Quantum QT1080 Technical data

lQ QT1080

z 8 completely independent QT touch sensing fields

z Designed for low-power portable applications

z 100% autocal for life - no adjustments required

z Direct outputs - either encoded or ‘per key’

z Fully debounced results

z 2.8V ~ 5.0V single supply operation

z 45µA current typ @ 3V in 360ms LP mode

z AKS™ Adjacent Key Suppression

z Spread spectrum bursts for superior noise rejection

z Sync pin for excellent LF noise rejection

z 10ms ‘fast mode’ for use in slider applications

z Pb-free packages: 32-QFN and 48-SSOP

APPLICATIONS

 MP3 players
 Mobile phones

 PC peripherals
 Television controls

8 KEY QT

25

OUT_0

26

OUT_1

27

OUT_2

28

OUT_3

29

OUT_4

30

OUT_5

31

OUT_6

OUT_7

32

 Pointing devices
 Remote controls

OUCH

DETECT

24 23 222120 19 18 17

1

23456 78

SS

SYNC/LP

VSS

QT1080
32-QFN

VDD

/RST

™ S

SNS7K

SNS7

N.C.

OSC

SNS6K

SNS6

SNS0

SNS0K

ENSOR

SNS5K

SNS5

16

SNS4K

15

SNS4

14

SNS3K

13

SNS3

12

SNS2K

11

SNS2

10

SN1K

9

SNS1

IC

QT1080 charge-transfer (“QT’”) QTouch IC is a self-contained digital controller capable of detecting near-proximity or touch on up to 8
electrodes. It allows electrodes to project independent sense fields through any dielectric such as glass or plastic. This capability
coupled with its continuous self-calibration feature can lead to entirely new product concepts, adding high value to product designs. The
devices are designed specifically for human interfaces, like control panels, appliances, gaming devices, lighting controls, or anywhere a
mechanical switch or button may be found; they may also be used for some material sensing and control applications.

Each of the channels operates independently of the others, and each can be tuned for a unique sensitivity level by simply changing a
corresponding external Cs capacitor.

AKS™ Adjacent Key Suppression (patent pending) suppresses touch from weaker responding keys and allows only a dominant key to
detect, for example to solve the problem of large fingers on tightly spaced keys.

Spread spectrum burst technology provides superior noise rejection. These devices also have a SYNC/LP pin which allows for
synchronization with additional similar parts and/or to an external source to suppress interference, or, an LP (low power) mode which
conserves power.

By using the charge transfer principle, this device delivers a level of performance clearly superior to older technologies yet is highly
cost-effective.

This part is available in both 32-QFN and 48-SSOP lead-free packages.

LQ

AVAILABLE OPTIONS

A

48-SSOP32-QFNT

QT1080-IS48GQT1080-ISG-40ºC to +85ºC

Copyright © 2004-2005 QRG Ltd

QT1080 R11.03/0905

1 - OVERVIEW

The QT1080 is an easy to use, 8 touch-key sensor IC based
on Quantum’s patented charge-transfer principles for robust
operation and ease of design. This device has many
advanced features which provide for reliable, trouble-free
operation over the life of the product.

Burst operation: The device operates in ‘burst mode’. Each
key is acquired using a burst of charge-transfer sensing
pulses whose count varies depending on the value of the
reference capacitor Cs and the load capacitance Cx. In LP
mode, the device sleeps in an ultra-low current state
between bursts to conserve power. The keys signals are
acquired using two successive bursts of pulses:

Burst A: Keys 0, 1, 4, 5
Burst B: Keys 2, 3, 6, 7

Bursts always operate in A-B sequence.

Self-calibration: On power-up, all 8 keys are self-calibrated
within 350 milliseconds (typical) to provide reliable operation
under almost any conditions.

Auto-recalibration: The device can time out and recalibrate
each key independently after a fixed interval of continuous
touch detection, so that the keys can never become ‘stuck
on’ due to foreign objects or other sudden influences. After
recalibration the key will continue to function normally. The
delay is selectable to be either 10s, 60s, or infinite
(disabled).

The device also auto-recalibrates a key when its signal
reflects a sufficient decrease in capacit ance. In this case the
device recalibrates after ~2 seconds so as to recover normal
operation quickly.

Drift compensation operates to correct the reference level
of each key slowly but automatically over time, to suppress
false detections caused by changes in temperature,
humidity, dirt and other environmental effects.

The drift compensation is asymmetric: in the increasing
capacitive load direction the device drifts more slowly than in
the decreasing direction. In the increasing direction, the rate
of compensation is 1 count of signal per 2 seconds; in the
opposing direction, it is 1 count every 500ms.

Detection Integrator (‘DI’) confirmation reduces the
effects of noise on the QT1080 outputs. The ‘detect
integrator’ mechanism requires consecutive detections over
a number of measurement bursts for a touch to be confirmed
and indicated on the outputs. In a like manner, the end of a
touch (loss of signal) has to be confirmed over a number of
measurement bursts. This process acts as a type of
‘debounce’ against noise.

In normal operation, both the start and end of a touch must
be confirmed for 6 measurement bursts. In a special ‘Fast
Detect‘ mode (available via jumper resistors), confirmation of
the start of a touch requires only 2 sequential detections, but
confirmation of the end of a touch is still 6 bursts.

Fast detect is only available when AKS is disabled.

Spread Spectrum operation: The bursts operate over a
spread of frequencies, so that external fields will have
minimal effect on key operation and emissions are very
weak. Spread spectrum operation works with the ‘detect
integrator’ (DI) mechanism to dramatically reduce the
probability of false detection due to noise.

Sync Mode: The QT1080 features a Sync mode to allow the
device to slave to an external signal source, such as a mains
signal (50/60Hz), to limit interference effects. This is
performed using the SYNC/LP pin. Sync mode operates by
triggering two sequential acquire bursts, in sequence A-B
from the Sync signal (see above); thus, each Sync pulse
causes all 8 keys to be acquired.

Low Power (LP) Mode: The device features an LP mode for
microamp levels of current drain with a slower response
time, to allow use in battery operated devices. On detection
of touch, the device automatically reverts to its normal mode
and asserts the DETECT pin active to wake up a host
controller. The device remains in normal, full acquire speed
mode until another pulse is seen on its SYNC/LP pin, upon
which it goes back to LP mode.

AKS™ Adjacent Key Suppression is a patent-pending
feature that can be enabled via jumper resistors. AKS works
to prevent multiple keys from responding to a single touch, a
common complaint about capacitive touch panels. This can
happen with closely spaced keys, or with control surfaces
that have water films on them.

AKS operates by comparing signal strengths from keys
within a group of keys to suppress touch detections from
those that have a weaker signal change than the dominant
one.

The QT1080 has two different AKS groupings of keys,
selectable via option resistors. These groupings are:

y AKS operates in two groups of 4 keys.

y AKS operates over all 8 keys.

These two modes allow the designer to provide AKS while
also providing for shift or function operations.

If AKS is disabled, all keys can operate simultaneously.

Outputs: There are two output modes: one per key, and
binary coded.

One per key outputs:
key. This mode has two output drive options, push-pull and
open-drain. The outputs can also be made either active-high
or active-low. These options are set via external
configuration resistors.

Binary coded outputs:
one possible key in detect. If more than one key is detecting,
only the first one touched will be indicated.

Simplified Mode: To reduce the need for option resistors,
the simplified operating mode places the part into fixed
settings with only the AKS feature being selectable. LP
mode is also possible in this configuration. Simplified mode
is suitable for most applications.

In this mode there is one output pin per

In this mode, 3 output lines encode for

lQ

2 QT1080 R11.03/0905

1.1 - Wiring

Table 1.1 Pinlist

32-QFN

Pin

5

-

48-SSOP

Pin

OscillatorIOSC374

38, 39, 40,

41, 42

I/OSNS0436

I/OSNS1458

I/OSNS24710

I/OSNS3112

I/OSNS4314

I/OSNS5516

I/OSNS6718

I/OSNS6K819

I/OSNS7920

11, 12, 13,

14, 15, 16

2123

‡

Pin Type

I CMOS input only
I/O CMOS I/O
O CMOS push-pull output
OD CMOS open drain output
O/OD CMOS push pull or open-drain output (option selected)
Pwr Power / ground

Sense pin and

option select

Sense pin and

option select

Sense pin and

option select

Sense pin and

option select

Sense pin and

option select

Sense pin and

option select

Sense pin and

option select

Sense pin and

mode select

Sense pin and mode

or option select

Out 2O/ODOUT_22727
Out 3O/ODOUT_32828

Resistor to Vdd and optional

spread spectrum RC network

To Cs0 and/or
option resistor

To Cs1 and/or

option resistor*

To Cs2 and/or

option resistor*

To Cs3 and/or

option resistor*

To Cs4 and/or

option resistor*

To Cs5 and/or

option resistor*

To Cs6 and/or

option resistor*

To Cs6 + Key and/or

mode resistor

†

To Cs7 and/or mode resistor

or option resistor*

Also, binary coded output 2

In binary coded mode, these

pins are clamped internally to

Vss

100K resistor to VssSpread spectrum driveSpread spectrumODSS331

†

If UnusedNotesFunctionTypeName

-Leave open--n/c34 -

VddActive low resetReset inputI/RST352

-+2.8 ~ +5.0VPowerPwrVdd363

-

-Leave open--n/c

Option resistor

OpenTo Cs0 + KeySense pinI/OSNS0K447

Open or

option resistor*

OpenTo Cs1 + KeySense pinI/OSNS1K469

Open or

option resistor*

OpenTo Cs2 + KeySense pinI/OSNS2K4811

Open or

option resistor*

OpenTo Cs3 + KeySense pinI/OSNS3K213

Open or

option resistor*

OpenTo Cs4 + KeySense pinI/OSNS4K415

Open or

option resistor*

OpenTo Cs5 + KeySense pinI/OSNS5K617

Open or

option resistor*

Open or
mode resistor
Open or mode

†

or option

resistor

resistor*

OpenTo Cs7 + KeySense pinI/OSN7K1021

-Leave open--n/c

-0VGroundPwrVss1722

-Leave open--n/c18, 19, 20 -

Vdd or VssRising edge sync or LP pulseSync In or LP InISYNC/LP

OpenActive = any key in detectDetect StatusO/ODDETECT2224

-Leave open--n/c23, 24 ­OpenAlso, binary coded output 0Out 0O/ODOUT_02525
OpenAlso, binary coded output 1Out 1O/ODOUT_12626
Open
Open
OpenOut 4O/ODOUT_42929

OpenOut 5O/ODOUT_53030
OpenOut 6O/ODOUT_63131
OpenOut 7O/ODOUT_73232

†

Notes

†

Mode resistor is required only in Simplified mode (see Figure 1.2)

* Option resistor is required only in Full Options mode (see Figure 1.1)

‡

Pin is either Sync or LP depending on options selected (functions SL_0, SL_1, see Figure 1.1)

lQ

3 QT1080 R11.03/0905

Figure 1.1 Connection Diagram - Full Options; Shown for 32-QFN Package

KEY 3

KEY 4

KEY 5

KEY 6

KEY 7

Vunreg

R

SNS3

10K

R

SNS4

10K

R

SNS5

10K

R

SNS6

R

SNS7

10K

10K

4.7nF

4.7nF

4.7nF

4.7nF

4.7nF

*4.7uF

C

S3

C

S4

C

S5

C

S6

C

S7

+2.8 ~ +5V

Voltage Reg

2.2K

R

S3

Vdd / Vss

2.2K

R

S4

Vdd / Vss

2.2K

R

S5

Vdd / Vss

2.2K

R

S6

Vdd / Vss

2.2K

R

S7

Vdd / Vss

MOD_1

POL

OUT_D

SL_0

SL_1

*4.7uF

VDD

*100nF

3

SNS3

SNS3K

SNS4

SNS4K

SNS5

SNS5K

SNS6

SNS6K

SNS7

SNS7K

VDD

12

1M

13

14

1M

15

16

1M

17

18

1M

19

20

1M

21

2

/RST

QT1080

*Note: One bypass cap to be tightly wired
between Vdd and Vss. Follow manufacturer’s
recommendations for input and output capacitors.

11

SNS2K

SNS2

SNS1K

SNS1

SNS0K

SNS0

OSC

10

9

8

7

6

4

MOD_0

1M

AKS_1

1M

AKS_0

1M

VDD

Rb1

Rb2

32-QFN

1

SS

OUT_7

OUT_6

OUT_5

OUT_4

OUT_3

OUT_2

OUT_1

OUT_0

32

31

30

29

28

27

26

25

SYNC or LP IN

DETECT OUT

22

23

24

VSS

SYNC/LP

DETECT

4.7nF

R

2.2K

2.2K

2.2K

S2

C

S2

4.7nF

R

S1

C

S1

4.7nF

R

S0

C

S0

Vdd / Vss

Vdd / Vss

Vdd / Vss

Recommended Rb1, Rb2 Values

Vdd Range Rb1 Rb2

2.8 ~ 3.59V 12K 22K

3.6 ~ 5V

15K 27K

100nF

R

SNS2

10K

R

SNS1

10K

R

SNS0

10K

OUT_7

OUT_6

OUT_5

OUT_4

OUT_3

OUT_2

OUT_1

OUT_0

OUT_0

KEY 2

KEY 1

KEY 0

Table 1.2
AKS / Fast-Detect Options

Table 1.3
Max On-Duration

Table 1.4

Polarity & Output

Table 1.5
SYNC/

LP Function

FAST-DETECTAKS MODEAKS_0AKS_1

OffOffVssVss
EnabledOffVddVss
OffOn, in 2 groupsVssVdd
OffOn, globalVddVdd

MAX ON-DURATION MODEMOD_0MOD_1

10 seconds (nom) to recalibrateVssVss
60 seconds (nom) to recalibrateVddVss
Infinite (disabled)VssVdd
(reserved)VddVdd

OUT_n, DETECT PIN MODEPOLOUT_D

Binary coded, active high, push-pullVssVss
Direct, active low, open-drainVddVss
Direct, active high, push-pullVssVdd
Direct, active low, push-pullVddVdd

SYNC/LP PIN MODESL_0SL_1

SyncVssVss
LP mode: 110ms nom response timeVddVss
LP mode: 200ms nom response timeVssVdd
LP mode: 360ms nom response timeVddVdd

lQ

4 QT1080 R11.03/0905

Figure 1.2 Connection Diagram - Simplified Mode; Shown for 32-QFN

SMR resistor installed between SNS6K and SNS7.

KEY 3

KEY 4

KEY 5

KEY 6

KEY 7

DETECT OUT

Vunreg

R

SNS3

10K

R

SNS4

10K

R

SNS5

10K

R

SNS6

10K

R

SNS7

10K

LP IN

4.7nF

4.7nF

4.7nF

4.7nF

4.7nF

*4.7uF

C

S3

C

S4

C

S5

C

S6

C

S7

+2.8 ~ +5V

Voltage Reg

R

S3

2.2K

R

S4

2.2K

R

S5

2.2K

R

S6

2.2K

R

S7

2.2K

SMR

*4.7uF

VDD

*100nF

3

SNS3

SNS3K

SNS4

SNS4K

SNS5

SNS5K

SNS6

SNS6K

SNS7

SNS7K

VDD

12

13

14

15

16

17

18

19

1M

20

21

2

/RST

QT1080

*Note: One bypass cap to be tightly wired
between Vdd and Vss. Follow manufacturer’s
recommendations for input and output capacitors.

SNS2K

SNS2

SNS1K

SNS1

SNS0K

SNS0

OSC

11

10

9

8

7

6

4

AKS_0

1M

Vdd / Vss

VDD

Rb1

Rb2

Recommended Rb1, Rb2 Values

4.7nF

R

S2

2.2K

4.7nF

R

S1

2.2K

4.7nF

R

S0

2.2K

Vdd Range Rb1 Rb2

2.8 ~ 3.59V 12K 22K

3.6 ~ 5V

R

10K

C

S2

R

10K

C

S1

R

10K

C

S0

15K 27K

SNS2

KEY 2

SNS1

KEY 1

SNS0

KEY 0

32-QFN

22

23

24

VSS

SYNC/LP

DETECT

SS

OUT_7

OUT_6

OUT_5

OUT_4

OUT_3

OUT_2

OUT_1

OUT_0

1

32

31

30

29

28

27

26

25

100nF

OUT_7

OUT_6

OUT_5

OUT_4

OUT_3

OUT_2

OUT_1

OUT_0

OUT_0

Table 1.6
AKS Resistor Options

Table 1.7
Functions in Simplified Mode

Output Drive,
SYNC/LP pin
Max on-duration delay
Detect Pin

Polarity

FAST-DETECTAKS MODEAKS_0

EnabledOffVss

OffOn, globalVdd

Direct outputs, push-pull, active high
200ms nom LP function; sync not available
60 seconds (nom)
Active high on any detect

lQ

5 QT1080 R11.03/0905