BU21026MUV_技术文档

Datasheet

Resistive touch screen controller LSI series

4-wire Resistive

Touch Screen Controller

BU21026MUV

General Description

Key Specifications

BU21026MUV is a low power 4-wire resistive touch

screen controller. BU21026MUV measures coordinates

and touch pressures with a 12bit A/D converter.

BU21026MUV has a digital filter for noise reduction.

 Power supply voltage

 Temperature range

 Standby current

 Operating current

 Coordinate resolution

1.65V to 3.60V

-30℃ to 85℃

0.8uA (Max.)

120uA (Typ.)

12Bits

Features

W(Typ) x D(Typ) x H(Max)

4.00mm x 4.00mm x 1.00mm

 4-wire resistive touch screen controller

 Single 1.65V to 3.60V supply.

 Low standby current ( 0.8uA max)

 12bit SAR A/D converter

 2-wire serial interface

 Command base interface

 Digital filter

Package

VQFN020V4040

 Touch pressure measurement

 Auto power down control

 Built-in clock oscillation circuit

.

Applications

 Equipment with a built in user interface of 4-wire

resistive touch screen

 Portable device such as smart phone, tablet, PDA.

 Digital still camera, digital video camera, portable TV.

 PC / PC peripheral equipment such as laptop PC,

touch screen monitor, printer.

VDD

Typical Application Circuit(s)

3

1.0μF 0.1μF

2

2.2kΩ

GND

Master

( 2-wire serial

interface )

Auxilary Input

AUX

XP

SDA

SCL

INT

SDA

10Ω

SCL

0.1μF

YP

GPIO

BU21026

10Ω

XN

YN

AD1

AD0

0.1μF

Touch

Screen

1

5

GND

4

1. 4-wire resistive touch screen

2. Pull-up resistor for 2-wire serial interface

3. Bypass capacitors

4. Diodes for ESD protection

5. Low pass filter for noise reduction

〇Product structure : Silicon monolithic integrated circuit 〇This product has no designed protection against radioactive rays

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Contents

General Description........................................................................................................................................................................1

Features..........................................................................................................................................................................................1

Applications ....................................................................................................................................................................................1

Key Specifications...........................................................................................................................................................................1

Package..........................................................................................................................................................................................1

Typical Application Circuit(s)...........................................................................................................................................................1

Contents .........................................................................................................................................................................................2

Pin Configuration(s)........................................................................................................................................................................3

Pin Description(s) ...........................................................................................................................................................................3

Equivalent circuit.............................................................................................................................................................................3

Block Diagram(s) ............................................................................................................................................................................4

Description of Block(s)....................................................................................................................................................................4

Power on Reset...........................................................................................................................................................................4

A/D Converter .............................................................................................................................................................................4

Touch Screen I/F.........................................................................................................................................................................4

Touch Detection ..........................................................................................................................................................................5

Digital Filter .................................................................................................................................................................................5

Absolute Maximum Ratings ............................................................................................................................................................6

Thermal Resistance^{(Note 1)}...............................................................................................................................................................6

Recommended Operating Conditions.............................................................................................................................................6

Electrical Characteristics.................................................................................................................................................................6

Power on Reset Timing Chart.........................................................................................................................................................7

2-wire Serial Interface Timing Chart................................................................................................................................................7

2-wire Serial Interface.....................................................................................................................................................................8

Start Condition.............................................................................................................................................................................8

Stop Condition.............................................................................................................................................................................8

Data Transfer ..............................................................................................................................................................................8

Acknowledge Bit (sending)..........................................................................................................................................................8

Acknowledge Bit (receiving)........................................................................................................................................................8

Address Byte...............................................................................................................................................................................8

Command Byte ...........................................................................................................................................................................9

Write Protocol............................................................................................................................................................................11

Read Protocol ...........................................................................................................................................................................12

Operation......................................................................................................................................................................................13

Position Detection of Touch Screen...........................................................................................................................................13

Touch Pressure Measurement ..................................................................................................................................................13

A/D Conversion Time ................................................................................................................................................................14

A/D Sampling Time with 2-wire Serial Interface ........................................................................................................................14

Operational Notes.........................................................................................................................................................................15

Ordering Information.....................................................................................................................................................................17

Marking Diagrams.........................................................................................................................................................................17

Physical Dimension, Tape and Reel Information...........................................................................................................................18

Revision History............................................................................................................................................................................19

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Pin Configuration(s)

(N.C.) 16

(N.C.) 17

GND 18

(N.C.) 19

(N.C.) 20

10 (N.C.)

9

8

7

6

(N.C.)

VDD

AUX

(N.C.)

TOP VIEW

Pin Description(s)

Pin No.

1

Pin Name

I/O

I

Function

Slave address bit1 input

Figure

AD1

SCL

SDA

AD0

INT

-

A

B

A

-

2

I/O Serial clock

I/O Serial data

3

4

I

O

-

Slave address bit0 input

5

Interrupt output. Pin polarity is active low.

6

(N.C.)

7

AUX

VDD

-

I

Auxiliary input

Power supply

(N.C.)

C

-

8

-

9

-

10

11

12

13

14

15

16

17

18

19

20

-

(N.C.)

-

XP

YP

-

I/O Screen interface

C

-

(N.C.)

XN

YN

-

I/O Screen interface

C

-

(N.C.)

Ground

(N.C.)

-

GND

-

Equivalent circuit

PAD

Figure. A

Figure. B

Figure. C

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Block Diagram(s)

VDD

Touch

Detection

XP

YP

XN

YN

INT

Control

Logic

&

SDA

SCL

A/D

Converter

2-wire Serial

Interface

Touch Screen

Interface

AD1

AD0

Digital Filter

AUX

Clock

Oscillator

Power On

Reset

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

(VREF - 1.5LSB) ~ VREF

(VREF - 2.5LSB) ~ (VREF - 1.5LSB)

(VREF - 3.5LSB) ~ (VREF - 2.5LSB)

:

OUTPUT

FFFh

FFEh

FFDh

:

1.5LSB ~ 2.5LSB

0.5LSB ~ 1.5LSB

002h

001h

000h

0 ~ 0.5LSB

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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Touch Detection

A touch detection function of BU21026MUV is automatically enabled after wakeup. BU21026MUV inform that touch screen

is touched or not by INT pin when touch detection is enabled. Output level of INT becomes low during screen is touched. In

this state, XP pin is pulled-up high by pull-up resistor (R_PU) and YN pin is connected to GND. A resistance of R_PUis

selectable from either 50 kohm (default) or 90 kohm by the setup command. When the screen isn’t touched, XP is

connected to VDD trough the pull-up resistor. When the screen is touched, XP is connected to GND trough the screen and

BU21026MUV detect touch.

When a received command is not setup (1011), the touch detection is disabled and R_PUis disconnected from XP pin. And

output level of INT is fixed high or low by each command (see Table 3 for details about operation code).

When BU21026MUV receives software reset command (0101), touch detection is enabled after the 2^ndacknowledge timing.

When BU21026MUV receives A/D conversion with PD=0 command touch detection is enabled after an A/D conversion is

finished.

When BU21026MUV receives a driving screen voltage or an A/D conversion with PD=1 command, touch detection is not

enable automatically. A method for re-enable the touch detection is sending new command that return to enable touch

detection. The set power command is almost same as an A/D conversion command.

VDD

INT

OFF

ON

R_PU

XP

YP

Control

logic

XN

YN

ON

GND

Touch Detection Circuit

Digital Filter

BU21026MUV has a Median Average Filter (MAF) as a digital filter for noise reduction. When the MAF is enabled,

BU21026MUV operates A/D conversion 7 times and stores converted data. Next, these stored data are sorted. An output

data of MAF is an average value of middle three values of the sorted data. An abnormal value becomes difficult to affect the

results. So noise reduction performance of MAF is higher than one of normal average filter. When the MAF is disabled,

BU21026MUV operates A/D conversion one times and output the converted data The MAF is enabled in defaults and is

changed by the setup command.

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Absolute Maximum Ratings

PARAMETER

SYMBOL

VDD

RATING

-0.3 to 4.5

UNIT

V

Power supply voltage

Input voltage

VIN

-0.3 to VDD+0.3

-50 to 125

V

Storage temperature range

Tstg

℃

Caution: Operating the IC over the absolute maximum ratings may damage the IC. The damage can either be a short circuit between pins or an open circuit

between pins and the internal circuitry. Therefore, it is important to consider circuit protection measures, such as adding a fuse, in case the IC is operated over

the absolute maximum ratings.

Thermal Resistance^{(Note 1)}

Thermal Resistance (Typ)

PARAMETER

SYMBOL

UNIT

1s^{(Note 3)}

2s2p^{(Note 4)}

VQFN020V4040

153.9

13

37.4

7

Junction to Ambient

Junction to Top Characterization Parameter^{(Note 2)}

θ_JA

°C/W

Ψ_JT

(Note 1)Based on JESD51-2A(Still-Air)

(Note 2)The thermal characterization parameter to report the difference between junction temperature and the temperature at the top center of the outside

surface of the component package.

(Note 3)Using a PCB board based on JESD51-3.

Layer Number of

Measurement Board

Material

FR-4

Board Size

Single

114.3mm x 76.2mm x 1.57mmt

Top

Copper Pattern

Thickness

Footprints and Traces

70μm

(Note 4)Using a PCB board based on JESD51-5, 7.

Layer Number of

Material

Thermal Via^{(Note 5)}

Board Size

114.3mm x 76.2mm x 1.6mmt

2 Internal Layers

Measurement Board

Pitch

Diameter

4 Layers

FR-4

1.20mm

Φ0.30mm

Top

Bottom

Copper Pattern

Thickness

Copper Pattern

Thickness

Copper Pattern

Thickness

70μm

Footprints and Traces

70μm

74.2mm x 74.2mm

35μm

74.2mm x 74.2mm

(Note 5) This thermal via connects with the copper pattern of all layers..

Recommended Operating Conditions

PARAMETER

SYMBOL

MIN.

TYP.

MAX.

UNIT

Power supply voltage

VDD

Tj

1.65

-30

3.00

25

3.60

85

V

Operating temperature range

℃

(Unless otherwise specified Tj=25[℃], VDD=3.00[V], GND=0.00[V])

Electrical Characteristics

PARAMETER

SYMBOL

MIN.

TYP.

MAX.

UNIT

CONDITION

Low-level input voltage

High-level input voltage

Low-level output voltage

High-level output voltage

A/D converter resolution

Differential non-linearity error

Integral non-linearity error

Internal clock frequency

Active current

VIL

VIH

VOL

VOH

AD

-0.3

-

0.3xVDD

VDD+0.3

0.2

V

0.7xVDD

-

0

-

V

IL = 3.6mA

VDD-0.2

-

VDD

12

V

IL = -3.6mA

-

-3.5

-5

2.6

-

Bits

LSB

MHz

uA

Programmable 8/12 bits

DNL

INL

3.5

-

5

Freq

Idd

4.0

120

-

5.1

450

8.2kSPS (operation )

After reset releasing

Standby current

Ist

-

0.8

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BU21026MUV

Power on Reset Timing Chart

t_{F_VDD}

t_{R_VDD}

1.65～3.60V

VDD

1.4V

t_RDY

0.2V

0V

t_{OFF_VDD}

(Unless otherwise specified Tj=25[℃], VDD=3.00[V], GND=0.00[V])

RATING

TYP.

PARAMETER

SYMBOL

UNIT CONDITION

MIN.

0.3

10

0.5

-

MAX.

Off period of VDD

Rise time for VDD

Fall time for VDD

t_{OFF_VDD}

t_{R_VDD}

t_{F_VDD}

t_RDY

-

100

-

s

us

ms

Ready time for device

2

2-wire Serial Interface Timing Chart

t_{HD_STA}

t_{SU_DAT}

t_{HD_DAT}

t_{SU_STA}

t_{HD_STA}

t_{SU_STO}

t_BUF

SDA

t_LOW

t_HIGH

t_R

t_F

SCL

START

CONDITION

REPEATED

START

STOP

CONDITION

START

CONDITION

(Unless otherwise specified Tj=25[℃], VDD=3.00[V], GND=0.00[V])

RATING

TYP.

PARAMETER

SYMBOL

UNIT

CONDITION

MIN.

-

MAX.

400

-

SCL clock frequency

f_SCL

t_{HD_STA}

t_LOW

t_HIGH

t_{SU_STA}

t_{HD_DAT}

t_{SU_DAT}

t_R

-

KHz

us

ns

us

Hold time for (repeated) START condition

Low period of SCL

0.6

1.3

0.6

0

100

20

High period of SCL

-

Setup time for repeated START condition

Data hold time

-

0.9

-

300

-

Data setup time

Rise time for both SCL and SDA

Fall time for both SCL and SDA

Setup time for STOP condition

Bus free time between a STOP and START condition

t_F

t_{SU_STO}

t_BUF

0.6

1.3

-

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BU21026MUV

2-wire Serial Interface

BU21026MUV supports a 2-wire serial interface a device that controls transfer is called a master. A device that controlled by

the master is called a slave. BU21026MUV is a slave device.

BU21026MUV has a write protocol and a read protocol. The write protocol consists of a start condition, an address byte, a

command byte, and a stop condition. The read protocol consists of a start condition, an address byte, one or two data bytes,

and a stop condition.

Start Condition

BU21026MUV recognizes as a start condition that falling edge of SDA while SCL is set “H”. If the start condition is received,

BU21026MUV will be in the state that can be transfer and received data. When the start condition is fulfilled, BU21026MUV

recognize the (repeated) start condition also in data transfer.

Stop Condition

BU21026MUV recognizes as a stop condition that rising edge of SDA while SCL is set “H”. If the stop condition is received,

BU21026MUV will be in the state that cannot be transfer and received data.

Data Transfer

Data is transferred with the most significant bit (MSB) first and 8-bits long. Each byte has to be followed by an acknowledge

bit. A Timing of SDA data receiving is rising edge of SCL. A state of SDA can only change when SCL set to “L”. If SDA is

changed while SCL is set “H”, a start or stop condition will recognized by BU21026MUV.

Acknowledge Bit (sending)

After the master sends a byte to BU21026MUV, an acknowledge bit is used in order that BU21026MUV may return a

response to the master. At this time, the master needs to set SDA into a high impedance state. When BU21026MUV

receives effectively data, it sets SDA to “L” (ACK). Otherwise SDA is set to “H” (NACK).

Acknowledge Bit (receiving)

After the master receives a byte from BU21026MUV, an acknowledge bit is used for judgment of whether BU21026MUV

continues data transfer. In this case, the master needs to set SDA. When SDA is set to “L” (ACK), BU21026MUV continues

data transfer. When SDA is set to “H” (NACK), BU21026MUV ends data transfer.

Address Byte

BU21026MUV recognizes one byte data as an address byte after a start condition. The address byte is consisted a 7-bit

slave address and a read-write bit. If a received slave address is matched with its one, BU21026MUV issues an

acknowledge to the master. Otherwise BU21026MUV doesn’t issue an acknowledge to the master and stops data transfer.

Upper 5 bits of the 7-bit slave address are “10010”. And lower 2 bits of the 7-bit slave address are programmable by AD1

and AD0. The read-write bit (R/WB) determines direction. When it is ‘1’, the master reads from BU21026MUV. When it is ‘0’,

the master writes to BU21026MUV.

Table 1. Address Byte

MSB

7

S6

LSB

0

R/WB

BIT

6

S5

0

5

S4

0

4

S3

1

3

S2

0

2

S1

1

S0

NAME

SLAVE

1

AD1

AD0

-

BIT 7-1 : S6-0

Slave address

BIT 0 : R/WB

0: The master writes to BU21026MUV

1: The master reads from BU21026MUV.

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Command Byte

BU21026MUV has a command byte after the address byte. Upper 4 bits of the command byte select an operation code.

And lower 4 bits of the command byte select an operand. Effects of the operands are changed by the operation code.

Table 2. Command Byte

MSB

7

LSB

0

BIT

6

5

4

3

2

1

NAME

C3

C2

C1

C0

O3

O2

O1

O0

BIT 7-4 : C3-0

Operation code:

It is select an operation of the command. Detail is shown in Table 3.

BIT 3-0 : O3-0

Operand:

It has 3 types. The operand type is selected by the operation code. When the operation

code is not “0101” or “1011”, the option type is 0. When it is “1011”, the option type is 1.

When it is “0101” option type is 2. Detail is shown in Table 3 and 4.

Table 3. Operation Code Function

INT

POLARITY

OPERAND

TYPE

C3

C2

C1

C0

FUNCTION

AD-INPUT X-DRIVER Y-DRIVER

0

1

0

1

0

1

0

1

0

1

0

1

0

1

0

1

0

1

0

1

0

1

0

1

0

1

0

1

0

1

Set Power

Reserved

Measure AUX

Reserved

Set Power

Software Reset

Reserved

Drive X

OFF

-

OFF

-

OFF

-

H

0

-

AUX

-

OFF

-

OFF

-

H

0

-

OFF

-

OFF

-

OFF

-

H

0

2

-

H

-

OFF

Keep

YP

XP

YN

XP

ON

OFF

ON

L

0

1

0

Drive Y

OFF

XN-ON

Keep

ON

L

Drive Z

YP-ON

Keep

OFF

ON

L

Setup

Keep

Measure X

Measure Y

Measure Z1

Measure Z2

L

OFF

XN-ON

YP-ON

Set Power (0000, 0100)

This code is used for returning to a state for touch detection without A/D conversion after sending screen drive command.

After this command, A/D converted data is set to 0.

Software Reset (0101)

BU21026MUV resets an A/D converted data, setup settings, and state of analog blocks to the initial state. If

BU21026MUV receives this code during an A/D conversion, the A/D conversion is stopped.

Drive X (1000), Drive Y (1001), Drive Z (1010)

BU21026MUV starts driving screen voltage by each code. PD is not effective. So, Driving is continuous until reserving

another command that changes state of driving screen voltage.

Measure AUX (0010), Measure X (1100), Measure Y (1101), Measure Z1 (1110), Measure Z2 (1111)

BU21026MUV starts driving screen voltage and A/D conversion. A PD of operand set, state of BU21026MUV after A/D

conversion is finished.

Setup (1011)

The setup command has a special operand (type is 1). The operand has MAF and pull-up resistor settings. Detail is

shown in Table 4.

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Table 4.Operands of Each Type

OPERAND

TYPE

O3

O2

C1

C0

0

1

2

X

L1

X

PD

L0

X

M

MAF

X

PU90

X

Operand Type 0

O3 : X

Don’t care

O2 : PD

Power down setting.

0 : The analog blocks off and touch detection is enable automatically after A/D conversion is finished.

1 : The analog blocks keep measuring state after A/D conversion is finished.

O1 : M

A/D comversion mode setting.

0 : The resolution of A/D conversion is 12-bit. The Conversion clock frequency is 1MHz.

1 : The resolution of A/D conversion is 8-bit. The conversion clock frequency is 2MHz

O0 : X

Don’t care

Operand Type 1

O3 -2: L1-0

Fixed. Must write “00”.

O1 : MAF

Median Average Filter (MAF) Setting

0 : MAF is enabled (default).

1 : MAF is disabled.

O0 : PU90

Pull-up resistor setting.

0 : 50 kohm (default).

1 : 90 kohm

Operand Type 2

O3 -0: X

Don’t care

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Write Protocol

An command write is started in BU21026MUV when the master sends the start condition, the slave address of

BU21026MUV, and zero in bit 0( 8^thbit) for writing, as shown in Table 1. If the slave address is matched with its own,

BU21026MUV issues an acknowledge to the master. When the master receives the acknowledge from BU21026MUV, the

master send the command byte. When BU21026MUV received next 8 bits, it issues another acknowledge to the master.

After the acknowledge is received by the master, the master sends the stop or repeated start condition for ending write.

STOP or

Repeated START

START

Driving

Acquisition

Conversion

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

16

17

18

SCL

Address Byte

Command Byte

SDA

1

0

1

0

AD1 AD0

0

C3

C2

C1

C0

O3

O2

O1

O0

0

ACK

FROM

BU21025

ACK

FROM

BU21025

SLAVE ADDR

R/WB

Figure 1. Write Protocol

If a receiving command in BU21026MUV is not the software reset or setup, BU21026MUV starts driving screen voltage

when C0 is latched by rising edge of SCL. Next, if the received type of operation code is measurement, BU21026MUV

starts acquisition in A/D converter when next falling edge of SCL. BU21026MUV stops acquisition and starts A/D conversion

when BU21026MUV receive the stop or repeated start condition.

When BU21026MUV receives a command other than software reset during the A/D conversion, the command is ignored.

And if the command is ignored, BU21026MUV doesn’t return an acknowledge at the ACK timing behind the command byte.

(18^thtiming in Figure. 1)

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Read Protocol

A data read is started in BU21026MUV when the master sends the start condition, the slave address of BU21026MUV, and

one in bit 0( 8^thbit) for reading, as shown in Table 1. If the slave address is matched with its own, BU21026MUV issues an

acknowledge to the master. Next, BU21026MUV send upper 8-bit (D11-4) of an A/D converted 12-bit data as data byte 1

and wait an acknowledge from the master. After receiving the acknowledge, the data byte 2 is sent. Upper 4 bits of it are

lower 4 bits (D3-0) of the A/D converted 12-bit data, and lower 4 bits of it are all zero. In next acknowledge timing, the

master send a not-acknowledge and the stop or repeated start condition for ending read. In the last acknowledge timing,

BU21026MUV doesn’t check the acknowledge and stop sending data. So if the master send an acknowledge and continue

reading a byte, the read data become 0xFF. In the 8-bit mode, all of an A/D converted 8-bit data is in the data byte 1. So,

the master doesn’t need to read the data byte 2.

STOP or

Repeated START

START

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

16

17

18

19

20

21

22

23

24

25

26

27

SCL

Address Byte

Data Byte 1

Data Byte 2

SDA

1

0

1

0

AD1 AD0

1

0

D11 D10

D9

D8

D7

D6

D5

D4

0

D3

D2

D1

D0

0

1

ACK

FROM

MASTER

ACK

FROM

MASTER

NACK

FROM

MASTER

SLAVE ADDR

R/WB

Figure 2. Read Protocol

If an A/D conversion is not finished until falling edge SCL after first acknowledge timing with read mode, SCL pin is

stretched by BU21026MUV.In this state, SCL pin is forced to low by BU21026MUV and SDA value is invalid data. This state

is ended when the A/D conversion is finished. After this state end, the master can control the SCL line and read converted

data.

With stretch function, the master can access immediately after sending a conversion command. If performance of an A/D

conversion is needed, the master send the read command after the A/D conversion is finished. Detail of a A/D conversion

time is shown in Table 5.

Stretch

Conversion

STOP or

Repeated START

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

16

17

18

19

20

21

22

23

24

25

26

27

SCL

SCL low force

by

BU21025

Address Byte

Data Byte 1

Data Byte 2

SDA

1

0

1

0

AD1 AD0

1

0

X

D11 D10

D9

D8

D7

D6

D5

D4

0

D3

D2

D1

D0

0

1

ACK

FROM

MASTER

ACK

FROM

MASTER

NACK

FROM

MASTER

SLAVE ADDR

R/WB

INVALID

DATA

Figure 3. Read with Stretch

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BU21026MUV

Operation

Position Detection of Touch Screen

The 4-wire resistive touch screen is mainly constituted in two resistive plates, X and Y. If screen is pressed, these 2 plates

are connected.

A position of touch screen is detected by applying voltage to one plate and measuring voltage of another plate. This

measurement voltage is divided by touch position. In X-position detection, X-plate is applied voltage. And Voltage of Y-plate

is measured. In Y-position detection, Y-plate is applied voltage. And Voltage of Y-plate is measured. The master needs to

detection 2 times for detecting X and Y position

When screen is not touched, a measuring plate is high impedance from another plate. So, it can’t get voltage. And a value

of the A/D conversion became unknown. If unknown values are used for calculating the coordinates, the coordinates will not

show touch points. So it is require to filter unknown values when the calculate coordinates.

VDD

ON

XP

YP

XP

YP

VREFP

AIN

VREFN

XN

YN

XN

YN

ON

GND

Figure 4. X-Position Detection Mode

Figure 5. Y-Position Detection Mode

Touch Pressure Measurement

These are two methods for measuring touch resistance. The first method requires that a resistance of X-plate (R_X-plate) is

known. In this method, the calculation of touch resistance (R_TOUCH) needs X position and 2 additional measurement data (Z₁

and Z₂) that shown in Figure 6 and 7. The equation is as follows,

X



^postion









Z₂

R_TOUCH R_X-plate



1

4096 Z₁



The second method requires that both resistance of X-plate and resistance of Y-plate (R_Y-plate) are known. In this method,

the calculation of R_TOUCHneeds X and Y position and Z1. The equation is as follows,

R_X-plate X_position

Y









4096

Z₁







^position

R_TOUCH





1 -R_Y-plate 1-











4096





VDD

ON

XP

YP

XP

YP

VREFP

AIN

VREFN

XN

YN

XN

YN

ON

GND

Figure 6. Z1-Position Detection Mode

Figure 7. Z2-Position Detection Mode

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TSZ22111 • 15 • 001

BU21026MUV

A/D Conversion Time

When MAF is disabled, an A/D conversion takes 66 internal core clocks (CCLK) with 12-bit mode and 38 CCLK with 8-bit

mode. When MAF is enabled, it takes 476 CCLK with 12-bit mode and 244 CCLK with 8-bit mode. In MAF mode, the

number of sampling becomes 7. So the A/D conversion cycles become large.

The A/D conversion clocks and time are shown in Table 5. The number of CCLK and time are counted from a stop or

repeated start condition after sending a conversion command. In this table, the time is calculated by CCLK is 4MHz in

typically.

Table 5. A/D Conversion Time (CCLK = 4MHz)

MAF

MODE

12-bit

8-bit

NUMBER OF CCLK

TIME [us]

119.0

61.0

476

244

66

Enable

12-bit

8-bit

16.5

Disable

38

9.5

A/D Sampling Time with 2-wire Serial Interface

The master need to send a conversion command and a read command for getting an A/D converted data. So, a throughput

rate is affected by 2-wire serial interface frequency. Each write cycle takes 20 SCL and each read cycle takes 29 SCL

(12-bit mode) or 20 SCL (8-bit mode). Note that each a start and a stop condition take 1 SCL in this count.

When the 2-wire serial interface frequency is 400 KHz, one period become 2.5us. Each A/D sampling time takes 241.5us

(49 x 2.5 us + 119.0 us) with 12-bit mode and MAF. So, a control throughput rate becomes 4.14 kSPS. In MAF mode,

BU21026MUV operates A/D conversion 7 times. It means that an operation throughput rate is increased 7 times. It

becomes 28.99 kSPS.

Table 6. Control and Operation Throughput

2-WIRE SERIAL

INTERFACE

FREQENCY

A/D

CONTROL

THROUGHPUT THROUGHPUT

OPERATION

NUMBER

OF SCL

CYCLE TIME

[us]

MAF

MODE

CONVERSION

TIME [us]

[kSPS]

12-bit

8-bit

12-bit

8-bit

12-bit

8-bit

12-bit

8-bit

49

40

49

40

49

40

49

40

119.0

61.0

16.5

9.5

119.0

61.0

16.5

9.5

609.0

461.0

506.5

409.5

241.5

161.0

139.0

109.5

1.64

2.17

1.97

2.44

4.14

6.21

7.19

9.13

11.49

15.18

-

28.99

43.48

-

Enable

Disable

Enable

Disable

100 kHz

(10us period)

400 kHz

(2.5us period)

www.rohm.com

TSZ02201-0L5L0FF00890-1-2

4.Aug.2016 Rev.001

14/19

TSZ22111 • 15 • 001

BU21026MUV

Operational Notes

1. Reverse Connection of Power Supply

Connecting the power supply in reverse polarity can damage the IC. Take precautions against reverse polarity when

connecting the power supply, such as mounting an external diode between the power supply and the IC’s power

supply pins.

2. Power Supply Lines

Design the PCB layout pattern to provide low impedance supply lines. Furthermore, connect a capacitor to ground at

all power supply pins. Consider the effect of temperature and aging on the capacitance value when using electrolytic

capacitors.

3. Ground Voltage

Ensure that no pins are at a voltage below that of the ground pin at any time, even during transient condition.

4. Ground Wiring Pattern

When using both small-signal and large-current ground traces, the two ground traces should be routed separately but

connected to a single ground at the reference point of the application board to avoid fluctuations in the small-signal

ground caused by large currents. Also ensure that the ground traces of external components do not cause variations

on the ground voltage. The ground lines must be as short and thick as possible to reduce line impedance.

5. Thermal Consideration

Should by any chance the maximum junction temperature rating be exceeded the rise in temperature of the chip may

result in deterioration of the properties of the chip. In case of exceeding this absolute maximum rating, increase the

board size and copper area to prevent exceeding the maximum junction temperature rating.

6. Recommended Operating Conditions

These conditions represent a range within which the expected characteristics of the IC can be approximately

obtained. The electrical characteristics are guaranteed under the conditions of each parameter.

7. Inrush Current

When power is first supplied to the IC, it is possible that the internal logic may be unstable and inrush current may

flow instantaneously due to the internal powering sequence and delays, especially if the IC has more than one power

supply. Therefore, give special consideration to power coupling capacitance, power wiring, width of ground wiring,

and routing of connections.

8. Operation Under Strong Electromagnetic Field

Operating the IC in the presence of a strong electromagnetic field may cause the IC to malfunction.

9. Testing on Application Boards

When testing the IC on an application board, connecting a capacitor directly to a low-impedance output pin may

subject the IC to stress. Always discharge capacitors completely after each process or step. The IC’s power supply

should always be turned off completely before connecting or removing it from the test setup during the inspection

process. To prevent damage from static discharge, ground the IC during assembly and use similar precautions during

transport and storage.

10. Inter-pin Short and Mounting Errors

Ensure that the direction and position are correct when mounting the IC on the PCB. Incorrect mounting may result in

damaging the IC. Avoid nearby pins being shorted to each other especially to ground, power supply and output pin.

Inter-pin shorts could be due to many reasons such as metal particles, water droplets (in very humid environment)

and unintentional solder bridge deposited in between pins during assembly to name a few.

11. Unused Input Pins

Input pins of an IC are often connected to the gate of a MOS transistor. The gate has extremely high impedance and

extremely low capacitance. If left unconnected, the electric field from the outside can easily charge it. The small charge

acquired in this way is enough to produce a significant effect on the conduction through the transistor and cause

unexpected operation of the IC. So unless otherwise specified, unused input pins should be connected to the power

supply or ground line.

12. Regarding the Input Pin of the IC

In the construction of this IC, P-N junctions are inevitably formed creating parasitic diodes or transistors. The

operation of these parasitic elements can result in mutual interference among circuits, operational faults, or physical

damage. Therefore, conditions which cause these parasitic elements to operate, such as applying a voltage to an

input pin lower than the ground voltage should be avoided. Furthermore, do not apply a voltage to the input pins

when no power supply voltage is applied to the IC. Even if the power supply voltage is applied, make sure that the

input pins have voltages within the values specified in the electrical characteristics of this IC.

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TSZ02201-0L5L0FF00890-1-2

4.Aug.2016 Rev.001

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TSZ22111 • 15 • 001

BU21026MUV

Operational Notes – continued

13. Ceramic Capacitor

When using a ceramic capacitor, determine a capacitance value considering the change of capacitance with

temperature and the decrease in nominal capacitance due to DC bias and others.

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TSZ02201-0L5L0FF00890-1-2

4.Aug.2016 Rev.001

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TSZ22111 • 15 • 001

BU21026MUV

Ordering Information

B U 2 1 0 2 6 M U V -

E 2

Part Number

Package

MUV: VQFN020V4040

Packaging and forming specification

E2: Embossed tape and reel

(VQFN020V4040)

Marking Diagrams

VQFN020V4040 (TOP VIEW)

Part Number Marking

B U 2 1 0

2 6 M U V

LOT Number

1PIN MARK

Part Number Marking

Package

Orderable Part Number

BU21026MUV

VQFN020V4040 BU21026MUV-E2

www.rohm.com

TSZ02201-0L5L0FF00890-1-2

4.Aug.2016 Rev.001

17/19

TSZ22111 • 15 • 001

BU21026MUV

Physical Dimension, Tape and Reel Information

Package Name

VQFN020V4040

www.rohm.com

TSZ22111 • 15 • 001

TSZ02201-0L5L0FF00890-1-2

4.Aug.2016 Rev.001

18/19

BU21026MUV

Revision History

Date

Revision

001

Changes

04.Aug.2016

New Release

www.rohm.com

TSZ02201-0L5L0FF00890-1-2

4.Aug.2016 Rev.001

19/19

TSZ22111 • 15 • 001

Notice

Precaution on using ROHM Products

1. Our Products are designed and manufactured for application in ordinary electronic equipments (such as AV equipment,

OA equipment, telecommunication equipment, home electronic appliances, amusement equipment, etc.). If you

intend to use our Products in devices requiring extremely high reliability (such as medical equipment ^{(Note 1)}, transport

equipment, traffic equipment, aircraft/spacecraft, nuclear power controllers, fuel controllers, car equipment including car

accessories, safety devices, etc.) and whose malfunction or failure may cause loss of human life, bodily injury or

serious damage to property (“Specific Applications”), please consult with the ROHM sales representative in advance.

Unless otherwise agreed in writing by ROHM in advance, ROHM shall not be in any way responsible or liable for any

damages, expenses or losses incurred by you or third parties arising from the use of any ROHM’s Products for Specific

Applications.

(Note1) Medical Equipment Classification of the Specific Applications

JAPAN

USA

EU

CHINA

CLASSⅢ

CLASSⅣ

CLASSⅡb

CLASSⅢ

2. ROHM designs and manufactures its Products subject to strict quality control system. However, semiconductor

products can fail or malfunction at a certain rate. Please be sure to implement, at your own responsibilities, adequate

safety measures including but not limited to fail-safe design against the physical injury, damage to any property, which

a failure or malfunction of our Products may cause. The following are examples of safety measures:

[a] Installation of protection circuits or other protective devices to improve system safety

[b] Installation of redundant circuits to reduce the impact of single or multiple circuit failure

3. Our Products are designed and manufactured for use under standard conditions and not under any special or

extraordinary environments or conditions, as exemplified below. Accordingly, ROHM shall not be in any way

responsible or liable for any damages, expenses or losses arising from the use of any ROHM’s Products under any

special or extraordinary environments or conditions. If you intend to use our Products under any special or

extraordinary environments or conditions (as exemplified below), your independent verification and confirmation of

product performance, reliability, etc, prior to use, must be necessary:

[a] Use of our Products in any types of liquid, including water, oils, chemicals, and organic solvents

[b] Use of our Products outdoors or in places where the Products are exposed to direct sunlight or dust

[c] Use of our Products in places where the Products are exposed to sea wind or corrosive gases, including Cl2,

H2S, NH3, SO2, and NO2

[d] Use of our Products in places where the Products are exposed to static electricity or electromagnetic waves

[e] Use of our Products in proximity to heat-producing components, plastic cords, or other flammable items

[f] Sealing or coating our Products with resin or other coating materials

[g] Use of our Products without cleaning residue of flux (even if you use no-clean type fluxes, cleaning residue of

flux is recommended); or Washing our Products by using water or water-soluble cleaning agents for cleaning

residue after soldering

[h] Use of the Products in places subject to dew condensation

4. The Products are not subject to radiation-proof design.

5. Please verify and confirm characteristics of the final or mounted products in using the Products.

6. In particular, if a transient load (a large amount of load applied in a short period of time, such as pulse. is applied,

confirmation of performance characteristics after on-board mounting is strongly recommended. Avoid applying power

exceeding normal rated power; exceeding the power rating under steady-state loading condition may negatively affect

product performance and reliability.

7. De-rate Power Dissipation depending on ambient temperature. When used in sealed area, confirm that it is the use in

the range that does not exceed the maximum junction temperature.

8. Confirm that operation temperature is within the specified range described in the product specification.

9. ROHM shall not be in any way responsible or liable for failure induced under deviant condition from what is defined in

this document.

Precaution for Mounting / Circuit board design

1. When a highly active halogenous (chlorine, bromine, etc.) flux is used, the residue of flux may negatively affect product

performance and reliability.

2. In principle, the reflow soldering method must be used on a surface-mount products, the flow soldering method must

be used on a through hole mount products. If the flow soldering method is preferred on a surface-mount products,

please consult with the ROHM representative in advance.

For details, please refer to ROHM Mounting specification

Notice-PGA-E

Rev.003

Precautions Regarding Application Examples and External Circuits

1. If change is made to the constant of an external circuit, please allow a sufficient margin considering variations of the

characteristics of the Products and external components, including transient characteristics, as well as static

characteristics.

2. You agree that application notes, reference designs, and associated data and information contained in this document

are presented only as guidance for Products use. Therefore, in case you use such information, you are solely

responsible for it and you must exercise your own independent verification and judgment in the use of such information

contained in this document. ROHM shall not be in any way responsible or liable for any damages, expenses or losses

incurred by you or third parties arising from the use of such information.

Precaution for Electrostatic

This Product is electrostatic sensitive product, which may be damaged due to electrostatic discharge. Please take proper

caution in your manufacturing process and storage so that voltage exceeding the Products maximum rating will not be

applied to Products. Please take special care under dry condition (e.g. Grounding of human body / equipment / solder iron,

isolation from charged objects, setting of Ionizer, friction prevention and temperature / humidity control).

Precaution for Storage / Transportation

1. Product performance and soldered connections may deteriorate if the Products are stored in the places where:

[a] the Products are exposed to sea winds or corrosive gases, including Cl2, H2S, NH3, SO2, and NO2

[b] the temperature or humidity exceeds those recommended by ROHM

[c] the Products are exposed to direct sunshine or condensation

[d] the Products are exposed to high Electrostatic

2. Even under ROHM recommended storage condition, solderability of products out of recommended storage time period

may be degraded. It is strongly recommended to confirm solderability before using Products of which storage time is

exceeding the recommended storage time period.

3. Store / transport cartons in the correct direction, which is indicated on a carton with a symbol. Otherwise bent leads

may occur due to excessive stress applied when dropping of a carton.

4. Use Products within the specified time after opening a humidity barrier bag. Baking is required before using Products of

which storage time is exceeding the recommended storage time period.

Precaution for Product Label

A two-dimensional barcode printed on ROHM Products label is for ROHM’s internal use only.

Precaution for Disposition

When disposing Products please dispose them properly using an authorized industry waste company.

Precaution for Foreign Exchange and Foreign Trade act

Since concerned goods might be fallen under listed items of export control prescribed by Foreign exchange and Foreign

trade act, please consult with ROHM in case of export.

Precaution Regarding Intellectual Property Rights

1. All information and data including but not limited to application example contained in this document is for reference

only. ROHM does not warrant that foregoing information or data will not infringe any intellectual property rights or any

other rights of any third party regarding such information or data.

2. ROHM shall not have any obligations where the claims, actions or demands arising from the combination of the

Products with other articles such as components, circuits, systems or external equipment (including software).

3. No license, expressly or implied, is granted hereby under any intellectual property rights or other rights of ROHM or any

third parties with respect to the Products or the information contained in this document. Provided, however, that ROHM

will not assert its intellectual property rights or other rights against you or your customers to the extent necessary to

manufacture or sell products containing the Products, subject to the terms and conditions herein.

Other Precaution

1. This document may not be reprinted or reproduced, in whole or in part, without prior written consent of ROHM.

2. The Products may not be disassembled, converted, modified, reproduced or otherwise changed without prior written

consent of ROHM.

3. In no event shall you use in any way whatsoever the Products and the related technical information contained in the

Products or this document for any military purposes, including but not limited to, the development of mass-destruction

weapons.

4. The proper names of companies or products described in this document are trademarks or registered trademarks of

ROHM, its affiliated companies or third parties.

Notice-PGA-E

Rev.003


型号：	BU21026MUV
厂家：	ROHM
描述：	4-wire Resistive Touch Screen Controller
文件：	总23页 (文件大小：2090K)
中文：	中文翻译
下载：	下载PDF数据表文档文件

BU21026MUV [ROHM]

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