〇Product structure : Silicon monolithic integrated circuit 〇This product has no designed protection against radioactive rays
.
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TSZ02201-0L5L0FF00890-1-2
© 2016 ROHM Co., Ltd. All rights reserved.
4.Aug.2016 Rev.001
TSZ22111 • 14 • 001
www.rohm.com
Resistive touch screen controller LSI series
4-wire Resistive
Touch Screen Controller
BU21026MUV
General Description
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.
Features
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
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.
Key Specifications
Power supply voltage 1.65V to 3.60V
Temperature range -30℃ to 85℃
Standby current 0.8uA (Max.)
Operating current 120uA (Typ.)
Coordinate resolution 12Bits
Package
VQFN020V4040 4.00mm x 4.00mm x 1.00mm
Typical Application Circuit(s)
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
XP
YP
XN
YN
VDD
BU21026
GND
AD0
AD1
SDAAUX
INT
SCL
Auxilary Input SDA
SCL
GPIO
VDD
GND GND
GND
1.0μF
2.2kΩ
0.1μF
2.2kΩ
Master
( 2-wire serial
interface )
0.1μF
0.1μF
0.1μF
0.1μF
10Ω
10Ω
10Ω
10Ω
GND
Touch
Screen
3
2
5
1
4
W(Typ) x D(Typ) x H(Max)
Datashee
t
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TSZ02201-0L5L0FF00890-1-2
© 2016 ROHM Co., Ltd. All rights reserved.
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TSZ22111 • 15 • 001
BU21026MUV
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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© 2016 ROHM Co., Ltd. All rights reserved.
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TSZ22111 • 15 • 001
BU21026MUV
Pin Configuration(s)
Pin Description(s)
Pin No.
Pin Name
I/O
Function
Figure
1
AD1
I
Slave address bit1 input
A
2
SCL
I/O
Serial clock
B
3
SDA
I/O
Serial data
B
4
AD0
I
Slave address bit0 input
A
5
INT
O
Interrupt output. Pin polarity is active low.
A
6
-
-
(N.C.)
-
7
AUX
I
Auxiliary input
C
8
VDD
-
Power supply
-
9
-
-
(N.C.)
-
10
-
-
(N.C.)
-
11
XP
I/O
Screen interface
C
12
YP
I/O
Screen interface
C
13
-
-
(N.C.)
-
14
XN
I/O
Screen interface
C
15
YN
I/O
Screen interface
C
16
-
-
(N.C.)
-
17
-
-
(N.C.)
-
18
GND
-
Ground
-
19
-
-
(N.C.)
-
20
-
-
(N.C.)
-
Equivalent circuit
PAD
PAD
PAD
Figure. A Figure. B Figure. C
16
17
18
19
20
1AD1
2SCL
3SDA
4AD0
5INT
10
9
8
7
6
(N.C.)
(N.C.)
VDD
AUX
(N.C.)
15 YN
14 XN
13 (N.C.)
12 YP
11 XP
TOP VIEW
(N.C.)
(N.C.)
GND
(N.C.)
(N.C.)
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TSZ02201-0L5L0FF00890-1-2
© 2016 ROHM Co., Ltd. All rights reserved.
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TSZ22111 • 15 • 001
BU21026MUV
Block Diagram(s)
Touch Screen
Interface
Clock
Oscillator
A/D
Converter
Control
Logic
&
2-wire Serial
Interface
INT
Digital Filter
Touch
Detection
SDA
SCL
AD1
AD0
Power On
Reset
XP
YP
XN
YN
AUX
VDD
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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TSZ22111 • 15 • 001
BU21026MUV
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 (RPU) and YN pin is connected to GND. A resistance of RPU is
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 RPU is 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 2nd acknowledge 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.
Y-plate
X-plate
ON
GND
XP
YP
XN
YN
ON RPU
INTVDD
OFF
Control
logic
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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TSZ22111 • 15 • 001
BU21026MUV
Absolute Maximum Ratings
PARAMETER
SYMBOL
RATING
UNIT
Power supply voltage
VDD
-0.3 to 4.5
V
Input voltage
VIN
-0.3 to VDD+0.3
V
Storage temperature range
Tstg
-50 to 125
℃
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)
PARAMETER
SYMBOL
Thermal Resistance (Typ)
UNIT
1s(Note 3)
2s2p(Note 4)
VQFN020V4040
Junction to Ambient
θJA
153.9
37.4
°C/W
Junction to Top Characterization Parameter(Note 2)
ΨJT
13
7
°C/W
(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
Board Size
Single
FR-4
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
Measurement Board
Material
Board Size
Thermal Via(Note 5)
Pitch
Diameter
4 Layers
FR-4
114.3mm x 76.2mm x 1.6mmt
1.20mm
Φ0.30mm
Top
2 Internal Layers
Bottom
Copper Pattern
Thickness
Copper Pattern
Thickness
Copper Pattern
Thickness
Footprints and Traces
70μm
74.2mm x 74.2mm
35μm
74.2mm x 74.2mm
70μm
(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
1.65
3.00
3.60
V
Operating temperature range
Tj
-30
25
85
℃
Electrical Characteristics
PARAMETER
SYMBOL
MIN.
TYP.
MAX.
UNIT
CONDITION
Low-level input voltage
VIL
-0.3
-
0.3xVDD
V
High-level input voltage
VIH
0.7xVDD
-
VDD+0.3
V
Low-level output voltage
VOL
0
-
0.2
V
IL = 3.6mA
High-level output voltage
VOH
VDD-0.2
-
VDD
V
IL = -3.6mA
A/D converter resolution
AD
-
-
12
Bits
Programmable 8/12 bits
Differential non-linearity error
DNL
-3.5
-
3.5
LSB
Integral non-linearity error
INL
-5
-
5
LSB
Internal clock frequency
Freq
2.6
4.0
5.1
MHz
Active current
Idd
-
120
450
uA
8.2kSPS (operation )
Standby current
Ist
-
-
0.8
uA
After reset releasing
(Unless otherwise specified Tj=25[℃], VDD=3.00[V], GND=0.00[V])
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© 2016 ROHM Co., Ltd. All rights reserved.
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TSZ22111 • 15 • 001
BU21026MUV
Power on Reset Timing Chart
1.4V
0.2V
1.65～3.60V
0V
tOFF_VDD
tRDY
tF_VDD tR_VDD
VDD
PARAMETER
SYMBOL
RATING
UNIT
CONDITION
MIN.
TYP.
MAX.
Off period of VDD
tOFF_VDD
0.3
-
-
s
Rise time for VDD
tR_VDD
10
-
100
us
Fall time for VDD
tF_VDD
0.5
-
-
ms
Ready time for device
tRDY
-
-
2
ms
2-wire Serial Interface Timing Chart
tHD_STA
tHIGH
tSU_STA
tHD_DAT
tSU_DAT
tR
tLOW tF
tHD_STA tSU_STO tBUF
START
CONDITION
REPEATED
START
CONDITION
STOP
CONDITION
START
CONDITION
SDA
SCL
PARAMETER
SYMBOL
RATING
UNIT
CONDITION
MIN.
TYP.
MAX.
SCL clock frequency
fSCL
-
-
400
KHz
Hold time for (repeated) START condition
tHD_STA
0.6
-
-
us
Low period of SCL
tLOW
1.3
-
-
us
High period of SCL
tHIGH
0.6
-
-
us
Setup time for repeated START condition
tSU_STA
0.6
-
-
us
Data hold time
tHD_DAT
0
-
0.9
us
Data setup time
tSU_DAT
100
-
-
ns
Rise time for both SCL and SDA
tR
20
-
300
ns
Fall time for both SCL and SDA
tF
20
-
300
ns
Setup time for STOP condition
tSU_STO
0.6
-
-
us
Bus free time between a STOP and START condition
tBUF
1.3
-
-
us
(Unless otherwise specified Tj=25[℃], VDD=3.00[V], GND=0.00[V])
(Unless otherwise specified Tj=25[℃], VDD=3.00[V], GND=0.00[V])
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TSZ22111 • 15 • 001
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
BIT
MSB
7
6
5
4
3
2
1
LSB
0
NAME
S6
S5
S4
S3
S2
S1
S0
R/WB
SLAVE
1
0
0
1
0
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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TSZ22111 • 15 • 001
BU21026MUV
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
BIT
MSB
7
6
5
4
3
2
1
LSB
0
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
C3
C2
C1
C0
FUNCTION
AD-INPUT
X-DRIVER
Y-DRIVER
INT
POLARITY
OPERAND
TYPE
0
0
0
0
Set Power
OFF
OFF
OFF
H
0
0
0
0
1
Reserved
-
-
-
-
-
0
0
1
0
Measure AUX
AUX
OFF
OFF
H
0
0
0
1
1
Reserved
-
-
-
-
-
0
1
0
0
Set Power
OFF
OFF
OFF
H
0
0
1
0
1
Software Reset
OFF
OFF
OFF
H
2
0
1
1
0
Reserved
-
-
-
-
-
0
1
1
1
Reserved
-
-
-
-
-
1
0
0
0
Drive X
OFF
ON
OFF
L
0
1
0
0
1
Drive Y
OFF
OFF
ON
L
0
1
0
1
0
Drive Z
OFF
XN-ON
YP-ON
L
0
1
0
1
1
Setup
Keep
Keep
Keep
Keep
1
1
1
0
0
Measure X
YP
ON
OFF
L
0
1
1
0
1
Measure Y
XP
OFF
ON
L
0
1
1
1
0
Measure Z1
YN
XN-ON
YP-ON
L
0
1
1
1
1
Measure Z2
XP
XN-ON
YP-ON
L
0
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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TSZ22111 • 15 • 001
BU21026MUV
Table 4.Operands of Each Type
OPERAND
TYPE
O3
O2
C1
C0
0
X
PD
M
X
1
L1
L0
MAF
PU90
2
X
X
X
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
11/19
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TSZ22111 • 15 • 001
BU21026MUV
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( 8th bit) 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.
AD1001 1 0 00 C3 C2 C1 C0 O3 O2 O1 O0AD0 0
R/WBSLAVE ADDR ACK
FROM
BU21025
Address Byte Command Byte
Acquisition Conversion
Driving
SCL
SDA
ACK
FROM
BU21025
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18
STOP or
Repeated STARTSTART
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.
(18th timing in Figure. 1)
12/19
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© 2016 ROHM Co., Ltd. All rights reserved.
4.Aug.2016 Rev.001
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TSZ22111 • 15 • 001
BU21026MUV
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( 8th bit) 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.
AD1001 1 0 01 D11 D10 D9 D8 D7 D6 D5 D4AD0 0
R/WBSLAVE ADDR ACK
FROM
MASTER
Address Byte Data Byte 1
SCL
SDA
ACK
FROM
MASTER
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18
D3 D2 D1 D0
Data Byte 2
100 0 0
19 20 21 22 23 24 25 26 27
START
STOP or
Repeated START
NACK
FROM
MASTER
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.
AD1001 1 0 01 D11 D10 D9 D8 D7 D6 D5 D4AD0 0
R/WBSLAVE ADDR ACK
FROM
MASTER
Address Byte Data Byte 1
SCL
SDA
ACK
FROM
MASTER
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18
D3 D2 D1 D0
Data Byte 2
100 0 0
19 20 21 22 23 24 25 26 27
STOP or
Repeated START
NACK
FROM
MASTER
Conversion
X
Stretch
SCL low force
by
BU21025
INVALID
DATA
Figure 3. Read with Stretch
13/19
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© 2016 ROHM Co., Ltd. All rights reserved.
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TSZ22111 • 15 • 001
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.
Y-plate
X-plate
VDD
ON
ON
AIN
VREFP
VREFN
GND
XP
YP
XN
YN
Y-plate
X-plate
VDD
ON
ON
AIN
VREFP
VREFN
GND
XP
YP
XN
YN
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 (RX-plate) is
known. In this method, the calculation of touch resistance (RTOUCH) needs X position and 2 additional measurement data (Z1
and Z2) that shown in Figure 6 and 7. The equation is as follows,
1
1
2
postion
-plateXTOUCH Z
Z
4096
X
R R
The second method requires that both resistance of X-plate and resistance of Y-plate (RY-plate) are known. In this method,
the calculation of RTOUCH needs X and Y position and Z1. The equation is as follows,
4096
Y
-1 R - 1
Z
4096
4096
X R
R position
plate-Y
1
positionplate-X
TOUCH
Y-plate
X-plate
ON
AIN
VREFP
VREFN
GND
XN
YN
VDD
ON
XP
YP
Y-plate
X-plate
ON
AIN
VREFP
VREFN
GND
XN
YN
VDD
ON
XP
YP
Figure 6. Z1-Position Detection Mode Figure 7. Z2-Position Detection Mode
14/19
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© 2016 ROHM Co., Ltd. All rights reserved.
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www.rohm.com
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
NUMBER OF CCLK
TIME [us]
Enable
12-bit
476
119.0
8-bit
244
61.0
Disable
12-bit
66
16.5
8-bit
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
MAF
MODE
NUMBER
OF SCL
A/D
CONVERSION
TIME [us]
CYCLE TIME
[us]
CONTROL
THROUGHPUT
[kSPS]
OPERATION
THROUGHPUT
[kSPS]
100 kHz
(10us period)
Enable
12-bit
49
119.0
609.0
1.64
11.49
8-bit
40
61.0
461.0
2.17
15.18
Disable
12-bit
49
16.5
506.5
1.97
-
8-bit
40
9.5
409.5
2.44
-
400 kHz
(2.5us period)
Enable
12-bit
49
119.0
241.5
4.14
28.99
8-bit
40
61.0
161.0
6.21
43.48
Disable
12-bit
49
16.5
139.0
7.19
-
8-bit
40
9.5
109.5
9.13
-
15/19
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© 2016 ROHM Co., Ltd. All rights reserved.
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www.rohm.com
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.
16/19
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© 2016 ROHM Co., Ltd. All rights reserved.
4.Aug.2016 Rev.001
www.rohm.com
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.
17/19
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© 2016 ROHM Co., Ltd. All rights reserved.
4.Aug.2016 Rev.001
www.rohm.com
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
Part Number Marking
Package
Orderable Part Number
BU21026MUV
VQFN020V4040
BU21026MUV-E2
VQFN020V4040 (TOP VIEW)
2 6 M U V
Part Number Marking
LOT Number
1PIN MARK
B U 2 1 0
18/19
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© 2016 ROHM Co., Ltd. All rights reserved.
4.Aug.2016 Rev.001
www.rohm.com
TSZ22111 • 15 • 001
BU21026MUV
Physical Dimension, Tape and Reel Information
Package Name
VQFN020V4040
19/19
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© 2016 ROHM Co., Ltd. All rights reserved.
4.Aug.2016 Rev.001
www.rohm.com
TSZ22111 • 15 • 001
BU21026MUV
Revision History
Date
Revision
Changes
04.Aug.2016
001
New Release
Notice-PGA-E Rev.003
© 2015 ROHM Co., Ltd. All rights reserved.
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
CLASSⅢ
CLASSⅡb
CLASSⅢ
CLASSⅣ
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
© 2015 ROHM Co., Ltd. All rights reserved.
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
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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.
DatasheetDatasheet
Notice – WE Rev.001
© 2015 ROHM Co., Ltd. All rights reserved.
General Precaution
1. Before you use our Pro ducts, you are requested to care fully read this document and fully understand its contents.
ROHM shall n ot be in an y way responsible or liabl e for fa ilure, malfunction or acci dent arising from the use of a ny
ROHM’s Products against warning, caution or note contained in this document.
2. All information contained in this docume nt is current as of the issuing date and subj ect to change without any prior
notice. Before purchasing or using ROHM’s Products, please confirm the la test information with a ROHM sale s
representative.
3. The information contained in this doc ument is provi ded on an “as is” basis and ROHM does not warrant that all
information contained in this document is accurate an d/or error-free. ROHM shall not be in an y way responsible or
liable for an y damages, expenses or losses incurred b y you or third parties resulting from inaccur acy or errors of or
concerning such information.
