BU21049GUL

TSZ02201-0Y1Y0F300010-1-2

© 2011 ROHM Co., Ltd. All rights reserved.

31.JAN.2012 Rev.001

www.rohm.co

TSZ22111・15・001

3/23

Datasheet

Datasheet

●Block diagram

●OVERVIEW

The BU21049GUL is a touch screen controller corresponding to a 4-wire resistive touch screen.

12-bit SAR A/D converter, clock oscillating circuit, power on reset circuit and LDO for inside blocks is built in one by one,

and it operates with a 1.65V - 3.60V single power supply.

The BU21049GUL can detect single point coordinates and touch pressure as existing 4-wire resistive touch screen

controllers, and can generate data based on the prearranged touch screen parameters to detect dual coordinates.

Communication with the BU21049GUL is used 2-wire serial interface. The BU21049GUL operate as i2c slave device.

The host processor can get control of the BU21049GUL by write to registers in the BU21049GUL and can select 2

operation mode which command control or automatic control. In automatic control, the BU21049GUL scan a touch screen

and covert to touch data when touch screen is touched. The touch data is saved in the internal registers and read by the

host processor at any time.

・

Preprocess

The A/D converting is continuously done some times in one driving time. The data is median average processed.

The median average processing is done that sorting the data and calculation that takes the average from the center of the

sorting data. There is some effective for reduce noise influence.

・

Interrupt control

The BU21049GUL will output an interrupt signal to the host processor with the INT pin, if a touch is detected. (In automatic

control, after scan of the 1st touch data is completed).

The INT pin polarity with active low.

・

Power control

After a conversion function is completed, the BU21049GUL will be a power down automatically in order to reduce current

consumption. In automatic control, it return from a power down and restart scan automatically by operating a touch screen

during a power down.

・

Power on reset

The BU21049GUL builds in the power-on-reset circuit.

The RSTB pin can short VDD, if the host processor is not control the RSTB pin. If shorted, registers of the BU21049GUL

initialization with power-on.

VD D

XP

IN T

PG N D

PVD D

V R E F

LD O

XN

YP

YN

LD O

M

U

X

AU X

SAR

AD C

Co n tro l

Lo gic

&

2 w ire

Se ria l

I/F

To u c h

Sc re e n

Driv e rs

& I/F

OS C

SD A

SC L

AD 0

AD 1

RS T B

PO R

GN D

P E NIRQ