QT60645B-A Datasheet PDF - Quantum Research Group

QT60645B-A View Datasheet(PDF) - Quantum Research Group

Part Name

Description

Manufacturer

QT60645B-A

32, 48, 64 KEY QMatrix™ KEYPANEL SENSOR ICS

Quantum Research Group

QT60645B-A Datasheet PDF : 42 Pages

1 2 3 4 5 6 7 8 9 10 Next Last

Figure 1-5 QT60xx5B Basic Circuit Model

Short sample gate dwell times after the X

edges will limit the effect of moisture

XX ddrriivvee

((11 ooff 88))

XXnn

electrode

SSaammpplele

YY lliinnee sswwiittcchh ((11 ooff88))

CCxx

((11 ooff 88))

CCaanncceelllalatitoionn

sswwititcchheess

e lect rod e

RReesseett sswwiittcchh

CCzz11

spreading from key to key by taking

advantage of the RC filter-like nature of

continuous films; a short dwell time will limit

the time that the charge has to travel

through the impedance of the film (Section

3.13). This effect is independent of the

frequency of burst repetition, intra-burst

pulse spacing, or X drive pulse width.

Burst mode operation permits reduced

To 60xxx AD C

CCss

CChhaarrggee

InInteteggrraat toorr

CCaa CCzz22

XXnn

power consumption and reduces RF

emissions, while permitting excellent

response time.

A mmpp

RReesseet t

sswwitictchh

1.3 Matrix Configuration

From 60xxx

O ffset Control

88--bbiitt

Offffsseett DDAACC

SSaammpplele

sswwitictchh

AAmmpp

oouut t

The matrix scanning configuration is shown

in Figure 1-5. The ‘X’ drives are sequentially

pulsed in groupings of bursts; an 8:1 analog

V Vouotut mux acts as the sample switch for all ‘Y’

lines. At the intersection of each ‘X’ and ‘Y’

absolute signals yet still respond to very small signal

changes. Subranging is provided by two offset mechanisms

which can be thought of as 'coarse' and 'fine' offsets.

line in the matrix itself, where a key is

desired, should be an interdigitated electrode set similar to

those shown in Figure 1-2. The outermost electrode or the

key border should always be connected to an ‘X’ drive;

The 'coarse' method uses one or two switched Cz capacitors flooding the area around keys with X fill to a width of up to

to subtract charge from the charge integrator to create up to 10mm can help in suppressing moisture films further.

two step offsets, to bring the analog signal back to a more

reasonable level. This action occurs during the course of the

burst.

Although it is referred to as a ‘matrix’, there is no restriction

on where individual keys can be located. The term ‘matrix’

refers to the electrical configuration of keys, not the physical

The 'fine' method of offset uses an 8-bit R2R ladder DAC

arrangement. Consult Quantum for application assistance on

driven by the X drive lines to create an offset in the amplifier key design.

stage. The DAC is driven after the burst has ceased and the

charge accumulated, so there is no conflict in this dual-use of 1.4 Communications

the X lines.

The device uses two variants of SPI communications,

Slave-only and Master-Slave. Over this interface is a

command and data transfer structure

Figure 1-6 Circuit Block Diagram (8x8 Matrix Shown)

designed for high levels of flexibility using

SP I

Host

✟X{1. .7 }

YC0 .

YC1 .

YC2 .

YC3 .

YC4 .

YC5 .

YC6 .

YC7 .

Timin g &

Ch arge

Neutralizin g

C ontrol

(PL D)

Transfer S trobe

Y0 Y1 Y2 Y3 Y4 Y5 Y6 Y7

minimal numbers of bytes. For more

information see Sections 4 and 5.

Device variations: Refer to Section 3.1 for

differences between the parts covered by

this datasheet.

2 Signal Processing

The devices calibrate and process all

signals using a number of algorithms

specifically designed to provide for high

survivability in the face of adverse

environmental challenges. They provide a

Y S0. .Y S2

Q T6 0xx 5

AIN

X0 .

X1 .

X2 .

X3 .

X4 .

X5 .

X6 .

XS .

Transfer S elect

R2R

DAC

Signal Offset

G ain

Amp

✟

C harge

I n te g ra t o r

“

T ra n s fe r

M ux

✟

large number of processing options which

can be user-selected to implement very

flexible, robust keypanel solutions.

2.1 Negative Threshold