TSC2102 datasheet(43/54 Pages) TI

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TSC2102

SLAS379A− APRIL 2003 − REVISED JUNE 2004

www.ti.com

CONVERSION TIME CALCULATIONS FOR THE TSC2102

Touch Screen Conversion Initiated At Touch Detect

The time needed to get a converted X/Y coordinate for reading can be calculated by (not including the time needed to send

the command over the SPI bus):

coordinate +

PRE )

SNS )

PVS

125 ns

OSC )

AVG

BITS )

8MHz

ƒconv

) n

1 )

) 1

OSC )

OSC

where:

tcoordinate = time to convert X/Y coordinate

tPVS = Panel voltage stabilization time

tPRE = precharge time

tSNS = sense time

NAVG = number of averages; for no averaging, NAVG = 1

NBITS = number of bits of resolution

ƒconv = A/D converter clock frequency

tOSC = Oscillator clock period

n1 = 6 ; if ƒconv = 8 MHz

7 ; if

ƒconv ≠ 8 MHz

n2 = 4 ; if tPVS = 0 µs

0 ; if tPVS ≠ 0 µs

n3 = 0 ; if tSNS = 32 µs

2 ; if tSNS ≠ 32 µs

NOTE: The above formula is exactly valid only when the audio DAC is powered down. Also, after touch detect, the formula holds true from second

conversion onwards. For continuous touch and D15−D14 = 00/10/11, the high duration of the PINTDAV signal is given by tPRE + tSNS with

an oscillator clock of 8 MHz.

Programmed

for Self

Controlled

X−Y Scan

Mode

Detecting Touch

Sample,Conversion &

Averaging for

Y−Coordinate

Reading

X−Data

Reading

Y−Data

Detecting

Touch

Sample,Conversion &

Averaging for

X−Coordinate

Detecting

Touch

Sample,Conversion &

Averaging for

Y−Coordinate

Detecting

Touch

SS DEACTIVATED

Touch Is Detected

(As PENIRQ

[D15−D14 = 00])

PINTDAV

(As PENIRQ & DATA_AVA

[D15−D14 = 10/11])

PINTDAV

Touch Is Detected

(As DATA_AVA

[D15−D14 = 01])

PINTDAV

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