Datasheet

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96
97
98
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102
2.5 3 3.5
SNR (dB)
Vdd (V)
OVERVIEW
TSC2301
SLAS371D – SEPTEMBER 2002 – REVISED AUGUST 2004
TYPICAL CHARACTERISTICS (continued)
At T
A
= +25 °C, +V
DD
= +3.3 V, V
REF
= +2.5 V, f
SAMPLE
= 125 kHz, unless otherwise noted.
SNR OF MONO PATH
vs
SUPPLY VOLTAGE
Figure 43.
The TSC2301 is an analog interface circuit for human interface devices. A register-based architecture eases
integration with microprocessor-based systems through a standard SPI bus. All peripheral functions are
controlled through the registers and onboard state machines.
The TSC2301 consists of the following blocks (refer to the block diagram on p. 2):
1. Touch screen interface
2. Keypad interface
3. Battery monitors
4. Auxiliary inputs
5. Temperature monitor
6. Current output digital-to-analog converter
7. Audio codec and signal processing
Communication to the TSC2301 is via a standard SPI serial interface. This interface requires that the slave select
signal be driven low to communicate with the TSC2301. Data is then shifted into or out of the TSC2301 under
control of the host microprocessor, which also provides the serial data clock.
Control of the TSC2301 and its functions is accomplished by writing to different registers in the TSC2301. A
simple command protocol is used to address the 16-bit registers. Registers control the operation of the touch
screen A/D converter, keypad scanner, and audio codec.
The result of measurements made are placed in the TSC2301 memory map and can be read by the host at any
time. Three signals are available from the TSC2301 to indicate that data is available for the host to read. The
DAV output indicates that an analog-to-digital conversion has completed and that data is available. The KBIRQ
output indicates that an unmasked key on the keypad has been pressed and de-bounced. The PENIRQ output
indicates that a touch has been detected on the touch screen.
A typical application of the TSC2301 is shown in Figure 44 .
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