UCB1300BE Просмотр технического описания (PDF) - Philips Electronics

Номер в каталоге

Компоненты Описание

производитель

UCB1300BE

Advanced modem/audio analog front-end

Philips Electronics 

Philips Semiconductors

Advanced modem/audio analog front-end

Preliminary specification

UCB1300

TOUCH SCREEN INTERFACE

The UCB1300 contains a universal resistive touch screen interface for 4-wire resistive touch screen, capable of

performing position, pressure and plate resistance measurements. In addition the touch screen can be programmed to

generate interrupts when the touch screen is pressed. The last mode is also active when the UCB1300 is set in the

stand-by mode.

ts..power

tsc_mode (interrupt)

vdda1

touch screen

bias voltage

ts..ground

tsc_mode

(pressure)

vssa3

adc_input[2:0]

1kΩ

analog mux

vssa1

tsc_bias_ena

Current sense input

tsc_mode_sel

Fig.11 Block diagram of the touch screen interface.

to adc input

The touch screen interface connects to the touch screen by four wires: TSPX, TSMX, TSPY and TSMY. Each of these

pins can be programmed to be floating, powered or grounded in the touch screen switch matrix. The setting of each touch

screen pin is programmable through the touch screen control register. Possible conflicting settings (grounding and

powering of a touch screen pin at the same time) are detected by the UCB1300. In that case the touch screen pin will be

grounded.

In position mode, opening the TS..gnd switch can take a long time. To avoid unpredictable delays after changing the

plates configuration, the touch screen interface should be programmed to pressure mode for the duration 1 SIB frame

before resuming a position measurement.

The UCB1300’s internal voltage reference (Vref) is used as reference voltage for the touch screen bias circuit. This makes

the touch screen biasing independent of supply voltage and temperature variations. Four low pass filters, one on each

touch screen terminal, are built in to minimize the noise coupled from the LCD into the touch screen signals. An LCD

typically generates large noise glitches on the touch screen, since they are closely coupled. The influence of the glitches

1999 Jul 20

17

Share Link: