Datasheet

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OVERVIEW
TSC2004
SBAS408E – JUNE 2007 – REVISED MARCH 2008
The TSC2004 is an analog interface circuit for a human interface touch screen device. A register-based
architecture eases integration with microprocessor-based systems through a standard I
2
C bus. All peripheral
functions are controlled through the registers and onboard state machines. The TSC2004 features include:
• Very low-power touch screen controller
• Very small onboard footprint
• Relieves host from tedious routine tasks by flexible preprocessing, saving resources for more critical tasks
• Ability to work on very low supply voltage
• Minimal connection interface allows easiest isolation and reduces the number of dedicated I/O pins required
• Miniature, yet complete; requires no external supporting component. ( NOTE: Although the TSC2004 can use
an external reference, it is also possible to use SNSVDD as the reference.)
• Enhanced ESD protection
The TSC2004 consists of the following blocks (refer to the block diagram on the front page):
• Touch Screen Interface
• Auxiliary Input (AUX)
• Temperature Sensor
• Acquisition Activity Preprocessing
• Internal Conversion Clock
• I
2
C Interface
Communication with the TSC2004 is done via an I
2
C serial interface. The TSC2004 is an I
2
C slave device;
therefore, data are shifted into or out of the TSC2004 under the control of the host microprocessor, which also
provides the serial data clock.
Control of the TSC2004 and its functions is accomplished by writing to different registers in the TSC2004. A
simple command protocol (compatible with I
2
C) is used to address these registers. This protocol can be an I
2
C
write-addressing followed by multiple control bytes, or multiple combinations of control/data bytes to be written
into different registers (two bytes each). Reading from registers is performed by writing an I
2
C read-addressing to
the TSC, followed by one or multiple sequential reads from the registers.
The address of the register to be read can be written in TSC Control Byte 0 with the register address and
read-bit (as described in the previous paragraph), and serves as a pointer to the register map where the first
read starts. This designated register address is static; there is no need to write a register address again unless it
is overwritten by a new register address, or if the TSC is reset (by a software reset or by the RESET pin).
The measurement result is placed in the TSC2004 registers and may be read by the host at any time. This
preprocessing frees up the host so that resources can be redirected for more critical tasks. Two optional signals
are also available from the TSC2004 to indicate that data are available for the host to read. PINTDAV is a
programmable interrupt/status output pin. When PINTDAV is programmed as a DAV output, it indicates that an
A/D conversion has completed and that data are available. When this pin is programmed as a PENIRQ output, it
indicates that a touch has been detected on the touch screen. The status register of the TSC2004 provides an
extended status reading including the state of DAV and PENIRQ without the cost of any dedicated pin. Figure 24
shows a typical application of the TSC2004.
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