TI TSC2006IRTJR

 TSC2006
SBAS415A – JUNE 2007 – REVISED NOVEMBER 2007
1.2V to 3.6V, 12-Bit, Nanopower, 4-Wire
TOUCH SCREEN CONTROLLER with SPI™ Interface
FEATURES
APPLICATIONS
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(1)
4-Wire Touch Screen Interface
Ratiometric Conversion
Single 1.2V to 3.6V Supply
Preprocessing to Reduce Bus Activity
High-Speed SPI-Compatible Interface
Internal Detection of Screen Touch
Register-Based Programmable:
– 10-Bit or 12-Bit Resolution
– Sampling Rates
– System Timing
On-Chip Temperature Measurement
Touch Pressure Measurement
Auto Power-Down Control
Low Power:
– 707µW at 1.8V, 50SSPS
– 544µW at 1.6V, 50SSPS
– 280µW at 1.2V, 50SSPS
– 69µW at 1.6V, 8.2kSPS Eq. Rate
– 43µW 1.2V, 8.2kSPS Eq. Rate
Enhanced ESD Protection:
– ±8kV HBM
– ±1kV CDM
– Target ±25kV Air Gap Discharge
– Target ±12kV Contact Discharge
4 × 4 QFN-20 and 0.4mm 4 × 4 XTQFN-20(1)
Packages
Personal Digital Assistants
Cellular Phones
Portable Instruments
Point-of-Sale Terminals
MP3 Players, Pagers
Multiscreen Touch Control
DESCRIPTION
The TSC2006 is a very low-power touch screen
controller designed to work with power-sensitive,
handheld applications that are based on advanced
low-voltage processors. It works with a supply voltage
as low as 1.2V, which can be supplied by a
single-cell battery. It contains a complete,
ultralow-power, 12-bit, analog-to-digital (A/D) resistive
touch screen converter, including drivers and the
control logic to measure touch pressure.
In addition to these standard features, the TSC2006
offers
preprocessing
of
the
touch
screen
measurements to reduce bus loading, thus reducing
the consumption of host processor resources that can
then be redirected to more critical functions.
The TSC2006 supports an SPI-compatible serial bus
up to 25MHz. It offers programmable resolution of 10
or 12 bits to accommodate different screen sizes and
performance needs.
The TSC2006 is available in a miniature 20-lead,
4 × 4 QFN package, and is characterized for the
–40°C to +85°C industrial temperature range.
XTQFN package available Q2, 2008.
U.S. Patent No. 6246394; other patents pending.
PENIRQ
VREF
Touch
Screen
Drivers
Interface
Mux
SAR
ADC
TEMP
AUX
Internal
Clock
Pre-Processing
X+
XY+
Y-
PINTDAV
DAV
CS
SPI
Serial
Interface
and
Control
SCLK
SDI
RESET
SDO
1
2
3
Please be aware that an important notice concerning availability, standard warranty, and use in critical applications of
Texas Instruments semiconductor products and disclaimers thereto appears at the end of this data sheet.
SPI is a trademark of Motorola, Inc.
All other trademarks are the property of their respective owners.
PRODUCTION DATA information is current as of publication date.
Products conform to specifications per the terms of the Texas
Instruments standard warranty. Production processing does not
necessarily include testing of all parameters.
Copyright © 2007, Texas Instruments Incorporated
TSC2006
www.ti.com
SBAS415A – JUNE 2007 – REVISED NOVEMBER 2007
This integrated circuit can be damaged by ESD. Texas Instruments recommends that all integrated circuits be handled with
appropriate precautions. Failure to observe proper handling and installation procedures can cause damage.
ESD damage can range from subtle performance degradation to complete device failure. Precision integrated circuits may be more
susceptible to damage because very small parametric changes could cause the device not to meet its published specifications.
ORDERING INFORMATION (1)
PRODUCT
TYPICAL
INTEGRAL
LINEARITY
(LSB)
TYPICAL
GAIN
ERROR
(LSB)
NO MISSING
CODES
RESOLUTION
(BITS)
TSC2006
–0.8 to +1.4
+0.1
11
(1)
PACKAGE
TYPE
PACKAGE
DESIGNATOR
SPECIFIED
TEMPERATURE
RANGE
PACKAGE
MARKING
20-Pin,
4 × 4 QFN
RTJ
–40°C to +85°C
TSC2006I
ORDERING
NUMBER
TRANSPORT
MEDIA,
QUANTITY
TSC2006IRTJT
Small Tape
and Reel, 250
TSC2006IRTJR
Tape and
Reel, 3000
For the most current package and ordering information, see the Package Option Addendum located at the end of this data sheet, or see
the TI website at www.ti.com.
ABSOLUTE MAXIMUM RATINGS (1)
Over operating free-air temperature range (unless otherwise noted).
Voltage range
TSC2006
UNIT
Analog input X+, Y+, AUX to SNSGND
–0.4 to SNSVDD + 0.1
V
Analog input X–, Y– to SNSGND
–0.4 to SNSVDD + 0.1
V
SNSVDD to SNSGND
–0.3 to 5
V
SNSVDD to AGND
–0.3 to 5
V
I/OVDD to DGND
–0.3 to 5
V
–2.40 to +0.3
V
Digital input voltage to DGND
SNSVDD to I/OVDD
–0.3 to I/OVDD + 0.3
V
Digital output voltage to DGND
–0.3 to I/OVDD + 0.3
V
Power dissipation
(TJ Max - TA)/θJA
Thermal impedance, θJA
39.97
°C/W
Operating free-air temperature range, TA
–40 to +85
°C
Storage temperature range, TSTG
–65 to +150
°C
+150
°C
Vapor phase (60 sec)
+215
°C
Infrared (15 sec)
+220
°C
X+, X–, Y+, Y–
±12
kV
X+, X–, Y+, Y–
±25
kV
QFN package
Junction temperature, TJ Max
Lead temperature
IEC contact discharge
(2)
IEC air discharge (2)
(1)
(2)
2
Stresses beyond those listed under Absolute Maximum Ratings may cause permanent damage to the device. These are stress ratings
only, and functional operation of the device at these or any other conditions beyond those indicated is not implied. Exposure to
absolute-maximum rated conditions for extended periods may affect device reliability.
Test method based on IEC standard 61000-4-2. Contact Texas Instruments for test details.
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TSC2006
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SBAS415A – JUNE 2007 – REVISED NOVEMBER 2007
ELECTRICAL CHARACTERISTICS
At TA = –40°C to +85°C, SNSVDD = VREF = +1.2V to +3.6V, I/OVDD (1) = +1.2V to +3.6V, unless otherwise noted.
TSC2006
PARAMETER
TEST CONDITIONS
MIN
TYP
MAX
UNIT
AUXILIARY ANALOG INPUT
Input voltage range
0
Input capacitance
VREF
12
Input leakage current
–1
V
pF
+1
µA
12
Bits
+3
LSB (2)
A/D CONVERTER
Resolution
Programmable: 10 or 12 bits
No missing codes
12-bit resolution
11
Integral linearity
–3
Differential linearity
Bits
–1.2 to 0.7
–0.7 to 0.6
4
LSB
Offset error
SNSVDD =1.6V, VREF = 1.6V, fSCLK = 10MHz, filter off
–5
2.2
+5
LSB
Gain error
SNSVDD =1.6V, VREF = 1.6V, fSCLK = 10MHz, filter off
–3
0.1
+3
LSB
REFERENCE INPUT
VREF range
1.2
VREF input current drain
Non-continuous AUX mode, SNSVDD = VREF = 1.6V,
TA = +25°C, fADC = 2MHz, fSCLK = 10MHz
Input impedance
A/D converter not converting
SNSVDD
V
2.7
µA
1
GΩ
49
kΩ
Y+, X+
6
Ω
Y–, X–
5
TOUCH SENSORS
PENIRQ 50kΩ pull-up resistor,
TA = +25°C, SNSVDD = 3V, VREF = 2.5V
RIRQ
Switch
on-resistance
Switch drivers drive current (3)
100ms duration
Ω
50
mA
INTERNAL TEMPERATURE SENSOR
Temperature range
–40
Differential method (4)
Resolution
TEMP1 (5)
Differential method (4)
Accuracy
TEMP1 (5)
+85
°C
SNSVDD = 1.6V
0.3
°C/LSB
SNSVDD = 3V
1.6
°C/LSB
SNSVDD = 1.6V
0.3
°C/LSB
SNSVDD = 3V
1.6
°C/LSB
SNSVDD = 1.6V
±3
°C/LSB
SNSVDD = 3V
±2
°C/LSB
SNSVDD = 1.6V
±3
°C/LSB
SNSVDD = 3V
±2
°C/LSB
INTERNAL OSCILLATOR
SNSVDD = 1.2V, TA = +25°C
Clock frequency, fOSC
SNSVDD = 1.6V
3.2
3.3
SNSVDD = 3.0V, TA = +25°C
Frequency drift
(1)
(2)
(3)
(4)
(5)
3.7
MHz
4.3
MHz
3.9
MHz
SNSVDD = 12V
0.112
%/°C
SNSVDD = 1.6V
–0.009
%/°C
SNSVDD = 3.0V
–0.025
%/°C
I/OVDD must be ≤ SNSVDD.
LSB means Least Significant Bit. With VREF = +2.5V, one LSB is 610µV.
Assured by design, but not tested. Exceeding 50mA source current may result in device degradation.
Difference between TEMP1 and TEMP2 measurement; no calibration necessary.
Temperature drift is –2.1mV/°C.
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SBAS415A – JUNE 2007 – REVISED NOVEMBER 2007
ELECTRICAL CHARACTERISTICS (continued)
At TA = –40°C to +85°C, SNSVDD = VREF = +1.2V to +3.6V, I/OVDD = +1.2V to +3.6V, unless otherwise noted.
TSC2006
PARAMETER
TEST CONDITIONS
MIN
TYP
MAX
UNIT
DIGITAL INPUT/OUTPUT
Logic family
CMOS
VIH
VIL
Logic level
IIL
1.2V ≤ I/OVDD < 1.6V
0.7 × I/OVDD
I/OVDD + 0.3
V
1.6V ≤ I/OVDD ≤ 3.6V
0.7 × I/OVDD
I/OVDD + 0.3
V
1.2V ≤ I/OVDD < 1.6V
–0.3
0.2 × I/OVDD
V
1.6V ≤ I/OVDD ≤ 3.6V
–0.3
0.3 × I/OVDD
V
–1
1
µA
SCLK pin or CS pin
CIN
10
pF
VOH
IOH = 2 TTL loads
I/OVDD – 0.2
I/OVDD
V
VOL
IOL = 2 TTL loads
0
0.2
V
ILEAK
Floating output
–1
1
µA
COUT
Floating output
10
pF
1.2
3.6
V
1.2
SNSVDD
V
625
µA
Data format
Straight Binary
POWER-SUPPLY REQUIREMENTS
Power-supply voltage
SNSVDD
Specified performance
I/OVDD (6)
Filter off, M = W = 1, C[3:0] =
(1,0,0,0), RM = 1, CL[1:0] =
(0,1), cont AUX mode, fADC =
2MHz, without reading data
register
Quiescent supply current
(7) (8)
SNSVDD = I/OVDD = VREF = 1.6V
500
TA = +25°C, filter on, M = 15,
W = 7, PSM = 1, C[3:0] =
(0,0,0,0), RM = 1, CL[1:0] =
(0,1), BTD[2:0] = (1,0,1),
50SSPS, MAVEX = MAVEY =
MAVEZ = 1, fADC = 2MHz,
sensor drivers supply included
SNSVDD = I/OVDD = VREF = 1.2V
233
µA
340
µA
SNSVDD = I/OVDD = VREF = 3.0V
745
µA
TA = +25°C, filter off, M = W =
1, PSM = 1, C[3:0] = (0,0,0,0),
RM = 1, CL[1:0] = (0,1),
BTD[2:0] = (1,0,1), 50SSPS,
MAVEX = MAVEY = MAVEZ
= 1, fADC = 2MHz, sensor
drivers supply included
SNSVDD = I/OVDD = VREF = 1.2V
215
µA
318
µA
SNSVDD = I/OVDD = VREF = 3.0V
706
µA
TA = +25°C, filter off, M = W =
1, C[3:0] = (0,1,0,1), RM = 1,
CL[1:0] = (0,1), non-cont AUX
mode, fADC = 2MHz, fSCLK =
5.5MHz
SNSVDD = I/OVDD = VREF = 1.2V
272
µA
SNSVDD = I/OVDD = VREF = 1.6V
361
µA
SNSVDD = I/OVDD = VREF = 3.0V
694
µA
SNSVDD = I/OVDD = VREF = 1.2V,
~11.3kSPS effective rate
348
µA
SNSVDD = I/OVDD = VREF = 1.6V,
~12.7kSPS effective rate
469
µA
SNSVDD = I/OVDD = VREF = 3.0V,
~13.3kSPS effective rate
894
µA
SNSVDD = I/OVDD = VREF = 1.2V,
~1.17kSPS effective rate
36.0
µA
SNSVDD = I/OVDD = VREF = 1.6V,
~1.17kSPS effective rate
43.2
µA
SNSVDD = I/OVDD = VREF = 3.0V,
~1.17kSPS effective rate
78.6
µA
TA = +25°C, CS high, SCLK = 0, SNSVDD = I/OVDD = VREF = 1.6V
0.023
TA = +25°C, filter on, M = 7, W
= 3, C[3:0] = (0,1,0,1), RM =
1, CL[1:0] = (0,1), MAVEAUX
= 1, non-cont AUX mode, fADC
= 2MHz, fSCLK = 3.5MHz, full
speed
TA = +25°C, filter on, M = 7, W
= 3, C[3:0] = (0,1,0,1), RM =
1, CL[1:0] = (0,1), MAVEAUX
= 1, non-cont AUX mode, fADC
= 2MHz, fSCLK = 3.5MHz,
reduced speed (8.2kSPS
equivalent rate)
Power-down supply current
(6)
(7)
(8)
4
x
SNSVDD = I/OVDD = VREF = 1.6V
x
x
SNSVDD = I/OVDD = VREF = 1.6V
x
0.8
µA
I/OVDD must be ≤ SNSVDD.
Supply current from SNSVDD.
For detailed information on test condition parameter and bit settings, see the Digital Interface section.
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TSC2006
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SBAS415A – JUNE 2007 – REVISED NOVEMBER 2007
PIN CONFIGURATION
(1)
SUBGND
Y+
X+
SNSVDD
VREF
RTJ PACKAGE(1)
QFN-20
(TOP VIEW)
15
14
13
12
11
X-
16
10
AGND
Y-
17
9
AUX
SNSGND
18
8
NC
NC
19
7
I/OVDD
CS
20
6
DGND
TSC2006
1
2
3
4
5
SDO
SCLK
SDI
PINTDAV
RESET
Thermal Pad
The thermal pad is internally connected to SUBGND. The thermal pad can be connected to the analog ground or left
floating. Keep the thermal pad separate from the digital ground, if possible.
PIN ASSIGNMENTS
PIN
NO.
PIN
NAME
I/O
A/D
1
SDO
I/O
D
Serial data output. This output is the MISO signal for the SPI protocol.
2
SCLK
I
D
Serial clock input
3
SDI
I
D
Serial data input. This input is the MOSI signal for the SPI protocol.
4
PINTDAV
O
D
Interrupt output. Data available or PENIRQ, depending on setting. Pin polarity with active low.
5
RESET
I
D
System reset. All register values reset to default values.
6
DGND
Digital ground
7
I/OVDD
Digital I/O interface voltage
8, 19
NC
9
AUX
10
AGND
11
VREF
12
SNSVDD
13
DESCRIPTION
No connection
I
A
Auxiliary channel input
I
A
X+
I
A
X+ channel input
14
Y+
I
A
Y+ channel input
15
SUBGND
16
X–
I
A
X– channel input
17
Y–
I
A
Y– channel input
18
SNSGND
20
CS
I
D
Analog ground
External reference input
Power supply for sensor drivers and other analog blocks
Substrate ground (for ESD current)
Sensor driver return
Chip select. This input is the slave select (SS) signal for the SPI protocol.
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SBAS415A – JUNE 2007 – REVISED NOVEMBER 2007
TIMING INFORMATION
The TSC2006 supports SPI programming in mode CPOL = 0 and CPHA = 0. The falling edge of SCLK is used to
change output (MISO) data and the rising edge is used to latch input (MOSI) data. Eight SCLKs are required to
complete the Byte 1 command cycle, and 24 SCLKs are required for the Byte 0 command cycle. CS can stay low
during the entire 24 SCLKs of a Byte 0 command cycle, or multiple mixed cycles of reading and writing of bytes
and register accesses, as long as the corresponding addresses are supplied.
CS (SS)
tC(SCLK)
tSU(SCLKF-CSR)
tSU(CSF-SCLK1R)
tWH(SCLK)
tF
tR
tWL(SCLK)
SCLK
tWH(CS)
tH(SCLKF-SDOVALID)
SDO (MISO)
MSB OUT
tDIS(CSR-SDOZ)
BIT 1
BIT 0
BIT 1
BIT 0
tD(CSF-SDOVALID)
tSU(SDI-SCLKR)
SDI (MOSI)
tH(SDI-SCLKR)
MSB IN
NOTE: CPOL = 0, CPHA = 0, Byte 0 cycle requires 24 SCLKs, and Byte 1 cycle requires eight SCLKs.
Figure 1. Detailed I/O Timing
TIMING REQUIREMENTS (1)
All specifications typical at –40°C to +85°C, SNSVDD = I/OVDD = 1.6V, unless otherwise noted.
PARAMETER
tWL(RESET) (2)
tC(SCLK)
Reset low time
SPI serial clock cycle time
TEST CONDITIONS
MIN
MAX
UNIT
SNSVDD ≥ 1.6V
10
µs
1.2V ≤ SNSVDD < 1.6V
13
µs
SNSVDD = I/OVDD ≥ 2.7V and ≤ 3.6V,
40% to 60% duty cycle
40
ns
SNSVDD = I/OVDD ≥ 1.6V and < 2.7V,
40% to 60% duty cycle
100
ns
SNSVDD = I/OVDD = 1.2V
40% to 60% duty cycle
182
ns
SNSVDD = I/OVDD ≥ 2.7V and ≤ 3.6V,
10pF load
25
MHz
SNSVDD = I/OVDD ≥ 1.6V and < 2.7V,
10pF load
10
MHz
5.5
MHz
fSCLK
SPI serial clock frequency
tWH(SCLK)
SPI serial clock high time
0.4 × tC(SCLK)
0.6 × tC(SCLK)
ns
tWL(SCLK)
SPI serial clock low time
0.4 × tC(SCLK)
0.6 × tC(SCLK)
ns
tSU(CSF-SCLK1R)
Enable lead time
tD(CSF-SDOVALID)
Slave access time
tH(SCLKF-SDOVALID)
MISO data hold time
tWH(CS)
Sequential transfer delay
tSU(SDI-SCLKR)
SNSVDD = I/OVDD = 1.2V, 10pF load
30
6
ns
15
ns
13
ns
15
ns
MOSI data setup time
4
ns
tH(SDI-SCLKR)
MOSI data hold time
4
tDIS(CSR-SDOZ)
Slave MISO disable time
tSU(SCLKF-CSR)
Enable lag time
tR
Rise time
SNSVDD = I/OVDD = 3V, fSCLK = 25MHz
3
ns
tF
Fall time
SNSVDD = I/OVDD = 3V, fSCLK = 25MHz
3
ns
(1)
(2)
6
ns
15
30
ns
ns
All input signals are specified with tR = tF = 5ns (10% to 90% of I/OVDD) and timed from a voltage level of (VIL + VIH)/2.
Refer to Figure 34.
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SBAS415A – JUNE 2007 – REVISED NOVEMBER 2007
TYPICAL CHARACTERISTICS
At TA = –40°C to +85°C, SNSVDD = VREF = +1.2V to +3.6V, I/OVDD = +1.2V to +3.6V, fADC = fOSC/2, fSCLK = 10MHz,
12-bit mode, and non-continuous AUX measurement, unless otherwise noted.
CHANGE IN OFFSET
vs TEMPERATURE
CHANGE IN GAIN
vs TEMPERATURE
2.0
2.0
SNSVDD = I/OVDD = VREF
1.0
SNSVDD = 3.0V
0.5
0
-0.5
SNSVDD = 1.6V
SNSVDD = 1.2V
-1.0
-1.5
SNSVDD = 3.0V
1.0
SNSVDD = 1.2V
0.5
0
-0.5
SNSVDD = 1.6V
-1.0
-1.5
-2.0
-2.0
-40
-20
0
20
40
60
80
100
-40
0
20
40
60
Temperature (°C)
Figure 2.
Figure 3.
SNSVDD SUPPLY CURRENT
vs TEMPERATURE
SNSVDD SUPPLY CURRENT
vs SNSVDD SUPPLY VOLTAGE
1.50
I/OVDD = SNSVDD = VREF
900
SNSVDD Supply Current (mA)
1000
-20
Temperature (°C)
1100
SNSVDD Supply Current (mA)
SNSVDD = I/OVDD = VREF
1.5
Delta from +25°C (LSB)
Delta from +25°C (LSB)
1.5
SNSVDD = 3.0V, fSCLK = 10MHz
800
700
600
SNSVDD = 1.6V, fSCLK = 10MHz
500
400
SNSVDD = 1.2V, fSCLK = 5.5MHz
300
1.25
80
100
I/OVDD = SNSVDD = VREF
TA = +25°C
fADC = 1MHz, fSCLK = 10MHz
1.00
fADC = 2MHz, fSCLK = 10MHz
0.75
0.50
fADC = 1MHz, fSCLK = 5.5MHz
0.25
fADC = 2MHz, fSCLK = 5.5MHz
200
0
-40
-20
0
20
40
60
80
100
1.2
1.6
2.0
2.4
Temperature (°C)
SNSVDD (V)
Figure 4.
Figure 5.
2.8
3.2
3.6
SNSVDD SUPPLY CURRENT
vs SNSVDD SUPPLY VOLTAGE
SNSVDD Supply Current (mA)
1.2
1.0
0.8
TA = +25°C
I/OVDD = SNSVDD
VREF = 1.6V
tPVS, tPRE, tSNS = Default Values
M = 15, W = 7(1)
M = 1, W = 1(1)
0.6
0.4
0.2
TSC-Initiated Mode Scan X, Y, Z at 50SSPS
Touch Sensor modeled by: 2kW for X-Plane
2kW for Y-Plane
(2)
1kW for Z (Touch Resistance)
0
1.6
2.0
(1)
See Table 1
(2)
See Figure 25
2.4
2.8
SNSVDD (V)
3.2
3.6
Figure 6.
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SBAS415A – JUNE 2007 – REVISED NOVEMBER 2007
TYPICAL CHARACTERISTICS (continued)
At TA = –40°C to +85°C, SNSVDD = VREF = +1.2V to +3.6V, I/OVDD = +1.2V to +3.6V, fADC = fOSC/2, fSCLK = 10MHz,
12-bit mode, and non-continuous AUX measurement, unless otherwise noted.
POWER-DOWN SUPPLY CURRENT
vs TEMPERATURE
POWER-DOWN SUPPLY CURRENT
vs SNSVDD SUPPLY VOLTAGE
60
SNSVDD = I/OVDD = VREF
Power-Down Supply Current (nA)
Power-Down Supply Current (nA)
1000
800
SNSVDD = 3.0V
600
SNSVDD = 3.6V
400
200
SNSVDD = I/OVDD = VREF
TA = +25°C
45
30
15
SNSVDD = 1.6V
0
0
-40
-20
0
20
60
80
100
1.2
3.2
I/OVDD SUPPLY CURRENT
vs TEMPERATURE
I/OVDD SUPPLY CURRENT
vs I/OVDD SUPPLY VOLTAGE
I/OVDD = SNSVDD = VREF
TA = 25°C
20
15
I/OVDD = 1.2V, fSCLK = 5.5MHz
I/OVDD Supply Current (mA)
80
I/OVDD = 1.6V, fSCLK = 5.5MHz
10
70
fADC = 2MHz, fSCLK = 10MHz
60
fADC = 2MHz, fSCLK = 5.5MHz
50
40
30
20
fADC = 1MHz, fSCLK = 10MHz
10
fADC = 1MHz, fSCLK = 5.5MHz
0
0
20
40
Temperature (°C)
60
80
3.6
90
5
100
1.2
1.6
2.0
2.4
2.8
3.2
3.6
I/OVDD (V)
Figure 9.
Figure 10.
REFERENCE INPUT CURRENT
vs TEMPERATURE
REFERENCE INPUT CURRENT
vs SNSVDD SUPPLY VOLTAGE
4
8
SNSVDD = I/OVDD = VREF
Reference Input Current (mA)
SNSVDD = I/OVDD = VREF
3
SNSVDD = 1.6V
2
SNSVDD = 1.2V
1
0
7
6
5
4
3
2
1
-40
-20
0
20
40
60
80
100
1.2
Temperature (°C)
1.6
2.0
2.4
2.8
3.2
3.6
SNSVDD (V)
Figure 11.
8
2.8
Figure 8.
25
-20
2.4
Figure 7.
I/OVDD = 1.6V, fSCLK = 10MHz
-40
2.0
SNSVDD (V)
I/OVDD = SNSVDD = VREF
Reference Input Current (mA)
1.6
Temperature (°C)
30
I/OVDD Supply Current (mA)
40
Figure 12.
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TYPICAL CHARACTERISTICS (continued)
At TA = –40°C to +85°C, SNSVDD = VREF = +1.2V to +3.6V, I/OVDD = +1.2V to +3.6V, fADC = fOSC/2, fSCLK = 10MHz,
12-bit mode, and non-continuous AUX measurement, unless otherwise noted.
SWITCH ON-RESISTANCE
vs TEMPERATURE
SWITCH ON-RESISTANCE
vs TEMPERATURE
7
9
X+
Y+
6
Y+
8
RON (W)
RON (W)
4
X-
Y-
X-
3
Y5
3
X+, Y+: SNSVDD = 3V to Pin
X-, Y-: Pin to GND
1
-40
0
-20
60
80
100
-40
TEMP Diode Voltage (mV)
Y+
X+
X-
6
Y5
X+, Y+: SNSVDD to Pin
X-, Y-: Pin to GND
TA = +25°C
588
586
750
80
95.3mV
TEMP2
650
600
TEMP1
550
138.2mV
500
I/OVDD = SNSVDD = 3V
VREF = 2.5V
400
SNSVDD (V)
20
40
Temperature (°C)
Figure 15.
Figure 16.
TEMP1 DIODE VOLTAGE
vs SNSVDD SUPPLY VOLTAGE
TEMP2 DIODE VOLTAGE
vs SNSVDD SUPPLY VOLTAGE
1.6
2.0
100
Measurement Includes
A/D Converter Offset
and Gain Errors
700
450
2.4
SNSVDD = I/OVDD = VREF
TA = +25°C
2.8
3.2
-40
3.6
Measurement Includes
A/D Converter Offset
and Gain Errors
584
582
580
578
576
704
TEMP2 Diode Voltage (mV)
1.2
60
TEMP DIODE VOLTAGE
vs TEMPERATURE
800
3
20
40
Temperature (°C)
SWITCH ON-RESISTANCE
vs SNSVDD SUPPLY VOLTAGE
10
4
0
Figure 14.
850
7
-20
Figure 13.
11
8
X+, Y+: SNSVDD = 1.8V to Pin
X-, Y-: Pin to GND
2
20
40
Temperature (°C)
9
RON (W)
6
4
2
TEMP1 Diode Voltage (mV)
X+
7
5
702
-20
0
SNSVDD = I/OVDD = VREF
TA = +25°C
60
80
100
Measurement Includes
A/D Converter Offset
and Gain Errors
700
698
696
694
692
1.2
1.6
2.0
2.4
2.8
3.2
3.6
1.2
1.6
2.0
2.4
SNSVDD (V)
SNSVDD (V)
Figure 17.
Figure 18.
2.8
3.2
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TYPICAL CHARACTERISTICS (continued)
At TA = –40°C to +85°C, SNSVDD = VREF = +1.2V to +3.6V, I/OVDD = +1.2V to +3.6V, fADC = fOSC/2, fSCLK = 10MHz,
12-bit mode, and non-continuous AUX measurement, unless otherwise noted.
INTERNAL OSCILLATOR CLOCK FREQUENCY
vs TEMPERATURE
INTERNAL OSCILLATOR CLOCK FREQUENCY
vs TEMPERATURE
3.75
SNSVDD = I/OVDD = VREF = 3.0V
Internal Clock Frequency (MHz)
Internal Clock Frequency (MHz)
4.00
3.95
3.90
3.85
3.80
-20
0
20
40
60
80
100
3.65
3.60
-40
-20
0
20
40
60
80
Temperature (°C)
Temperature (°C)
Figure 19.
Figure 20.
INTERNAL OSCILLATOR CLOCK FREQUENCY
vs TEMPERATURE
INTERNAL OSCILLATOR CLOCK FREQUENCY
vs SNSVDD SUPPLY VOLTAGE
3.4
100
4.00
SNSVDD = I/OVDD = VREF = 1.2V
Internal Clock Frequency (MHz)
Internal Clock Frequency (MHz)
3.70
3.55
-40
3.3
3.2
3.1
3.0
2.9
2.8
3.90
3.80
3.70
3.60
3.50
3.40
SNSVDD = I/OVDD = VREF
TA = +25°C
3.30
3.20
-40
10
SNSVDD = I/OVDD = VREF = 1.6V
-20
0
20
40
60
80
100
1.2
1.6
2.0
2.4
Temperature (°C)
SNSVDD (V)
Figure 21.
Figure 22.
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3.2
3.6
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OVERVIEW
The TSC2006 is an analog interface circuit for a human interface touch screen device. A register-based
architecture eases integration with microprocessor-based systems through a standard SPI bus. All peripheral
functions are controlled through the registers and onboard state machines. The TSC2006 features include:
• Very low-power touch screen controller
• Very small onboard footprint
• Relieves host from tedious routine tasks by flexible preprocessing, saving resources for more critical tasks
• Ability to work on very low supply voltage
• Minimal connection interface allows easiest isolation and reduces the number of dedicated I/O pins required
• Miniature, yet complete; requires no external supporting component. (NOTE: Although the TSC2006 can use
an external reference, it is also possible to use SNSVDD as the reference.)
• Enhanced ESD protection up to 8kV
The TSC2006 consists of the following blocks (refer to the block diagram on the front page):
• Touch Screen Interface
• Auxiliary Input (AUX)
• Temperature Sensor
• Acquisition Activity Preprocessing
• Internal Conversion Clock
• SPI Interface
Communication with the TSC2006 is done via an SPI serial interface. The TSC2006 is an SPI slave device;
therefore, data are shifted into or out of the TSC2006 under the control of the host microprocessor, which also
provides the serial data clock.
Control of the TSC2006 and its functions is accomplished by writing to different registers in the TSC2006. A
simple serial command protocol (compatible with SPI), is used to address these registers.
The measurement result is placed in the TSC2006 registers and may be read by the host at any time. This
preprocessing frees up the host so that resources can be redirected for more critical tasks. Two optional signals
are also available from the TSC2006 to indicate that data are available for the host to read. PINTDAV is a
programmable interrupt/status output pin that can be programmed to indicate a pen-touch, data available, or the
combination of both. Figure 23 shows a typical application of the TSC2006.
1.6VDC
1m F
1 mF
1 mF
0.1mF
0.1mF
AGND
0.1mF
Host
Processor
DGND
VREF
I/OVDD
X+
SNSVDD
SNSGND
PINTDAV
RESET
GPIO
Y+
SDO
TSC2006
X-
SDI
SDI
CS
SUBGND
DGND
AUX
AGND
Y-
SNSGND
SCLK
Touch
Screen
GPIO
SCLK
(PINTDAV is optional;
software implementation
polling of the Status
register is possible)
SDO
Auxilary Input
AGND
CS
Figure 23. Typical Circuit Configuration
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TOUCH SCREEN OPERATION
A resistive touch screen operates by applying a voltage across a resistor network and measuring the change in
resistance at a given point on the matrix where the screen is touched by an input (stylus, pen, or finger). The
change in the resistance ratio marks the location on the touch screen.
The TSC2006 supports the resistive 4-wire configurations, as shown in Figure 24. The circuit determines location
in two coordinate pair dimensions, although a third dimension can be added for measuring pressure.
4-WIRE TOUCH SCREEN COORDINATE PAIR MEASUREMENT
A 4-wire touch screen is typically constructed as shown in Figure 24. It consists of two transparent resistive
layers separated by insulating spacers.
Conductive Bar
Transparent Conductor (ITO)
Bottom Side
Y+
X+
Silver
Ink
Transparent
Conductor (ITO)
Top Side
XY-
Insulating Material (Glass)
ITO = Indium Tin Oxide
Figure 24. 4-Wire Touch Screen Construction
The 4-wire touch screen panel works by applying a voltage across the vertical or horizontal resistive network.
The A/D converter converts the voltage measured at the point where the panel is touched. A measurement of the
Y position of the pointing device is made by connecting the X+ input to a data converter chip, turning on the Y+
and Y– drivers, and digitizing the voltage seen at the X+ input. The voltage measured is determined by the
voltage divider developed at the point of touch. For this measurement, the horizontal panel resistance in the X+
lead does not affect the conversion because of the high input impedance of the A/D converter.
Voltage is then applied to the other axis, and the A/D converter converts the voltage representing the X position
on the screen. This process provides the X and Y coordinates to the associated processor.
Measuring touch pressure (Z) can also be done with the TSC2006. To determine pen or finger touch, the
pressure of the touch must be determined. Generally, it is not necessary to have very high performance for this
test; therefore, 10-bit resolution mode is recommended (however, data sheet calculations are shown using 12-bit
resolution mode). There are several different ways of performing this measurement. The TSC2006 supports two
methods. The first method requires knowing the X-plate resistance, the measurement of the X-Position, and two
additional cross panel measurements (Z2 and Z1) of the touch screen (see Figure 25). Equation 1 calculates the
touch resistance:
R TOUCH + RX−plate @
ǒ
Ǔ
XPostition Z 2
*1
4096 Z 1
(1)
The second method requires knowing both the X-plate and Y-plate resistance, measurement of the X-Position
and the Y-Position, and Z1. Equation 2 also calculates the touch resistance:
RX−plate @ XPostition 4096
Y
R TOUCH +
*1 *R Y−plate @ 1* Position
4096
4096
Z1
ǒ
12
Ǔ
ǒ
Ǔ
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Measure X-Position
X+
Y+
Touch
X-Position
Y-
X-
Measure Z1-Position
Y+
X+
Touch
Z1-Position
X-
Y-
Y+
X+
Touch
Z2-Position
X-
YMeasure Z2-Position
Figure 25. Pressure Measurement
When the touch panel is pressed or touched and the drivers to the panel are turned on, the voltage across the
touch panel often overshoots and then slowly settles down (decays) to a stable dc value. This effect is a result of
mechanical bouncing caused by vibration of the top layer sheet of the touch panel when the panel is pressed.
This settling time must be accounted for, or else the converted value will be in error. Therefore, a delay must be
introduced between the time the driver for a particular measurement is turned on, and the time a measurement is
made.
In some applications, external capacitors may be required across the touch screen for filtering noise picked up by
the touch screen (for example, noise generated by the LCD panel or back-light circuitry). The value of these
capacitors provides a low-pass filter to reduce the noise, but will cause an additional settling time requirement
when the panel is touched.
The TSC2006 offers several solutions to this problem. A programmable delay time is available that sets the delay
between turning the drivers on and making a conversion. This delay is referred to as the panel voltage
stabilization time, and is used in some of the TSC2006 modes. In other modes, the TSC2006 can be
commanded to turn on the drivers only without performing a conversion. Time can then be allowed before the
command is issued to perform a conversion.
The TSC2006 touch screen interface can measure position (X,Y) and pressure (Z). Determination of these
coordinates is possible under three different modes of the A/D converter:
• TSMode1—conversion controlled by the TSC2006 initiated by TSC;
• TSMode2—conversion controlled by the TSC2006 initiated by the host responding to the PENIRQ signal; or
• TSMode3—conversion completely controlled by the host processor.
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INTERNAL TEMPERATURE SENSOR
In some applications, such as battery recharging, an ambient temperature measurement is required. The
temperature measurement technique used in the TSC2006 relies on the characteristics of a semiconductor
junction operating at a fixed current level. The forward diode voltage (VBE) has a well-defined characteristic
versus temperature. The ambient temperature can be predicted in applications by knowing the +25°C value of
the VBE voltage and then monitoring the delta of that voltage as the temperature changes.
The TSC2006 offers two modes of temperature measurement. The first mode requires calibration at a known
temperature, but only requires a single reading to predict the ambient temperature. The TEMP1 diode, shown in
Figure 26, is used during this measurement cycle. This voltage is typically 580mV at +25°C with a 10µA current.
The absolute value of this diode voltage can vary by a few millivolts; the temperature coefficient (TC) of this
voltage is very consistent at –2.1mV/°C. During the final test of the end product, the diode voltage is stored at a
known room temperature, in system memory, for calibration purposes by the user. The result is an equivalent
temperature measurement resolution of 0.3°C/LSB (1LSB = 610µV with VREF = 2.5V).
SNSVDD
TEMP2
TEMP1
+IN
Converter
-IN
AGND
Figure 26. Functional Block Diagram of Temperature Measurement Mode
The second mode does not require a test temperature calibration, but uses a two-measurement (differential)
method to eliminate the need for absolute temperature calibration and for achieving 2°C/LSB accuracy. This
mode requires a second conversion of the voltage across the TEMP2 diode with a resistance 80 times larger
than the TEMP1 diode. The voltage difference between the first (TEMP1) and second (TEMP2) conversion is
represented by:
DV + kT
q @ ln(N)
(3)
Where:
N = the resistance ratio = 80.
k = Boltzmann's constant = 1.3807 × 10–23 J/K (joules/kelvins).
q = the electron charge = 1.6022 × 10–19 C (coulombs).
T = the temperature in kelvins (K).
This method can provide much improved absolute temperature measurement, but a lower resolution of
1.6°C/LSB. The resulting equation to solve for T is:
q @ DV
T+
k @ ln(N)
(4)
Where:
ΔV = VBE (TEMP2) – VBE(TEMP1) (in mV)
∴ T = 2.648 ⋅ ΔV (in K)
or T = 2.648 ⋅ ΔV – 273 (in °C)
Temperature 1 and/or temperature 2 measurements have the same timing as Figure 42.
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ANALOG-TO-DIGITAL CONVERTER
Figure 27 shows the analog inputs of the TSC2006. The analog inputs (X, Y, and Z touch panel coordinates, chip
temperature and auxiliary inputs) are provided via a multiplexer to the Successive Approximation Register (SAR)
Analog-to-Digital (A/D) converter. The A/D architecture is based on capacitive redistribution architecture, which
inherently includes a sample-and-hold function.
SNSVDD
VREF
PINTDAV
SNSVDD
Level Shift
(1)
RIRQ
50kW
Data
Available
Pen Touch
Control
Logic
Preprocessing
Zone
Detect
X+
TEMP2
TEMP1
MAV
C3-C0
AGND
XSNSVDD
Y+
+IN
Y-
+REF
Converter
-IN
-REF
SNSGND
AUX
AGND
(1)
Untrimmed resistor; see the typical value in the Electrical Characteristics.
Figure 27. Simplified Diagram of the Analog Input Section
A unique configuration of low on-resistance switches allows an unselected A/D converter input channel to
provide power and an accompanying pin to provide ground for driving the touch panel. By maintaining a
differential input to the converter and a differential reference input architecture, it is possible to negate errors
caused by the driver switch on-resistances.
The A/D converter is controlled by two A/D Converter Control registers. Several modes of operation are possible,
depending on the bits set in the control registers. Channel selection, scan operation, preprocessing, resolution,
and conversion rate may all be programmed through these registers. These modes are outlined in the sections
that follow for each type of analog input. The conversion results are stored in the appropriate result register.
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Data Format
The TSC2006 output data are in Straight Binary format as shown in Figure 28. This figure shows the ideal output
code for the given input voltage and does not include the effects of offset, gain, or noise.
FS = Full-Scale Voltage = VREF(1)
1LSB = VREF(1)/4096
1LSB
11...111
Output Code
11...110
11...101
00...010
00...001
00...000
0V
Input Voltage
(2)
FS - 1LSB
(V)
(1)
Reference voltage at converter: +REF – (–REF). See Figure 27.
(2)
Input voltage at converter, after multiplexer: +IN – (–IN). See Figure 27.
Figure 28. Ideal Input Voltages and Output Codes
Reference
The TSC2006 uses an external voltage reference that applied to the VREF pin. It is possible to use VDD as the
reference voltage because the upper reference voltage range is the same as the supply voltage range, .
Variable Resolution
The TSC2006 provides either 10-bit or 12-bit resolution for the A/D converter. Lower resolution is often practical
for measuring slow changing signals such as touch pressure. Performing the conversions at lower resolution
reduces the amount of time it takes for the A/D converter to complete its conversion process, which also lowers
power consumption.
Conversion Clock and Conversion Time
The TSC2006 contains an internal clock (oscillator) that drives the internal state machines that perform the many
functions of the part. This clock is divided down to provide a conversion clock for the A/D converter. The division
ratio for this clock is set in the A/D Converter Control register (see Table 15). The ability to change the
conversion clock rate allows the user to choose the optimal values for resolution, speed, and power dissipation. If
the 4MHz (oscillator) clock is used directly as the A/D converter clock (when CL[1:0] = (0,0)), the A/D converter
resolution is limited to 10-bits. Using higher resolutions at this speed does not result in more accurate
conversions. 12-bit resolution requires that CL[1:0] is set to (0,1) or (1,0).
Regardless of the conversion clock speed, the internal clock runs nominally at 3.9MHz at a 3V supply (SNSVDD)
and slows down to 3.7MHz at a 1.6V supply. The conversion time of the TSC2006 depends on several functions.
While the conversion clock speed plays an important role in the time it takes for a conversion to complete, a
certain number of internal clock cycles are needed for proper sampling of the signal. Moreover, additional times
(such as the panel voltage stabilization time), can add significantly to the time it takes to perform a conversion.
Conversion time can vary, depending on the mode in which the TSC2006 is used. Throughout this data sheet,
internal and conversion clock cycles are used to describe the amount of time that many functions take. These
times must be taken into account when considering the total system design.
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Touch Detect
PINTDAV can be programmed to generate an interrupt to the host. Figure 29 details an example for the
Y-position measurement. While in the power-down mode, the Y– driver is on and connected to GND. The internal
pen-touch signal depends on whether or not the X+ input is driven low. When the panel is touched, the X+ input
is pulled to ground through the touch screen and the internal pen-touch output is set to low because of the
detection on the current path through the panel to GND, which initiates an interrupt to the processor. During the
measurement cycles for X- and Y-Position, the X+ input is disconnected, which eliminates any leakage current
from the pull-up resistor to flow through the touch screen, thus causing no errors.
Analog VDD
Plane
SNSVDD
PINTDAV
SNSVDD
Level
Shifter
Y+
Pen Touch
Control
Logic
Data Available
TEMP1
High when
the X+ or Y+
driver is on.
X+
TEMP2
(1)
RIRQ
50kW
Sense
DGND
Y-
ON
High when the X+ or Y+
driver is on, or when any
sensor connection/short
circuit tests are activated.
SNSGND
(1)
Vias go to system analog ground plane.
AGND
Untrimmed resistor; see the typical value in the Electrical Characteristics.
Figure 29. Example of a Pen-Touch Induced Interrupt via the PINTDAV Pin
In modes where the TSC2006 must detect whether or not the screen is still being touched (for example, when
doing a pen-touch initiated X, Y, and Z conversion), the TSC2006 must reset the drivers so that the RIRQ resistor
is connected again. Because of the high value of this pull-up resistor, any capacitance on the touch screen inputs
causes a long delay time, and may prevent the detection from occurring correctly. To prevent this possible delay,
the TSC2006 has a circuit that allows any screen capacitance to be precharged, so that the pull-up resistor does
not have to be the only source for the charging current. The time allowed for this precharge, as well as the time
needed to sense if the screen is still touched, can be set in the configuration register.
This configuration underscores the need to use the minimum possible capacitor values on the touch screen
inputs. These capacitors may be needed to reduce noise, but too large a value will increase the needed
precharge and sense times, as well as the panel voltage stabilization time.
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Preprocessing
The TSC2006 offers an array of powerful preprocessing operations that reduce unnecessary traffic on the bus
and reduce host processor loading. This reduction is especially critical for the serial interface, where limited
bandwidth is a tradeoff, keeping the connection lines to a minimum.
All data acquisition tasks are looking for specific data that meet certain criteria. Many of these tasks fall into a
predefined range, while other tasks may be looking for a value in a noisy environment. If these data are all to be
retrieved by host processor for processing, the limited bus bandwidth quickly saturates, along with the host
processor processing capability. In any case, the host processor must always be reserved for more critical tasks,
not for routine work.
The preprocessing unit consists of two main functions: the combined MAV filter (median value filter and
averaging filter), followed by the zone detection.
Preprocessing—Median Value Filter and Averaging Value Filter
The first preprocessing function, a combined MAV filter, can be operated independently as a median value filter
(MVF), an averaging value filter (AVF), and a combined filter (MAVF).
If the acquired signal source is noisy because of the digital switching circuit, it may be necessary to evaluate the
data without noise. In this case, the median value filter (MVF) operation helps to discard the noise. The array of
N converted results is first sorted. The return value is either the middle (median value) of an array of M converted
results, or the average value of a window size of W of converted results:
• N = the total number of converted results used by the MAV filter
• M = the median value filter size programmed
• W = the averaging window size programmed
If M = 1, then N = W. A special case is W = 1, which means the MAVF is bypassed. Otherwise, if W > 1, only
averaging is performed on these converted results. In either case, the return value is the averaged value of
window size W of converted results. If M > 1 and W = 1, then N = M, meaning only the median value filter is
operating. The return value is the middle position converted result from the array of M converted results. If M > 1
and W > 1, then N = M. In this case, W < M. The return value is the averaged value of middle portion W of
converted results out of the array of M converted results. Since the value of W is an odd number in this case, the
averaging value is calculated with the middle position converted result counted twice (so a total of W + 1
converted results are averaged).
Table 1. Median Value Filter Size Selection
M1
M0
MEDIAN VALUE FILTER
M=
POSSIBLE AVERAGING WINDOW SIZE
W=
0
0
1
1, 4, 8, 16
0
1
3
1
1
0
7
1, 3
1
1
15
1, 3, 7
Table 2. Averaging Value Filter Size Selection
AVERAGING VALUE FILTER SIZE SELECTION
W=
18
W1
W0
M = 1 (Averaging Only)
M>1
0
0
1
1
0
1
4
3
1
0
8
7
1
1
16
Reserved
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NOTE: The default setting for MAVF is MVF (median value filter with averaging bypassed) for any invalid
configuration. For example, if (M1, M0, W1, W0) = (1,0,1,0), the MAVF performs as it was configured for
(1,0,0,0), median filter only with filter size = 7 and no averaging. The only exception is M > 1 and (W1, W0) =
(1,1). This setting is reserved and should not be used.
Table 3. Combined MAV Filter Setting
M
W
INTERPRETATION
N=
=1
=1
Bypass both MAF and AVF
W
The converted result
=1
>1
Bypass MVF only
W
Average of W converted results
>1
=1
Bypass AVF only
M
Median of M converted results
M
Average of middle W of M converted results with the median
counted twice
>1
>1
M>W
OUTPUT
The MAV filter is available for all analog inputs including the touch screen inputs, temperature measurements
TEMP1 and TEMP2, and the AUX measurement.
N measurements input
into temporary array
N Acquired
Data
N
M=1
N
W
Averaging output
from window W
M > 1 and W = 1
N
M
Median value
from array M
M > 1 and W > 1
N
M
Averaging output
from window W
Sort by
descending order
W
Figure 30. MAV Filter Operation (patent pending)
Zone Detection
The Zone Detection unit is capable of screening all processed data from the MAVF and retaining only the data of
interest (data that fit the prerequisite). This unit can be programmed to send an alert if a predefined condition set
by two threshold value registers is met. Three different zones may be set:
1. Above the upper limit (X ≥ Threshold High)
2. Between the two thresholds (Threshold Low < X < Threshold High)
3. Below the lower limit (X ≤ Threshold Low)
The AUX and temperatures TEMP1 and TEMP2 have separate threshold value registers that can be enabled or
disabled. This function is not available to the touch screen inputs. Once the preset condition is met, the DAV
output to the PINTDAV pin is pulled low and the corresponding DAV bit is set.
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DIGITAL INTERFACE
The TSC2006 communicates through a standard SPI bus. The SPI allows full-duplex, synchronous, serial
communication between a host processor (the master) and peripheral devices (slaves). The SPI master
generates the synchronizing clock and initiates transmissions. The SPI slave devices depend on a master to start
and synchronize transmissions.
A transmission begins when initiated by a master SPI. The byte from the master SPI begins shifting in on the
slave SDI (MOSI—master out, slave in) pin under the control of the master serial clock. As the byte shifts in on
the SDI (MOSI) pin, a byte shifts out on the SDO (MISO—master in, slave out) pin to the master shift register.
The idle state of the TSC2006 serial clock is logic low, which corresponds to a clock polarity setting of 0 (typical
microprocessor SPI control bit CPOL = 0). The TSC2006 interface is designed so that with a clock phase bit
setting of 0 (typical microprocessor SPI control bit CPHA = 0), the master begins driving its MOSI pin and the
slave begins driving its MISO pin half an SCLK before the first serial clock edge. The CS (SS, slave select) pin
can remain low between transmissions.
Table 4. Standard SPI Signal Names vs Common Serial Interface Signal Names
SPI SIGNAL NAMES
COMMON SERIAL INTERFACE NAMES
SS (Slave Select)
CS (Chip Select)
MISO (Master In Slave Out)
SDO (Serial Data Out)
MOSI (Master Out Slave In)
SDI (Serial Data In)
CONTROL BYTE
Table 5. Control Byte Format:
Start a Conversion and Mode Setting
MSB
D7
D6
D5
D4
D3
D2
D1
LSB
D0
1
(Control Byte 1)
C3
C2
C1
C0
RM
SWRST
STS
0
(Control Byte 0)
A3
A2
A1
A0
Reserved
(Write '0')
PND0
R/W
Table 6. Control Byte 1 Bit Register Description (D7 = 1)
BIT
NAME
D7
Control Byte ID
D6-D3
C3-C0
D2
RM
D1
SWRST
D0
STS
DESCRIPTION
1
Converter Function Select as detailed in Table 7
0: 10 Bit
1: 12 Bit
Software Reset
1: Reset all register values to default
Stop bit for all converter functions
Bit D7: Control Byte ID
1: Control Byte 1 (start conversion and channel select and conversion-related configuration).
0: Control Byte 0 (read/write data registers and non-conversion-related controls).
Bits D6-D3: C3-C0
Converter function select bits. These bits select the input to be converted, and the converter function to be
executed. Table 7 lists the possible converter functions.
20
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Table 7. Converter Function Select
C3
C2
C1
C0
FUNCTION
0
0
0
0
Touch screen scan function: X, Y, Z1, and Z2 coordinates converted and the results returned
to X, Y, Z1, and Z2 data registers. Scan continues until either the pen is lifted or a stop bit is
sent.
0
0
0
1
Touch screen scan function: X and Y coordinates converted and the results returned to X and
Y data registers. Scan continues until either the pen is lifted or a stop bit is sent.
0
0
1
0
Touch screen scan function: X coordinate converted and the results returned to X data
register.
0
0
1
1
Touch screen scan function: Y coordinate converted and the results returned to Y data
register.
0
1
0
0
Touch screen scan function: Z1 and Z2 coordinates converted and the results returned to Z1
and Z2 data registers.
0
1
0
1
Auxiliary input converted and the results returned to the AUX data register.
0
1
1
0
A temperature measurement is made and the results returned to the Temperature
Measurement 1 data register.
0
1
1
1
A differential temperature measurement is made and the results returned to the Temperature
Measurement 2 data register.
1
0
0
0
Auxiliary input is converted continuously and the results returned to the AUX data register.
1
0
0
1
Touch screen panel connection to X-axis drivers is tested. The test result is output to
PINTDAV and shown in STATUS register.
1
0
1
0
Touch screen panel connection to Y-axis drivers is tested. The test result is output to
PINTDAV and shown in STATUS register.
1
0
1
1
RESERVED (Note: any condition caused by this command can be cleared by setting the STS
bit to 1).
1
1
0
0
Touch screen panel short-circuit (between X and Y plates) is tested through Y-axis. The test
result is output to PINTDAV and shown in the STATUS register.
1
1
0
1
Turn on X+, X– drivers
1
1
1
0
Turn on Y+, Y– drivers
1
1
1
1
Turn on Y+, X– drivers
Touch Screen Scan Function for XYZ or XY
C3-C0 = 0000 or 0001: These scan functions can collaborate with the PSM bit that defines the control mode of
converter functions. If the PSM bit is set to '1', these scan function select commands are recommended to be
issued before a pen touch is detected in order to allow the TSC2006 to initiate and control the scan processes
immediately after the screen is touched. If these functions are not issued before a pen touch is detected, the
TSC2006 waits for the host to write these functions before starting a scan process. If PSM stays as '1' after a
TSC-initiated scan function is complete, the host is not required to write these function select bits again for each
of the following pen touches after the detected touch. In the host-controlled converter function mode (PSM = 0),
the host must send these functions select bits repeatedly for each scan function after a detected pen touch.
Touch Screen Sensor Connection Tests for X-Axis and Y-Axis
Range of resistances of different touch screen panels can be selected by setting the TBM bits in CFR1; see
Table 20. Once the resistance of the sensor panel is selected, two continuity tests are run separately for the
X-axis and Y-axis. The unit under test must pass both connection tests to ensure that a proper connection is
secured.
C3-C0 = 1001: PINTDAV = 0 during this connection test. A '1' shown at end of the test indicates the X-axis
drivers are well-connected to the sensor; otherwise, X-axis drivers are poorly connected. If drivers fail to connect,
then PINTDAV stays low until a stop bit (STS set to '1') is issued.
C3-C0 = 1010: PINTDAV = 0 during this connection test. A '1' shown at end of the test indicates the Y-axis
drivers are well-connected to the sensor; otherwise, Y-axis drivers are poorly connected. If the drivers are fail to
connect, then PINTDAV stays low until a stop bit (STS set to '1') is issued.
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Touch Sensor Short-Circuit Test
If the TBM bits of CFR1 detailed in Table 20 are all set to '1', a short-circuit in the touch sensor can be detected.
C3-C0 = 1011: Reserved.
C3-C0 = 1100: PINTDAV = 0 during this short-circuit test. A '1' shown at end of the test indicates there is no
short-circuit detected (through Y-axis) between the flex and stable layers. If there is a short-circuit detected,
PINTDAV stays low until a stop bit (STS set to '1') is issued.
RM—Resolution select. If RM = 1, the conversion result resolution is 12-bit; otherwise, the resolution is 10-bit.
This bit is the same RM bit shown in CFR0.
SWRST—Software reset input. All register values are set to default value if a '1' is written to this bit. This bit must
be set to '0' in Control Byte 1 in order to cancel the software reset and resume normal operation.
STS—Stop bit for all converter functions. When writing a '1' to this register, this bit aborts the converter function
currently running in the TSC2006. A '0' must be written to this register in order to end the stop bit. This bit can
only stop converter functions; it does not reset any data, status, or configuration registers. This bit is the same
STS bit shown in CFR0, but can only be read through the CFR0 register with different interpretations.
Table 8. STS Bit Operation
OPERATION
VALUE
DESCRIPTION
Write
0
Normal operation
Write
1
Stop converter functions and power down
Table 9. Control Byte 0 Bit Register Description (D7 = 0)
BIT
NAME
D7
Control Byte ID
D6-D3
A3-A0
D2
RESERVED
DESCRIPTION
1: Control Byte 1—start conversion, channel select, and converison-related configuration
0: Control Byte 0—read/write data registers and non-conversion-related controls
Register Address Bits as detailed in Table 10
A '0' must be set in this bit for normal operation
Power Not Down Control
D1
PND0
1: A/D converter biasing circuitry is always on between conversions, but is shut down after the converter
function stops
0: A/D converter biasing circuitry is shut down either between conversions or after the converter function
stops
TSC Internal Register Data Flow Control
D0
R/W
1: Read from TSC internal registers
0: Write to TSC internal registers
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Table 10. Internal Register Map
REGISTER ADDRESS
A3
A2
A1
A0
REGISTER CONTENT
READ/WRITE
0
0
0
0
X measurement result
R
0
0
0
1
Y measurement result
R
0
0
1
0
Z1 measurement result
R
0
0
1
1
Z2 measurement result
R
0
1
0
0
AUX measurement result
R
0
1
0
1
Temp1 measurement result
R
0
1
1
0
Temp2 measurement result
R
0
1
1
1
Status
1
0
0
0
AUX high threshold
R/W
1
0
0
1
AUX low threshold
R/W
1
0
1
0
Temp high threshold (apply to both TEMP1 and TEMP2)
R/W
1
0
1
1
Temp low threshold (apply to both TEMP1 and TEMP2)
R/W
1
1
0
0
CFR0
R/W
1
1
0
1
CFR1
R/W
1
1
1
0
CFR2
R/W
1
1
1
1
Converter function select status
R
R
R/W—Register read and write control. A '1' indicates the contents of the internal register addressed by A3-A0 are
sent to SDO at the next SPI interface clock cycle. A '0' indicates the data following Control Byte 0 on SDI are
written into registers addressed by A3-A0.
START A CONVERTER FUNCTION (CONTROL BYTE 1)
Control Byte 1 must begin with D7 = 1, as shown in Figure 31. Control Byte 1 starts the converter function that is
chosen by C3-C0, as shown in Table 7. After sending Control Byte 1, the master does not need to hold CS low,
and can release CS for operating other slave devices that share the same SCLK. After the converter function
completes or stops, the preprocessed data or data set are stored in data registers and can be read by sending
Control Byte 0 with Read Bit and a proper address in A3-A0. For the detailed operating procedures, see the
Operation section.
Control Byte 1 Write
CS
(SS)
1
2
3
4
5
6
7
8
D7
D6
D5
D4
D3
D2
D1
D0
SCLK
SDI
(MOSI)
1
MSB
LSB
Figure 31. Interface Timing — Control Byte 1
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REGISTER ACCESS (Control Byte 0 with R/W Bit)
Control byte 0, beginning with D7 = 0, is used to access the internal registers. This control byte uses the last bit,
D0, to control the flow of data. If D0 is '1', then the content of the register pointed by the address bits (A3-A0) is
output to SDO (MISO) in the next cycle. Otherwise, the data coming from SDI (MOSI) are written to the register
properly pointed to by the address bits in the control byte (if the write mode is available for the pointed register).
After Control Byte 0 with Read/Write Bit followed by a 16-bit word on SDO/SDI completes, the master can hold
CS low to send another Control Byte 0 with Read/Write Bit followed by a 16-bit word on SDO/SDI as many times
as the master is able to operate.
Read Register Via Control Byte 0
CS
(SS)
1
2
3
4
5
6
7
8
D7
D6
D5
D4
D3
D2
D1
D0
0
A3
A2
A1
A0
1
2
3
7
8
11
D8
D5
15
16
D1
D0
SCLK
SDI
(MOSI)
1
MSB
0
LSB
D15 D14 D13
D9
D4
Hi-Z
SDO
(MISO)
Hi-Z
MSB
LSB
Figure 32. Interface Timing — Sending Control Byte 0 with Read Bit
Write to Register Via Control Byte 0
CS
(SS)
1
2
3
4
5
6
7
8
D7
D6
D5
D4
D3
D2
D1
D0
0
A3
A2
A1
A0
1
2
3
7
8
11
12
15
16
D9
D8
D5
D4
D1
D0
SCLK
SDI
(MOSI)
MSB
D15 D14 D13
0
LSB
MSB
LSB
Hi-Z
SDO
(MISO)
Figure 33. Interface Timing — Sending Control Byte 0 with Write Bit
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COMMUNICATION PROTOCOL
The TSC2006 is controlled entirely by registers. Reading and writing to these registers are accomplished by the
use of Control Byte 0, which includes a 4-bit address plus one read/write TSC register control bit. The data
registers defined in Table 10 are all 16-bit, right-adjusted. NOTE: Except for some configuration registers and the
Status register that are full 16-bit registers, the value registers are 12-bit (or 10-bit) data preceded by four (or six)
zeros.
Configuration Register 0
Table 11. Configuration Register 0 (Reset Value = 4000h for Read; 0000h for Write)
MSB
D15
D14
D13
D12
D11
D10
D9
D8
D7
D6
D5
D4
D3
D2
D1
LSB
D0
PSM
STS
RM
CL1
CL0
PV2
PV1
PV0
PR2
PR1
PR0
SN2
SN1
SN0
DTW
LSM
PSM—Pen status/control mode. Reading this bit allows the host to determine if the screen is touched. Writing to
this bit selects the mode used to control the flow of converter functions that are either initiated and/or controlled
by host or under control of the TSC2006 responding to a pen touch. When reading, the PSM bit indicates if the
pen is down or not. When writing to this register, this bit determines if the TSC2006 controls the converter
functions, or if the converter functions are host-controlled. The default state is the host-controlled converter
function mode (0). The other state (1) is the TSC-initiated scan function mode that must only collaborate with
C3-C0 = 0000 or 0001 in order to allow the TSC2006 to initiate and control the scan function for XYZ or XY when
a pen touch is detected.
Table 12. PSM Bit Operation
OPERATION
VALUE
DESCRIPTION
Read
0
No screen touch detected
Read
1
Screen touch detected
Write
0
Converter functions initiated and/or controlled by host
Write
1
Converter functions initiated and controlled by the TSC2006
STS—A/D converter status. When reading, this bit indicates if the converter is busy or not busy. Continuous
scans or conversions can be stopped by writing a '1' to this bit, immediately aborting the running converter
function (even if the pen is still down) and causing the A/D converter to power down. The default state for write is
0 (normal operation), and the default state for read is 1 (converter is not busy). NOTE: The same bit can be
written through Control Byte 1.
Table 13. STS Bit Operation
OPERATION
VALUE
Read
0
DESCRIPTION
Converter is busy
Read
1
Converter is not busy
Write
0
Normal operation
Write
1
Stop converter function and power down
RM—Resolution control. The A/D converter resolution is specified with this bit. See Table 14 for a description of
these bits. This bit is the same whether reading or writing, and defaults to 0. Note that the same bit can be
written through Control Byte 1.
Table 14. A/D Converter Resolution Control
RM
FUNCTION
0
10-bit resolution. Power-up and reset default.
1
12-bit resolution
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CL1, CL0—Conversion clock control. These two bits specify the clock rate that the A/D converter uses to
perform conversion, as shown in Table 15. These bits are the same whether reading or writing.
Table 15. A/D Converter Conversion Clock Control
(1)
CL1
CL0
FUNCTION
0
0
fADC = fOSC/1. This is referred to as the 4MHz A/D converter clock rate, 10-bit resolution only. (1)
0
1
fADC = fOSC/2. This is referred to as the 2MHz A/D converter clock rate.
1
0
fADC = fOSC/4. This is referred to as the 1MHz A/D converter clock rate.
1
1
fADC = fOSC/4. This is referred to as the 1MHz A/D converter clock rate.
For SNSVDD = 1.2V at –40°C, a lower A/D converter clock rate should be used to allow enough time for conversion settling.
PV2-PV0—Panel voltage stabilization time control. These bits specify a delay time from the moment the touch
screen drivers are enabled to the time the voltage is sampled and a conversion is started. These bits allow the
user to adjust the appropriate settling time for the touch panel and external capacitances. See Table 16 for
settings of these bits. The default state is 000, indicating a 0µs stabilization time. These bits are the same
whether reading or writing.
Table 16. Panel Voltage Stabilization Time Control
PV2
PV1
PV0
STABILIZATION TIME (tPVS)
0
0
0
0µs
0
0
1
100µs
0
1
0
500µs
0
1
1
1ms
1
0
0
5ms
1
0
1
10ms
1
1
0
50ms
1
1
1
100ms
PR2-PR0—Precharge time selection. These bits set the amount of time allowed for precharging any pin
capacitance on the touch screen prior to sensing if a pen touch is happening.
Table 17. Precharge Time Selection
PR2
PR1
PR0
PRECHARGE TIME(tPRE)
0
0
0
20µs
0
0
1
84µs
0
1
0
276µs
0
1
1
340µs
1
0
0
1.044ms
1
0
1
1.108ms
1
1
0
1.300ms
1
1
1
1.364ms
SNS2-SNS0—Sense time selection. These bits set the amount of time the TSC2006 waits to sense whether the
screen is touched after converting a coordinate.
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Table 18. Sense Time Selection
SNS2
SNS1
SNS0
SENSE TIME (tSNS)
0
0
0
32µs
0
0
1
96µs
0
1
0
544µs
0
1
1
608µs
1
0
0
2.080ms
1
0
1
2.144ms
1
1
0
2.592ms
1
1
1
2.656ms
DTW—Detection of pen touch in wait (patent pending). Writing a '1' to this bit enables pen touch detection in the
background while waiting for the host to issue the converter function in host-initiated/controlled modes. This
background detection allows the TSC2006 to pull high at PINTDAV to indicate no pen touch detected while
waiting for the host to issue the converter function. If the host polls a high state at PINTDAV before the convert
function is sent, the host can abort the issuance of the convert function and stay in the polling PINTDAV mode
until the next pen touch is detected.
LSM—Longer sampling mode. When this bit is set to '1', the extra 500ns of sampling time is added to the normal
sampling cycles of each conversion. This additional time is represented as approximately two internal oscillator
clock cycles. For SNSVDD = 1.2V at –40°C, the LSM bit should be set to '1' so that the sampled signal has
enough time to settle.
Configuration Register 1
Configuration register 1 (CFR1) defines the connection test-bit modes configuration and batch delay selection.
Table 19. Configuration Register 1 (Reset Value = 0000h)
MSB
D15
D14
D13
D12
Resrvd Resrvd Resrvd Resrvd
D11
D10
D9
D8
D7
D6
D5
D4
D3
D2
D1
LSB
D0
TBM3
TBM2
TBM1
TBM0
Resrvd
Resrvd
Resrvd
Resrvd
Resrvd
BTD2
BTD1
BTD0
TBM3-TBM0—Connection test-bit modes (patent pending). These bits specify the mode of test bits used for the
predefined range of the combined X-axis and Y-axis touch screen panel resistance (RTS).
Table 20. Touch Screen Resistance Range and Test-Bit Modes
TEST-BIT MODES
RTS
(kΩ)
TBM3
TBM2
TBM1
TBM0
0
0
0
0
0.17
0
0
0
1
0.17 < RTS ≤ 0.52
0
0
1
0
0.52 < RTS ≤ 0.86
0
0
1
1
0.86 < RTS ≤ 1.6
0
1
0
0
1.6 < RTS ≤ 2.2
0
1
0
1
2.2 < RTS ≤ 3.6
0
1
1
0
3.6 < RTS ≤ 5.0
0
1
1
1
5.0 < RTS ≤ 7.8
1
0
0
0
7.8 < RTS ≤ 10.5
1
0
0
1
10.5 < RTS ≤ 16.0
1
0
1
0
16.0 < RTS ≤ 21.6
1
0
1
1
21.6 < RTS ≤ 32.6
1
1
0
0
Reserved
1
1
0
1
Reserved
1
1
1
0
Reserved
1
1
1
1
Only for short-circuit panel test
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BTD2-BTD0—Batch Time Delay mode. These are the selection bits that specify the delay before a
sample/conversion scan cycle is triggered. When it is set, Batch Time Delay mode uses a set of timers to
automatically trigger a sequence of sample-and-conversion events. The mode works for both TSC-initiated scans
(XYZ or XY) and host-initiated scans (XYZ or XY).
A TSC-initiated scan (XYZ or XY) can be configured by setting the PSM bit in CFR0 to '1' and C[3:0] in Control
Byte 1 to '0000' or '0001'. In the case of a TSC-initiated scan (XYZ or XY), the sequence begins with the TSC
responding to a pen touch. After the first processed sample set completes during the batch delay, the scan
enters a wait mode until the end of the batch delay is reached. If a pen touch is still detected at that moment, the
scan continues to process the next sample set, and the batch delay is resumed. The throughput of the processed
sample sets (shown in Table 21 as sample sets per second, or SSPS) is regulated by the selected batch delay
during the time of the detected pen touch. A TSC-initiated scan (XYZ or XY) can be configured by setting the
PSM bit in CFR0 to '1' and C[3:0] in Control Byte 1 to '0000' or '0001'. Note that the throughput of the processed
sample set also depends on the settings of stabilization, precharge, and sense times, and the total number of
samples to be processed per coordinates. If the accrual time of these factors exceeds the batch delay time, the
accrual time dominates. Batch delay time starts when the pen touch initiates the scan function that converts
coordinates.
A host-initiated scan (XYZ or XY) can be configured by setting the PSM bit in CFR0 to '0' and C[3:0] in Control
Byte 1 to '0000' or '0001'. For the host-initiated scan (XYZ or XY), the host must set TSC internal register C[3:0]
in Control Byte 1 to '0000' or '0001' initially after a pen touch is detected; see Conversion Controlled by TSC2006
Initiated by Host (TSMode 2), in the Theory of Operation section. After the scan (XYZ or XY) is engaged, the
throughput of the processed sample sets is regulated by the selected batch delay timer, as long as the initial
detected touch is not interrupted.
Table 21. Touch Screen Throughput and Batch Selection Bits
BATCH DELAY SELECTION
THROUGHPUT FOR TSC-INITIATED
OR HOST-INITIATED SCAN, XYZ OR XY
(SSPS)
BTD2
BTD1
BTD0
DELAY TIME
(ms)
0
0
0
0
Normal operation throughput depends on settings.
0
0
1
1
1000
0
1
0
2
500
0
1
1
4
250
1
0
0
10
100
1
0
1
20
50
1
1
0
40
25
1
1
1
100
10
For example, if stabilization time, precharge time, and sense time are selected as 100µs, 84µs, and 96µs,
respectively, and the batch delay time is 2ms, then the scan function enters wait mode after the first processed
sample set until the 2ms of batch delay time is reached. When the scan function starts to process the second
sample set (if the screen is still touched), the batch delay restarts at 2ms (in this example). This procedure
remains regulated by 2ms until the pen touch is not detected or the scan function is stopped by a stop bit or any
reset form.
28
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Configuration Register 2
Configuration register 2 (CFR2) defines the preprocessor configuration.
Table 22. Configuration Register 2 (Reset Value = 0000h)
MSB
D15
D14
D13
D12
D11
D10
D9
D8
D7
D6
D5
D4
D3
D2
D1
LSB
D0
PINTS1
PINTS0
M1
M0
W1
W0
TZ1
TZ0
AZ1
AZ0
Resrvd
MAVE
X
MAVE
Y
MAVE
Z
MAVE
AUX
MAVE
TEMP
PINTS1 (default 0)—This bit controls the output format of the PINTDAV pin. When this bit is set to '0', the output
format is shown as the AND-form of internal signals of PENIRQ and DAV). When this bit is set to '1', PINTDAV
outputs PENIRQ only.
PINTS0 (default 0)—This bit selects what is output on the PINTDAV pin. If this bit set to '0', the output format of
PINTDAV depends on the selection made on the PINTS1 bit. If this bit set to '1', the internal signal of DAV is
output on PINTDAV.
Table 23. PINTSx Selection
PINTS1
PINTS0
0
0
PINTDAV PIN OUTPUT =
An AND combination of PENIRQ (active low) and DAV (active high).
0
1
Data available, DAV (active low).
1
0
An interrupt, PENIRQ (active low) generated by pen-touch.
1
1
Data available, DAV (active low).
M1, M0, W1, W0 (default 0000)—Preprocessing MAV filter control. Note that when the MAV filter is processing
data, the STS bit and the corresponding DAV bits in the status register indicate that the converter is busy until all
conversions necessary for the preprocessing are complete. The default state for these bits is 0000, which
bypasses the preprocessor. These bits are the same whether reading or writing.
TZ1 and TZ0, or AZ1 and AZ0 (default 00)—Zone detection bit definition (for TEMP or AUX measurements).
TZ1 and TZ0 are for the TEMP measurement. AZ1 and AZ0 are for the AUX measurement. The action taken in
zone detection is to store the processed data in the corresponding data registers and to update the
corresponding DAV bits in status register. If the processed data do not meet the selected criteria, these data are
ignored and the corresponding DAV bits are not updated. When zone detection is disabled, the processed data
are simply stored in the corresponding data registers and the corresponding DAV bits are updated without any
comparison of criteria. Note that the converted samples are always processed according to the setting of the
MAVE bits for AUX/TEMP before zone detection takes effect. See Table 30 for thresholds.
Table 24. Zone Detection Bit Definition
TZ1/AZ1
TZ0/AZ0
0
0
FUNCTION
Zone detection is disabled.
0
1
When the processed data are below low threshold
1
0
When the processed data are between low and high thresholds
1
1
When the processed data are above high threshold
MAVE (default is 00000)—MAV filter function enable bit. When the corresponding bit is set to '1', the MAV filter
setup is applied to the corresponding measurement.
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Converter Function Select Register
The Converter Function Select (CFN) register reflects the converter function select status.
Table 25. Converter Function Select Status Register (Reset Value = 0000h)
MSB
D15
D14
D13
D12
D11
D9
D8
D7
D6
D5
D4
D3
D2
D1
LSB
D0
CFN9
CFN8
CFN7
CFN6
CFN5
CFN4
CFN3
CFN2
CFN1
CFN0
D10
CFN15 CFN14 CFN13 CFN12 CFN11 CFN10
CFN15-CFN0—Converter function select status. These bits represent the converter function currently running,
which is set in bits C3-C0 of Control Byte 1. When the CFNx bit shows '1', where x is the decimal value of
converter function select bits C3-C0, it indicates that the converter function that is set in bits C3-C0 is running.
For example, when CFN2 shows '1', it indicates the converter function set in bits C3-C0 ('0010') is running. The
CFNx bits are reset to 0000h whenever the converter function is complete, stopped by STS bit, or reset (by the
hardware reset from the RESET pin or the software reset from SWRST bit in Control Byte 1). However, if the
TSC-initiated scan function mode is issued (by setting the PSM bit in the CFR0 register to '1'), the CFN0 or
CFN1 bit will not be reset when the corresponding converter function is complete because there is no pen touch.
This event allows the TSC2006 to immediately initiate the scan process (corresponding to CFN0 or CFN1 set to
'1') when the next pen touch is detected.
Table 26. STATUS Register (Reset Value = 0004h)
MSB
D15
D14
D13
D12
D11
D10
D9
D8
D7
D6
D5
D4
D3
D2
D1
LSB
D0
DAV
Due
X
DAV
Due
Y
DAV
Due
Z1
DAV
Due
Z2
DAV
Due
AUX
DAV
Due
TEMP1
DAV
Due
TEMP2
RESRVD
(read '0')
RESET
Flag
X
CON
Y
CON
RESRVD
(read '0')
Y
SHR
PDST
ID1
ID0
DAV Bits—Data available bits. These seven bits mirror the operation of the internal signals of DAV. When any
processed data are stored in data registers, the corresponding DAV bit is set to '1'. It stays at '1' until the
register(s) updated to the processed data have been read out by the host.
Table 27. DAV Function
DAV
DESCRIPTION
0
No new processed data are available.
1
Processed data are available. This bit stays at 1 until the host has read out all updated registers.
RESET Flag—See Table 28 for the interpretation of the RESET flag bits.
Table 28. RESET Flag Bits
RESET Flag
DESCRIPTION
0
Device was reset since last status poll (hardware or software reset).
1
Device has not been reset since last status poll.
X CON—This bit is '1' if the X axis of the touch screen panel is properly connected to the X drivers. This bit is the
connection test result.
Y CON—This bit is '1' if the Y axis of the touch screen panel is properly connected to the Y drivers. This bit is the
connection test result.
Y SHR—This bit is '1' if there is no short-circuit tested at the Y axis of the touch screen panel. This bit is the
short-circuit test result.
PDST—Power down status. This bit reflects the setting of the PND0 bit in Control Byte 0. When this bit shows '0',
it indicates A/D converter bias circuitry is still powered on after each conversion and before the next sampling;
otherwise, it indicates A/D converter bias circuitry is powered down after each conversion and before the next
sampling. However, it is powered down between conversion sets. Because this status bit is synchronized with
the internal clock, it does not reflect the setting of the PND0 bit until a pen touch is detected or a converter
function is running.
ID[1:0] Device ID bits: These bits represent the version ID of TSC2006. This version defaults to '00'.
30
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DATA REGISTERS
The data registers of the TSC2006 hold data results from conversions. All data registers default to 0000h upon
device reset.
X, Y, Z1, Z2, AUX, TEMP1 and TEMP2 REGISTERS
The results of all A/D conversions are placed in the appropriate data registers, as described in Table 10. The
data format of the result word (R) of these registers is right-justified, as shown in Table 29.
Table 29. Internal Register Format
MSB
D15
D14
D13
D12
D11
D10
D9
D8
D7
D6
D5
D4
D3
D2
D1
LSB
D0
0
0
0
0
R11
R10
R9
R8
R7
R6
R5
R4
R3
R2
R1
R0
Register Map
The TSC2006 has several 16-bit registers that allow control of the device, as well as providing a location to store
results from the TSC2006 until read out by the host microprocessor. Table 30 shows the memory map.
Table 30. Register Content and Reset Values (1)
D15
D14
D13
D12
D11
D10
D9
D8
D7
D6
D5
D4
D3
D2
D1
D0
RESET
VALUE
(HEX)
0
X
0
0
0
0
R11
R10
R9
R8
R7
R6
R5
R4
R3
R2
R1
R0
0000
1
Y
0
0
0
0
R11
R10
R9
R8
R7
R6
R5
R4
R3
R2
R1
R0
0000
2
Z1
0
0
0
0
R11
R10
R9
R8
R7
R6
R5
R4
R3
R2
R1
R0
0000
3
Z2
0
0
0
0
R11
R10
R9
R8
R7
R6
R5
R4
R3
R2
R1
R0
0000
4
AUX
0
0
0
0
R11
R10
R9
R8
R7
R6
R5
R4
R3
R2
R1
R0
0000
5
Temp1
0
0
0
0
R11
R10
R9
R8
R7
R6
R5
R4
R3
R2
R1
R0
0000
6
Temp2
0
0
0
0
R11
R10
R9
R8
R7
R6
R5
R4
R3
R2
R1
R0
0000
(2)
S3
S2
S1
S0
0004
0FFF
A3-A0
(HEX)
(1)
(2)
REGISTER
NAME
7
Status
8
9
Rsvd
S15
S14
S13
S12
S11
S10
S9
0
S7
S6
S5
AUX High
0
0
0
0
R11
R10
R9
R8
R7
R6
R5
R4
R3
R2
R1
R0
AUX Low
0
0
0
0
R11
R10
R9
R8
R7
R6
R5
R4
R3
R2
R1
R0
0000
A
Temp High
0
0
0
0
R11
R10
R9
R8
R7
R6
R5
R4
R3
R2
R1
R0
0FFF
B
Temp Low
0
0
0
0
R11
R10
R9
R8
R7
R6
R5
R4
R3
R2
R1
R0
0000
C
CFR0
R15
R14
R13
R12
R11
R10
R9
R8
R7
R6
R5
R4
R3
R2
R1
R0
4000
D
CFR1
0
0
0
0
R11
R10
R9
R8
0
0
0
0
0
R2
R1
R0
0000
E
CFR2
R15
R14
R13
R12
R11
R10
R9
R8
R7
R6
0
R4
R3
R2
R1
R0
0000
F
Converter
Function
Select Status
R15
R14
R13
R12
R10
R9
R8
R7
R6
R5
R4
R3
R2
R1
R0
0000
Rsvd
(2)
For all combination bits, the pattern marked as Reserved must not be used. The default pattern is read back after reset.
This bit is reserved.
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REGISTER RESET
There are three way to reset the TSC2006. First, at power-on, a power good signal generates a prolonged reset
pulse internally to all registers.
Second, an external pin, RESET, is available to perform a system reset or allow other peripherals (such as a
display) to reset the device if the pulse meets the timing requirement (at least 10µs wide). Any RESET pulse less
than 5µs is rejected. To accommodate the timing drift between devices because of process variation, a RESET
pulse width between 5µs to 10µs falls into the gray area that is not recognized, and the result is undetermined;
this situation should be avoided. Refer to Figure 34 for details. A good reset pulse must be low for at least 10µs.
There is an internal spike filter to reject spikes up to 20ns wide.
tWL(RESET) < 5ms
tR
tR
tWL(RESET) ³ 10ms
RESET
State
Normal Operation
Resetting
Initial Condition
NOTE: See Timing Requirements for more information.
Figure 34. External Reset Timing
Finally, a software reset can be activated by writing a '1' to CB1.1 (bit 1 of control byte 1). It should be noted this
reset is not self-clearing, so the user must write a '0' to remove the software reset.
A reset clears all registers and loads default values. A power-on reset and external (hardware) reset take
precedence over a software reset. If a software reset is not cleared by the user, it is cleared by either a power-on
reset or an external (hardware) reset.
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THEORY OF OPERATION
TOUCH SCREEN MEASUREMENTS
As noted previously in the discussion of the A/D converter, several operating modes can be used that allow great
flexibility for the host processor. This section examines these different modes.
Conversion Controlled by TSC2006 Initiated by TSC2006 (TSMode 1)
In TSMode 1, before a pen touch can be detected, the TSC2006 must be programmed with PSM = 1 and one of
two scan modes:
1. X-Y-Z Scan (converter function select bits C[3:0] = Control Byte 1 D[6:3] = 0000); or
2. X-Y Scan (converter function select bits C[3:0] = Control Byte 1 D[6:3] = 0001).
See Table 7 for more information on the converter function select bits.
When the touch panel is touched, and the internal pen-touch signal to activates, the PINTDAV output is lowered
if it is programmed as PENIRQ. The TSC2006 then executes the preprogrammed scan function without a host
intervention.
At the same time, the TSC2006 starts up its internal clock. It then turns on the Y-drivers, and after a programmed
panel voltage stabilization time, powers up the A/D converter and converts the Y coordinate. If preprocessing is
selected, several conversions may take place. When data preprocessing is complete, the Y coordinate result is
stored in a temporary register.
If the screen is still touched at this time, the X-drivers are enabled, and the process repeats, but measures the X
coordinate instead, and stores the result in a temporary register.
If only X and Y coordinates are to be measured, then the conversion process is complete. A set of X and Y
coordinates are stored in the X and Y registers. Figure 35 shows a flowchart for this process. The time it takes to
go through this process depends upon the selected resolution, internal conversion clock rate, panel voltage
stabilization time, precharge and sense times, and whether preprocessing is selected. The time needed to get a
complete X and Y coordinate (sample set) reading can be calculated by:
ǒ
Ǔ
ǒ ǒ
Ǔ ǒ Ǔ ǒ ǓǓ
f
L
OH DLY1
t COORDINATE + OH1 )2 @ t PVS)t PRE)t SNS)
)2 @ N @ (B)2) @ OSC )OHCONV @ 1 ) PPRO
f OSC
f OSC
f ADC
f OSC
f OSC
(5)
Where:
tCOORDINATE = time to complete X/Y coordinate reading.
tPVS = panel voltage stabilization time, as given in Table 16.
tPRE = precharge time, as given in Table 17.
tSNS = sense time, as given in Table 18.
N = number of measurements for MAV filter input, as given in Table 3 as N.
(For no MAV: M1-0[1:0] = '00', W1-0[1:0] = '00', N = 1.)
B = number of bits of resolution.
fOSC = TSC onboard OSC clock frequency. See Electrical Characteristics for supply frequency (SNSVDD).
fADC = A/D converter clock frequency, as given in Table 15.
OH1 = overhead time #1 = 2.5 internal clock cycles.
OHDLY1 = total overhead time for tPVS, tPRE, and tSNS = 10 internal clock cycles.
OHCONV = total overhead time for A/D conversion = 3 internal clock cycles.
LPPRO = preprocessor preprocessing time as given in Table 31.
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Table 31. Preprocessing Delay
LPPRO =
M=
W=
FOR B = 12 BIT
1
1, 4, 8, 16
2
2
3, 7
1
28
24
7
3
31
27
15
1
31
29
15
3
34
32
15
7
38
36
Programmed for
Self-Control
(PSM = 1)
X-Y Scan Mode
(Control Byte1
D[6:3] = 0001)
FOR B = 10 BIT
Reading
X-Data
Register
CS Deactivated
Reading
Y-Data
Register
tCOORDINATE
Detecting Touch
PINTDAV Programmed:
Sample, Conversion, and
Preprocessing for
Y Coordinate
Touch is Detected
Detecting
Touch
Sample, Conversion, and
Preprocessing for
X Coordinate
Detecting
Touch
Sample, Conversion, and
Preprocessing for
Y Coordinate
Detecting
Touch
Touch is Detected
As PENIRQ,
CFR2, D[15:14] = 10
As DAV,
CFR2, D[15:14] = 11 or 01
Touch is Detected
As PENIRQ and DAV,
CFR2, D[15:14] = 00
Figure 35. Example of X and Y Coordinate Touch Screen Scan using TSMode 1
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If the pressure of the touch is also to be measured, the process continues in the same way, but measuring the Z1
and Z2 values instead, and storing the results in temporary registers. Once the complete sample set of data (X,
Y, Z1, and Z2) are available, they are loaded in the X, Y, Z1, and Z2 registers. This process is illustrated in
Figure 36. As before, this process time depends upon the settings previously described. The time for a complete
X, Y, Z1, and Z2 coordinate reading is given by:
ǒ
ǒ ǒ
Ǔ
Ǔ ǒ Ǔ ǒ ǓǓ
f
L
OH DLY1
t COORDINATE + OH2 )3 @ t PVS)t PRE)t SNS)
)4 @ N @ (B)2) @ OSC )OHCONV @ 1 ) PPRO
f OSC
f OSC
f ADC
f OSC
f OSC
(6)
Where:
OH2 = overhead time #2 = 3.5 internal clock cycles.
Programmed for
Self-Control
(PSM = 1)
X-Y-Z1-Z2 Scan Mode
(Control Byte1
D[6:3] = 0000)
Reading
X-Data
Register
CS Deactivated
Reading Reading
Y-Data Z1-Data
Register Register
Reading
Z2-Data
Register
tCOORDINATE
Detecting
Touch
Sample, Conversion,
Sample, Conversion,
Detecting
Detecting
and Preprocessing for
and Preprocessing for
Touch
Touch
X Coordinate
Y Coordinate
PINTDAV Programmed:
Touch is Detected
Touch is Detected
Sample, Conversion,
Sample, Conversion,
Detecting
and Preprocessing for
and Preprocessing for
Touch
Y Coordinate
Z1 Coordinate and Z2 Coordinate
Detecting
Touch
Touch is Detected
As PENIRQ,
CFR2, D[15:14] = 10
As DAV,
CFR2, D[15:14] = 11 or 01
Touch is Detected
As PENIRQ and DAV,
CFR2, D[15:14] = 00
Figure 36. Example of X, Y, and Z Coordinate Touch Screen Scan using TSMode 1
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Conversion Controlled by TSC2006 Initiated by Host (TSMode 2)
In TSMode 2, the TSC2006 detects when the touch panel is touched and causes the internal Pen-Touch signal
to activate, which lowers the PINTDAV output if it is programmed as PENIRQ. The host recognizes the interrupt
request, and then writes to the A/D Converter Control register to select one of the two touch screen scan
functions:
1. X-Y-Z Scan (converter function select bits C[3:0] = Control Byte 1 D[6:3] = 0000); or
2. X-Y Scan (converter function select bits C[3:0] = Control Byte 1 D[6:3] = 0001).
See Table 7 for more information on the converter function select bits.
The conversion process then as shown in Figure 37; see previous sections for more details.
The main difference between this mode and the previous mode is that the host, not the TSC2006, decides when
the touch screen scan begins.
The time needed to convert both X and Y coordinates under host control (not including the time needed to send
the command over the SPI bus) is given by:
ǒ
Ǔ
ǒ ǒ
Ǔ ǒ Ǔ ǒ ǓǓ
f
L
OH DLY1
t COORDINATE + OH1 )2 @ t PVS)t PRE)t SNS)
)2 @ N @ (B)2) @ OSC )OHCONV @ 1 ) PPRO
f OSC
f OSC
f ADC
f OSC
f OSC
Programmed
CS
Programmed
for
Deactivated
for
HostX-Y
Controlled
Scan Mode
Mode
(PSM = 0)
CS
Deactivated
Reading
X-Data
Register
Reading
Y-Data
Register
(7)
CS
Deactivated
tCOORDINATE
Detecting
Touch
PINTDAV Programmed:
Waiting for Host to
Write Into
Control Byte 1 D[6:3]
Sample, Conversion,
and Preprocessing for
Y Coordinate
Sample, Conversion,
Detecting Sample, Conversion, Detecting
Detecting
and Preprocessing for
and Preprocessing for
Touch
Touch
Touch
Y Coordinate
X Coordinate
Touch is Detected
As PENIRQ,
CFR2, D[15:14] = 10
Touch is Detected
As DAV,
CFR2, D[15:14] = 11 or 01
Touch is Still Here
As PENIRQ and DAV,
CFR2, D[15:14] = 00
Figure 37. Example of an X and Y Coordinate Touch Screen Scan using TSMode 2
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Conversion Controlled by Host (TSMode 3)
In TSMode 3, the TSC2006 detects when the touch panel is touched and causes the internal Pen-Touch signal
to be active, which lowers the PINTDAV output if it is programmed as PENIRQ. The host recognizes the interrupt
request. Instead of starting a sequence in the TSC2006, which then reads each coordinate in turn, the host must
now control all aspects of the conversion. Generally, upon receiving the interrupt request, the host turns on the X
drivers. (NOTE: If drivers are not turned on, the device detects this condition and turns them on before the scan
starts. This situation is why the event of Turn On Drivers is shown as optional in Figure 38 and Figure 39.) After
waiting for the settling time, the host then addresses the TSC2006 again, this time requesting an X coordinate
conversion.
The process is then repeated for the Y and Z coordinates. The processes are outlined in Figure 38 and
Figure 39. Figure 38 shows two consecutive scans on X and Y. Figure 39 shows a single Z scan.
The time needed to convert any single coordinate X or Y under host control (not including the time needed to
send the command over the SPI bus) is given by:
ǒ
Ǔ ǒ
Ǔ ǒ Ǔ ǒ Ǔ
f
L
OHDLY2
t COORDINATE + OH1 ) t PRE)t SNS)
) N @ (B)2) @ OSC )OH CONV @ 1 ) PPRO
f OSC
f OSC
f OSC
f ADC
f OSC
(8)
Where:
OHDLY2 = total overhead time for tPRE and tSNS = 6 internal clock cycles.
Programmed for:
Programmed
CS
Turn On
for HostDeactivated X+ and
Controlled
XMode
(1)
Drivers
(PSM = 0)
X
Scan
Mode
Programmed for:
CS
Deactivated
Reading
X-Data
Register
Turn On
Y+ and
YDrivers
(1)
Y
Scan
Mode
tCOORDINATE
Detecting
Touch
PINTDAV Programmed:
Waiting for Host to Write Into
Control Byte 1 D[6:3]
Touch is Detected
Sample, Conversion,
and Preprocessing
for X Coordinate
CS
Deactivated
CS
Reading Deactivated
Y-Data
Register
tCOORDINATE
Detecting Waiting for Host to Write Into
Control Byte 1 D[6:3]
Touch
Sample, Conversion,
and Preprocessing
for Y Coordinate
Detecting
Touch
Waiting for Host to
Write Into Control
Byte 1 D[6:3]
Touch is Detected
Touch is Detected
As PENIRQ,
CFR2, D[15:14] = 10
As DAV,
CFR2, D[15:14] = 11 or 01
As PENIRQ and DAV,
CFR2, D[15:14] = 00
NOTE: (1) Optional. If not turned on, it will be turned on by the Scan mode, once detected.
Figure 38. Example of X and Y Coordinate Touch Screen Scan using TSMode 3
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The time needed to convert any Z1 and Z2 coordinate under host control (not including the time needed to send
the command over the SPI bus) is given by:
ǒ
Ǔ ǒ
Ǔ ǒ Ǔ ǒ Ǔ
f
L
OHDLY2
t COORDINATE + OH2 ) t PRE)t SNS)
) N @ (B)2) @ OSC )OH CONV @ 1 ) PPRO
f OSC
f OSC
f OSC
f ADC
f OSC
(9)
Programmed for:
Turn On
Programmed
CS
Y+
for
Deactivated
Host-Controlled
and
Mode
X(PSM = 0)
Drivers(1)
CS
Deactivated
Z
Scan
Mode
Reading
Z1-Data
Register
CS
Deactivated
Reading
Z2-Data
Register
tCOORDINATE
Detecting
Touch
Waiting for Host to Write
Into Control Byte 1 D[6:3]
PINTDAV Programmed:
Sample, Conversion, Sample, Conversion,
and Preprocessing
and Preprocessing
for Z1 Coordinate
for Z2 Coordinate
Detecting
Touch
Touch is Detected
Waiting for Host to Write
Into Control Byte 1 D[6:3]
Touch is Detected
As PENIRQ,
CFR2, D[15:14] = 10
As DAV,
CFR2, D[15:14] = 11 or 01
As PENIRQ and DAV,
CFR2D[15:14] = 00
NOTE: (1) Optional. If not turned on, it will be turned on by the Scan mode, once detected.
Figure 39. Example of Z1 and Z2 Coordinate Touch Screen Scan
(without Panel Stabilization Time) using TSMode 3
If the drivers are not turned on befire the touch screen mode is programmed, the panel stabilization time should
be included. In this case, the time needed to convert an single X or Y under host control (not including the time
needed to send the command over the SPI bus) is given by:
ǒ
Ǔ ǒ
Ǔ ǒ Ǔ ǒ Ǔ
f
L
OH DLY1
t COORDINATE + OH2 ) t PVS)t PRE)t SNS)
) N @ (B)2) @ OSC )OHCONV @ 1 ) PPRO
f OSC
f OSC
f OSC
f ADC
f OSC
CS
Deactivated
Programmed for
Host-Controlled
Mode
(PSM = 0)
Programmed
for
Z1-Z2
Scan Mode
CS
Deactivated
Reading
Z1-Data
Register
Reading
Z2-Data
Register
(10)
CS
Deactivated
tCOORDINATE
Detecting
Touch
Waiting for Host to Write
Into Control Byte 1 D[6:3]
PINTDAV Programmed:
Sample, Conversion, and
Preprocessing for Z1, Z2 Coordinates
Detecting
Touch
Waiting for Host to Write
Into Control Byte 1 D[6:3]
Touch is Detected
As PENIRQ,
CFR2, D[15:14] = 10
As DAV,
CFR2, D[15:14] = 11 or 01
Touch is Still Here
As PENIRQ and DAV,
CFR2D[15:14] = 00
Figure 40. Example of a Z1 and Z2 Coordinate Touch Screen Scan
(with Panel Stabilization Time) using TSMode 3
38
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SBAS415A – JUNE 2007 – REVISED NOVEMBER 2007
The time needed to convert any single coordinate (either X or Y) under host control (not including the time
needed to send the command over the SPI bus) is given by:
ǒ
Ǔ ǒ
Ǔ ǒ Ǔ ǒ Ǔ
f
L
OH DLY1
t COORDINATE + OH1 ) t PVS)t PRE)t SNS)
) N @ (B)2) @ OSC )OHCONV @ 1 ) PPRO
f OSC
f OSC
f OSC
f ADC
f OSC
CS
Deactivated
Programmed for
Host-Controlled
Mode
(PSM = 0)
Programmed
for
X
Scan Mode
CS
Deactivated
(11)
CS
Deactivated
Reading
X-Data
Register
tCOORDINATE
Detecting
Touch
Waiting for Host to Write
Into Control Byte 1 D[6:3]
Sample, Conversion, and
Preprocessing for X Coordinate
Detecting
Touch
Waiting for Host to Write
Into Control Byte 1 D[6:3]
PINTDAV Programmed:
Touch is Detected
As PENIRQ,
CFR2, D[15:14] = 10
As DAV,
CFR2, D[15:14] = 11 or 01
Touch is Still Here
As PENIRQ and DAV,
CFR2, D[15:14] = 00
Figure 41. Example of a Single X Coordinate Touch Screen Scan
(with Panel Stabilization Time) using TSMode 3
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TSC2006
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SBAS415A – JUNE 2007 – REVISED NOVEMBER 2007
AUXILIARY AND TEMPERATURE MEASUREMENT
The TSC2006 can measure the voltage from the auxiliary input (AUX) and from the internal temperature sensor.
Applications for the AUX can include external temperature sensing, ambient light monitoring for controlling
backlighting, or sensing the current drawn from batteries. There are two converter functions that can be used for
the measurement of the AUX:
1. Non-continuous AUX measurement shown in Figure 42 (converter function select bits C[3:0] = Control Byte 1
D[6:3] = 0101); or
2. Continuous AUX Measurement shown in Figure 43 (converter function select bits C[3:0] = Control Byte 1
D[6:3] = 1000).
See Table 7 for more information on the converter function select bits.
There are also two converter functions for the measurement of the internal temperature sensor:
1. TEMP1 measurement (converter function select bits C[3:0] = Control Byte 1 D[6:3] = 0110); or
2. TEMP2 measurement (converter function select bits C[3:0] = Control Byte 1 D[6:3] = 0111).
See Table 7 for more information on the converter function select bits.
For the detailed calculation of the internal temperature sensor, please see the Internal Temperature Sensor
section. These two converter functions have the same timing as the non-continuous AUX measurement
operation as shown in Figure 42; therefore, Equation 12 can also be used for internal temperature sensor
measurement. The time needed to make a non-continuous auxiliary measurement or an internal temperature
sensor measurement is given by:
ǒ
Ǔ ǒ Ǔ ǒ Ǔ
f
L
t COORDINATE + OH3 ) N @ (B)2) @ OSC )OH CONV @ 1 ) PPRO
f OSC
f OSC
f ADC
f OSC
(12)
Where:
OH3 = overhead time #3 = 3.5 internal clock cycles.
CS
Deactivated
Programmed for
Non-Continuous
AUX Measurement
CS
Deactivated
CS
Deactivated
Reading
AUX-Data
Register
tCOORDINATE
No Touch
Detected
Host Write to
Control Byte 1 D[6:3]
Sample, Conversion, and
Averaging for AUX Measurement
No Touch
Detected
Waiting for Host to
Read AUX Data
As DAV
Figure 42. Non-Touch Screen, Non-Continuous AUX Measurement
The time needed to make continuous auxiliary measurement is given by:
ǒ
Ǔ ǒ Ǔ ǒ Ǔ
f
L
t COORDINATE + OH3 ) N @ (B)2) @ OSC )OH CONV @ 1 ) PPRO
f OSC
f OSC
f ADC
f OSC
CS
Deactivated
No Touch
Detected
Programmed for
Continuous
AUX Measurement
Host to Write to
Control Byte 1 D[6:3]
(13)
CS
Deactivated
Reading
AUX-Data
Register
CS
Deactivated
CS
Reading Deactivated
AUX-Data
Register
tCOORDINATE
tCOORDINATE
tCOORDINATE
Sample, Conversion,
and Averaging for
AUX Measurement
Sample, Conversion,
and Averaging for
AUX Measurement
Sample, Conversion,
and Averaging for
AUX Measurement
As DAV
Figure 43. Non-Touch Screen, Continuous AUX Measurement
40
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SBAS415A – JUNE 2007 – REVISED NOVEMBER 2007
LAYOUT
The following layout suggestions should obtain optimum performance from the TSC2006. However, many
portable applications have conflicting requirements for power, cost, size, and weight. In general, most portable
devices have fairly clean power and grounds because most of the internal components are very low power. This
situation would mean less bypassing for the converter power and less concern regarding grounding. Still, each
application is unique and the following suggestions should be reviewed carefully.
For optimum performance, care should be taken with the physical layout of the TSC2006 circuitry. The basic
SAR architecture is sensitive to glitches or sudden changes on the power supply, reference, ground connections,
and digital inputs that occur just prior to latching the output of the analog comparator. Therefore, during any
single conversion for an n-bit SAR converter, there are n windows in which large external transient voltages can
easily affect the conversion result. Such glitches might originate from switching power supplies, nearby digital
logic, and high power devices. The degree of error in the digital output depends on the reference voltage, layout,
and the exact timing of the external event. The error can change if the external event changes in time with
respect to the SCLK input.
With this possibility in mind, power to the TSC2006 should be clean and well-bypassed. A 0.1µF ceramic bypass
capacitor should be added between (SNSVDD to AGND and SNSGND) or (I/OVDD to DGND). A 0.1µF
decoupling capacitor between VREF to AGND is also needed unless the SNSVDD is used as a reference input
and is connected to VREF. These capacitors must be placed as close to the device as possible. A 1µF to 10µF
capacitor may also be needed if the impedance of the connection between SNSVDD and the power supply is
high. The I/OVDD must be shorted to the same supply plane as the SNSVDD. Short both SNSVDD and I/OVDD
to the analog VDD plane.
The A/D converter architecture offers no inherent rejection of noise or voltage variation in regards to using an
external reference input, which is of particular concern when the reference input is tied to the power supply for
auxiliary input and temperature measurements. Any noise and ripple from the supply appear directly in the digital
results. While high-frequency noise can be filtered out by the built-in MAV filter, voltage variation as a result of
line frequency (50Hz or 60Hz) can be difficult to remove. Some package options have pins labeled as NC (no
connection). It is recommended that these NC pins be connected to the ground plane. Avoid any active trace
going under the analog pins listed in the Pin Assignments table, unless they are shielded by a ground or power
plane.
All GND (AGND, DGND, SUBGND and SNSGND) pins should be connected to a clean ground point. In many
cases, this point is the analog ground. Avoid connections that are too near the grounding point of a
microcontroller or digital signal processor. If needed, run a ground trace directly from the converter to the
power-supply entry or battery connection point. The ideal layout includes an analog ground plane dedicated to
the converter and associated analog circuitry.
In the specific case of use with a resistive touch screen, care should be taken with the connection between the
converter and the touch screen. Because resistive touch screens have fairly low resistance, the interconnection
should be as short and robust as possible. Loose connections can be a source of error when the contact
resistance changes with flexing or vibrations.
As indicated previously, noise can be a major source of error in touch-screen applications (for example,
applications that require a back-lit LCD panel). This electromagnetic interfence (EMI) noise can be coupled
through the LCD panel to the touch screen and cause flickering of the converted A/D converter data. Several
things can be done to reduce this error; for example, use a touch screen with a bottom-side metal layer
connected to ground to couple the majority of noise to ground. Another way to filter out this type of noise is by
using the TSC2006 built-in MAV filter (see the Preprocessing section). Filtering capacitors, from Y+, Y–, X+, and
X– to ground, can also help. Note, however, that the use of these capacitors increases screen settling time and
requires longer panel voltage stabilization times, and also increases precharge and sense times for the PINTADV
circuitry of the TSC2006. The resistor value varies depending on the touch screen sensor used. The internal
50kΩ pull-up resistor (RIRQ) may be adequate for most of sensors.
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PACKAGE OPTION ADDENDUM
www.ti.com
20-Jul-2007
PACKAGING INFORMATION
Orderable Device
Status (1)
Package
Type
Package
Drawing
Pins Package Eco Plan (2)
Qty
TSC2006IRTJR
PREVIEW
QFN
RTJ
20
3000
TBD
Call TI
Call TI
TSC2006IRTJT
PREVIEW
QFN
RTJ
20
250
TBD
Call TI
Call TI
Lead/Ball Finish
MSL Peak Temp (3)
(1)
The marketing status values are defined as follows:
ACTIVE: Product device recommended for new designs.
LIFEBUY: TI has announced that the device will be discontinued, and a lifetime-buy period is in effect.
NRND: Not recommended for new designs. Device is in production to support existing customers, but TI does not recommend using this part in
a new design.
PREVIEW: Device has been announced but is not in production. Samples may or may not be available.
OBSOLETE: TI has discontinued the production of the device.
(2)
Eco Plan - The planned eco-friendly classification: Pb-Free (RoHS), Pb-Free (RoHS Exempt), or Green (RoHS & no Sb/Br) - please check
http://www.ti.com/productcontent for the latest availability information and additional product content details.
TBD: The Pb-Free/Green conversion plan has not been defined.
Pb-Free (RoHS): TI's terms "Lead-Free" or "Pb-Free" mean semiconductor products that are compatible with the current RoHS requirements
for all 6 substances, including the requirement that lead not exceed 0.1% by weight in homogeneous materials. Where designed to be soldered
at high temperatures, TI Pb-Free products are suitable for use in specified lead-free processes.
Pb-Free (RoHS Exempt): This component has a RoHS exemption for either 1) lead-based flip-chip solder bumps used between the die and
package, or 2) lead-based die adhesive used between the die and leadframe. The component is otherwise considered Pb-Free (RoHS
compatible) as defined above.
Green (RoHS & no Sb/Br): TI defines "Green" to mean Pb-Free (RoHS compatible), and free of Bromine (Br) and Antimony (Sb) based flame
retardants (Br or Sb do not exceed 0.1% by weight in homogeneous material)
(3)
MSL, Peak Temp. -- The Moisture Sensitivity Level rating according to the JEDEC industry standard classifications, and peak solder
temperature.
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