fields

Sense

wire

Sense

wire

Unshielded

Electrode

Shielded

Electrode

Figure 2-1 Drift Compensation

Threshold

Signal Hysteresis

Reference

Output

Vss (Gnd)

Low - 12 counts

Vdd

High - 6 counts

Tie Pin 5 to:Gain

Table 1-1 Gain Setting Strap Options

2.1.5 F

ORCED

ENSOR

ECALIBRATION

The QT113 has no recalibration pin; a forced recalibration is

accomplished only when the device is powered up. However,

supply drain is low so it is a simple matter to treat the entire

IC as a controllable load; simply driving the QT113's Vdd pin

directly from another logic gate or a microcontroller port

(Figure 2-2) will serve as both power and 'forced recal'. The

source resistance of most CMOS gates and microcontrollers

are low enough to provide direct power without problem. Note

that many 8051-based micros have only a weak pullup drive

capability and will require CMOS buffering. 74HC or 74AC

series gates can directly power the QT113, as can most other

microcontrollers.

Option strap configurations are read by the QT113 only on

powerup. Configurations can only be changed by powering

the QT113 down and back up again; again, a microcontroller

can directly alter most of the configurations and cycle power

to put them in effect.

2.1.6 R

ESPONSE

IME

The QT113's response time is highly dependent on burst

length, which in turn is dependent on Cs and Cx (see Figures

4-1, 4-2). With increasing Cs, response time slows, while

increasing levels of Cs reduce response time. Figure 4-3

shows the typical effects of Cs and Cx on response time.

2.2 OUTPUT FEATURES

The QT113 is designed for maximum flexibility and can

accommodate most popular sensing requirements. These

are selectable using strap options on pins OPT1 and OPT2.

All options are shown in Table 2-1.

2.2.1 DC M

ODE

UTPUT

The output of the QT113 can respond in a DC mode, where

the output is active-low upon detection. The output will

remain active-low for the duration of the detection, or until the

Max On-Duration expires (if not infinite), whichever occurs

first. If a max on-duration timeout occurs first, the sensor

performs a full recalibration and the output becomes inactive

until the next detection.

In this mode, three Max On-Duration timeouts are available:

10 seconds, 60 seconds, and infinite.

Infinite timeout is useful in applications where a prolonged

detection can occur and where the output must reflect the

detection no matter how long. In infinite timeout mode, the

designer should take care to be sure that drift in Cs, Cx, and

Vdd do not cause the device to ‘stick on’ inadvertently even

when the target object is removed from the sense field.

2.2.2 T

OGGLE

ODE

UTPUT

This makes the sensor respond in an on/off mode like a flip

flop. It is most useful for controlling power loads, for example

in kitchen appliances, power tools, light switches, etc.

Max On-Duration in Toggle mode is fixed at 10 seconds.

When a timeout occurs, the sensor recalibrates but leaves

the output toggle state unchanged.

2.2.3 H

EART

EAT

™ O

UTPUT

The QT113 output has a full-time HeartBeat™ ‘health’

indicator superimposed on it. This operates by taking 'Out'

into a 3-state mode for 300µs once after every QT burst. This

output state can be used to determine that the sensor is

operating properly, or, it can be ignored using one of several

simple methods.

The HeartBeat indicator can be sampled by using a pulldown

resistor on Out, and feeding the resulting negative-going

pulse into a counter, flip flop, one-shot, or other circuit. Since

Out is normally high, a pulldown resistor will create negative

HeartBeat pulses (Figure 2-3) when the sensor is not

detecting an object; when detecting an object, the output will

remain low for the duration of the detection, and no

HeartBeat pulse will be evident.

If the sensor is wired to a microcontroller as shown in Figure

2-4, the microcontroller can reconfigure the load resistor to

either ground or Vcc depending on the output state of the

QT113, so that the pulses are evident in either state.

Electromechanical devices like relays will usually ignore this

short pulse. The pulse also has too low a duty cycle to visibly

affect LED’s. It can be filtered completely if desired, by

adding an RC timeconstant to filter the output, or if interfacing

directly and only to a high-impedance CMOS input, by doing

nothing or at most adding a small non-critical capacitor from

Out to ground (Figure 2-5).

2.2.4 O

UTPUT

RIVE

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

damage. When set to operate in a proximity mode (at high

gain) the current should be limited to 1mA to prevent gain

shifting side effects from occurring, which happens when the

load current creates voltage drops on the die and bonding

wires; these small shifts can materially influence the signal

level to cause detection instability as described below.

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

power supply, and sensitivity shifts can occur with changes in

Vdd, as happens when loads are switched on. This can

5 R1.05/0405

Figure 2-2 Powering From a CMOS Port Pin

0.01µF

CMOS

microcontroller

OUT

PORT X.m

PORT X.n

Vdd

Vss

QT113

infiniteVddGnd

DC Out

10sGndGnd

Toggle

60sGndVdd

DC Out

10sVddVdd

DC Out

Max On-

Duration

Tie

Pin 4 to:

Tie

Pin 3 to:

Table 2-1 Output Mode Strap Options

induce detection ‘cycling’, whereby an object is detected, the

load is turned on, the supply sags, the detection is no longer

sensed, the load is turned off, the supply rises and the object

is reacquired, ad infinitum. To prevent this occurrence, the

output should only be lightly loaded if the device is operated

from an unregulated supply, e.g. batteries. Detection

‘stiction’, the opposite effect, can occur if a load is shed when

Out is active.

The output of the QT113 can directly drive a resistively

limited LED. The LED should be connected with its cathode

to the output and its anode towards Vcc, so that it lights when

the sensor is active. If desired the LED can be connected

from Out to ground, and driven on when the sensor is

inactive.

3 - CIRCUIT GUIDELINES

3.1 SAMPLE CAPACITOR

Charge sampler Cs can be virtually any plastic film or

medium-K ceramic capacitor. The acceptable Cs range is

from 10nF to 500nF depending on the sensitivity required;

larger values of Cs demand higher stability to ensure reliable

sensing. Acceptable capacitor types include PPS film,

polypropylene film, NPO/C0G ceramic, and X7R ceramic.

3.2 OPTION STRAPPING

The option pins Opt1 and Opt2 should never be left floating.

If they are floated, the device will draw excess power and the

options will not be properly read on powerup. Intentionally,

there are no pullup resistors on these lines, since pullup

resistors add to power drain if tied low.

The Gain input should be connected to either Vdd or Gnd.

Tables 1-1 and 2-1 show the option strap configurations

available.

3.4 POWER SUPPLY, PCB LAYOUT

The power supply can range from 2.5 to 5.0 volts. At 3 volts

current drain averages less than 600µA in most cases, but

can be higher if Cs is large. Increasing Cx values will actually

decrease power drain. Operation can be from batteries, but

be cautious about loads causing supply droop (see Output

Drive, Section 2.2.4).

As battery voltage sags with use or fluctuates slowly with

temperature, the QT113 will track and compensate for these

changes automatically with only minor changes in sensitivity.

If the power supply is shared with another electronic system,

care should be taken to assure that the supply is free of

digital spikes, sags, and surges which can adversely affect

the QT113. The QT113 will track slow changes in Vdd, but it

can be affected by rapid voltage steps.

if desired, the supply can be regulated using a conventional

low current regulator, for example CMOS regulators that have

low quiescent currents. Bear in mind that such regulators

generally have very poor transient line and load stability; in

some cases, shunting Vdd to Vss with a 4.7K resistor to

induce a continuous current drain can have a very positive

effect on regulator performance.

Parts placement: The chip should be placed to minimize the

SNS2 trace length to reduce low frequency pickup, and to

reduce stray Cx which degrades gain. The Cs and Rseries

resistors (see Figure 1-1) should be placed as close to the

body of the chip as possible so that the SNS2 trace between

Rseries and the SNS2 pin is very short, thereby reducing the

antenna-like ability of this trace to pick up high frequency

signals and feed them directly into the chip.

For best EMC performance the circuit should be made

entirely with SMT components.

SNS trace routing: Keep the SNS2 electrode trace (and the

electrode itself) away from other signal, power, and ground

traces including over or next to ground planes. Adjacent

switching signals can induce noise onto the sensing signal;

6 R1.05/0405

Figure 2-4

Using a micro to obtain HB pulses in either output state

Figure 2-3

Getting HearBeat pulses with a pull-down resistor

+2.5 to 5

OUT

OPT1

OPT2

GAIN

SNS1

SNS2

Vss

Vdd

HeartBeat™ Pulses

Microcontroller

PORT_M.x

PORT_M.y

OUT

OPT1

OPT2

GAIN

SNS1

SNS2

Figure 2-5 Eliminating HB Pulses

OUT

OPT1

OPT2

GAIN

SNS1

SNS2

CM OS

100pF

GATE OR

MICRO INPUT

any adjacent trace or ground plane next to or under either

SNS trace will cause an increase in Cx load and desensitize

the device.

For proper operation a 100nF (0.1uF) ceramic bypass

capacitor must be used directly between Vdd and Vss;

the bypass cap should be placed very close to the

device’s power pins.

3.5 ESD PROTECTION

The QT113 includes internal diode protection on its pins to

absorb and protect the device from most induced discharges,

up to 20mA. The electrode should always be insulated

against direct ESD; a glass or plastic panel is usually enough

as a barrier to ESD. Glass breakdown voltages are typically

over 10kV per mm thickness.

ESD protection can be enhanced by adding a series resistor

Rseries (see Figure 1-1) in line with the electrode, of value

between 1K and 50K ohms. The optimal value depends on

the amount of load capacitance Cx; a high value of Cx means

Rseries has to be low. The pulse waveform on the electrode

should be observed on an oscilloscope, and the pulse should

look very flat just before the falling edge. If the pulse voltage

never flattens, the gain of the sensor is reduced and there

can be sensing instabilties.

Rseries and Cs should both be placed very close to the

chip.

The use of semiconductor transient protection devices,

Zeners, or MOV's on the sense lead is not advised; these

devices have extremely large amounts of parasitic

capacitance which will swamp the QT113 and render it

unstable or diminish gain.

3.6 EMC ISSUES

External AC fields (EMI) due to RF transmitters or electrical

noise sources can cause false detections or unexplained

shifts in sensitivity.

The influence of external fields on the sensor is reduced by

means of the Rseries described above in Section 3.5. The Cs

capacitor and Rseries (see Figure 1-1) form a natural

low-pass filter for incoming RF signals; the roll-off frequency

of this network is defined by -

2✜R

series

If for example Cs = 22nF, and Rseries = 10K ohms, the rolloff

frequency to EMI is 723Hz, vastly lower than any credible

external noise source (except for mains frequencies).

However, Rseries and Cs must both be placed very close to

the body of the IC so that the lead lengths between them and

the IC do not form an unfiltered antenna at very high

frequencies.

7 R1.05/0405

4.1 ABSOLUTE MAXIMUM SPECIFICATIONS

Operating temp.............................................................. as designated by suffix

Storage temp..................................................................... -55

C to +125

.................................................................................-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 V

, any pin........................................................... infinite

Voltage forced onto any pin.................................................. -0.6V to (Vdd + 0.6) Volts

4.2 RECOMMENDED OPERATING CONDITIONS

................................................................................. +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

µs300Heartbeat pulse widthT

Cx = 10pF; See Figure 4-3ms30Response timeT

Cs = 10nF to 500nF; Cx = 0ms750.5Burst lengthT

Cs = 10nF to 500nF; Cx = 0ms802.1Burst spacing intervalT

µs2Transfer durationT

µs2Charge durationT

Cs, Cx dependentms550Recalibration timeT

NotesUnitsMaxTypMinDescriptionParameter

4.4 SIGNAL PROCESSING

Option pin selectedsecs10, 60, infinitePost-detection recalibration timer duration

ms/level100Negative drift compensation rate

ms/level1,000Positive drift compensation rate

samples3Consensus filter length

Note 1%17Hysteresis

Option pin selectedcounts6 or 12Threshold differential

NotesUnitsMaxTypMinDescription

Note 1: Percentage of signal threshold

8 R1.05/0405

4.5 DC SPECIFICATIONS

Vdd = 3.0V, Cs = 10nF, Cx = 5pF, T

= recommended range, unless otherwise noted

Note 2fF281,000Sensitivity rangeS

bits149Acquisition resolutionA

pF1000Load capacitance rangeC

OPT1, OPT2µA±1Input leakage currentI

OUT, 1mA source

Vdd-0.7High output voltage

OUT, 4mA sink

0.6Low output voltage

OPT1, OPT2V2.2High input logic levelV

OPT1, OPT2

0.8Low input logic level

Required for proper startupV/s100Supply turn-on slopeV

DDS

µA1,500600Supply currentI

V5.252.45Supply voltageV

NotesUnitsMaxTypMinDescriptionParameter

Note 2: Sensitivity depends on value of Cx and Cs. Refer to Figures 4-1, 4-2.

9 R1.05/0405

Figure 4-1 - Typical Threshold Sensitivity vs. Cx,

High Gain, at Selected Values of Cs; Vdd = 3.0

0.01

0.10

1.00

10.00

0 10203040

Cx Load, pF

Detection Threshold, pF

10nF

20nF

50nF

100nF

200nF

500nF

Figure 4-2 - Typical Threshold Sensitivity vs. Cx,

Low Gain, at Selected Values of Cs; Vdd = 3.0

0.01

0.10

1.00

10.00

0 10203040

Cx Load, pF

Detection Threshold, pF

10nF

20nF

50nF

100nF

200nF

500nF

Chart 4-3 - Typical Response Time vs. Cx;

Vdd = 3.0

1.00

10.00

100.00

1000.00

0 10203040

Cx Load, pF

Response Time, ms

10nF

20nF

50nF

100nF

200nF

500nF

4.6 MECHANICAL

0.0150.0080.3810.203Y

0.390.329.9068.128x

BSC0.30.3BSC7.0627.62Aa

0.16-4.064-S1

0.140.123.5563.048S

-0.015-0.381r

0.150.123.813.048R

Typical0.1020.098Typical2.5912.489F

0.0650.0551.6511.397L1

0.0220.0140.5590.355L

-0.01-0.254P

-0.035-0.889Q

BSC0.30.3BSC7.627.62m

Typical0.430.355Typical10.9229.017M

0.3250.38.2557.62A

0.280.247.112 6.096a

NotesMaxMinNotesMaxMin

InchesMillimeters

SYMBOL

8-pin Dual-In-Line

8º0º8º0ºØ

0.030.2290.7620.381ß

0.010.0070.2490.19e

0.040.021.0160.508E

0.0190.0140.4830.355L

BSC0.050.050BSC1.271.27D

0.010.0040.7620.101h

0.0680.0541.7281.371H

0.1570.153.9883.81Aa

0.2440.2296.1985.816W

0.1960.1894.9794.800M

NotesMaxMinNotesMaxMin

InchesMillimeters

SYMBOL

8-pin SOIC

10 R1.05/0405

5 - ORDERING INFORMATION

QT1 + FG or QT113-IGSOIC-8

Lead-Free

-40 - 85CQT113-ISG

QT113-GPDIP

Lead-Free

0 - 70CQT113-DG

MARKINGPACKAGETEMP RANGEPART

11 R1.05/0405

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.