Quantum QT1101-ISG User Manual

lQ QT1101-ISG

" Patented charge-transfer (‘QT’) design
" 10 independent QT sensing fields (keys)
" 2.8V ~ 5.5V single supply operation
" 40µA current typ @ 3V in 360ms LP mode
" 100% autocal for life - no adjustments required
" Serial 1 or 2 wire interface with auto baud rate
" Fully debounced results
" Patented AKS™ Adjacent Key Suppression
" Spread spectrum bursts for superior noise rejection
" Sync pin for excellent LF noise rejection
" ‘Fast mode’ for use in slider type applications
" Lead-free 32-QFN, 48-SSOP packages

APPLICATIONS

10 KEY QT

24 23 222120 19 18 17

SNS8

25

SNS8K

SNS9K

/CHANGE

SNS9

N.C.

1W

RX

26
27
28
29
30

31

32

OUCH

DETECT

™ S

SYNC/LP

VSS

SNS7K

SNS7

QT1101
32-QFN

1

2345678

SS

/RST

N.C.

VDD

OSC

SNS6K

SNS6

SNS0

SNS0K

ENSOR

SNS5K

16
15
14
13
12

11

10

9

SNS1

IC

SNS5
SNS4K
SNS4
SNS3K
SNS3
SNS2K
SNS2
SNS1K

! MP3 players
! Mobile phones

! PC peripherals
! Television controls

! Pointing devices
! Remote controls

QT1101 charge-transfer (“QT”) QTouchTM IC is a self-contained, patented digital controller capable of detecting near-proximity or touch
on up to 10 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.

Patented AKS™ Adjacent Key Suppression 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.

AVAILABLE OPTIONS

A

LQC

48-SSOP32-QFNT

QT1101-IS48GQT1101-ISG-400C to +850C

Copyright © 2005 QRG Ltd

QT1101 R4.03/0805

1 - OVERVIEW

The QT1101 is an easy to use, 10 touch-key sensor IC
based on Quantum’s patented charge-transfer (‘QT’)
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 three successive bursts of pulses:

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

Burst C: Keys 8, 9
Bursts always operate in A-B-C sequence.
Self-calibration: On power-up, all 10 keys are

self-calibrated within 450m s 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 capacitance. 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 QT1101 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 QT1101 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 three sequential acquire bursts, in sequence
A-B-C from the Sync signal (see above); thus, each Sync
pulse causes all 10 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 patented 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 QT1101 has two different AKS groupings of keys,
selectable via option resistors. These groupings are:

AKS operates in three groups of keys.
AKS operates over all 10 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: The QT1101 has a serial output using 1 or 2 wires,

RS232 data format, and automatic baud rate detection. A
simple protocol is employed.

The QT1101 operates in slave mode, i.e. it only sends data
to the host after receiving a request from the host.

An additional /CHANGE (state changed) signal allows the
use of the serial interface to be optimised, rather than being
polled continuously.

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.

Lq

2 QT1101 R4.03/0805

1.1 Wiring

Table 1.1 Pinlist

32-QFN

Pin

-

-

48 SSOP

Pin

100K ohm resistor to

†

100K ohm resistor to

39, 40,
41, 42

11, 12, 13,

14, 15, 16

2123

Spread spectrum driveSpread spectrumODSS331

OscillatorIOSC374

I/OSNS0436

I/OSNS1458

I/OSNS24710

I/OSNS3112

I/OSNS5516

I/OSNS6718
I/OSNS6K819

I/OSNS7920

‡

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

State changedOD/CHANGE3030

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 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*

0 = a key state has changed

Requires pull-up

†

Pin Type

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

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)

** See text

If UnusedNotesFunctionTypeName

Vss

Open---n/c34-

VddActive low resetReset inputI/RST352

-+2.8 ~ +5.0VPowerPwrVdd363

-

-Leave open--n/c385

Open---n/c

Open or

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
OpenTo Cs4Sense pinI/OSNS4314
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/OSNS7K1021
Open---n/c

-0VGroundPwrVss1722

Open---n/c18, 19, 20-

Vdd or Vss**Rising edge sync or LP pulseSync In or LP InISYNC/LP

OpenSee Table 1.4Detect StatusO/ODDETECT2224
Open---n/c23, 24­OpenTo Cs8Sense pinI/OSNS82525
OpenTo Cs8 + KeySense pinI/OSNS8K2626
OpenTo Cs9Sense pinI/OSNS92727
OpenTo Cs9 + KeySense pinI/OSNS9K2828
Open---n/c2929

Vss

-Requires pull-up to Vdd1W mode serial I/OI/OD1W3131

VddInput for 2W mode2W ReceiveIRX3232

†

Lq

3 QT1101 R4.03/0805

Figure 1.1 Connection Diagram - Full Options (32-QFN Package)

KEY 3

KEY 4

KEY 5

KEY 6

KEY 7

KEY 8

KEY 9

SYNC or LP

DETECT OUT

Vunreg

R

SNS3

10K

R

SNS4

10K

R

SNS5

10K

R

SNS6

10K

R

SNS7

10K

R

SNS8

10K

R

SNS9

10K

+2.8 ~ +5V

C

S3

C

S4

C

S5

C

S6

C

S7

C

S8

C

S9

Voltage Reg

2.2K

R

S3

Vdd / Vss

2.2K

R

S4

2.2K

R

S5

Vdd / Vss

2.2K

R

S6

Vdd / Vss

2.2K

R

S7

Vdd / Vss

2.2K

R

S8

2.2K

R

S9

Vdd

MOD_1

OUT_D

SL_0

SL_1

4.7uF

4.7nF

4.7nF

4.7nF

4.7nF

4.7nF

4.7nF

4.7nF

Pullup not required for push-pull mode
See Detect pin mode table below

4.7uF

100K

VDD

*100nF

3

SNS3

SNS3K

SNS4

SNS4K

SNS5

SNS5K

SNS6

SNS6K

SNS7

SNS7K

SNS8

SNS8K

SNS9

SNS9K

VDD

12

1M

13

14

15

16

1M

17

18

1M

19

20

1M

21

25

26

27

28

2

/RST

QT1101
32-QFN

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

11

SNS2K

SNS2

SNS1K

SNS1

SNS0K

SNS0

OSC

SS

10

9

8

7

6

4

1

MOD_0

1M

1M

1M

Rb1

Rb2

VDD

AKS_1

AKS_0

100nF

Vdd / Vss

Vdd / Vss

Vdd / Vss

Css

No Spread-spectrum:

R

SNS2

4.7nF

R

2.2K

2.2K

2.2K

S2

R

S1

R

S0

4.7nF

4.7nF

10K

C

S2

R

SNS1

10K

C

S1

R

SNS0

10K

C

S0

Recommended Rb1, Rb2 Values

With Spread-Spectrum

Vdd Range Rb1 Rb2

2.8

~ 2.99V 12K 27K

3.0 ~ 3.59V

3.6 ~ 5V 15K 27K

No Spread-Spectrum

Vdd Range Rb1 Rb2

2.8 ~ 2.99V 15K dni

3.0 ~ 3.59V 18K dni

3.6 ~ 5V 20K dni

12K 22K

dni = do not install

KEY 2

KEY 1

KEY 0

Replace Css with 100K resistor

32

23

24

SYNC/LP

DETECT

RX

1W

/CHANGE

N.C.

N.C.

100K

31

100K

30

29

5

Vdd

Vdd

2W DATA

DATA

/CHANGE

VSS

22

Table 1.2
AKS / Fast-Detect Options

Table 1.3
Max On-Duration

Table 1.4
Detect Pin Drive

Table 1.5
SYNC/LP Function

Lq

FAST-DETECTAKS MODEAKS_0AKS_1

OffOffVssVss
EnabledOffVddVss
OffOn, in 3 groupsVssVdd
OffOn, globalVddVdd

MAX ON-DURATION MODEMOD_0MOD_1

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

DETECT PIN MODEOUT_D

Open drain, active lowVss
Push-pull, active highVdd

SYNC/LP PIN MODESL_0SL_1

SyncVssVss
LP mode: 120ms response timeVddVss
LP mode: 200ms response timeVssVdd
LP mode: 360ms response timeVddVdd

4 QT1101 R4.03/0805

Figure 1.2 Connection Diagram - Simplified Mode (32-QFN Package)

SMR resistor installed between SNS6K, SNS7

KEY 3

KEY 4

KEY 5

KEY 6

KEY 7

KEY 8

KEY 9

DETECT OUT

Vunreg

R

SNS3

10K

R

SNS4

10K

R

SNS5

10K

R

SNS6

10K

R

SNS7

10K

R

SNS8

10K

R

SNS9

10K

LP IN

4.7nF

4.7nF

4.7nF

4.7nF

4.7nF

4.7nF

4.7nF

4.7uF

C

S3

C

S4

C

S5

C

S6

C

S7

C

S8

C

S9

+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

R

S8

2.2K

R

S9

2.2K

SMR

4.7uF

VDD

*100nF

3

SNS3

SNS3K

SNS4

SNS4K

SNS5

SNS5K

SNS6

SNS6K

SNS7

SNS7K

SNS8

SNS8K

SNS9

SNS9K

VDD

12

13

14

15

16

17

18

19

1M

20

21

25

26

27

28

2

/RST

QT1101
32-QFN

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

11

SNS2K

10

SNS2

9

SNS1K

8

SNS1

7

SNS0K

SNS0

OSC

SS

6

4

1

AKS_0

1M

Vdd / Vss

VDD

Rb1

Rb2

Css

100nF

No Spread-spectrum:

R

SNS2

4.7nF

R

2.2K

2.2K

2.2K

S2

R

S1

R

S0

4.7nF

4.7nF

10K

C

S2

R

SNS1

10K

C

S1

R

SNS0

10K

C

S0

Recommended Rb1, Rb2 Values

With Spread-Spectrum

Vdd Range Rb1 Rb2

2.8

~ 2.99V 12K 27K

3.0 ~ 3.59V

3.6 ~ 5V 15K 27K

No Spread-Spectrum

Vdd Range Rb1 Rb2

2.8 ~ 2.99V 15K dni

3.0 ~ 3.59V 18K dni

3.6 ~ 5V 20K dni

12K 22K

dni = do not install

KEY 2

KEY 1

KEY 0

Replace Css with 100K resistor

32

23

24

SYNC/LP

DETECT

RX

1W

/CHANGE

N.C.

N.C.

100K

31

100K

30

29

5

Vdd

Vdd

2W DATA

DATA

/CHANGE

VSS

22

Table 1.6
AKS Resistor Options

Table 1.7
Functions in Simplified Mode

SYNC/LP pin
Max on-duration delay
Detect Pin

Lq

FAST-DETECTAKS MODEAKS_0

EnabledOffVss

OffOn, globalVdd

200ms LP function; sync not available
60 seconds
Push-pull, active high

5 QT1101 R4.03/0805