AK4673 Datasheet, PDF (69/107 Pages) Asahi Kasei Microsystems – Stereo CODEC with MIC/HP-AMP and Touch Screen Controller

[AK4673]
TSC OPERATION OVERVIEW
■ A/D Converter for Touch Screen
The AK4673 incorporates a 12-bit successive approximation resistor (SAR) A/D converter for position measurement.
The architecture is based on a capacitive redistribution algorithm, and an internal capacitor array functions as the
sample/hold (S/H) circuit.
The SAR A/D converter output is a straight binary format as shown below:
Input Voltage
Output Code
(ΔVREF-1.5LSB)~ ΔVREF
FFFH
(ΔVREF-2.5LSB) ~
FFEH
(ΔVREF-1.5LSB)
---------
---------
0.5LSB ~ 1.5LSB
001H
0 ~ 0.5LSB
000H
ΔVREF: (VREF+) – (VREF-)
Table 58 Output Code
■ The Block Diagram of TSC block
Figure 62 shows the block diagram in touch screen controller block that consists of the 12bit ADC and control block of
the driver switches and peninterrupt output.
TSVDD
XP Driver SW
XP
TSVDD
YP Driver SW
YP
XN
XN Driver SW
Control
Logic
Block
YN
YN Driver SW
VREF+ VREF-
AIN+ _12bit
ADC
AIN-(SAR type)
PEN
INTERRUPT
PENIRQN
TSVDD
VSS3
Figure 62 Touch Screen Controller Block Diagram
MS0670-E-00
- 69 -
2007/09