ucb1300 NXP Semiconductors, ucb1300 Datasheet - Page 18

• Manufacturer Part Number: ucb1300
• Description: Advanced Modem/audio Analog Front-end
• Manufacturer: NXP Semiconductors

Philips Semiconductors
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.
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 (V
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
2000 Jun 26
ts..ground
Advanced modem/audio analog front-end
ts..power
(pressure)
adc_input[2:0]
tsc_mode
vssa3
1k
Fig.12 Block diagram of the touch screen interface.
ref
analog mux
) is used as reference voltage for the touch screen bias circuit. This makes
18
Current sense input
vssa1
touch screen
bias voltage
tsc_mode (interrupt)
tsc_mode_sel
tsc_bias_ena
to adc input
vdda1
Product specification
UCB1300