BU21026MUV Datasheet, PDF (4/23 Pages) Rohm – 4-wire Resistive Touch Screen Controller

BU21026MUV
Block Diagram(s)
VDD
XP
YP
XN
YN
Touch Screen
Interface
Touch
Detection
A/D
Converter
INT
Control
Logic
&
SDA
2-wire Serial
Interface
SCL
AD1
AD0
Digital Filter
AUX
Power On
Reset
Clock
Oscillator
GND
Description of Block(s)
Power on Reset
BU21026MUV requests that the Power on Reset Timing should be observed. If the Power on Reset Timing not be observed,
BU21026MUV may wakeup with a random state. The touch detection and 2-wire serial interface is enabled after taking the
device ready time.
A/D Converter
BU21026MUV has a 12-bit Successive Approximation Resistor (SAR) Analog to Digital (A/D) converter. This A/D converter
is used for measuring X and Y position and Auxiliary input voltage. Output format is in straight binary as shown in below
table.
A/D Convertor Output Format
INPUT VOLTAGE
OUTPUT
(VREF - 1.5LSB) ~ VREF
FFFh
(VREF - 2.5LSB) ~ (VREF - 1.5LSB)
FFEh
(VREF - 3.5LSB) ~ (VREF - 2.5LSB)
FFDh
:
:
1.5LSB ~ 2.5LSB
002h
0.5LSB ~ 1.5LSB
001h
0 ~ 0.5LSB
000h
Note: VREF = VREFP – VREFN, LSB = VREF / 4095
Touch Screen I/F
A touch screen interface is consisted many switches. These switches are used for the driving screen voltage and selection
an input of the A/D converter. State of these switches is selected by a command that sent from the master.
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4.Aug.2016 Rev.001