QT102_技术文档

LQ

QT102

QTOUCH

™

T

OGGLE-MODE

C

HARGE-TRANSFER IC

W

ITH

P

OWER

M

ANAGEMENT

FUNCTIONS

This datasheet is applicable to all revision 2.3 chips

The QT102 is a single key QTouch™ chip combining a touch-on / touch-off

toggle mode with timeout and timing override functions, oriented especially

towards power control of small appliances and battery-operated products. With

its tiny low-cost SOT-23 package, this device can suit almost any product

needing a power switch or other toggle-mode controlled function.

OUT

VSS

1

2

3

6

5

4

TIME

VDD

SNS

A unique 'Green' feature of the QT102 is the timeout function, which can turn

off power after a specified time delay ranging from minutes to hours.

Furthermore, external 'sustain' and 'cancel' functions permit designs where the

timeout needs to be extended further or terminated early. A user's interaction

with a product might trigger a 'sustain' input, prolonging the time to shutoff. A

safety sensor, such as a tip-over switch on a space heater, can feed the

'cancel' function to terminate early.

SNSK

Like all QTouch™ devices, the QT102 features automatic self-calibration, drift

compensation, and spread-spectrum burst modulation in order to provide for

the most reliable touch sensing possible. This device brings inexpensive,

easy-to-implement capacitive touch sensing to all kinds of appliances and

equipment, from toys to coffee makers. The small, low cost SOT-23 package

lets this unique combination of features reside in almost any product.

AT A GLANCE

Number of keys:

One toggle mode (touch-on / touch-off), plus programmable auto-off delay and external cancel

Patented spread-spectrum charge-transfer (direct mode)

6mm x 6mm or larger (panel thickness dependent); widely different sizes and shapes possible

Solid or ring electrode shapes

Technology:

Key outline sizes:

Electrode design:

PCB Layers required:

Electrode materials:

Electrode substrates:

Panel materials:

Panel thickness:

Key sensitivity:

Interface:

One

Etched copper, silver, carbon, Indium Tin Oxide (ITO)

PCB, FPCB, plastic films, glass

Plastic, glass, composites, painted surfaces (low particle density metallic paints possible)

Up to 50mm glass, 20mm plastic (electrode size dependent)

Settable via external capacitor

Digital output, active high or active low (hardware configurable)

Good

Moisture tolerance:

Power:

2V ~ 5.5V; 23µA at 2V

Package:

SOT23-6 (3x3mm) RoHS compliant

Signal processing:

Applications:

Self-calibration, auto drift compensation, noise filtering

Power switch replacement in countertop appliances, irons, battery powered toys, heaters, lighting

controls, automotive interior lighting, commercial and industrial equipment such as soldering

stations and cooking equipment

Patents:

QTouch™ (patented Charge-transfer method)

AVAILABLE OPTIONS

T_A

SOT23-6

-40ºC to +85ºC

QT102-ISG

LQ

C

QT102_2R3.04_0807

Contents

3.3 Output Polarity Selection

3.4 Output Drive

1 Overview

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

3

4

5

7

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

7

8

9

1.1 Introduction

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

1.2 Electrode Drive

3.5 Auto Off Delay

3.5.1 Introduction

1.3 Sensitivity

1.3.1 Introduction

3.5.2 Auto Off - Predefined Delay

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

. . . . . . . . . . . . . . . . . . . . . . . . . . . .

1.3.2 Increasing Sensitivity

1.3.3 Decreasing Sensitivity

3.5.3 Auto Off - User-programmed Delay

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

. . . . . . . . . . . . . . . . . . . . . . .

. . . . . . . . . . . . . . . . . . . .

. . . . . . . . . . . . . . .

. . . . . . . . . . . . . . . . . . . . . . . 12

3.5.4 Auto Off - Overriding the Auto Off Delay

3.5.5 Configuring the User-programmed Auto-off Delay

1.4 Recalibration Timeout

1.5 Forced Sensor Recalibration

1.6 Drift Compensation

3.6 Examples of Typical Applications

. . . . . . . . . . . . . . . . . . . . . . . . . . .

4 Specifications

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

1.7 Response Time

1.8 Spread Spectrum

4.1 Absolute Maximum Specifications

4.2 Recommended Operating Conditions

4.3 AC Specifications

. . . . . . . . . . . . . . . . . . . . . . . 13

. . . . . . . . . . . . . . . . . . . . 13

2 Wiring and Parts

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

2.1 Application Note

4.4 Signal Processing

4.5 DC Specifications

2.2 Cs Sample Capacitor

2.3 Rs Resistor

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

4.6 Mechanical Dimensions

4.7 Marking

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

2.4 Power Supply, PCB Layout

. . . . . . . . . . . . . . . . . . . . . . . . . . . .

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15

4.8 Moisture Sensitivity Level (MSL)

3 Operation

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

. . . . . . . . . . . . . . . . . . . . . . . . 15

3.1 Acquisition Modes

5 Datasheet Control

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16

3.1.1 Introduction

5.1 Changes

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16

3.1.2 OUT Pin ‘On’ (Fast Mode)

5.2 Numbering Convention

. . . . . . . . . . . . . . . . . . . . . . . . . . . . .

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16

3.1.3 OUT Pin ‘Off’ (Low Power Mode)

. . . . . . . . . . . . . . . . . . . . . . . . .

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

3.2 Signal Processing

3.2.1 Detect Integrator

3.2.2 Detect Threshold

lQ

2

QT102_2R3.04_0807

A series resistor, Rs, should be placed in line with SNSK to

the electrode to suppress electrostatic discharge (ESD) and

Electromagnetic Compatibility (EMC) effects.

1 Overview

1.1 Introduction

The QT102 is a single key device featuring a touch on / touch

off (toggle) output with a programmable auto switch-off

capability.

1.3 Sensitivity

1.3.1 Introduction

The sensitivity of the QT102 is a function of such things as:

The QT102 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 low cost, noncritical components are required

for operation.

•

the value of Cs

electrode size and capacitance

electrode shape and orientation

the composition and aspect of the object to be sensed

The QT102 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

four consecutive confirmations of a detection before the output

is activated.

the thickness and composition of any overlaying panel

material

•

the degree of ground coupling of both sensor and

object

1.3.2 Increasing Sensitivity

In some cases it may be desirable to increase sensitivity; for

example, when using the sensor with very thick panels having

a low dielectric constant. Sensitivity can often be increased by

using a larger electrode or reducing panel thickness.

Increasing electrode size can have diminishing returns, as

high values of Cx will reduce sensor gain.

The QT switches and charge measurement hardware

functions are all internal to the QT102.

1.2 Electrode Drive

Figure 1.1 shows the sense electrode connections (SNS,

SNSK) for the QT102.

The value of Cs also has a dramatic effect on sensitivity, and

this can be increased in value with the trade-off of slower

response time and more power. 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 better help

to propagate the field.

Figure 1.1 Sense Connections

VDD

SENSE

ELECTRODE

5

VDD

Rs

3

4

SNSK

SNS

Ground planes around and under the electrode and its SNSK

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. Metal areas

near the electrode will reduce the field strength and increase

Cx loading and should be avoided, if possible. Keep ground

away from the electrodes and traces.

Cs

1

OUT

6

Cx

TIME

VSS

2

1.3.3 Decreasing Sensitivity

In some cases the QT102 may be too sensitive. In this case

gain can be easily lowered further by decreasing Cs.

For optimum noise immunity, the electrode should only be

connected to the SNSK pin.

1.4 Recalibration Timeout

In all cases the sample capacitor Cs should be much larger

than the load capacitance (Cx). Typical values for Cx are

5 - 20pF while Cs is usually 1 - 50nF.

If an object or material obstructs the sense electrode the

signal may rise enough to create a detection, preventing

further operation. To stop this, the sensor includes a timer

which monitors detections. If a detection exceeds the timer

setting (known as the Max On-duration) the sensor performs a

full recalibration. This does not toggle the output state but

ensures that the QT102 will detect a new touch correctly. The

timer is set to activate this feature after ~ 30s. This will vary

slightly with Cs.

Note: Cx is not a physical discrete component on the PCB, it

is the capacitance of the touch electrode and wiring. It is show

in Figure 1.1 to aid understanding of the equivalent circuit.

Increasing amounts of Cx destroy gain, therefore it is

important to limit the amount of load capacitance on both SNS

terminals. This can be done, 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 SNS and

SNSK will become touch sensitive and should be treated with

caution to limit the touch area to the desired location.

lQ

3

QT102_2R3.04_0807

However, an obstruction over the sense pad, for which the

sensor has already made full allowance, 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.

1.5 Forced Sensor Recalibration

The QT102 has no recalibration pin; a forced recalibration is

accomplished when the device is powered up, after the

recalibration timeout or when the auto-off override is released.

However, supply drain is low so it is a simple matter to treat

the entire IC as a controllable load; driving the QT102's V^DD

pin directly from another logic gate or a microcontroller port

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 problems.

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.

1.7 Response Time

The QT102's response time is highly dependent on burst

length, which in turn is dependent on Cs and Cx. With

increasing Cs, response time slows, while increasing levels of

Cx reduce response time.

1.6 Drift Compensation

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

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

detections, nondetections, and sensitivity shifts will follow.

Drift compensation (Figure 1.2) 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 QT102 drift compensates using a

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

and hysteresis values are slaved to this reference.

1.8 Spread Spectrum

The QT102 modulates its internal oscillator by ±7.5 percent

during the measurement burst. This spreads the generated

noise over a wider band reducing emission levels. This also

reduces susceptibility since there is no longer a single

fundamental burst frequency.

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 1.2 Drift Compensation

Signal

Hysteresis

The QT102's drift compensation is 'asymmetric';

the reference level drift-compensates in one

direction faster than it does in the other.

Threshold

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

Reference

compensated for partially or entirely before even

approaching the sense electrode.

Output

lQ

4

QT102_2R3.04_0807

If desired, the supply can be regulated using a Low Dropout

(LDO) regulator. See Application Note AN-KD02 (see

Section 2.1) for further information on power supply

considerations.

2 Wiring and Parts

2.1 Application Note

Refer to Application Note AN-KD02, downloadable from the

Quantum website for more information on construction and

design methods. Go to http://www.qprox.com, click the

Support tab and then Application Notes.

Suggested regulator manufacturers:

•

Toko (XC6215 series)

Seiko (S817 series)

BCDSemi (AP2121 series)

2.2 Cs Sample Capacitor

Cs is the charge sensing sample capacitor. The required Cs

value depends on the thickness of the panel and its dielectric

constant. Thicker panels require larger values of Cs. Typical

values are 1nF to 50nF depending on the sensitivity required;

larger values of Cs demand higher stability and better

dielectric to ensure reliable sensing.

Parts placement: The chip should be placed to minimize the

SNSK trace length to reduce low frequency pickup, and to

reduce Cx which degrades gain. The Cs and Rs resistors (see

Figure 2.1) should be placed as close to the body of the chip

as possible so that the trace between Rs and the SNSK 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. A ground plane can be used under the chip and

the associated discretes, but the trace from the Rs resistor

and the electrode should not run near ground, to reduce

loading.

The Cs capacitor should be a stable type, such as X7R

ceramic or PPS film. For more consistent sensing from unit to

unit, 5 percent tolerance capacitors are recommended. X7R

ceramic types can be obtained in 5 percent tolerance at little

or no extra cost. In applications where high sensitivity (long

burst length) is required the use of PPS capacitors is

recommended.

For best EMC performance the circuit should be made entirely

with SMT components.

Electrode trace routing: Keep the 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;

any adjacent trace or ground plane next to, or under, the

electrode trace will cause an increase in Cx load and

desensitize the device.

2.3 Rs Resistor

Series resistor Rs is in line with the electrode connection and

should be used to limit ESD currents and to suppress radio

frequency interference (RFI). It should be approximately

4.7kꢀ to 33kꢀ.

Although this resistor may be omitted, the device may become

susceptible to external noise or RFI. For details of how to

select these resistors see the Application Note AN-KD02

(Section 2.1).

Important Note: for proper operation a 100nF (0.1µF)

ceramic bypass capacitor must be used directly between

V

DD and VSS, to prevent latch-up if there are substantial

DD transients; for example, during an ESD event. The

bypass capacitor should be placed very close to the

device’s power pins.

2.4 Power Supply, PCB Layout

The power supply can range between 2.0V and 5.5V. If the

power supply is shared with another electronic system, care

should be taken to ensure that the supply is free of digital

spikes, sags, and surges which can adversely affect the

device. The QT102 will track slow changes in V^DD, but it can

be badly affected by rapid voltage fluctuations. It is highly

recommended that a separate voltage regulator be used just

for the QT102 to isolate it from power supply shifts caused by

other components.

lQ

5

QT102_2R3.04_0807

Table 2.1 Pin Descriptions

NAME

TYPE

DESCRIPTION

1

2

3

OUT

VSS

SNSK

O

P

IO

To switched circuit and output polarity selection resistor (Rop)

Ground power pin

To Cs capacitor and to sense electrode

To Cs capacitor and multiplier configuration resistor (Rm)

Rm must be fitted and connected to either VSS or VDD. Refer to Section 3.5 for details.

Positive power pin

Timeout configuration pin, which must be connected to either VSS, VDD, OUT or an RC network. Refer to

Section 3.5 for details.

4

5

6

SNS

VDD

TIME

IO

P

I

O

OD

IO

P

Input only

Output only, push-pull

Open drain output

Input and output

Ground or power

Figure 2.1 Basic Circuit Configuration

(active high output, 15 minute auto switch-off)

Note: bypass capacitor to be tightly

VDD

SENSE

ELECTRODE

wired between VDD and VSS and

5

kept close to QT102 pin 5.

VDD

RS

1

3

4

OUT

SNSK

SNS

CS

Rop

6

TIME

Rm

VSS

2

Re Figure 2.1, check the following sections for component values:

•

Section 2.2, page 5: Cs capacitor (Cs)

Section 2.3, page 5: Sample resistor (Rs)

Section 2.4, page 5: Voltage levels

Section 3.5.2, page 8: Rm

Section 3.3, page 7: Rop

lQ

6

QT102_2R3.04_0807

The DI can also be viewed as a 'consensus' filter, that

requires four successive detections to create an output.

3 Operation

3.1 Acquisition Modes

3.2.2 Detect Threshold

The device detects a touch when the signal has crossed a

threshold level. The threshold level is fixed at 10 counts.

3.1.1 Introduction

The OUT pin of the QT102 can be configured to be active

high or active low (see Section 3.3).

3.3 Output Polarity Selection

•

If active high then

The output (OUT pin) of the QT102 can be configured to have

an active high or active low output by means of the output

configuration resistor Rop. The resistor is connected between

the output and either Vss or V^DD(see Figure 3.3 and

Table 3.1). A typical value for Rop is 100kꢀ.

‘on’ is high

‘off’ is low

If active low then

‘on’ is low

‘off’ is high

Figure 3.3 Output Polarity

The acquisition mode depends on the state of the OUT pin

(on or off) and whether a touch is detected. In the following

text ‘on’ is when the output is in its active state.

SENSE

ELECTRODE

3.1.2 OUT Pin ‘On’ (Fast Mode)

The QT102 runs in Fast mode when the OUT pin is on. In this

mode the device runs at maximum speed at the expense of

increased current consumption. The delay between bursts in

Fast mode is approximately 2.6ms, as shown in Figure 3.1.

VDD

5

RS

VDD

Rop

3

4

Vop

SNSK

SNS

Figure 3.1 Fast Mode Bursts

CS

(Output in On condition)

1

OUT

SNSK

QT102

~2.6ms

6

TIME

Rm

VSS

2

3.1.3 OUT Pin ‘Off’ (Low Power Mode)

The QT102 runs in Low Power (LP) mode if the OUT pin is off.

In this mode it sleeps for approximately 85ms at the end of

each burst, saving power but slowing response. On detecting

a possible key touch, it temporarily switches to Fast mode

until either the key touch is confirmed or found to be spurious

(via the detect integration process). If the touch is confirmed

the QT102 will switch to Fast mode as shown in Figure 3.2. If

a touch is denied the device will revert to normal LP mode

operation automatically.

Table 3.1 Output Configuration

Name

(Vop)

Vss

Function

(Output polarity)

Active high

V

DD

Active low

Note that some devices such as Digital Transistors have an

internal biasing network that will naturally pull the OUT pin to

its inactive state. If these are being used then the resistor Rop

is not required (see Figure 3.4).

Figure 3.2 Low Power Mode/Touch Detection

Figure 3.4 Output Connected to Digital Transistor

SENSE

ELECTRODE

fast detect

integrator

~85ms

SNSK

QT102

sleep

VDD

5

OUT

RS

VDD

Load

3

4

SNSK

SNS

3.2 Signal Processing

CS

1

3.2.1 Detect Integrator

OUT

It is desirable to suppress detections generated by electrical

noise or from quick brushes with an object. To accomplish

this, the QT102 incorporates a ‘detect integration’ (DI) 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 QT102, the required count is four.

6

TIME

Rm

VSS

2

lQ

7

QT102_2R3.04_0807

Table 3.2 Predefined Auto-off Delay

(Active High Output)

3.4 Output Drive

The OUT pin is active high and can sink or source up to 2mA.

When a large value of Cs (>20nF) is used the OUT current

should be limited to <1mA to prevent gain-shifting side effects,

which happen 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.

Vt

Auto-off delay (t_o)

Vss

Vdd

OUT

Infinity (remain on until toggled to off)

15 minutes

60 minutes

Table 3.3 Predefined Auto-off Delay

(Active Low Output)

3.5 Auto Off Delay

Vt

Auto-off delay (t_o)

3.5.1 Introduction

Vss

15 minutes

In addition to toggling the output on/off with key touch, the

QT102 can automatically switch the output off after a specific

time. This feature can be used to save power in situations

where the switched device could be left on inadvertently.

V

OUT

DD

Infinity (remain on until toggled to off)

60 minutes

Table 3.4 Auto-off Delay Multiplier

Vm

Vss

Auto-off delay multiplier

t_ox 1

The QT102 has:

V

DD

t_ox 24

•

three predefined delay times (Section 3.5.2)

the ability to set a user-programmed delay

(Section 3.5.3)

3.5.3 Auto Off - User-programmed Delay

If a user-programmed delay is required a resistor and capacitor

can be used to set the auto-off delay (see Table 3.5 and

Figure 3.6 The delay time is dependent on the RC time constant

(Rt x Ct) the output polarity and the supply voltage. Section 3.5.5

gives full details of how to configure the QT102 to have auto-off

delay times ranging from 1 minute to up to 24 hours.

•

the ability to override the auto off delay (Section 3.5.4)

The TIME and SNS pins are used to configure the Auto Off

delay and must always be connected in one of the ways

described in Sections 3.5.2, 3.5.3 and 3.5.4.

3.5.2 Auto Off - Predefined Delay

Table 3.5 Programmable Auto Off Delay

(Vm = Vss (delay multiplier = 1), VDD = 3.5V)

Output Type Auto Off Delay (seconds)

To configure the predefined delay the TIME pin is hard wired

to Vss, Vdd or OUT as shown in Tables 3.2 and 3.3. This

provides nominal values of 15 minutes, 60 minutes or infinity

(remains on until toggled off).

Active high

(Rt x Ct x 15) / 42

Active low

(Rt x Ct x 15) / 14.3

A single 1Mꢀ resistor (Rm) is connected between the SNS pin

and the logic level Vm to provide three auto off functions:

delay multiplication, delay override and delay retriggering. On

power-up the logic level at Vm is assessed and the delay

multiplication factor is set to x1 or x24 accordingly (see

Figure 3.5 and Table 3.4). At the end of each acquisition

cycle the logic level of Vm is monitored to see if an Auto off

delay override is required (see Section 3.5.4).

K values (42 and 14.3) are obtained from Figures 3.10

and 3.11.

Note: Rt is in kꢀ, Ct is in nF.

Figure 3.6 Programmable Delay

SENSE

ELECTRODE

Setting the delay multiplier to x24 will decrease the key

sensitivity. To compensate, it may be necessary to increase

the value of Cs.

VDD

Figure 3.5 Predefined Delay

5

RS

VDD

SENSE

3

4

ELECTRODE

SNSK

SNS

CS

1

OUT

Rt

Ct

VDD

6

TIME

Rm

5

RS

VSS

2

Rop

VDD

3

4

SNSK

SNS

CS

Vm

1

OUT

6

3.5.4 Auto Off - Overriding the Auto Off Delay

In normal operation the QT102 output is turned off

TIME

Vt

Rm

VSS

2

Rop

automatically after the auto-off delay. In some applications it

may be useful to extend the auto-off delay (‘sustain’ function)

or to switch the output off immediately ('cancel' function). This

can be achieved by pulsing the voltage on the delay multiplier

resistor Rm as shown in Figures 3.7 and 3.8.

Vm

lQ

8

QT102_2R3.04_0807

Figure 3.9 Overriding Auto Off

Figure 3.7 Override Pulse (Delay Multiplier x1)

SENSE

ELECTRODE

O

OUT

Vm

P

t

off

Bursts

VDD

5

RS

VDD

SNSK

3

4

SNSK

SNS

C

CS

P - override (reload auto off delay)

O - switch output off (toff burst time + 50ms)

C - sensor recalibration

1

OUT

3.5.5 Configuring the User-programmed Auto-off

6

TIME

Rm

Delay

VSS

2

Rop

As described in Section 3.5.3, page 8, the QT102 can be

configured to give auto-off delays ranging from minutes to

hours by means of a simple CR network and the delay

multiplier input.

VDD Vm

VSS

Tp

With the delay multiplier set at x1 the auto-off delay is

calculated as follows:

Delay value = integer value of Rt x Ct x 15 seconds.

K

Figure 3.8 Override Pulse (Delay Multiplier x24)

And Rt x Ct = Delay (in seconds) x K

15

SENSE

ELECTRODE

Note: Rt is in kꢀ, Ct is in nF.

To ensure correct operation it is recommended that the value

of Rt x Ct is between 4 and 240.

K

VDD

5

RS

VDD

Values outside this range may be interpreted as the hard

wired options TIME linked to OUT and TIME linked to ‘off’

respectively, causing the QT102 to use the relevant

predefined auto-off delays.

3

4

SNSK

SNS

CS

1

OUT

The charts in Figures 3.10 and 3.11 show typical values of K

versus supply voltage for a QT102 with active high or active

low output.

6

TIME

Rm

VSS

2

Rop

Example using the formula to calculate Rt and Ct

VDD Vm

VSS

Requirements:

•

Active high output (Vop connected to VSS)

Auto-off delay 45 minutes

VDD = 3.5V

Tp

To ensure the pulse is detected it must be present for a time

greater than the burst length as shown in Table 3.6.

Proceed as follows:

1. Calculate Auto-off delay in seconds 45 x 60 = 2700

2. Obtain K from Figure 3.10, K= 42

Table 3.6 Time Delay Pulse

Pulse Duration

Action

tp > burst time + 10ms

(typical value 25ms)

Retrigger (reload auto-off delay

counter)

Switch output to off state and

inhibit further touch detection until

Vm returns to original state

3. Calculate Rt x Ct = 2700 x 42 = 7560

15

tp > burst time + 50ms

(typical value 65ms)

4. Decide on a value for Rt or Ct (e.g.Ct = 47nF)

5. Calculate Rt = 7560 = 160k

47

While Vm is held in the override state the QT102 inhibits

bursts and waits for Vm to return to its original state. When

Vm returns to its original state the QT102 performs a sensor

recalibration before continuing in its current output state.

As an alternative to calculation, Figures 3.12 and 3.13 show

charts of typical curves of auto-off delay against resistor and

capacitor values for active high and active low outputs at

various values of VDD (delay multiplier = x1).

Figure 3.9 shows override pulses being applied to a QT102

with delay multiplier set to x1.

lQ

9

QT102_2R3.04_0807

Figure 3.10 Active High Output

Figure 3.11 Active Low Output

QT102 Active Low output

QT102 Active High output

20

19

18

17

16

15

14

13

12

53

51

49

47

45

43

41

39

37

35

33

31

29

2

2.5

3

3.5

4

4.5

5

2

2.5

3

3.5

4

4.5

5

VDD (volts)

Figure 3.12 Auto-off Delay, Active High Output,

Vm = Vss (delay multiplier = x1)

QT102 Active High output, VDD = 4V

Ct=100nF

QT102 Active High output, VDD = 5V

Ct=100nF

4000

3500

3000

2500

2000

1500

1000

500

4000

3500

3000

2500

2000

1500

1000

500

Ct=47nF

Ct=22nF

Ct=10nF

Ct=22nF

Ct=10nF

0

10

30

50

70

90

110 130 150 170 190 210

10

30

50

70

90

110 130

150

170 190

210

Timing Resistor Rt (K ohms)

QT102 Active High output, VDD = 2V

QT102 Active High output, VDD = 3V

4000

3500

3000

2500

2000

1500

1000

500

4000

3500

3000

2500

2000

1500

1000

500

Ct=100nF

Ct=47nF

Ct=100nF

Ct=47nF

Ct=22nF

Ct=10nF

0

10

30

50

70

90

110 130 150 170 190 210

10

30

50

70

90

110

130

150 170

190

210

Timing Resistor Rt (K ohms)

lQ

10

QT102_2R3.04_0807

Figure 3.13 Auto-off Delay, Active Low Output,

Vm = Vss (delay multiplier = x1)

QT102 Active Low output, VDD = 5V

QT102 Active Low output, VDD = 4V

4000

3500

3000

2500

2000

1500

1000

500

4000

3500

3000

2500

2000

1500

1000

500

Ct=100nF

Ct=47nF

Ct=22nF

Ct=100nF Ct=47nF

Ct=22nF

Ct=10nF

0

20

40

60

80

100 120 140 160 180 200

0

20

40

60

80

100 120 140 160 180 200

Timing Resistor Rt (K ohms)

QT102 Active Low output, VDD = 3V

QT102 Active Low output, VDD = 2V

4000

3500

3000

2500

2000

1500

1000

500

Ct=100nF

Ct=47nF

Ct=100nF

Ct=47nF

Ct=22nF

Ct=10nF

3500

3000

2500

2000

1500

1000

500

Ct=22nF

Ct=10nF

0

20

40

60

80

100 120 140 160 180 200

0

20

40

60

80

100 120 140 160 180 200

Timing Resistor Rt (K ohms)

Example using a chart to calculate Rt and Ct

Requirements:

•

Active low output (Vop connected to VSS)

Auto-off delay 10 hours

VDD = 4V

1. Calculate Auto-off delay in seconds 10 x 60 x 60 = 36000. This value is outside of the range of the charts so use the x24

multiplier (connect Rm to VDD).

Note: this will decrease the key sensitivity, so it may be necessary to increase the value of Cs.

2. Find 36000 = 1500 on the 4V chart in Figure 3.13

24

3. This shows the following Rt / Ct combinations: 100nF / 10k, 47nF / 27k, 22nF / 60k or 10nF / 130k

Note: the Auto-off delay times shown are nominal and will vary slightly from chip to chip and with capacitor and resistor

tolerance.

lQ

11

QT102_2R3.04_0807

3.6 Examples of Typical Applications

Figure 3.14 Application 1

Active low, driving PNP transistor, auto off time 500s x 24 (3.33 hours)

+3V

100nF

1M

Rm

(x24)

SENSE

ELECTRODE

DTA143

5

VDD

RS

1

3

4

OUT

SNSK

SNS

CS

10k

22nF

Rt

Ct

47k

6

TIME

2.2k

Load

10nF

VSS

2

Auto off time obtained from 3V chart in Figure 3.13

Setting the delay multiplier to x24 will decrease the key sensitivity, so it may be necessary to increase the value of Cs.

Figure 3.15 Application 2

Active high, driving high impedance, auto off time 135s x 1 (2.25 minutes)

+5V

100nF

SENSE

ELECTRODE

5

VDD

Rs

1

3

4

OUT

SNSK

SNS

CS

10k

6.8nF

Rt

Ct

10k

6

TIME

Rop

2.2k

Rm

47nF

VSS

2

Auto off time obtained from 5V chart in Figure 3.12.

lQ

12

QT102_2R3.04_0807

4 Specifications

4.1 Absolute Maximum Specifications

Operating temp. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . -40^OC to +85^OC

Storage temp. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . -55^OC to +125^OC

V

DD. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0 to +6.5V

Max continuous pin current, any control or drive pin. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ±20mA

Short circuit duration to V^SS, any pin. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . infinite

Short circuit duration to V^DD, any pin. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . infinite

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

CAUTION: Stresses beyond those listed under ‘Absolute Maximum Specifications’ may cause permanent damage

to the device. This is a stress rating only and functional operation of the device at these or other conditions

beyond those indicated in the operational sections of this specification is not implied. Exposure to absolute

maximum specification conditions for extended periods may affect device reliability.

4.2 Recommended Operating Conditions

VDD. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . +2.0 to 5.5V

Short-term supply ripple+noise. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ±5mV

Long-term supply stability. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ±100mV

Cs value. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1nF to 50nF

Cx value. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 to 20pF

4.3 AC Specifications

VDD = 3.0V, Cs = 10nF, Cx = 5pF, Ta = recommended range, unless otherwise noted

Parameter

Description

Recalibration time

Min

Typ

Max

Units

Notes

Cs and Cx dependent

T

RC

PC

250

2

ms

µs

T

Charge duration

Transfer duration

±7.5% spread spectrum variation

TPT

2

µs

TG1

Time between end of burst and

start of the next (Fast mode)

2.6

ms

T

G

2

Time between end of burst and

start of the next (LP mode)

85

20

ms

Increases with reducing VDD

Vdd, Cs and Cx dependent. See

Section 2.2 for capacitor selection.

T

BL

Burst length

ms

T

R

Response time

100

4.4 Signal Processing

Description

Min

Typ

Max

Units

Notes

Threshold differential

Hysteresis

10

2

counts

samples

secs

Consensus filter length

Recalibration timer duration

4

40

Will vary with VDD

lQ

13

QT102_2R3.04_0807

4.5 DC Specifications

VDD = 3.0V, Cs = 10nF, Cx = 5pF, Ta = recommended range, unless otherwise noted

Parameter

Notes

Description

Min

Typ

Max

Units

V

DD

Supply voltage

2

5

5.5

V

I

DD

Supply current

600

µA

Depending on supply and run mode

Iddl

Supply current, LP Mode

23

37

90

2V

3V

5V

µA

V

DDS

Supply turn-on slope

Low input logic level

High input logic level

Low output voltage

High output voltage

Input leakage current

Load capacitance range

Acquisition resolution

100

2.2

V/s

V

Required for proper start-up

V

IL

0.8

0.6

V

HL

OL

V

OUT, 4mA sink

V

OH

IL

V

DD-0.7

0

V

OUT, 1mA source

I

±1

100

14

µA

pF

bits

C

X

A

R

9

4.6 Mechanical Dimensions

D

e

L

E

Aa W

2QNN

Pin 1

ø

M

H

h

Note: the part marking shown is for high volume parts. Samples may be shipped marked 02NN.

Package type: SOT23-6

Millimeters

Inches

Symbol

Min

2.8

2.6

1.5

0.9

0.0

-

0.35

0.09

Max

3.10

3.0

1.75

1.3

0.15

-

0.5

Notes

Min

0.110

0.102

0.059

0.035

0

Max

0.122

0.118

0.069

0.051

0.006

-

0.02

0.022

0.008

Notes

M

W

Aa

H

h

D

L

E

0.95 BSC

-

0.038 BSC

0.014

0.004

0.55

0.2

e

Ø

0^o

10^o

0^o

10^o

lQ

14

QT102_2R3.04_0807

4.7 Marking

SOT23-6 Part Number

Marking

QT102-ISG

2QNN (where NN is variable)

Note: the part marking shown is for high volume parts. Samples may be shipped marked 02NN.

4.8 Moisture Sensitivity Level (MSL)

MSL Rating

Peak Body Temperature

Specifications

IPC/JEDEC J-STD-020C

MSL1

260^OC

lQ

15

QT102_2R3.04_0807

5 Datasheet Control

5.1 Changes

Changes this issue (datasheet issue 4)

Front page

Section 1.2

Section 2.2

Section 3.3, 3.5.2, 3.5.3, 3.5.4, 3.5.5, 3.6

Section 4.2, 4.5

Section 5.1

5.2 Numbering Convention

Part Number

Datasheet Issue Number

QT102_MXN.nn_mmyy

Chip Revision

(Where M= Major chip revision,

Datasheet Release Date;

(Where mm = Month, yy = Year)

N = minor chip revision,

X = Prereleased Product

[or R = Released Product])

A minor chip revision (N) is defined as a revision change which does not affect product functionality or datasheet.

The value of N is usually only stated for released parts (R).

lQ

16

QT102_2R3.04_0807

NOTES:

lQ

17

QT102_2R3.04_0807

lQ

Patented and patents pending

Corporate Headquarters

1 Mitchell Point

Ensign Way, Hamble SO31 4RF

Great Britain

Tel: +44 (0)23 8056 5600 Fax: +44 (0)23 8045 3939

www.qprox.com

North America

651 Holiday Drive Bldg. 5 / 300

Pittsburgh, PA 15220 USA

Tel: 412-391-7367 Fax: 412-291-1015

The specifications set out in this document are subject to change without notice. All products sold and services supplied by QRG are subject

to QRG’s Terms and Conditions of sale and services. QRG patents, trademarks and Terms and Conditions can be found online at

http://www.qprox.com/about/legal.php. Numerous further patents are pending, one or more which may apply to this device or the applications

thereof.

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 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.

Developer: Kevin Snoad


型号：	QT102
厂家：	QUANTUM RESEARCH GROUP
描述：	QTOUCH™ TOGGLE-MODE CHARGE-TRANSFER IC WITH POWER MANAGEMENT FUNCTIONS 的QTouch ™翻转模式充电-TRANSFER IC与电源管理功能
文件：	总18页 (文件大小：174K)
中文：	中文翻译
下载：	下载PDF数据表文档文件

QT102 [QUANTUM]

相关型号：

QT1080

QT1080

QT1080-IS48G

QT1080-ISG

QT1081

QT1081-IS48G

QT1081-ISG

QT10C-SERIES

QT10E-SERIES

QT10HC-SERIES

QT10T-SERIES

QT110