TSC2200_技术文档

TSC2200

SBAS191F – FEBRUARY 2001 – REVISED APRIL 2004

PDA ANALOG INTERFACE CIRCUIT

FEATURES

ꢀ 4-WIRE TOUCH SCREEN INTERFACE AND

APPLICATIONS

ꢀ PERSONAL DIGITAL ASSISTANTS

ꢀ CELLULAR PHONES

ꢀ MP3 PLAYERS

4-BY-4 KEYPAD INTERFACE

ꢀ RATIOMETRIC CONVERSION

ꢀ SINGLE 2.7V TO 3.6V SUPPLY

ꢀ SERIAL INTERFACE

DESCRIPTION

ꢀ INTERNAL DETECTION OF SCREEN TOUCH

The TSC2200 is a complete PDA analog interface circuit. It

contains a complete 12-bit, Analog-to-Digital (A/D) resistive

touch screen converter including drivers, the control to mea-

sure touch pressure, keyboard controller, and an 8-bit Digital-

to-Analog (D/A) converter output for LCD contrast control.

The TSC2200 interfaces to the host controller through a

standard SPI™ serial interface. The TSC2200 offers program-

mable resolution and sampling rates from 8- to 12-bits and up

to 125kHz to accommodate different screen sizes.

AND KEYPAD

ꢀ PROGRAMMABLE 8-, 10-, OR 12-BIT

RESOLUTION

ꢀ PROGRAMMABLE SAMPLING RATES

ꢀ DIRECT BATTERY MEASUREMENT (0.5V to 6V)

ꢀ ON-CHIP TEMPERATURE MEASUREMENT

ꢀ TOUCH-PRESSURE MEASUREMENT

ꢀ FULL POWER-DOWN CONTROL

The TSC2200 also offers two battery-measurement inputs

capable of reading battery voltages up to 6V, while operating

at only 2.7V. It also has an on-chip temperature sensor

capable of reading 0.3°C resolution. The TSC2200 is available

in a TSSOP-28 and a QFN-32 package.

ꢀ TSSOP-28 AND QFN-32 PACKAGES

SPI is a registered trademark of Motorola.

US Patent No. 624639.

C1 C2 C3 C4 R1 R2 R3 R4

Keyboard Scanner

and State Control

MISO

SS

SCLK

X+

Clock

X–

Y+

Y–

Touch Panel

Drivers

Serial

Interface

and

MOSI

Control

Logic

Temp Sensor

DAV

A/D Converter

PENIRQ

KBIRQ

MUX

V_BAT1

Battery Monitor

V_BAT2

AUX1

AUX2

Internal 2.5V

Reference

V_REF

ARNG

A_OUT

D/A Converter

Please be aware that an important notice concerning availability, standard warranty, and use in critical applications of

Texas Instruments semiconductor products and disclaimers thereto appears at the end of this data sheet.

PRODUCTION DATA information is current as of publication date.

Products conform to specifications per the terms of Texas Instruments

standard warranty. Production processing does not necessarily include

testing of all parameters.

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ABSOLUTE MAXIMUM RATINGS⁽¹⁾

ELECTROSTATIC

DISCHARGE SENSITIVITY

This integrated circuit can be damaged by ESD. Texas

Instruments recommends that all integrated circuits be handled

with appropriate precautions. Failure to observe proper han-

dling and installation procedures can cause damage.

V_DDto GND ........................................................................ –0.3V to +6.0V

V_BATInput Voltage to GND ............................................... –0.3V to +6.0V

Analog Input Voltage to GND (except V_BAT) ........... –0.3V to V_DD+ 0.3V

Digital Input Voltage to GND ................................... –0.3V to V_DD+ 0.3V

Operating Temperature Range ...................................... –40°C to +105°C

Storage Temperature Range .........................................–65°C to +150°C

Junction Temperature (T_JMax) .................................................... +150°C

TSSOP Package

ESD damage can range from subtle performance degrada-

tion to complete device failure. Precision integrated circuits

may be more susceptible to damage because very small

parametric changes could cause the device not to meet its

published specifications.

Power Dissipation .................................................... (T_JMax – T_A)/θ_JA

θ_JAThermal Impedance .......................................................... 90°C/W

Lead Temperature, Soldering

Vapor Phase (60s) ............................................................ +215°C

Infrared (15s) ..................................................................... +220°C

NOTE: (1) Stresses above those listed under “Absolute Maximum Ratings”

may cause permanent damage to the device. Exposure to absolute maximum

conditions for extended periods may affect device reliability.

INTEGRAL

SPECIFIED

LINEARITY

PACKAGE

TEMPERATURE

RANGE

PACKAGE

MARKING

ORDERING

NUMBER

TRANSPORT

MEDIA, QUANTITY

PRODUCT

ERROR (LSB) PACKAGE-LEAD DESIGNATOR⁽¹⁾

TSC2200

±2

"

TSSOP-28

PW

"

–40°C to +85°C

TSC2200I

TSC2200IPW

TSC2200IPWR

TSC2200IRHB

TSC2200IRHBR

Rails, 50

"

QFN-32

"

Tape and Reel, 2000

Tubes, 72

TSC2200

±2

RHB

–40°C to +85°C

TSC2200I

"

Tape and Reel, 2500

NOTE: (1) For the most current specifications and package information, refer to our web site at www.ti.com.

TIMING CHARACTERISTICS⁽¹⁾⁽²⁾

At –40°C to +85°C, +V_DD= +2.7V, V_REF= +2.5V, unless otherwise noted.

TSC2200

TYP

PARAMETER

CONDITIONS

MIN

MAX

UNITS

SCLK Period

t_sck

t_Lead

t_Lag

t_td

t_su

t_hi

t_ho

t_a

t_dis

t_v

30

15

30

10

0

ns

Enable Lead Time

Enable Lag Time

Sequential Transfer Delay

Data Setup Time

Data Hold Time (inputs)

Data Hold Time (outputs)

Slave Access Time

Slave D_OUTDisable Time

Data Valid

15

10

30

Rise Time

Fall Time

t_r

t_f

NOTES: (1) All input signals are specified with t_r= t_f= 5ns (10% to 90% of V_DD) and timed from a voltage level of (V_IL+ V_IH)/2. (2) See timing diagram below.

TIMING DIAGRAM

All specifications typical at –40°C to +85°C, +V_DD= +2.7V.

SS

t_td

t_Lag

t_sck

t_Lead

t_f

t_r

t_wsck

SCLK

MISO

t_wsck

t_v

t_ho

t_dis

MSB OUT

t_hi

BIT 6 ... 1

LSB OUT

LSB IN

t_a

t_su

MOSI

MSB IN

TSC2200

2

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SBAS191F

ELECTRICAL CHARACTERISTICS

At –40°C to +85°C, +V_DD= +2.7V, internal V_REF= +2.5V, conversion clock = 2MHz, and 12-bit mode, unless otherwise noted.

TSC2200IPW

TSC2200IRHB

TYP

PARAMETER

CONDITIONS

MIN

TYP

MAX

MIN

MAX

UNITS

AUXILIARY ANALOG INPUT

Input Voltage Range

0

+V_REF

ꢀ

V

Input Capacitance

Input Leakage Current

25

±1

ꢀ

pF

µA

BATTERY MONITOR INPUT

Input Voltage Range

Input Capacitance

Input Leakage Current

Accuracy

0.5

6.0

ꢀ

V

25

±1

ꢀ

pF

µA

%

–3

+3

ꢀ

TEMPERATURE MEASUREMENT

Temperature Range

Temperature Resolution

Accuracy

–40

+85

°C

0.3

±2

ꢀ

A/D CONVERTER

Resolution

No Missing Codes

Integral Linearity

Offset Error

Gain Error

Noise

Power-Supply Rejection

Programmable: 8-, 10-, or 12-Bits

12-Bit Resolution

12

ꢀ

Bits

11

ꢀ

±2

±6

±3

ꢀ

LSB

µVrms

dB

Excluding Reference Error

30

80

ꢀ

D/A CONVERTER

Output Current Range

Resolution

Set by Resistor from ARNG to GND

650

500

µA

Bits

LSB

8

ꢀ

Integral Linearity

±2

ꢀ

VOLTAGE REFERENCE

Voltage Range

Internal 2.5V

Internal 1.25V

2.45

1.225

2.5

1.25

20

2.55

1.275

ꢀ

1.285

V

Reference Drift

External Reference Input Range

Current Drain

ppm/°C

V

µA

1.0

V_DD

ꢀ

20

ꢀ

DIGITAL INPUT/OUTPUT

Internal Clock Frequency

Logic Family

8

ꢀ

MHz

CMOS

Logic Levels:V_IH

I_IH= +5µA

I_IL= +5µA

I_OH= 2 TTL Loads

I_OL= 2 TTL Loads

0.7V_DD

–0.3

0.8V_DD

ꢀ

V

V_IL

V_OH

V_OL

0.3V_DD

0.4

ꢀ

POWER-SUPPLY REQUIREMENTS

Power-Supply Voltage, +V_DD

Quiescent Current

Specified Performance

See Note (1)

2.7

3.6

2.3

ꢀ

2.5

V

1.25

500

ꢀ

mA

µA

See Note (2)

Power-Down

3

ꢀ

TEMPERATURE RANGE

Specified Performance

–40

+85

ꢀ

°C

ꢀ Specifications same as TSC2200IPW.

NOTES: (1) AUX1 conversion, no averaging, no REF power down, 50µs conversion. (2) AUX1 conversion, no averaging, external reference, 50µs conversion.

TSC2200

SBAS191F

3

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PIN CONFIGURATION

Top View

TSSOP

Top View

QFN

+V_DD

X+

1

2

3

4

5

6

7

8

9

28 AUX1

27 AUX2

26 ARNG

25 A_OUT

24 PENIRQ

23 MISO

22 DAV

21 MOSI

20 SS

Y+

X–

Y–

1

2

3

4

5

6

7

8

24 NC

Y–

23 A_OUT

22 PENIRQ

21 MISO

20 DAV

19 MOSI

18 SS

GND

V_BAT1

V_BAT2

V_REF

GND

V_BAT1

V_BAT2

V_REF

KBIRQ

R1

TSC2200

KBIRQ 10

R1 11

19 SCLK

18 C4

17 SCLK

R2 12

17 C3

R3 13

16 C2

R4 14

15 C1

PIN DESCRIPTION

TSSOP

QFN

NAME DESCRIPTION

1

29, 30

31

32

1

V_DD

X+

Power Supply

X+ Position Input

Y+ Position Input

X– Position Input

Y– Position Input

Ground

2

3

Y+

4

X–

5

2

Y–

6

3

GND

V_BAT1

V_BAT2

V_REF

7

4

Battery Monitor Input 1

8

5

Battery Monitor Input 2

9

6

Voltage Reference Input/Output

10

11

12

13

14

15

16

17

18

19

20

21

22

23

24

25

26

27

28

—

7

KBIRQ Keyboard Interrupt (active LOW)

8

R1

R2

Row 1

10

11

12

13

14

15

16

17

18

19

20

21

22

23

26

27

28

9, 24, 25

Row 2

R3

Row 3

R4

Row 4

C1

Column 1

Column 2

Column 3

Column 4

Serial Clock Input

C2

C3

C4

SCLK

SS

Slave Select Input (active LOW). Data will not be clocked in to MOSI unless SS is LOW. When SS is HIGH, MISO is high impedance.

Serial Data Input. Data is clocked in at SCLK falling edge.

MOSI

DAV

MISO

Data Available (active LOW)

Serial Data Output. Data is clocked out at SCLK falling edge. High impedance when SS is HIGH.

PENIRQ Pen Interrupt

A_OUT

Analog Output Current from D/A Converter

ARNG D/A Converter Analog Output Range Set

AUX2

AUX1

NC

Auxiliary A/D Converter Input 2

Auxiliary A/D Converter Input 1

No Connection

TSC2200

4

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SBAS191F

TYPICAL CHARACTERISTICS

At T_A= +25°C, +V_DD= +2.7V, conversion clock = 2MHz, 12-bit mode, and V_REF= +2.5V, unless otherwise noted.

POWER-DOWN SUPPLY CURRENT

vs TEMPERATURE

CONVERSION SUPPLY CURRENT vs TEMPERATURE

1.86

1.85

1.84

1.83

1.82

1.81

1.80

1.79

1.78

10

8

6

4

2

0

–60

–40

–20

0

20

40

60

80

100

–40

–20

0

20

40

60

80

100

Temperature (°C)

POWER-DOWN SUPPLY CURRENT vs

SUPPLY VOLTAGE

INTERNAL OSCILLATOR FREQUENCY vs V_DD

8.7

8.6

8.5

8.4

8.3

8.2

8.1

0.30

0.25

0.20

0.15

0.10

0.05

0

2.5

2.7

2.9

3.1

3.3

3.5

3.7

2.7

2.9

3.1

3.3

3.5

3.7

Supply Voltage (V)

V_DD(V)

CHANGE IN GAIN ERROR vs TEMPERATURE

CHANGE IN OFFSET ERROR vs TEMPERATURE

0.5

0.4

0.5

0.4

0.3

0.2

0.1

0

–0.1

–0.2

–0.3

–0.4

–0.5

–0.1

–0.2

–0.3

–0.4

–0.5

–60

–40

–20

0

20

40

60

80

100

–60

–40

–20

0

20

40

60

80

100

Temperature (°C)

TSC2200

SBAS191F

5

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TYPICAL CHARACTERISTICS (Cont.)

At T_A= +25°C, +V_DD= +2.7V, conversion clock = 2MHz, 12-bit mode, and V_REF= +2.5V, unless otherwise noted.

INTERNAL REFERENCE vs TEMPERATURE

1.25V Reference

INTERNAL REFERENCE vs V_DD

2.55

2.54

2.53

2.52

2.51

2.50

2.49

2.48

2.47

2.46

2.45

1.275

1.270

1.265

1.260

1.255

1.250

1.245

1.240

1.235

1.230

1.225

2.55

2.54

2.53

2.52

2.51

2.50

2.49

2.48

2.47

2.46

2.45

1.275

1.270

1.265

1.260

1.255

1.250

1.245

1.240

1.235

1.230

1.225

1.25V Reference

2.5V Reference

–60

2.5

–40

–20

0

20

40

60

80

100

2.5

–60

2.7

2.9

3.1

3.3

3.5

3.7

100

Temperature (°C)

V_DD(V)

INTERNAL OSCILLATOR FREQUENCY

vs TEMPERATURE

TOUCH SCREEN DRIVER ON-RESISTANCE

vs TEMPERATURE

8.8

8.6

8.4

8.2

8.0

7.8

7.6

7.4

8.0

7.5

7.0

6.5

6.0

5.5

5.0

4.5

4.0

–40

–20

0

20

40

60

80

100

–40

–20

0

20

40

60

80

Temperature (°C)

SWITCH-ON RESISTANCE vs V_DD

TEMP1 DIODE VOLTAGE vs TEMPERATURE

800

750

700

650

600

550

500

450

400

6.2

6.1

6.0

5.9

5.8

5.7

5.6

5.5

5.4

5.3

–40

–20

0

20

40

60

80

2.7

2.9

3.1

3.3

3.5

3.7

Supply Voltage (V)

Temperature (°C)

TSC2200

6

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SBAS191F

TYPICAL CHARACTERISTICS (Cont.)

At T_A= +25°C, +V_DD= +2.7V, conversion clock = 2MHz, 12-bit mode, and V_REF= +2.5V, unless otherwise noted.

TEMP1 DIODE VOLTAGE vs SUPPLY VOLTAGE

TEMP2 DIODE VOLTAGE vs TEMPERATURE

900

800

700

600

500

612.0

611.8

611.6

611.4

611.2

611.0

610.8

610.6

610.4

610.2

610.0

–60

–40

–20

0

20

40

60

80

100

2.5

2.7

2.9

3.1

3.3

3.5

3.7

V_DD(V)

Temperature (°C)

TEMP2 DIODE VOLTAGE vs SUPPLY VOLTAGE

DAC OUTPUT CURRENT vs TEMPERATURE

1.00

0.95

0.90

0.85

0.80

0.75

0.70

0.65

0.60

727.06

727.04

727.02

727.00

727.98

727.96

727.94

727.92

727.90

2.5

2.7

2.9

3.1

3.3

3.5

3.7

–60

–40

–20

0

20

40

60

80

100

V_DD(V)

Temperature (°C)

DAC MAX CURRENT vs V_DD

0.895

0.890

0.885

0.880

0.875

0.870

0.865

0.860

0.855

2.5

2.7

2.9

3.1

3.3

3.5

3.7

V_DD(V)

TSC2200

SBAS191F

7

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Communication to the TSC2200 is via a standard SPI serial

interface. This interface requires that the Slave Select signal be

driven LOW to communicate with the TSC2200. Data is then

shifted into or out of the TSC2200 under control of the host

microprocessor, which also provides the serial data clock.

OVERVIEW

The TSC2200 is an analog interface circuit for human inter-

face devices. A register-based architecture eases integration

with microprocessor-based systems through a standard SPI

bus. All peripheral functions are controlled through the reg-

isters and onboard state machines.

Control of the TSC2200 and its functions is accomplished by

writing to different registers in the TSC2200. A simple com-

mand protocol is used to address the 16-bit registers. Reg-

isters control the operation of the A/D converter, D/A con-

verter, and keypad scanner.

The TSC2200 consists of the following blocks (refer to the

block diagram on the front page):

•

Touch Screen Interface

Keypad Interface

The result of measurements made will be placed in the

TSC2200’s memory map and may be read by the host at any

time. Three signals are available from the TSC2200 to indicate

that data is available for the host to read. The DAV output

indicates that an A/D conversion has completed and that data

is available. The KBIRQ output indicates that a key on the

keypad has been pressed. The PENIRQ output indicates that

a touch has been detected on the touch screen. A typical

application of the TSC2200 is shown in Figure 1.

Battery Monitors

Auxiliary Inputs

Temperature Monitor

Current Output D/A Converter

+2.7V to +3.3V

Voltage

Regulator

1µF

+

LCD Contrast

to

0.1µF

10µF

TSC2200IPW

(Optional)

Auxiliary Input

1

2

3

4

5

6

7

8

9

+V_DD

X+

AUX1 28

AUX2 27

ARNG 26

Y+

Touch

Screen

25

X–

A_OUT

Pen Interrupt Request

Serial Data Out

Data Available

Serial Data In

Y–

PENIRQ 24

MISO 23

DAV 22

MOSI 21

SS 20

GND

V_BAT1

V_BAT2

V_REF

Slave Select

1µF

+

to

0.1µF

Serial Clock

10 KBIRQ

11 R1

SCLK 19

C4 18

10µF

Keypad

(Optional)

RRNG

12 R2

C3 17

13 R3

C2 16

14 R4

C1 15

Keyboard Interrupt Request

Main

Battery

Secondary

Battery

FIGURE 1. Typical Circuit Configuration.

8

TSC2200

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SBAS191F

OPERATION—TOUCH SCREEN

fore, the 8-bit resolution mode is recommended (however,

calculations will be shown with the 12-bit resolution mode).

There are several different ways of performing this measure-

ment. The TSC2200 supports two methods. The first method

requires knowing the X-plate resistance, measurement of the

X-position, and two additional cross panel measurements (Z₂

and Z₁) of the touch screen, as seen in Figure 3. Using

Equation 1 will calculate the touch resistance:

A resistive touch screen works by applying a voltage across

a resistor network and measuring the change in resistance at

a given point on the matrix where a screen is touched by an

input stylus, pen, or finger. The change in the resistance ratio

marks the location on the touch screen.

The TSC2200 supports the resistive 4-wire configurations

(see Figure 1). The circuit determines location in two coordi-

nate pair dimensions, although a third dimension can be

added for measuring pressure.

X-Position Z₂

R

_TOUCH= R_X-Plate

•

–1

(1)

4096

Z₁

THE 4-WIRE TOUCH SCREEN COORDINATE

PAIR MEASUREMENT

Measure X-Position

X+

Y+

A 4-wire touch screen is constructed as shown in Figure 2.

It consists of two transparent resistive layers separated by

insulating spacers.

Touch

X-Position

X–

Conductive Bar

Y–

Transparent

Conductor (ITO)

Transparent

Conductor (ITO)

Bottom Side

Measure Z₁-Position

Top Side

Y+

X+

Y+

X+

Touch

Z₁-Position

X–

Y–

Silver

Ink

X–

Y+

X+

Y–

Touch

Insulating

Material

(Glass)

Z₂-Position

ITO = Indium Tin Oxide

X–

Y–

Measure Z₂-Position

FIGURE 2. 4-Wire Touch Screen Construction.

FIGURE 3. Pressure Measurement.

The 4-wire touch screen panel works by applying a voltage

across the vertical or horizontal resistive network. The A/D

converter converts the voltage measured at the point the

panel is touched. A measurement of the Y-position of the

pointing device is made by connecting the X+ input to a data

converter chip, turning on the Y+ and Y– drivers, and

digitizing the voltage seen at the X+ input. The voltage

measured is determined by the voltage divider developed at

the point of touch. For this measurement, the horizontal

panel resistance in the X+ lead does not affect the conver-

sion due to the high input impedance of the A/D converter.

The second method requires knowing both the X-plate and

Y-plate resistance, measurement of X-position and Y-posi-

tion, and Z₁. Using Equation 2 will also calculate the touch

resistance:

(2)

X -Position 4096

Y -Position

R_TOUCH= R_X-Plate

•

−1 − R_Y-Plate• 1−

4096

Z₁

4096

When the touch panel is pressed or touched, and the drivers

to the panel are turned on, the voltage across the touch panel

will often overshoot and then slowly settle (decay) down to a

stable DC value. This is due to mechanical bouncing which

is caused by vibration of the top layer sheet of the touch

panel when the panel is pressed. This settling time must be

accounted for, or else the converted value will be in error.

Therefore, a delay must be introduced between the time the

driver for a particular measurement is turned on, and the time

measurement is made.

Voltage is then applied to the other axis, and the A/D

converter converts the voltage representing the X-position on

the screen. This provides the X- and Y-coordinates to the

associated processor.

Measuring touch pressure (Z) can also be done with the

TSC2200. To determine pen or finger touch, the pressure of

the “touch” needs to be determined. Generally, it is not

necessary to have very high performance for this test, there-

TSC2200

SBAS191F

9

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In some applications, external capacitors may be required

across the touch screen for filtering noise picked up by the

touch screen; i.e., noise generated by the LCD panel or

back-light circuitry. The value of these capacitors will provide

a low-pass filter to reduce the noise, but will cause an

additional settling time requirement when the panel is touched.

The TSC2200 touch screen interface can measure position (X

and Y) and pressure (Z). Determination of these coordinates

is possible under three different modes of the A/D converter:

conversion controlled by the TSC2200, initiated by detection

of a touch; conversion controlled by the TSC2200, initiated by

the host responding to the PENIRQ signal; or conversion

completely controlled by the host processor.

Several solutions to this problem are available in the TSC2200.

A programmable delay time is available that sets the delay

between turning the drivers on and making a conversion.

This is referred to as the Panel Voltage Stabilization time,

and is used in some of the modes available in the TSC2200.

In other modes, the TSC2200 can be commanded to turn on

the drivers only without performing a conversion. Time can

then be allowed before a conversion is started.

A/D CONVERTER

The analog inputs of the TSC2200 are shown in Figure 4. The

analog inputs (X, Y, and Z touch panel coordinates, battery

voltage monitors, chip temperature, and auxiliary inputs) are

provided via a multiplexer to the Successive Approximation

Register (SAR) A/D converter. The A/D converter architecture

is based on capacitive redistribution architecture that inher-

ently includes a sample-and-hold function.

+V_DD

V_REF

TEMP1

TEMP0

X+

X–

Ref ON/OFF

Y+

+REF

+IN

Y–

Converter

–IN

2.5V

–REF

Reference

7.5kΩ

V_BAT1

V_BAT2

2.5kΩ

Battery

On

Battery

On

AUX1

AUX2

GND

FIGURE 4. Simplified Diagram of the Analog Input Section.

TSC2200

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SBAS191F

A unique configuration of low on-resistance switches allows

an unselected A/D converter input channel to provide power

and an accompanying pin to provide ground for driving the

touch panel. By maintaining a differential input to the con-

verter and a differential reference input architecture, it is

possible to negate errors caused by the driver switch on-

resistances.

ing the conversions at lower resolutions reduces the amount of

time it takes for the A/D converter to complete its conversion

process, which lowers power consumption.

Conversion Clock and Conversion Time

The TSC2200 contains an internal 8MHz clock, which is used

to drive the state machines inside the device that perform the

many functions of the part. This clock is divided down to

provide a clock to run the A/D converter. The division ratio for

this clock is set in the A/D Converter Control Register. The

ability to change the conversion clock rate allows the user to

choose the optimal value for resolution, speed, and power. If

the 8MHz clock is used directly, the A/D converter is limited to

8-bit resolution; using higher resolutions at this speed will not

result in accurate conversions. Using a 4MHz conversion

clock is suitable for 10-bit resolution; 12-bit resolution requires

that the conversion clock run at 1MHz or 2MHz.

The A/D converter is controlled by an A/D Converter Control

Register. Several modes of operation are possible, depend-

ing upon the bits set in the control register. Channel selec-

tion, scan operation, averaging, resolution, and conversion

rate may all be programmed through this register. These

modes are outlined in the sections below for each type of

analog input. The results of conversions made are stored in

the appropriate result register.

Data Format

The TSC2200 output data is in Straight Binary format, as

shown in Figure 5. This figure shows the ideal output code for

the given input voltage and does not include the effects of

offset, gain, or noise.

Regardless of the conversion clock speed, the internal clock

will run nominally at 8MHz. The conversion time of the

TSC2200 is dependent upon several functions. Although the

conversion clock speed plays an important role in the time it

takes for a conversion to complete, a certain number of

internal clock cycles is needed for proper sampling of the

signal. Moreover, additional times, such as the Panel Voltage

Stabilization time, can add significantly to the time it takes to

perform a conversion. Conversion time can vary depending

upon the mode in which the TSC2200 is used. Throughout

this data sheet, internal and conversion clock cycles will be

used to describe the times that many functions take. In

considering the total system design, these times must be

taken into account by the user.

(1)

FS = Full-Scale Voltage = V_REF

1LSB = V_REF⁽¹⁾/4096

1LSB

11...111

11...110

11...101

Touch Detect

00...010

00...001

00...000

The pen interrupt (PENIRQ) output function is detailed in

Figure 6. While in the power-down mode, the Y– driver is ON

and connected to GND and the PENIRQ output is connected

to the X+ input. When the panel is touched, the X+ input is

0V

FS – 1LSB

Input Voltage⁽²⁾(V)

NOTES: (1) Reference voltage at converter: +REF – (–REF). See Figure 4.

(2) Input voltage at converter, after multiplexer: +IN – (–IN). See Figure 4.

PENIRQ

V_DD

FIGURE 5. Ideal Input Voltages and Output Codes.

TEMP1

TEMP2

50kΩ

Y+

HIGH Except

when TEMP1,

Reference

TEMP2 Activated

TEMP

DIODE

The TSC2200 has an internal voltage reference that can be

set to 1.25V or 2.5V, through the Reference Control Register.

X+

The internal reference voltage is only used in the single-

ended mode for battery monitoring, temperature measure-

ment, and for utilizing the auxiliary inputs. Optimal touch

screen performance is achieved when using a ratiometric

conversion, thus all touch screen measurements are done

automatically in the differential mode. An external reference

can also be applied to the V_REFpin, and the internal refer-

ence can be turned off.

Y–

ON

Y+ or X+ Drivers On,

or TEMP1, TEMP2

Measurements Activated

Variable Resolution

FIGURE 6. PENIRQ Functional Block Diagram.

The TSC2200 provides three different resolutions for the A/D

converter: 8-, 10-, or 12-bits. Lower resolutions are often

practical for measurements such as touch pressure. Perform-

TSC2200

SBAS191F

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pulled to ground through the touch screen and PENIRQ

output goes LOW due to the current path through the panel

to GND, initiating an interrupt to the processor. During the

measurement cycles for the X- and Y-positions, the X+ input

will be disconnected from the PENIRQ pull-down transistor to

eliminate any leakage current from the pull-up resistor to flow

through the touch screen, thus causing no errors.

The idle state of the serial clock for the TSC2200 is LOW,

which corresponds to a clock polarity setting of 0 (typical

microprocessor SPI control bit CPOL = 0). The TSC2200

interface is designed so that with a clock phase bit setting of

1 (typical microprocessor SPI control bit CPHA = 1), the

master begins driving its MOSI pin and the slave begins

driving its MISO pin on the first serial clock edge. The SS pin

should idle HIGH between transmissions. The TSC2200 will

only interpret command words that are transmitted after the

In modes where the TSC2200 needs to detect if the screen

is still touched (for example, when doing a PENIRQ-initiated

X, Y, and Z conversion), the TSC2200 must reset the drivers

so that the 50kΩ resistor is connected again. Due to the high

value of this pull-up resistor, any capacitance on the touch

screen inputs will cause a long delay time, and may prevent

the detection from occurring correctly. To prevent this, the

TSC2200 has a circuit that allows any screen capacitance to

be “precharged”, so that the pull-up resistor does not have to

be the only source for the charging current. The time allowed

for this precharge, as well as the time needed to sense if the

screen is still touched, can be set in the Configuration Control

register.

falling edge of SS

.

TSC2200 COMMUNICATION PROTOCOL

The TSC2200 is entirely controlled by registers. Reading and

writing these registers is accomplished by the use of a 16-bit

command, which is sent prior to the data for that register. The

command is constructed as shown in Table I.

The command word begins with an R/W bit, which specifies

the direction of data flow on the serial bus. The following four

bits specify the page of memory this command is directed to,

as shown in Table II. The next six bits specify the register

address on that page of memory to which the data is

directed. The last five bits are reserved for future use.

This illustrates the need to use the minimum capacitor values

possible on the touch screen inputs. These capacitors may

be needed to reduce noise, but too large a value will increase

the needed precharge and sense times, as well as panel

voltage stabilization time.

PG3

PG2

PG1

PG0

PAGE ADDRESSED

0

1

0

1

0

1

0

1

0

1

0

1

0

1

0

1

0

1

0

1

0

1

0

1

0

1

0

1

0

1

0

1

DIGITAL INTERFACE

Reserved

The TSC2200 communicates through a standard SPI bus.

The SPI allows full-duplex, synchronous, serial communica-

tion between a host processor (the master) and peripheral

devices (slaves). The SPI master generates the synchroniz-

ing clock and initiates transmissions. The SPI slave devices

depend on a master to start and synchronize transmissions.

A transmission begins when initiated by a master SPI. The

byte from the master SPI begins shifting in on the slave

MOSI pin under the control of the master serial clock. As the

byte shifts in on the MOSI pin, a byte shifts out on the MISO

pin to the master shift register.

TABLE II. Page Addressing.

MSB

LSB

BIT 15 BIT 14 BIT 13 BIT 12

BIT 11 BIT 10

BIT 9

BIT 8

BIT 7

BIT 6

BIT 5

BIT 4

BIT 3

BIT 2

BIT 1

BIT 0

R/W PG3 PG2 PG1

PG0

ADDR5 ADDR4 ADDR3 ADDR2 ADDR1 ADDR0

X

TABLE I. TSC2200 Command Word.

TSC2200

12

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SBAS191F

To read all the first page of memory, for example, the host

processor must send the TSC2200 the command 8000_H—this

specifies a read operation beginning at Page 0, Address 0. The

processor can then start clocking data out of the TSC2200. The

TSC2200 will automatically increment its address pointer to the

end of the page; if the host processor continues clocking data

out past the end of a page, the TSC2200 will simply send back

the value FFFF_H.

PAGE 0: DATA REGISTERS

PAGE 1: CONTROL REGISTERS

ADDR

REGISTER

ADDR

REGISTER

00

01

02

03

04

05

06

07

08

09

0A

0B

0C

0D

0E

0F

10

11

12

13

14

15

16

17

18

19

1A

1B

1C

1D

1E

1F

X

Y

Z₁

Z₂

00

01

02

03

04

05

06

07

08

09

0A

0B

0C

0D

0E

0F

10

11

12

13

14

15

16

17

18

19

1A

1B

1C

1D

1E

1F

ADC

KEY

DACCTL

REF

RESET

KPDATA

BAT1

BAT2

AUX1

AUX2

CONFIG

Reserved

KPMASK

Reserved

Likewise, writing to Page 1 of memory would consist of the

processor writing the command 0800_H, which would specify a

write operation, with PG0 set to 1, and all the ADDR bits set

to 0. This would result in the address pointer pointing at the

first location in memory on Page 1. See the TSC2200 Memory

Map section for details of register locations. Figure 7 shows an

example of a complete data transaction between the host

processor and the TSC2200.

TEMP1

TEMP2

DAC

Reserved

ZERO

Reserved

TSC2200 MEMORY MAP

The TSC2200 has several 16-bit registers that allow control of

the device as well as provide a location for results from the

TSC2200 to be stored until read by the host microprocessor.

These registers are separated into two pages of memory in the

TSC2200: a Data page (Page 0) and a Control page (Page 1).

The memory map is shown in Table III.

TABLE III. TSC2200 Memory Map.

Write Operation

SS

Read Operation

SCLK

MOSI

MISO

Command Word

Data

Command Word

Data

FIGURE 7. Write and Read Operation of TSC2200 Interface.

TSC2200

SBAS191F

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the TSC2200, bits in control registers may refer to slightly

different functions depending upon if you are reading the

register or writing to it. A summary of all registers and bit

locations is shown in Table IV.

TSC2200 CONTROL REGISTERS

This section will describe each of the registers that were

shown in the memory map of Table III. The registers are

grouped according to the function they control. Note that in

RESET

VALUE

ADDR REGISTER

PAGE

(HEX)

NAME

D15 D14

D13 D12 D11

D10

D9

D8

D7

D6

D5

D4

D3

D2

D1

D0

(HEX)

0

1

00

01

02

03

04

05

06

07

08

09

0A

0B

0C

0D

0E

0F

10

11

12

13

14

15

16

17

18

19

1A

1B

1C

1D

1E

1F

00

01

02

03

04

05

06

07

08

09

0A

0B

0C

0D

0E

0F

10

11

12

13

14

15

16

17

18

19

1A

1B

1C

1D

1E

1F

X

Y

Z₁

Z₂

0

R11

R10

K10

R10

X

1

0

1

R9

K9

R9

X

1

0

1

R8

K8

R8

X

1

0

1

R7

K7

R7

D7

1

0

1

R6

K6

R6

D6

1

0

1

R5

K5

R5

D5

1

0

1

R4

K4

R4

D4

1

0

1

R3

K3

R3

D3

1

0

1

R2

K2

R2

D2

1

0

1

R1

K1

R1

D1

1

0

1

R0

K0

R0

D0

1

0

1

x

X

0

0000

007F

FFFF

0000

FFFF

4000

8000

0002

FFFF

FFC0

FFFF

0000

FFFF

KPDATA

BAT1

BAT2

AUX1

AUX2

TEMP1

TEMP2

DAC

Reserved

ZERO

Reserved

ADC

K15 K14

K13 K12 K11

0

X

1

0

1

0

X

1

0

1

0

X

1

0

1

0

X

1

0

1

R11

X

1

0

1

PSM STS AD3 AD2 AD1 AD0 RS1 RS0 AV1 AV0 CL1 CL0 PV2 PV1 PV0

STC SCS DB2 DB1 DB0

DPD

X

1

KEY

DACCTL

REF

X

0

X

0

1

X

0

X

1

X

0

X

1

M8

1

X

0

X

1

M7

1

X

0

X

0

X

0

INT

X

0

X

0

X

0

X

0

1

0

X

1

0

X

1

0

X

1

DL1 DL0 PND RFV

X

RESET

X

CONFIG

Reserved

KPMASK

Reserved

DAVB PR2 PR1 PR0 SN2 SN1 SN0

1

M6

1

M5

1

M4

1

M3

1

M2

1

M1

1

M0

1

M15 M14 M13 M12 M11 M10 M9

1

NOTE: X = Don’t Care.

TABLE IV. Register Summary for TSC2200.

TSC2200

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SBAS191F

TSC2200 A/D CONVERTER CONTROL REGISTER

(PAGE 1, ADDRESS 00_H)

lifted or the process is stopped. Continuous scans or conver-

sions can be stopped by writing a 1 to this bit. This will

immediately halt a conversion (even if the pen is still down)

and cause the A/D converter to power down. The default

state is continuous conversions, but if this bit is read after a

reset or power-up, it will read 1.

The A/D converter in the TSC2200 is shared between all the

different functions. A control register determines which input

is selected, as well as other options. The result of the

conversion is placed in one of the result registers in Page 0

of memory, depending upon the function selected.

STS

The A/D Converter Control Register controls several aspects

of the A/D converter. The register is formatted as shown in

Table VI.

READ/WRITE VALUE

DESCRIPTION

Read

Write

0

1

0

1

Converter is Busy

Conversions are Complete, Data is Available

Normal Operation

Bit 15: PSM—Pen Status/Control Mode. Reading this bit

allows the host to determine if the screen is touched. Writing

to this bit determines the mode used to read coordinates:

host controlled, or under control of the TSC2200 responding

to a screen touch. When reading, the PENSTS bit indicates

if the pen is down or not. When writing to this register, this bit

determines if the TSC2200 controls the reading of coordi-

nates, or if the coordinate conversions are host-controlled.

The default state is host-controlled conversions (0).

Stop Conversion and Power Down

TABLE VII. STS Bit Operation.

Bits [13:10]: AD3–AD0—A/D Converter Function Select.

These bits control which input is to be converted, and what

mode the converter is placed in. These bits are the same

whether reading or writing. A complete listing of how these

bits are used is shown in Table VIII.

Bits[9:8]: RS1, RS0—Resolution Control. The A/D converter

resolution is specified with these bits. A description of these

bits is shown in Table IX. These bits are the same whether

reading or writing.

PSM

READ/WRITE

VALUE

DESCRIPTION

Read

Write

0

1

0

1

No Screen Touch Detected

Screen Touch Detected

Conversions Controlled by Host

Conversions Controlled by TSC2200

RS1

RS0

FUNCTION

TABLE V. PSM Bit Operation.

0

1

0

1

0

1

12-Bit Resolution. Power up and reset default.

8-Bit Resolution

Bit 14: STS—A/D Converter Status. When reading, this bit

indicates if the converter is busy, or if conversions are

complete and data is available. Writing a 0 to this bit will

cause touch screen scans to continue until either the pen is

10-Bit Resolution

12-Bit Resolution

TABLE IX. A/D Converter Resolution Control.

MSB

LSB

BIT 15 BIT 14 BIT 13 BIT 12 BIT 11

BIT 10 BIT 9 BIT 8

AD0 RS1 RS0

BIT 7

BIT 6

BIT 5

BIT 4

BIT 3

BIT 2

BIT 1

BIT 0

PSM STS AD3 AD2 AD1

AV1

AV0

CL1

CL0

PV2

PV1

PV0

X

TABLE VI. A/D Converter Control Register.

A/D3

A/D2

A/D1

A/D0

FUNCTION

Invalid. No registers will be updated. This is the default state after a reset.

0

1

Touch screen scan function: X and Y coordinates converted and the results returned to the X and Y data registers.

Scan continues until either the pen is lifted or a stop bit is sent.

0

1

0

Touch screen scan function: X, Y, Z₁, and Z₂coordinates converted and the results returned to the X, Y, Z₁, and Z₂

data registers. Scan continues until either the pen is lifted or a stop bit is sent.

0

1

0

1

0

1

0

1

0

1

0

1

0

1

0

1

0

1

Touch screen scan function: X coordinate converted and the results returned to the X data register.

Touch screen scan function: Y coordinate converted and the results returned to the Y data register.

Touch screen scan function: Z₁and Z₂coordinates converted and the results returned to the Z₁and Z₂data registers.

Battery Input 1 converted and the results returned to the BAT1 data register.

Battery Input 2 converted and the results returned to the BAT2 data register.

Auxiliary Input 1 converted and the results returned to the AUX1 data register.

Auxiliary Input 2 converted and the results returned to the AUX2 data register.

A temperature measurement is made and the results returned to the temperature measurement 1 data register.

Port scan function: Battery Input 1, Battery Input 2, Auxiliary Input 1, and Auxiliary Input measurements are made

and the results returned to the appropriate data registers.

1

0

A differential temperature measurement is made and the results returned to the temperature measurement 2 data

register.

1

0

1

0

1

Turn on X+, X– drivers.

Turn on Y+, Y– drivers.

Turn on Y+, X– drivers.

TABLE VIII. A/D Converter Function Select.

TSC2200

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Bits[7:6]: AV1, AV0—Converter Averaging Control. These

two bits allow you to specify the number of averages the

converter will perform, as shown in Table X. Note that when

averaging is used, the STS bit and the DAV output will

indicate that the converter is busy until all conversions

necessary for the averaging are complete. The default state

for these bits is 00, selecting no averaging. These bits are the

same whether reading or writing.

D/A CONVERTER CONTROL REGISTER

(PAGE 1, ADDRESS 02_H)

The single bit in this register controls the power down control

of the onboard D/A converter. This register is formatted as

shown in Table XIII.

Bit 15: DPD—D/A Converter Power Down. This bit controls

whether the D/A converter is powered up and operational, or

powered down. If the D/A converter is powered down, the

A_OUTpin will neither sink nor source current.

AV1

AV0

FUNCTION

0

1

0

1

0

1

None

DPD

4 Data Averages

8 Data Averages

16 Data Averages

VALUE

DESCRIPTION

0

1

D/A Converter is Powered and Operational

D/A Converter is Powered Down

TABLE X. A/D Conversion Averaging Control.

TABLE XIV. DPD Bit Operation.

Bits[5:4]: CL1, CL0—Conversion Clock Control. These two

bits specify the internal clock rate which the A/D converter uses

when performing a single conversion, as shown in Table XI.

These bits are the same whether reading or writing.

REFERENCE REGISTER

(PAGE 1, ADDRESS 03_H)

The TSC2200 has a register to control the operation of the

internal reference. This register is formatted as shown in

Table XV.

CL1

CL0

FUNCTION

0

1

0

1

0

1

8MHz Internal Clock Rate—8-Bit Resolution Only

4MHz Internal Clock Rate—10-Bit Resolution Only

2MHz Internal Clock Rate

Bit 4: INT—Internal Reference Mode. If this bit is written to a

1, the TSC2200 will use its internal reference; if this bit is a

zero, the part will assume an external reference is being

supplied. The default state for this bit is to select an external

reference (0). This bit is the same whether reading or writing.

1MHz Internal Clock Rate

TABLE XI. A/D Converter Clock Control.

Bits [3:1]: PV2 – PV0—Panel Voltage Stabilization Time

control. These bits allow you to specify a delay time from the

time a pen touch is detected to the time a conversion is

started. This allows you to select the appropriate settling time

for the touch panel used. Table XII shows the settings of

these bits. The default state is 000, indicating a 0ms stabili-

zation time. These bits are the same whether reading or

writing.

INT

VALUE

DESCRIPTION

0

1

External Reference Selected

Internal Reference Selected

TABLE XVI. INT Bit Operation.

Bits [3:2]: DL1, DL0—Reference Power-Up Delay. When

the internal reference is powered up, a finite amount of time

is required for the reference to settle. If measurements are

made before the reference has settled, these measurements

will be in error. These bits allow for a delay time for measure-

ments to be made after the reference powers up, thereby

assuring that the reference has settled. Longer delays will be

necessary depending upon the capacitance present at the

REF pin (see Typical Characteristics).

Bit 0: This bit is not used, and is a “don’t care” when writing.

It will always read as a zero.

PV2

PV1

PV0

FUNCTION

0

1

0

1

0

1

0

1

0

1

0

1

0

1

0µs Stabilization Time

100µs Stabilization Time

500µs Stabilization Time

1ms Stabilization Time

5ms Stabilization Time

10ms Stabilization Time

50ms Stabilization Time

100ms Stabilization Time

See Table XVII for the delays. The default state for these bits

is 00, selecting a 0µs delay. These bits are the same whether

reading or writing.

TABLE XII. Panel Voltage Stabilization Time Control.

MSB

LSB

BIT 15 BIT 14 BIT 13 BIT 12 BIT 11

BIT 10 BIT 9 BIT 8

BIT 7

BIT 6

BIT 5

BIT 4

BIT 3

BIT 2

BIT 1

BIT 0

DPD

X

TABLE XIII. D/A Converter Control Register.

MSB

LSB

BIT 15 BIT 14 BIT 13 BIT 12 BIT 11

BIT 10 BIT 9 BIT 8

BIT 7

BIT 6

BIT 5

BIT 4

BIT 3

BIT 2

BIT 1

BIT 0

X

INT

DL1

DL0

PDN

RFV

TABLE XV. Reference Register.

TSC2200

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SBAS191F

the register(s) updated by the conversion have been read.

When all updated data has been read by the host, the DAV

pin and this bit will return to a logic 1 (HIGH).

DL1

DL0

DELAY TIME

0

1

0

1

0

1

0µs

100µs

500µs

1000µs

DAVB

TABLE XVII. Reference Power-Up Delay Settings.

VALUE

DESCRIPTION

0

Data from A/D conversion is available. This will stay at 0

until the host has read all updated registers.

No new data is available.

Bit 1: PDN—Reference Power Down. If a 1 is written to this

bit, the internal reference will be powered down between

conversions. If this bit is a zero, the internal reference will be

powered at all times. The default state is to power down the

internal reference, so this bit will be a 1. This bit is the same

whether reading or writing.

1

TABLE XXII. PDN Bit Operation.

Bits [5:3]: PRE[2:0]—Precharge Time Selection. These bits

set the amount of time allowed for precharging any pin

capacitance on the touch screen prior to sensing if a screen

touch is happening.

PDN

VALUE

DESCRIPTION

PRE[2:0]

0

1

Internal Reference is Powered at All Times

Internal Reference is Powered Down Between Conversions

PRE2

PRE1

PRE0

TIME

0

1

0

1

0

1

0

1

0

1

0

1

0

1

20µs

84µs

276µs

340µs

1.044ms

1.108ms

1.300ms

1.364ms

TABLE XVIII. PDN Bit Operation.

Note that the PDN bit, in concert with the INT bit, creates a

few possibilities for reference behavior. These are detailed in

Table XIX.

TABLE XXIII. Precharge Times.

INT

PDN

REFERENCE BEHAVIOR

0

1

External Reference Used, Internal Reference Powered Down

External Reference Used, Interenal Reference Powered Down

Bits [2:0]: SNS[2:0]—Sense Time Selection. These bits set

the amount of time the TSC2200 will wait to sense a screen

1

0

1

Internal Reference Used, Always Powered Up

touch between coordinate axis conversions in PENIRQ

controlled mode.

-

Internal Reference Used, Will Power Up During Conversions

and Then Power Down

TABLE XIX. Reference Behavior Possibilities.

SNS[2:0]

SNS2

SNS1

SNS0

TIME

Bit 0: RFV—Reference Voltage control. This bit selects the

internal reference voltage, either 1.25V or 2.5V. The default

value is 1.25V. This bit is the same whether reading or writing.

0

1

0

1

0

1

0

1

0

1

0

1

0

1

32µs

96µs

544µs

608µs

2.080ms

2.144ms

2.592ms

2.656ms

RFV

VALUE

DESCRIPTION

0

1

1.25V Reference Voltage

2.5V Reference Voltage

TABLE XXIV. Sense Times.

TABLE XX. RFV Bit Operation.

TSC2200 KEYPAD REGISTERS

TSC2200 CONFIGURATION CONTROL REGISTER

(PAGE 1, ADDRESS 05_H)

The Keypad scanner hardware in the TSC2200 is controlled

by two registers: the Keypad Control register and the Keypad

Mask register. The Keypad Control register controls general

keypad functions such as scanning and de-bouncing, whereas

the Keypad Mask register allows certain keys to be masked

from being detected at all.

This control register controls the configuration of the precharge

and sense times for the touch detect circuit. The register is

formatted as shown in Table XXI.

Bit 6: DAVB = Data Available. This bit mirrors the operation

of the DAV pin. When any conversion is complete, the DAV

pin and this bit will be a logic 0 (LOW). It will stay LOW until

MSB

LSB

BIT 15 BIT 14 BIT 13 BIT 12 BIT 11

BIT 10 BIT 9 BIT 8

BIT 7

BIT 6

BIT 5

BIT 4

BIT 3

BIT 2

BIT 1

BIT 0

X

PRE2

PRE1

PRE0

SNS2

SNS1

SNS0

TABLE XXI. Configuration Control Register.

TSC2200

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KEYPAD CONTROL REGISTER

(PAGE 1, ADDRESS 01_H)

KEYPAD MASK REGISTER

(PAGE 1, ADDRESS 10_H)

The Keypad Control register is formatted as shown in Table XXV.

The Keypad Mask register is formatted as shown in Table XXIX.

This is the same format as used in the Keypad Data register

(Page 0, Address 04_H). Each bit in these registers represents

one key on the keypad. In the Mask register, if a bit is set (1),

then that key will not be detected in keyboard scans. Pressing

that key on the keypad will also not cause a KBIRQ, if the bit is

set. If the bit is cleared (0), the corresponding key will be

detected. A 16-key keypad is mapped into the Keypad Mask

(and Keypad Data) register, as shown in Table XXX. The default

value for this register is 0000_H, detecting all key presses.

Bit 15: STC = Keyboard Status. This bit reflects the opera-

tion of the KBIRQ pin, with inverted logic. This bit will go

HIGH when a key is pressed and de-bounced. The default

value for this bit is zero.

STC

VALUE

DESCRIPTION

0

1

No Keys Are Pressed

Keys Pressed and De-Bounced

TABLE XXVI. STC Bit Operation.

C1

C2

C3

C4

R1

R2

R3

R4

K0

K4

K8

K1

K5

K9

K2

K6

K10

K14

K3

K7

K11

K15

Bit 14: SCS = Keyboard Scan Status. When reading, this bit

indicates if the scanner or de-bouncer is busy or if scans are

complete and data is available. Writing a zero to this bit will

cause keyboard scans to continue until either the key is lifted

or the process is stopped. Continuous scans can be stopped

by writing a 1 to this bit. This will immediately halt a conver-

sion (even if a key is still down). The default value for this bit

when read is 1.

K12

K13

TABLE XXX. Keypad to Key Bit Mapping.

The result of a keypad scan will appear in the Keypad Data

register. Each bit will be set in this register, corresponding to

the key(s) actually pressed. For example, if only KEY1 was

pressed on a particular scan, the data in the register would

read as 0002_H; however, if keys 6, 8, and 13 were all pressed

simultaneously on that scan, the data would read as 2140_H.

SCS

READ/WRITE

VALUE

DESCRIPTION

Read

Write

0

1

0

1

Scanner or De-Bouncer Busy

Scans are Complete, Data is Available

Normal Operation

Multiple keys may be pressed simultaneously, and will generally

be decoded correctly by the keypad scan circuitry. However,

keys that land on three corners of a rectangle may cause a false

reading of a key on the fourth corner of the rectangle. For

example, if 0, 3, and 11 were pressed simultaneously, the

KEY0, KEY3, and KEY11 bits will be set, but the KEY8 bit will

also be set. Thus, when considering using multiple-key combi-

nations in an application, try to avoid combinations that put

three keys on the corners of a rectangle.

Stop Scans

TABLE XXVII. SCS Bit Operation.

Bits [13:11]: KBDB2-KBDB0 = Keyboard De-Bounce Con-

trol. These bits set the length of the de-bounce time for the

keypad, as shown in Table XXVIII. The default setting is a

2ms de-bounce time (000).

RESET REGISTER

(PAGE 1, ADDRESS 04_H)

KBDB2

KBDB1

KBDB0

FUNCTION

0

1

0

1

0

1

0

1

0

1

0

1

0

1

De-Bounce: 2ms

De-Bounce: 10ms

De-Bounce: 20ms

De-Bounce: 50ms

De-Bounce: 60ms

De-Bounce: 80ms

De-Bounce: 100ms

De-Bounce: 120ms

The TSC2200 has a special register, the RESET register, which

allows a software reset of the device. Writing the code BBXX_H,

as shown in Table XXXI, to this register will cause the TSC2200

to reset all its registers to their default, power-up values.

Writing any other values to this register will do nothing.

Reading this register or any reserved register will result in

reading back all 1’s, or FFFF_H.

TABLE XXVIII. Keypad De-Bounce Control.

MSB

LSB

BIT 15 BIT 14 BIT 13 BIT 12 BIT 11

BIT 10 BIT 9 BIT 8

BIT 7

BIT 6

BIT 5

BIT 4

BIT 3

BIT 2

BIT 1

BIT 0

STC SCS DB2 DB1 DB0

X

TABLE XXV. Keypad Control Register.

MSB

LSB

BIT 15 BIT 14 BIT 13 BIT 12 BIT 11

BIT 10 BIT 9 BIT 8

M10 M9 M8

BIT 7

BIT 6

BIT 5

BIT 4

BIT 3

BIT 2

BIT 1

BIT 0

M15

M14

M13

M12

M11

M7

M6

M5

M4

M3

M2

M1

M0

TABLE XXIX. Keypad Mask Register.

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SBAS191F

MSB

LSB

BIT 15 BIT 14 BIT 13 BIT 12 BIT 11

BIT 10 BIT 9 BIT 8

BIT 7

BIT 6

BIT 5

BIT 4

BIT 3

BIT 2

BIT 1

BIT 0

1

0

1

0

1

X

TABLE XXXI. Reset Register.

ZERO REGISTER

(PAGE 0, ADDRESS 10_H)

TSC2200 DATA REGISTERS

The data registers of the TSC2200 hold data results from

conversions or keypad scans, or the value of the D/A converter

output current. All of these registers default to 0000_Hupon

reset, except the D/A converter register, which is set to 0080_H,

representing the midscale output of the D/A converter.

This is a reserved data register, but instead of reading all 1’s

(FFFF_H), when read will return all 0’s (0000_H).

OPERATION—TOUCH SCREEN MEASUREMENTS

As noted previously in the discussion of the A/D converter,

several operating modes can be used, which allow great

flexibility for the host processor. These different modes will

now be examined.

X, Y, Z₁, Z₂, BAT1, BAT2, AUX1, AUX2, TEMP1,

AND TEMP2 REGISTERS

The results of all A/D conversions are placed in the appro-

priate data register (see Tables III and VIII). The data format

of the result word, R, of these registers is right-justified, as

shown in Table XXXII.

Conversion Controlled by TSC2200 Initiated at

Touch Detect

In this mode, the TSC2200 will detect when the touch panel is

touched and cause the PENIRQ line to go LOW. At the same

time, the TSC2200 will start up its internal clock. It will then turn

on the Y-drivers, and after a programmed Panel Voltage

Stabilization time, power up the A/D converter and convert the

Y-coordinate. If averaging is selected, several conversions

may take place; when data averaging is complete, the Y-

coordinate result will be stored in the Y-register.

KEYPAD DATA REGISTER

(PAGE 0, ADDRESS 04_H)

The Keypad Data register (Page 0, Address 04_H) is format-

ted as shown in Table XXXIII.

This is the same format as used in the Keypad Mask register

(Page 1, Address 10_H). Each bit in these registers represents

one key on the keypad. A 16-key keypad is mapped into the

Keypad Data register, see Table XXIX.

If the screen is still touched at this time, the X-drivers will be

enabled, and the process will repeat, but instead measuring

the X-coordinate and storing the result in the X-register.

If only X- and Y-coordinates are to be measured, then the

conversion process is complete. See Figure 8 for a flowchart

for this process. The time it takes to go through this process

depends upon the selected resolution, internal conversion

clock rate, averaging selected, panel voltage stabilization

time, and precharge and sense times.

D/A CONVERTER DATA REGISTER

(PAGE 0, ADDRESS 0B_H)

The data to be written to the D/A converter is written into the

D/A converter data register, which is formatted as shown in

Table XXXIV.

MSB

LSB

BIT 15 BIT 14 BIT 13 BIT 12 BIT 11

BIT 10 BIT 9 BIT 8

R10 R9 R8

BIT 7

BIT 6

BIT 5

BIT 4

BIT 3

BIT 2

BIT 1

BIT 0

0

R11

R7

R6

R5

R4

R3

R2

R1

R0

MSB

LSB

TABLE XXXII. Result Data Format.

MSB

LSB

BIT 15 BIT 14 BIT 13 BIT 12 BIT 11

BIT 10 BIT 9 BIT 8

K10 K9 K8

BIT 7

BIT 6

BIT 5

BIT 4

BIT 3

BIT 2

BIT 1

BIT 0

K15

K14

K13

K12

K11

K7

K6

K5

K4

K3

K2

K1

K0

TABLE XXXIII. Keypad Data Register.

MSB

LSB

BIT 15 BIT 14 BIT 13 BIT 12 BIT 11

BIT 10 BIT 9 BIT 8

BIT 7

BIT 6

BIT 5

BIT 4

BIT 3

BIT 2

BIT 1

BIT 0

X

D7

D6

D5

D4

D3

D2

D1

D0

TABLE XXXIV. D/A Converter Register.

TSC2200

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The time needed to get a complete X/Y-coordinate reading

can be calculated by:

N_BITS= Number of Bits of Resolution (see Table IX)

f_CONV= A/D Converter Clock Frequency (see Table XI)

(3)

If the pressure of the touch is also to be measured, the

process will continue in the same way, but measuring the Z₁

and Z₂values, and placing them in the Z₁and Z₂registers

(see Figure 9). As before, this process time depends upon

the settings described above. The time for a complete X, Y,

Z₁, and Z₂coordinate reading is given by:

1

t_COORDINATE= 2.5µs + 2 t_PVS+ t_PRE+ t_SNS+ 2N

N_BITS

•

+ 4.4µs

(

)

AVG

f_CONV

where,

t_COORDINATE= Time to Complete X/Y-Coordinate Reading

t_PVS= Panel Voltage Stabilization time (see Table XII)

t_PRE= Precharge time (see Table XXII)

(4)

1

t_COORDINATE= 4.75µs + 3 t_PVS+ t_PRE+ t_SNS+ 4N

N_BITS

•

+ 4.4µs

(

)

AVG

t_SNS= Sense time (see Table XXIII)

f_CONV

N_AVG= Number of Averages (see Table X); for no averag-

ing, N_AVG= 1

Touch Screen Scan

Screen

Touch

X and Y

Turn On Drivers: X+, X–

PENIRQ Initiated

Issue Interrupt

PENIRQ

No

Is Panel Voltage

Stabilization Done

No

Go to Host-Controlled

Conversion

Is PSM = 1

Yes

Power Up A/D Converter

Yes

Start Clock

Convert Y-Coordinates

Turn On Drivers: Y+, Y–

No

Is Panel Voltage

Stabilization Done

Is Data

Averaging Done

Yes

Store Y-Coordinates in

Y-Register

Power Up A/D Converter

Convert X-Coordinates

Power Down A/D Converter

Issue Data Available

Is Data

No

Averaging Done

Yes

Is Screen

Touched

Yes

Store X-Coordinates in

X-Register

No

Power Down A/D Converter

Turn Off Clock

Reset PENIRQ and

Scan Trigger

Reset PENIRQ and

Scan Trigger

Is Screen

Touched

No

Done

Yes

FIGURE 8. X- and Y-Coordinate Touch Screen Scan, Initiated by Touch.

TSC2200

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SBAS191F

Turn On Drivers: Y+, X–

Touch Screen Scan

X, Y, and Z

PENIRQ Initiated

No

Is Panel Voltage

Stabilization Done

Screen

Touch

Yes

Turn On Drivers: X+, X–

Issue Interrupt

PENIRQ

Power Up A/D Converter

No

Is Panel Voltage

Stabilization Done

Convert Z₁-Coordinates

No

Go to Host-Controlled

Conversion

Is PSM = 1

Yes

No

Is Data

Averaging Done

Power Up A/D Converter

Start Clock

Yes

Turn On Drivers: Y+, Y–

Convert Y-Coordinates

Store Z₁-Coordinates

in Z₁-Register

No

Is Panel Voltage

Stabilization Done

No

Is Data

Averaging Done

Convert Z₂-Coordinates

Yes

Power Up A/D Converter

No

Is Data

Averaging Done

Store Y-Coordinates

in Y-Register

Convert X-Coordinates

Yes

Power Down A/D Converter

Turn Off Clock

Store Z₂-Coordinates

in Z₂-Register

No

Is Data

Averaging Done

Reset PENIRQ and

Scan Trigger

Is Screen

Touched

Power Down A/D Converter

Issue Data Available

Yes

Done

Store X-Coordinates in

X-Register

Power Down A/D Converter

Turn Off Clock

Yes

Is Screen

Touched

Reset PENIRQ and

Scan Trigger

No

Is Screen

Touched

Turn Off Clock

Done

Yes

Reset PENIRQ and

Scan Trigger

Done

FIGURE 9. X- Y- and Z-Coordinate Touch Screen Scan, Initiated by Touch.

TSC2200

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Conversion Controlled by TSC2200 Initiated By

Host Responding to PENIRQ

scan functions. The conversion process then proceeds as

described above, and as outlined in Figures 10 through 14.

The main difference between this mode and the previous

mode is that the host, not the TSC2200, decides when the

touch screen scan begins.

In this mode, the TSC2200 will detect when the touch panel is

touched and cause the PENIRQ line to go LOW. The host will

recognize the interrupt request, and then write to the A/D

Converter Control register to select one of the touch screen

Screen

Touch

Touch Screen Scan

X and Y

Host Initiated

Issue Interrupt

PENIRQ

No

Go to Host-Controlled

Is PSM = 1

Conversion

Done

Host Writes A/D

Converter

Turn On Drivers: X+, X–

Control Register

Reset PENIRQ

Start Clock

No

Is Panel Voltage

Stabilization Done

Yes

Power Up A/D Converter

Turn On Drivers: Y+, Y–

Convert Y-Coordinates

No

Is Panel Voltage

Stabilization Done

Yes

No

Is Data

Averaging Done

Power Up A/D Converter

Yes

Convert X-Coordinates

Store Y-Coordinates

in Y-Register

Is Data

Averaging Done

No

Power Down A/D Converter

Issue Data Available

Yes

Store X-Coordinates in

X-Register

Is Screen

Touched

Yes

Power Down A/D Converter

Turn Off Clock

No

Is Screen

Touched

Turn Off Clock

No

Reset PENIRQ and

Scan Trigger

Done

Yes

FIGURE 10. X- and Y-Coordinate Touch Screen Scan, Initiated by Host.

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SBAS191F

Screen

Touch

Touch Screen Scan

X, Y, and Z

Turn On Drivers: Y+, X–

Host Initiated

Issue Interrupt

PENIRQ

No

Is Panel Voltage

Stabilization Done

No

Go to Host-Controlled

Conversion

Is PSM = 1

Turn On Drivers: X+, X–

Yes

Power Up A/D Converter

Done

No

Is Panel Voltage

Stabilization Done

Host Writes A/D

Converter

Convert Z₁-Coordinates

Control Register

Yes

Reset PENIRQ

Start Clock

Power Up A/D Converter

No

Is Data

Averaging Done

Convert Y-Coordinates

Yes

Store Z₁-Coordinates

in Z₁-Register

Turn On Drivers: Y+, Y–

No

Is Data

Averaging Done

Convert Z₂-Coordinates

No

Is Panel Voltage

Stabilization Done

Yes

Store Y-Coordinates

in Y-Register

Yes

No

Is Data

Averaging Done

Power Up A/D Converter

Power Down A/D Converter

Yes

Turn Off Clock

Convert X-Coordinates

Store Z₂-Coordinates

in Z₂-Register

Reset PENIRQ and

Scan Trigger

Is Screen

Touched

No

Is Data

Averaging Done

No

Power Down A/D Converter

Issue Data Available

Done

Yes

Store X-Coordinates in

X-Register

Is Screen

Touched

Yes

Power Down A/D Converter

Turn Off Clock

No

Is Screen

Touched

Turn Off Clock

No

Reset PENIRQ and

Scan Trigger

Done

Yes

FIGURE 11. X-, Y-, and Z-Coordinate Touch Screen Scan, Initiated by Host.

TSC2200

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Screen

Touch

Touch Screen Scan

X-Coordinate

Host Initiated

Issue Interrupt

PENIRQ

No

Go to Host-Controlled

Is PSM = 1

Convert X-Coordinates

Conversion

Done

No

Is Data

Averaging Done

Host Writes A/D

Converter

Control Register

Yes

Reset PENIRQ

Store X-Coordinates

in X-Register

No

Power Down A/D Converter

Issue Data Available

Start Clock

Are Drivers On

Yes

Turn On Drivers: Y+, Y–

Turn Off Clock

Done

Start Clock

No

Is Panel Voltage

Stabilization Done

Yes

Power Up A/D Converter

FIGURE 12. X-Coordinate Reading Initiated by Host.

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TSC2200

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SBAS191F

Screen

Touch

Touch Screen Scan

Y-Coordinate

Issue Interrupt

PENIRQ

Host Initiated

No

Go to Host-Controlled

Is PSM = 1

Store Y-Coordinates

in Y-Register

Conversion

Done

Power Down A/D Converter

Issue Data Available

Host Writes A/D

Converter

Control Register

Reset PENIRQ

Turn Off Clock

Done

No

Start Clock

Are Drivers On

Yes

Turn On Drivers: X+, X–

Start Clock

No

Is Panel Voltage

Stabilization Done

Yes

Power Up A/D Converter

Convert Y-Coordinates

No

Is Data

Averaging Done

Yes

FIGURE 13. Y-Coordinate Reading Initiated by Host.

TSC2200

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Screen

Touch

Touch Screen Scan

Z-Coordinate

Issue Interrupt

PENIRQ

Host Initiated

No

Go to Host-Controlled

Is PSM = 1

Conversion

Convert Z₂-Coordinates

Done

Host Writes A/D

Converter

Control Register

Is Data

Averaging Done

No

Reset PENIRQ

Are Drivers On

Yes

Store Z₂-Coordinates

in Z₂-Register

No

Start Clock

Power Down A/D Converter

Issue Data Available

Turn Off Clock

Done

Turn On Drivers: Y+, X–

Yes

Start Clock

No

Is Panel Voltage

Stabilization Done

Yes

Power Up A/D Converter

Convert Z₁-Coordinates

Is Data

No

Averaging Done

Yes

Store Z₁-Coordinates

in Z₁-Register

FIGURE 14. Z-Coordinate Reading Initiated by Host.

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SBAS191F

Conversion Controlled by the Host

The process is then repeated for Y- and Z-coordinates. The

processes are outlined in Figures 15 through 17.

In this mode, the TSC2200 will detect when the touch panel

is touched and cause the PENIRQ line to go LOW. The host

will recognize the interrupt request. Instead of starting a

sequence in the TSC2200 which then reads each coordinate

in turn, the host now must control all aspects of the conver-

sion. Generally, upon receiving the interrupt request, the host

will turn on the Y-drivers. After waiting for the settling time,

the host will then address the TSC2200 again, this time

requesting an X-coordinate conversion.

The time needed to convert any single coordinate under host

control (not including the time needed to send the command

over the SPI bus) is given by:

(5)

1

t_COORDINATE= 2.125µs + t_PVS+ N_AVGN_BITS

•

+ 4.4µs

f_CONV

Host-Controlled

X-Coordinate

Host Writes A/D

Converter-

Control Register

Screen

Touch

Issue Interrupt

PENIRQ

No

Start Clock

Are Drivers On

No

Go to Host-Controlled

Conversion

Yes

Is PSM = 1

Turn On Drivers: Y+, Y–

Start Clock

Done

Host Writes A/D

Converter

Control Register

Is Panel Voltage

Stabilization Done

Yes

Power Up A/D Converter

Convert X-Coordinates

No

Reset PENIRQ

Turn On Drivers: Y+, Y–

Done

No

Is Data

Averaging Done

Yes

Store X-Coordinates

in X-Register

Power Down A/D Converter

Issue Data Available

Turn Off Clock

Done

FIGURE 15. X-Coordinate Reading Controlled by Host.

TSC2200

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Host-Controlled

Y-Coordinate

Host Writes A/D

Converter

Control Register

Screen

Touch

Issue Interrupt

PENIRQ

No

Start Clock

Are Drivers On

No

Go to Host-Controlled

Conversion

Yes

Is PSM = 1

Turn On Drivers: X+, X–

Start Clock

Done

Host Writes A/D

Converter

Control Register

Is Panel Voltage

Stabilization Done

Yes

Power Up A/D Converter

Convert Y-Coordinate

No

Reset PENIRQ

Turn On Drivers: X+, X–

Done

No

Is Data

Averaging Done

Yes

Store Y-Coordinates

in Y-Register

Power Down A/D Converter

Issue Data Available

Turn Off Clock

Done

FIGURE 16. Y-Coordinate Reading Controlled by Host.

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TSC2200

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SBAS191F

Screen

Touch

Host-Controlled

Z-Coordinate

Issue Interrupt

PENIRQ

No

Convert Z₂-Coordinates

Go to Host-Controlled

Is PSM = 1

Conversion

Done

No

Is Data

Averaging Done

Host Writes A/D

Converter

Control Register

Yes

Reset PENIRQ

Turn On Drivers: Y+, X–

Done

Store Z₂-Coordinates

in Z₂-Register

Power Down A/D Converter

Issue Data Available

Host Writes A/D

Converter

Control Register

Turn Off Clock

Done

Reset PENIRQ

No

Is Data

Averaging Done

Start Clock

Turn On Drivers: Y+, X–

Yes

Start Clock

No

Is Panel Voltage

Stabilization Done

Yes

Power Up A/D Converter

Convert Z₁-Coordinates

No

Is Data

Averaging Done

Yes

Store Z₁-Coordinates

in Z₁-Register

FIGURE 17. Z-Coordinate Reading Controlled by Host.

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OPERATION—TEMPERATURE MEASUREMENT

Host Writes

A/D Converter

Control Register

In some applications, such as battery recharging, a measure-

ment of ambient temperature is required. The temperature

measurement technique used in the TSC2200 relies on the

characteristics of a semiconductor junction operating at a

fixed current level. The forward diode voltage (V_BE) has a

well-defined characteristic versus temperature. The ambient

temperature can be predicted in applications by knowing the

25°C value of the V_BEvoltage and then monitoring the delta

of that voltage as the temperature changes.

Temperature Input 1

Start Clock

Power Up Reference

Power Up

A/D Converter

Power Down

A/D Converter

The TSC2200 offers two modes of temperature measurement.

The first mode requires calibration at a known temperature, but

only requires a single reading to predict the ambient tempera-

ture. A diode, shown in Figure 18, is used during this measure-

ment cycle. This voltage is typically 600mV at +25°C with a

20µA current through it. The absolute value of this diode voltage

can vary by a few millivolts; the temperature coefficient (TC) of

this voltage is very consistent at –2.1mV/°C. During the final test

of the end product, the diode voltage would be stored at a

known room temperature, in system memory, for calibration

purposes by the user. The result is an equivalent temperature

measurement resolution of 0.3°C/LSB. This measurement of

what is referred to as Temperature 1 is illustrated in Figure 19.

Convert

Temperature Input 1

Power Down Reference

Issue Data Available

Is Data

Averaging Done

No

Turn Off Clock

Done

Yes

Store Temperature

Input 1 in TEMP1

Register

FIGURE 19. Single Temperature Measurement Mode.

X+

A/D

MUX

Converter

Host Writes

A/D Converter

Control Register

Temperature Input 2

Start Clock

Temperature Select

TEMP0 TEMP1

Power Up Reference

FIGURE 18. Functional Block Diagram of Temperature

Measurement Mode.

Power Up

A/D Converter

Power Down

A/D Converter

The second mode does not require a test temperature

calibration, but uses a two-measurement (differential) method

to eliminate the need for absolute temperature calibration

and for achieving 2°C/LSB accuracy. This mode requires a

second conversion with a 91 times larger current. The

voltage difference between the first (TEMP1) and second

(TEMP2) conversion, using 91 times the bias current, will be

represented by kT/q • ln (N), where N is the current

ratio = 91, k = Boltzmann’s constant (1.38054 • 10^-23

electrons volts/degrees Kelvin), q = the electron charge

(1.602189 • 10^-19°C), and T = the temperature in degrees

Kelvin. This method can provide much improved absolute

temperature measurement, but less resolution of 2°C/LSB.

The resultant equation for solving for °K is:

Convert

Temperature Input 2

Power Down Reference

Issue Data Available

Is Data

Averaging Done

No

Turn Off Clock

Done

Yes

Store Temperature

Input 2 in TEMP2

Register

q • ∆V

FIGURE 20. Additional Temperature Measurement for Differential

Temperature Reading.

°K =

(6)

k • ln(N)

where,

∆V = V I − V I

in mV

(

)

(

)

( )

91

1

°K = 2.573∆V°K/mV

°C = 2.573 • ∆V mV − 273°K

(

)

Figure 20 shows the Temperature 2 measurement.

TSC2200

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SBAS191F

OPERATION—BATTERY MEASUREMENT

Host Writes

A/D Converter

Control Register

An added feature of the TSC2200 is the ability to monitor the

battery voltage on the other side of a voltage regulator

(DC/DC converter), as shown in Figure 21. The battery

voltage can vary from 0.5V to 6V while maintaining the

voltage to the TSC2200 at 2.7V, 3.3V, etc. The input voltage

(V_BAT1or V_BAT2) is divided down by 4 so that a 6.0V battery

voltage is represented as 1.5V to the A/D converter. This

simplifies the multiplexer and control logic. In order to mini-

mize the power consumption, the divider is only ON during

the sampling of the battery input.

Battery Input 1

Start Clock

Power Up Reference

Power Up

A/D Converter

Power Down

A/D Converter

Convert

Battery Input 1

Power Down Reference

Issue Data Available

2.7V

DC/DC

Converter

Battery

0.5V

to

+

Is Data

Averaging Done

No

6.0V

V_DD

Turn Off Clock

Done

Yes

Store Battery Input 1

in BAT1 Register

0.125V to 1.5V

V_BAT

7.5kΩ

2.5kΩ

FIGURE 22. V_BAT1Measurement Process.

Host Writes

A/D Converter

Control Register

Battery Input 2

Start Clock

FIGURE 21. Battery Measurement Functional Block Diagram.

Power Up Reference

Flowcharts that detail the process of making a battery input

reading are shown in Figures 22 and 23.

Power Up

A/D Converter

Power Down

A/D Converter

The time needed to make temperature, auxiliary, or battery

measurements is given by:

(7)

Convert

Battery Input 2

Power Down Reference

Issue Data Available

1

t_READING= 2.625µs + t_REF+ N_AVGN_BITS

•

+ 4.4µs

f_CONV

where t_REFis the reference delay time as given in Table XVII.

Is Data

Averaging Done

No

Turn Off Clock

Done

Yes

Store Battery Input 2

in BAT2 Register

FIGURE 23. V_BAT2Measurement Process.

TSC2200

SBAS191F

31

www.ti.com

OPERATION—AUXILIARY MEASUREMENT

OPERATION—PORT SCAN

The two auxiliary voltage inputs can be measured in much

the same way as the battery inputs, as shown in Figures 24

and 25. Applications might include external temperature

sensing, ambient light monitoring for controlling the back-

light, or sensing the current drawn from the battery.

If making measurements of all the analog inputs (except the

touch screen) is desired on a periodic basis, the Port Scan

mode can be used. This mode causes the TSC2200 to

sample and convert both battery inputs and both auxiliary

inputs. At the end of this cycle, the battery and auxiliary result

registers will contain the latest values. Thus, with one write

to the TSC2200, the host can cause four different measure-

ments to be made.

Host Writes

A/D Converter

The flowchart for this process is shown in Figure 26. The time

needed to make a complete port scan is given by:

Control Register

Auxiliary Input 1

Start Clock

1

t_READING= 7.5µs+ t_REF+ 4N_AVGN_BITS

•

+ 4.4µs

(8)

f_CONV

Power Up Reference

Power Up

A/D Converter

Port Scan

Power Down

A/D Converter

Convert

Auxiliary Input 1

Convert

Auxiliary Input 1

Host Writes

A/D Converter

Control Register

Power Down Reference

Is Data

Averaging Done

No

Issue Data Available

Start Clock

Is Data

No

Averaging Done

Turn Off Clock

Done

Power Up Reference

Yes

Store Auxiliary Input 1

in AUX1 Register

Power Up

A/D Converter

Store Auxiliary Input 1

in AUX1 Register

Convert

Battery Input 1

FIGURE 24. AUX1 Measurement Process.

Convert

Auxiliary Input 2

Host Writes

A/D Converter

Control Register

Is Data

Averaging Done

No

Is Data

Averaging Done

No

Auxiliary Input 2

Yes

Start Clock

Yes

Store Battery Input 1

in BAT1 Register

Power Up Reference

Store Auxiliary Input 2

in AUX2 Register

Power Up

Convert

A/D Converter

Battery Input 2

Power Down

A/D Converter

Convert

Auxiliary Input 2

Power Down Reference

Issue Data Available

Is Data

Averaging Done

No

Power Down Reference

Is Data

Averaging Done

No

Issue Data Available

Yes

Store Battery Input 2

in BAT2 Register

Turn Off Clock

Done

Turn Off Clock

Done

Yes

Store Auxiliary Input 2

in AUX2 Register

FIGURE 26. Port Scan Mode.

FIGURE 25. AUX2 Measurement Process.

TSC2200

32

www.ti.com

SBAS191F

OPERATION—D/A CONVERTER

0.9

0.8

0.7

0.6

0.5

0.4

0.3

0.2

0.1

0

The TSC2200 has an onboard 8-bit D/A converter, config-

ured as shown in Figure 27. This configuration yields a

current sink (A_OUT) controlled by the value of a resistor

connected between the ARNG pin and ground. The D/A

converter has a control register that controls whether or not

the converter is powered up. The 8-bit data is written to the

D/A converter through the D/A converter data register.

V+

10k

100k

1M

10M

100M

R₁

ARNG Resistor (Ω)

V_BIAS

R₂

FIGURE 28. D/A Converter Output Current Range versus

RRNG Resistor Value.

A_OUT

D/A Converter

8 Bits

For example, consider an LCD that has a contrast control

voltage V_BIASthat can range from 2V to 4V, which draws

400µA when used, and an available +5V supply. Note that

this is higher than the TSC2200 supply voltage, but it is within

the absolute maximum ratings.

ARNG

RRNG

The maximum V_BIASvoltage is 4V, and this occurs when the

D/A converter current is 0, so only the 400µA load current

I

_LOADwill be flowing from 5V to V_BIAS. This means 1V will be

dropped across R₁, so R₁= 1V/400µA = 2.5kΩ.

FIGURE 27. D/A Converter Configuration.

The minimum V_BIASis 2V, which occurs when the D/A

converter current is at its full scale value, I_MAX. In this case,

5V – 2V = 3V will be dropped across R₁, so the current

through R₁will be 3V/2.5K = 1.2mA. This current is

I_MAX+ I_LOAD= I_MAX+ 400uA, so I_MAXmust be set to 800µA.

Looking at Figure 28, this means that RRNG should be

around 1MΩ.

This circuit is designed for flexibility in the output voltage at the

V_BIASpoint shown in Figure 27 to accommodate the widely

varying requirements for LCD contrast control bias. V+ can be

a higher voltage than the supply voltage for the TSC2200. The

only restriction is that the voltage on the A_OUTpin can never go

above the absolute maximum ratings for the device, and

should stay above 1.5V for linear operation.

Since the voltage at the A_OUTpin should not go below 1.5V,

this limits the voltage at the bottom of R₂to be 1.5V minimum;

this occurs when the D/A converter is providing its maximum

current, I_MAX. In this case, I_MAX+ I_LOADflows through R₁, and

I_MAXflows through R₂. Thus,

The D/A converter has an output sink range that is limited to

1mA. This range can be adjusted by changing the value of

RRNG shown in Figure 27. As this D/A converter is not

designed to be a precision device, the actual output current

range can vary as much as ±20%. Furthermore, the current

output will change due to variations in temperature; the D/A

converter has a temperature coefficient of approximately

–2µA/°C. To set the full-scale current, RRNG can be deter-

mined from the graph shown in Figure 28.

R₂I_MAX+ R₁(I_MAX+ I_LOAD) = 5V – 1.5V = 3.5V

(8)

We already have found R₁= 2.5kΩ, I_MAX= 800µA,

I_LOAD= 400µA, so we can solve this for R₂and find that it

should be 625Ω.

TSC2200

SBAS191F

33

www.ti.com

In the previous example, when the D/A converter current is

zero, the voltage on the A_OUTpin will rise above the TSC2200

supply voltage. This is not a problem, however, since V+ was

within the absolute maximum ratings of the TSC2200, so no

special precautions are necessary. Many LCD displays re-

quire voltages much higher than the absolute maximum

ratings of the TSC2200. In this case, the addition of an NPN

transistor, as shown in Figure 29, will protect the A_OUTpin

from damage.

OPERATION—KEYPAD INTERFACE

The TSC2200 contains a keypad interface that is suitable for

use with matrix keypads up to 4-by-4 keys. A control register,

the Keypad Control Register, is used to set the scan rate for

the keypad and de-bounce times. There is also a Keypad

Mask register which allows certain keys to be masked from

being read or causing the TSC2200 to detect a key press.

The results of keyboard scans are placed in the Keypad Data

register.

When a key press is detected, the TSC2200 automatically

scans the keypad and de-bounces the key press. It will then

drive the KBIRQ LOW. All keys pressed at the time of the

scan will then be reflected in the Keypad Data Register. This

mode is shown in Figure 30.

V+

R₁

V_BIAS

R₂

V_SUPPLY

Keypad Scan

KBIRQ Initiated

A_OUT

Keypad Touch

D/A Converter

8 Bits

Read KPDATA

Register

Start Clock

ARNG

RRNG

Scan and De-Bounce

Keys

Reset KBIRQ

Store Keypad Scan

Results in KPData Register

FIGURE 29. D/A Converter Circuit when Using V+ Higher

than V_SUPPLY

.

Issue Interrupt KBIRQ

Turn Off Clock

Done

FIGURE 30. Keypad Scan Initiated by Keypress.

TSC2200

34

www.ti.com

SBAS191F

The TSC2200 architecture offers no inherent rejection of

noise or voltage variation in regards to using an external

reference input. This is of particular concern when the

reference input is tied to the power supply. Any noise and

ripple from the supply will appear directly in the digital

results. While high-frequency noise can be filtered out,

voltage variation due to line frequency (50Hz or 60Hz) can

be difficult to remove.

LAYOUT

The following layout suggestions should provide optimum

performance from the TSC2200. However, many portable

applications have conflicting requirements concerning power,

cost, size, and weight. In general, most portable devices

have fairly “clean” power and grounds because most of the

internal components are very low power. This situation would

mean less bypassing for the converter’s power and less

concern regarding grounding. Still, each situation is unique

and the following suggestions should be reviewed carefully.

The GND pin should be connected to a clean ground point.

In many cases, this will be the “analog” ground. Avoid

connections that are too near the grounding point of a

microcontroller or digital signal processor. If needed, run a

ground trace directly from the converter to the power-supply

entry or battery-connection point. The ideal layout will in-

clude an analog ground plane dedicated to the converter and

associated analog circuitry.

For optimum performance, care should be taken with the

physical layout of the TSC2200 circuitry. The basic SAR

architecture is sensitive to glitches or sudden changes on the

power supply, reference, ground connections, and digital

inputs that occur just prior to latching the output of the analog

comparator. Therefore, during any single conversion for an

‘n-bit’ SAR converter, there are n ‘windows’ in which large

external transient voltages can easily affect the conversion

result. Such glitches might originate from switching power

supplies, nearby digital logic, and high power devices. The

degree of error in the digital output depends on the reference

voltage, layout, and the exact timing of the external event.

The error can change if the external event changes in time

with respect to the SCL input.

In the specific case of use with a resistive touch screen, care

should be taken with the connection between the converter

and the touch screen. Since resistive touch screens have

fairly low resistance, the interconnection should be as short

and robust as possible. Loose connections can be a source

of error when the contact resistance changes with flexing or

vibrations.

As indicated previously, noise can be a major source of error

in touch screen applications (e.g., applications that require a

back-lit LCD panel). This EMI noise can be coupled through

the LCD panel to the touch screen and cause “flickering” of

the converted data. Several things can be done to reduce

this error, such as utilizing a touch screen with a bottom-side

metal layer connected to ground. This will couple the major-

ity of noise to ground. Additionally, filtering capacitors, from

Y+, Y–, X+, and X– to ground, can also help. Note, however,

that the use of these capacitors will increase screen settling

time and require longer panel voltage stabilization times, as

well as increased precharge and sense times for the PENIRQ

circuitry of the TSC2200.

With this in mind, power to the TSC2200 should be clean and

well bypassed. A 0.1µF ceramic bypass capacitor should be

placed as close to the device as possible. A 1µF to 10µF

capacitor may also be needed if the impedance of the

connection between +V_DDand the power supply is HIGH.

A bypass capacitor is generally not needed because the

reference is buffered by an internal op amp. If an external

reference voltage originates from an op amp, make sure that

it can drive any bypass capacitor that is used without oscil-

lation.

TSC2200

SBAS191F

35

www.ti.com

PACKAGE MATERIALS INFORMATION

www.ti.com

5-Jan-2022

TAPE AND REEL INFORMATION

*All dimensions are nominal

Device

Package Package Pins

Type Drawing

SPQ

Reel

A0

B0

K0

P1

W

Pin1

Diameter Width (mm) (mm) (mm) (mm) (mm) Quadrant

(mm) W1 (mm)

TSC2200IPWR

TSC2200IRHBR

TSSOP

VQFN

PW

28

32

2000

3000

330.0

16.4

12.4

6.9

5.3

10.2

5.3

1.8

1.5

12.0

8.0

16.0

12.0

Q1

Q2

RHB

Pack Materials-Page 1

PACKAGE MATERIALS INFORMATION

www.ti.com

5-Jan-2022

*All dimensions are nominal

Device

Package Type Package Drawing Pins

SPQ

Length (mm) Width (mm) Height (mm)

TSC2200IPWR

TSC2200IRHBR

TSSOP

VQFN

PW

28

32

2000

3000

350.0

43.0

RHB

Pack Materials-Page 2

PACKAGE MATERIALS INFORMATION

www.ti.com

5-Jan-2022

TUBE

*All dimensions are nominal

Device

Package Name Package Type

Pins

SPQ

L (mm)

W (mm)

T (µm)

B (mm)

TSC2200IPW

TSC2200IRHB

PW

TSSOP

VQFN

28

32

50

73

530

381

10.2

6.73

3600

2286

3.5

0

RHB

Pack Materials-Page 3

GENERIC PACKAGE VIEW

RHB 32

5 x 5, 0.5 mm pitch

VQFN - 1 mm max height

PLASTIC QUAD FLATPACK - NO LEAD

Images above are just a representation of the package family, actual package may vary.

Refer to the product data sheet for package details.

4224745/A

www.ti.com

PACKAGE OUTLINE

RHB0032E

VQFN - 1 mm max height

S

C

A

L

E

3

.

0

PLASTIC QUAD FLATPACK - NO LEAD

5.1

4.9

B

A

PIN 1 INDEX AREA

(0.1)

5.1

4.9

SIDE WALL DETAIL

20.000

OPTIONAL METAL THICKNESS

C

1 MAX

SEATING PLANE

0.08 C

0.05

0.00

2X 3.5

(0.2) TYP

3.45 0.1

9

EXPOSED

THERMAL PAD

16

28X 0.5

8

17

SEE SIDE WALL

DETAIL

2X

SYMM

33

3.5

0.3

0.2

32X

24

0.1

C A B

C

1

0.05

32

25

PIN 1 ID

(OPTIONAL)

SYMM

0.5

0.3

32X

4223442/B 08/2019

NOTES:

1. All linear dimensions are in millimeters. Any dimensions in parenthesis are for reference only. Dimensioning and tolerancing

per ASME Y14.5M.

2. This drawing is subject to change without notice.

3. The package thermal pad must be soldered to the printed circuit board for thermal and mechanical performance.

www.ti.com

EXAMPLE BOARD LAYOUT

RHB0032E

VQFN - 1 mm max height

PLASTIC QUAD FLATPACK - NO LEAD

(

3.45)

SYMM

32

25

32X (0.6)

1

24

32X (0.25)

(1.475)

28X (0.5)

33

SYMM

(4.8)

(

0.2) TYP

VIA

8

17

(R0.05)

TYP

9

16

(1.475)

(4.8)

LAND PATTERN EXAMPLE

SCALE:18X

0.07 MIN

ALL AROUND

0.07 MAX

ALL AROUND

SOLDER MASK

OPENING

METAL

SOLDER MASK

OPENING

METAL UNDER

SOLDER MASK

NON SOLDER MASK

DEFINED

SOLDER MASK

DEFINED

(PREFERRED)

SOLDER MASK DETAILS

4223442/B 08/2019

NOTES: (continued)

4. This package is designed to be soldered to a thermal pad on the board. For more information, see Texas Instruments literature

number SLUA271 (www.ti.com/lit/slua271).

5. Vias are optional depending on application, refer to device data sheet. If any vias are implemented, refer to their locations shown

on this view. It is recommended that vias under paste be filled, plugged or tented.

www.ti.com

EXAMPLE STENCIL DESIGN

RHB0032E

VQFN - 1 mm max height

PLASTIC QUAD FLATPACK - NO LEAD

4X ( 1.49)

(0.845)

(R0.05) TYP

32

25

32X (0.6)

1

24

32X (0.25)

28X (0.5)

(0.845)

SYMM

33

(4.8)

17

8

METAL

TYP

16

9

SYMM

(4.8)

SOLDER PASTE EXAMPLE

BASED ON 0.125 mm THICK STENCIL

EXPOSED PAD 33:

75% PRINTED SOLDER COVERAGE BY AREA UNDER PACKAGE

SCALE:20X

4223442/B 08/2019

NOTES: (continued)

6. Laser cutting apertures with trapezoidal walls and rounded corners may offer better paste release. IPC-7525 may have alternate

design recommendations.

www.ti.com

IMPORTANT NOTICE AND DISCLAIMER

TI PROVIDES TECHNICAL AND RELIABILITY DATA (INCLUDING DATA SHEETS), DESIGN RESOURCES (INCLUDING REFERENCE

DESIGNS), APPLICATION OR OTHER DESIGN ADVICE, WEB TOOLS, SAFETY INFORMATION, AND OTHER RESOURCES “AS IS”

AND WITH ALL FAULTS, AND DISCLAIMS ALL WARRANTIES, EXPRESS AND IMPLIED, INCLUDING WITHOUT LIMITATION ANY

IMPLIED WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE OR NON-INFRINGEMENT OF THIRD

PARTY INTELLECTUAL PROPERTY RIGHTS.

These resources are intended for skilled developers designing with TI products. You are solely responsible for (1) selecting the appropriate

TI products for your application, (2) designing, validating and testing your application, and (3) ensuring your application meets applicable

standards, and any other safety, security, regulatory or other requirements.

These resources are subject to change without notice. TI grants you permission to use these resources only for development of an

application that uses the TI products described in the resource. Other reproduction and display of these resources is prohibited. No license

is granted to any other TI intellectual property right or to any third party intellectual property right. TI disclaims responsibility for, and you

will fully indemnify TI and its representatives against, any claims, damages, costs, losses, and liabilities arising out of your use of these

resources.

TI’s products are provided subject to TI’s Terms of Sale or other applicable terms available either on ti.com or provided in conjunction with

such TI products. TI’s provision of these resources does not expand or otherwise alter TI’s applicable warranties or warranty disclaimers for

TI products.

TI objects to and rejects any additional or different terms you may have proposed. IMPORTANT NOTICE

Mailing Address: Texas Instruments, Post Office Box 655303, Dallas, Texas 75265


型号：	TSC2200
厂家：	TEXAS INSTRUMENTS
描述：	具有 12 位 125kHz ADC 和键盘接口的可编程 4 线触摸屏控制器控制器
文件：	总47页 (文件大小：2091K)
中文：	中文翻译
下载：	下载PDF数据表文档文件

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