TSC2046E-Q1
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SBAS510 – JUNE 2010
LOW-VOLTAGE I/O TOUCH SCREEN CONTROLLER
Check for Samples: TSC2046E-Q1
FEATURES
APPLICATIONS
•
•
•
•
•
•
•
•
•
•
•
•
1
234
•
Qualified for Automotive Applications
Same Pinout as ADS7846
2.2-V to 5.25-V Operation
1.5-V to 5.25-V Digital I/O
Internal 2.5-V Reference
Direct Battery Measurement (0 V to 6 V)
On-Chip Temperature Measurement
Touch-Pressure Measurement
QSPI™ and SPI™ 3-Wire Interface
Auto Power-Down
Exceeds IEC 61000-4-2 ESD Requirements
– ±15kV Contact Discharge
– No External Components Needed
Available In a TSSOP-16 (PW) Package
Touch Screen Monitors
PW PACKAGE
(TOP VIEW)
+VCC
X+
Y+
X–
Y–
GND
VBAT
AUX
1
16
2
15
3
14
4
13
5
12
6
11
7
10
8
9
DCLK
CS
DIN
BUSY
DOUT
PENIRQ
IOVDD
VREF
DESCRIPTION
The TSC2046E is the next-generation version of the ADS7846 4-wire touch screen controller, supporting a
low-voltage I/O interface from 1.5 V to 5.25 V. The TSC2046E is 100% pin-compatible with the existing
ADS7846, and drops into the same socket. This design allows for an easy upgrade of current applications to the
new version. The TSC2046E also has an on-chip 2.5-V reference that can be used for the auxiliary input, battery
monitor, and temperature measurement modes. The reference can also be powered down when not used to
conserve power. The internal reference operates down to a supply voltage of 2.7 V, while monitoring the battery
voltage from 0 V to 6 V.
The low power consumption of less than 0.75 mW (typ) at 2.7 V (reference off), high-speed (up to 125-kHz
sample rate), and on-chip drivers make the TSC2046E an ideal choice for battery-operated systems such as
personal digital assistants (PDAs) with resistive touch screens, pagers, cellular phones, and other portable
equipment. The TSC2046E is available in a TSSOP-16 package and is specified over the -40°C to +125°C
temperature range.
ORDERING INFORMATION (1)
TA
-40°C to 125°C
(1)
PACKAGE
TSSOP - PW
Reel of 2000
ORDERABLE PART NUMBER
TSC2046EQPWRQ1
TOP-SIDE MARKING
T2046EQ
For the most current package and ordering information, see the Package Option Addendum at the end of this document, or see the TI
web site at www.ti.com.
1
2
3
4
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.
QSPI, SPI are trademarks of Motorola Inc.
Microwire is a trademark of National Semiconductor Corporation.
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 © 2010, Texas Instruments Incorporated
TSC2046E-Q1
SBAS510 – JUNE 2010
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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.
PENIRQ
P e n D e tec t
+VCC
X+
T e m pe ra ture
X−
SAR
Se n sor
IOVDD
Y+
DOUT
TSC2046E
Y−
BUSY
Comparator
6−Channel
MUX
Serial
Data
In/Out
CDAC
DCLK
Battery
Monitor
VBAT
CS
DIN
AUX
Internal 2.5V Reference
VRE F
TERMINAL FUNCTIONS
TERMINAL
NAME
NO.
DESCRIPTION
+VCC
1
Power supply
X+
2
X+ position input
Y+
3
Y+ position input
X-
4
X- position input
Y-
5
Y- position input
GND
6
Ground
VBAT
7
Battery monitor input
AUX
8
Auxiliary input to ADC
VREF
9
Voltage reference input/output
IOVDD
10
Digital I/O power supply
PENIRQ
11
Pen interrupt
DOUT
12
Serial data output. Data are shifted on the falling edge of DCLK. This output is high impedance when CS is high.
BUSY
13
Busy output. This output is high impedance when CS is high.
DIN
14
Serial data input. If CS is low, data sre latched on the rising edge of DCLK.
CS
15
Chip select input. Controls conversion timing and enables the serial input/output register.
CS high = power-down mode (ADC only).
DCLK
16
External clock input. This clock runs the SAR conversion process and synchronizes serial data I/O.
2
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ABSOLUTE MAXIMUM RATINGS (1)
(2)
over operating free-air temperature range (unless otherwise noted)
VCC
Supply voltage range
+VCC, IOVDD
-0.3 V to 6 V
Digital inputs
-0.3 V to +VCC + 0.3 V
Analog inputs
-0.3 V to +VCC + 0.3 V
VI
Input voltage range
PD
Power dissipation
qJA
Package thermal impedance, junction to free air
TA
Operating free-air temperature range
TJ
Maximum junction temperature
Tstg
Storage temperature range
250 mW
150°C
-65°C to 150°C
IEC Contact Discharge (3)
(1)
(2)
(3)
108.4°C
-40°C to 125°C
X+, X-, Y+, Y-
±15kV
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 under recommended operating
conditions is not implied. Exposure to absolute-maximum-rated conditions for extended periods may affect device reliability.
All voltages are referenced to GND.
Test method based on IEC Std 61000-4-2. Contact Texas Instruments for test details.
ELECTRICAL CHARACTERISTICS
TA = -40°C to 125°C, +VCC = 2.7V, VREF = 2.5V internal voltage, fSAMPLE = 125kHz, fCLK = 16 × fSAMPLE = 2MHz, 12-bit mode,
digital inputs = GND or IOVDD, +VCC ≥ IOVDD (unless otherwise noted)
PARAMETER
TEST CONDITIONS
MIN
TYP
MAX
UNIT
V
Analog Input
VI
Full-scale input voltage span
Positive Input-Negative Input
0
VREF
Positive Input
-0.2
+VCC + 0.2
Negative Input
-0.2
+0.2
VI
Absolute input voltage
V
Ci
Capacitance
25
pF
Ileak
Leakage current
0.1
µA
12
bits
System Performance
Resolution
No missing codes
11
bits
±2 LSB (1)
Integral linearity error
Offset error
Gain error
External VREF
Vn
Noise
Including internal VREF, RMS
PSRR
Power-supply rejection ratio
±6
LSB
±4
LSB
70
µV
70
dB
Sampling Dynamics
Conversion time
12
Acquisition time
CLK
cycles
3
Throughput rate
125
Multiplexer settling time
CLK
cycles
kHz
500
ns
Aperture delay
30
ns
Aperture jitter
100
ns
100
dB
5
Ω
Channel-to-channel isolation
VIN = 2.5 Vpp at 50 kHz
Switch Drivers
Y+, X+ on-resistance
Y-, X- on-resistance
Drive current (2)
(1)
(2)
Ω
6
Duration 100 ms
50
mA
LSB = least significant bit. With VREF equal to 2.5 V, one LSB is 610 µV.
Specified by design. Exceeding 50-mA source current may result in device degradation.
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ELECTRICAL CHARACTERISTICS (continued)
TA = -40°C to 125°C, +VCC = 2.7V, VREF = 2.5V internal voltage, fSAMPLE = 125kHz, fCLK = 16 × fSAMPLE = 2MHz, 12-bit mode,
digital inputs = GND or IOVDD, +VCC ≥ IOVDD (unless otherwise noted)
PARAMETER
TEST CONDITIONS
MIN
TYP
MAX
2.45
2.50
2.55
UNIT
Reference Output
Internal reference voltage
Internal reference drift
IQ
Quiescent current
PD1 = 1, PD0 = 0, SDA and SCL high
V
15
ppm/
°C
500
µA
Reference Input
VI
Input voltage
Input impedance
1
SER/DFR = 0, PD1 = 0, Internal reference off
+VCC
1
Internal reference on
V
GΩ
Ω
250
Battery Monitor
VI
Input voltage
ZI
Input impedance
Accuracy
0.5
Sampling battery
6
10
Battery monitor off
V
kΩ
1
GΩ
VBAT = 0.5 V to 5.5 V, External VREF = 2.5 V
-2
+2
VBAT = 0.5 V to 5.5 V, Internal reference
-3
+3
-40
125
%
Temperature Measurement
Temperature range
Resolution
Accuracy
Differential method
(3)
1.6
TEMP0 (4)
0.3
Differential method (3)
±2
TEMP0
(4)
°C
°C
°C
±3
Digital Input/Output
VIH
High-level input voltage
| IIH | ≤ 5 µA
0.7 ×
IOVDD
IOVDD +
0.3
V
VIL
Low-level input voltage
| IIL | ≤ 5 µA
-0.3
0.3 ×
IOVDD
V
VOH
High-level output voltage
IOH = -250 µA
VOL
Low-level output voltage
IOL = 250 µA
Ci
Input capacitance
All digital control input pins
0.8 ×
IOVDD
V
5
0.4
V
15
pF
Power Supply Requirements
+VCC
Supply voltage (5)
IOVDD
Supply voltage (6)
IQ
Quiescent current
Specified performance
2.7
3.6
Operating range
2.5
5.25
1.5
+VCC
Internal reference off
280
Internal reference on
970
fSAMPLE = 12.5 kHz
220
Power-down mode, CS = DCLK = DIN = IOVDD
PD
Power dissipation
10
+VCC = 2.7 V
V
V
650
µA
28
1.8
mW
125
°C
Temperature Range
TA
(3)
(4)
(5)
(6)
4
Operating free-air temperature
Specified performance
-40
Difference between TEMP0 and TEMP1 measurement. No calibration necessary.
Temperature drift is -2.1 mV/°C.s
TSC2046E operates down to 2.2V.
IOVDD must be ≤ +VCC.
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TYPICAL CHARACTERISTICS
At TA = +25°C, +VCC = +2.7V, IOVDD = +1.8V, VREF = External +2.5V, 12-bit mode, PD0 = 0, fSAMPLE = 125kHz,
fCLK = 16 × fSAMPLE = 2MHz (unless otherwise noted)
+VCC SUPPLY CURRENT vs TEMPERATURE
IOVDD SUPPLY CURRENT vs TEMPERATURE
30
350
IOVDD Supply Current (µA)
+VCC Supply Current (µA)
400
300
250
200
150
100
−40
−20
0
20
40
60
80
25
20
15
10
5
− 40
100
−20
Temperature (°C)
0
20
40
60
80
100
4.5
5.0
4.5
5.0
Temperature (°C)
POWER−DOWN SUPPLY CURRENT vs TEMPERATURE
+VCC SUPPLY CURRENT vs +VCC
140
450
400
+VCC Supply Current (µA)
Supply Current (nA)
120
100
80
60
fSAMPLE = 125kHz
350
300
250
200
f SAMPLE = 12.5kHz
150
100
40
−40
−20
0
20
40
60
80
100
2.0
2.5
3.0
Temperature (°C)
3.5
4.0
+VCC (V)
IOVDD SUPPLY CURRENT vs IOVDD
MAXIMUM SAMPLE RATE vs +VCC
60
1M
Sample Rate (Hz)
IOVDD Supply Current (µA)
+VCC ≥ IOVDD
50
40
fSAMPLE = 125kHz
30
20
10
100k
10k
fSAMPLE = 12.5kHz
0
1k
1.0
1.5
2.0
2.5
3.0
3.5
4.0
4.5
5.0
2.0
IOVDD (V)
2.5
3.0
3.5
4.0
+VCC (V)
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TYPICAL CHARACTERISTICS (continued)
At TA = +25°C, +VCC = +2.7V, IOVDD = +1.8V, VREF = External +2.5V, 12-bit mode, PD0 = 0, fSAMPLE = 125kHz,
fCLK = 16 × fSAMPLE = 2MHz (unless otherwise noted)
CHANGE IN OFFSET vs TEMPERATURE
0.6
0.10
0.4
Delta from +25°C (LSB)
Delta from +25°C (LSB)
CHANGE IN GAIN vs TEMPERATURE
0.15
0.05
0
−0.05
−0.10
−0.15
− 40
−20
0
20
40
60
80
0.2
0
−0.2
−0.4
−0.6
− 40
100
− 20
0
Temperature (°C)
40
60
80
100
REFERENCE CURRENT vs TEMPERATURE
REFERENCE CURRENT vs SAMPLE RATE
14
18
12
16
Reference Current (µA)
Reference Current (µA)
20
Temperature (°C)
10
8
6
4
14
12
10
8
2
6
−40
0
0
25
50
75
100
125
−20
0
20
40
60
80
100
Temperature (°C)
Sample Rate (kHz)
SWITCH ON−RESISTANCE vs TEMPERATURE
(X+, Y+: +VCC to Pin; X−, Y−: Pin to GND)
SWITCH ON− RESISTANCE vs +VCC
(X+, Y+: +VCC to Pin; X−, Y−: Pin to GND)
8
8
Y−
7
7
6
6
RON (Ω)
RON (Ω)
Y−
5
X+, Y+
5
X−
4
X−
3
X+, Y+
4
2
1
3
2.0
2.5
3.0
3.5
4.0
4.5
5.0
−40
−20
6
0
20
40
60
80
100
Temperature (°C)
+VCC (V)
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TYPICAL CHARACTERISTICS (continued)
At TA = +25°C, +VCC = +2.7V, IOVDD = +1.8V, VREF = External +2.5V, 12-bit mode, PD0 = 0, fSAMPLE = 125kHz,
fCLK = 16 × fSAMPLE = 2MHz (unless otherwise noted)
MAXIMUM SAMPLING RATE vs RIN
INTERNAL VREF vs TEMPERATURE
2.5080
INL: RIN = 500Ω
INL: RIN = 2kΩ
DNL: RIN = 500Ω
DNL: RIN = 2kΩ
1.8
1.6
1.4
2.5075
2.5070
Internal VREF (V)
Max Absolute Delta Error from
RIN = 0 (LSB)
2.0
1.2
1.0
0.8
0.6
2.5065
2.5060
3.5055
2.5050
2.5045
0.4
2.5040
0.2
2.5035
2.5030
20
40
60
80
100 120 140
Sampling Rate (kHz)
160
180
−40
−35
−30
−25
−20
−15
−10
−5
0
5
10
15
20
25
30
35
40
45
50
55
60
65
70
75
80
85
0
200
Temperature (°C)
INTERNAL VREF vs TURN− ON TIME
INTERNAL VREF vs +VCC
100
2.510
No Cap
(42µs)
12-Bit Settling
80
Internal VREF (%)
Internal VREF (V)
2.505
2.500
2.495
2.490
1µF Cap
(124µs)
12-Bit Settling
60
40
20
2.485
2.480
0
2.5
3.0
3.5
4.0
4.5
0
5.0
200
400
600
800
1000
1200
1400
Turn-On Time (µs)
+VCC (V)
TEMP DIODE VOLTAGE vs TEMPERATURE
TEMP0 DIODE VOLTAGE vs +VCC
850
604
750
90.1mV
TEMP1
700
650
600
550
TEMP0
135.1mV
500
450
TEMP0 Diode Voltage (mV)
TEMP Diode Voltage (mV)
800
602
600
598
596
−40
−35
−30
−25
−20
−15
−10
−5
0
5
10
15
20
25
30
35
40
45
50
55
60
65
70
75
80
85
594
2.7
3.0
3.3
+VCC (V)
Temperature (°C)
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TYPICAL CHARACTERISTICS (continued)
At TA = +25°C, +VCC = +2.7V, IOVDD = +1.8V, VREF = External +2.5V, 12-bit mode, PD0 = 0, fSAMPLE = 125kHz,
fCLK = 16 × fSAMPLE = 2MHz (unless otherwise noted)
TEMP1 DIODE VOLTAGE vs +VCC
TEMP1 Diode Voltage (mV)
720
718
716
714
712
710
2.7
3.0
3.3
+VCC (V)
8
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THEORY OF OPERATION
The TSC2046E is a classic successive approximation register (SAR) analog-to-digital converter (ADC). The
architecture is based on capacitive redistribution, which inherently includes a sample-and-hold function. The
converter is fabricated on a 0.6µm CMOS process.
The basic operation of the TSC2046E is shown in Figure 1. The device features an internal 2.5-V reference and
an internal clock. Operation is maintained from a single supply of 2.7 V to 5.25 V. The internal reference can be
overdriven with an external, low-impedance source between 2 V and +VCC. The value of the reference voltage
directly sets the input range of the converter.
The analog input (X-, Y-, and Z-position coordinates, auxiliary inputs, battery voltage, and chip temperature) to
the converter is provided via a multiplexer. A unique configuration of low on-resistance switches allows an
unselected ADC input channel to provide power and an accompanying pin to provide ground for an external
device. By maintaining a differential input to the converter and a differential reference architecture, it is possible
to negate the error from each touch panel driver switch on-resistance (if this is a source of error for the particular
measurement).
+2.7V to +5V
1µF
+
to
10µF
(Optional)
Touch
Screen
0.1 µF
TSC2046E
B1 +VCC
DCLK A2
C1 +VCC
CS A3
Serial/Conversion Clock
Chip Select
Serial Data In
D1 X+
DIN A4
E1 Y+
BUSY A5
Converter Status
G2 X−
DOUT A6
Serial Data Out
G3 Y−
PENIRQ B7
Pen Interrupt
To Battery
Auxiliary Input
Voltage
Regulator
G6 VBAT
IOVDD C7
E7 AUX
VREF D7
GND G4
G5 GND
NOTE: VFBGA package and pin names shown.
Figure 1. Basic Operation
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Analog Input
Figure 2 shows a block diagram of the input multiplexer on the TSC2046E, the differential input of the ADC, and
the differential reference of the converter. Table 1 and Table 2 show the relationship between the A2, A1, A0,
and SER/DFR control bits and the configuration of the TSC2046E. The control bits are provided serially via the
DIN pin—see the Digital Interface section of this data sheet for more details.
When the converter enters the Hold mode, the voltage difference between the +IN and -IN inputs (see Figure 2)
is captured on the internal capacitor array. The input current on the analog inputs depends on the conversion
rate of the device. During the sample period, the source must charge the internal sampling capacitor (typically 25
pF). After the capacitor has been fully charged, there is no further input current. The amount of charge transfer
from the analog source to the converter is a function of conversion rate.
+VCC
PENIRQ IOVDD
Level
Shifter
TEMP1
50kΩ
or
90kΩ
VREF
TEMP0
Logic
A2− A0
(Shown 001B)
SER/DFR
(Shown Low)
X+
X−
Ref On/Off
Y+
+IN
Y−
+REF
ADC
2.5V
Reference
−IN
−REF
7.5kΩ
VBAT
2.5kΩ
Battery
On
AUX
GND
Figure 2. Simplified Diagram of the Analog Input
Table 1. Input Configuration (DIN), Single-Ended Reference Mode (SER/DFR High)
A2
A1
A0
0
0
0
0
0
1
0
1
0
0
1
1
1
0
0
1
0
1
1
1
0
1
1
1
10
VBAT
AUXIN
Temp
Y-
X+
Y+
YPosition
XPosition
Z1Position
Z2Position
+IN
(TEMP0)
+IN
Measure
+IN
+IN
Measure
+IN
Measure
+IN
Measure
+IN
+IN
(TEMP1)
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XDrivers
YDrivers
Off
Off
Off
On
Off
Off
X-, On
Y+, On
X-, On
Y+, On
On
Off
Off
Off
Off
Off
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Table 2. Input Configuration (DIN), Differential Reference Mode (SER/DFR Low)
A2
A1
A0
+REF
-REF
Y-
X+
Y+
0
0
1
Y+
Y-
+IN
0
1
1
Y+
X-
+IN
1
0
0
Y+
X-
1
0
1
X+
X-
Y-Position
X-Position
Z1-Position
Z2-Position
Measure
Y+, YMeasure
+IN
Y+, XMeasure
+IN
Drivers
Measure
Y+, XX+, X-
Internal Reference
The TSC2046E has an internal 2.5-V voltage reference that can be turned on or off with the power-down control
bit, PD1 (see Table 5 and Figure 3). Typically, the internal reference voltage is only used in the single-ended
mode for battery monitoring, temperature measurement, and for using the auxiliary input. Optimal touch screen
performance is achieved when using the differential mode. The internal reference voltage of the TSC2046E must
be commanded to be off to maintain compatibility with the ADS7843. Therefore, after power-up, a write of
PD1 = 0 is required to ensure the reference is off (see the Typical Characteristics for power-up time of the
reference from power-down).
Reference
Power−Down
Band
Gap
VREF
Buffer
To
CDAC
Optional
Figure 3. Simplified Diagram of the Internal Reference
Reference Input
The voltage difference between +REF and -REF (see Figure 2) sets the analog input range. The TSC2046E
operates with a reference in the range of 1V to +VCC. There are several critical items concerning the reference
input and its wide voltage range. As the reference voltage is reduced, the analog voltage weight of each digital
output code (referred to as LSB size) is also reduced. The LSB (least significant bit) size is equal to the
reference voltage divided by 4096 in 12-bit mode. Any offset or gain error inherent in the ADC appears to
increase, in terms of LSB size, as the reference voltage is reduced. For example, if the offset of a given
converter is 2LSBs with a 2.5V reference, it is typically 5LSBs with a 1V reference. In each case, the actual
offset of the device is the same, 1.22mV. With a lower reference voltage, more care must be taken to provide a
clean layout including adequate bypassing, a clean (low-noise, low-ripple) power supply, a low-noise reference (if
an external reference is used), and a low-noise input signal.
The voltage into the VREF input directly drives the capacitor digital-to-analog converter (CDAC) portion of the
TSC2046E. Therefore, the input current is very low (typically less than 13µA).
There is also a critical item regarding the reference when making measurements while the switch drivers are ON.
For this discussion, it is useful to consider the basic operation of the TSC2046E (see Figure 1). This particular
application shows the device being used to digitize a resistive touch screen. A measurement of the current
Y-Position of the pointing device is made by connecting the X+ input to the ADC, turning on the Y+ and Ydrivers, and digitizing the voltage on X+ (Figure 4 shows a block diagram). For this measurement, the resistance
in the X+ lead does not affect the conversion (it does affect the settling time, but the resistance is usually small
enough that this is not a concern). However, because the resistance between Y+ and Y- is fairly low, the
on-resistance of the Y drivers does make a small difference. Under the situation outlined so far, it is not possible
to achieve a 0V input or a full-scale input regardless of where the pointing device is on the touch screen because
some voltage is lost across the internal switches. In addition, the internal switch resistance is unlikely to track the
resistance of the touch screen, providing an additional source of error.
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+VCC
VREF
Y+
X+
+IN
+REF
Converter
−IN
−REF
Y−
GND
Figure 4. Simplified Diagram of Single-Ended Reference
(SER/DFR High, Y Switches Enabled, X+ is Analog Input)
This situation can be remedied as shown in Figure 5. By setting the SER/DFR bit low, the +REF and -REF inputs
are connected directly to Y+ and Y-, respectively, making the analog-to-digital conversion ratiometric. The result
of the conversion is always a percentage of the external resistance, regardless of how it changes in relation to
the on-resistance of the internal switches. Note that there is an important consideration regarding power
dissipation when using the ratiometric mode of operation (see the Power Dissipation section for more details).
+VCC
Y+
X+
+IN
+REF
Converter
− IN
− REF
Y−
GND
Figure 5. Simplified Diagram of Differential Reference
(SER/DFR Low, Y Switches Enabled, X+ is Analog Input)
As a final note about the differential reference mode, it must be used with +VCCas the source of the +REF
voltage and cannot be used with VREF. It is possible to use a high-precision reference on VREF and single-ended
reference mode for measurements that do not need to be ratiometric. In some cases, it is possible to power the
converter directly from a precision reference. Most references can provide enough power for the TSC2046E, but
might not be able to supply enough current for the external load (such as a resistive touch screen).
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Touch Screen Settling
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 backlight circuitry). These capacitors
provide a low-pass filter to reduce the noise, but cause a settling time requirement when the panel is touched
that typically shows up as a gain error. There are several methods for minimizing or eliminating this issue. The
problem is that the input and/or reference has not settled to the final steady-state value prior to the ADC
sampling the input(s) and providing the digital output. Additionally, the reference voltage may still be changing
during the measurement cycle. Option 1 is to stop or slow down the TSC2046E DCLK for the required touch
screen settling time. This option allows the input and reference to have stable values for the Acquire period (3
clock cycles of the TSC2046E; see Figure 9). This option works for both the single-ended and the differential
modes. Option 2 is to operate the TSC2046E in the differential mode only for the touch screen measurements
and command the TSC2046E to remain on (touch screen drivers ON) and not go into power-down (PD0 = 1).
Several conversions are made, depending on the settling time required and the TSC2046E data rate. Once the
required number of conversions have been made, the processor commands the TSC2046E to go into its
power-down state on the last measurement. This process is required for X-Position, Y-Position, and Z-Position
measurements. Option 3 is to operate in the 15 Clock-per-Conversion mode, which overlaps the analog-to-digital
conversions and maintains the touch screen drivers on until commanded to stop by the processor (see
Figure 13).
Temperature Measurement
In some applications, such as battery recharging, a measurement of ambient temperature is required. The
temperature measurement technique used in the TSC2046E 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 VBEvoltage and then monitoring the delta of that voltage as the temperature changes. The TSC2046E offers
two modes of operation. The first mode requires calibration at a known temperature, but only requires a single
reading to predict the ambient temperature. A diode is used (turned on) during this measurement cycle. The
voltage across the diode is connected through the MUX for digitizing the forward bias voltage by the ADC with an
address of A2 = 0, A1 = 0, and A0 = 0 (see Table 1 and Figure 6 for details). This voltage is typically 600mV at
+25°C with a 20µA current through the diode. The absolute value of this diode voltage can vary by a few
millivolts. However, 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 would be stored at a known room temperature, in memory, for
calibration purposes by the user. The result is an equivalent temperature measurement resolution of 0.3°C/LSB
(in 12-bit mode).
+VCC
TE MP 0
T E M P1
MUX
ADC
Figure 6. Temperature Measurement Functional Block Diagram
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The second mode of operation does not require a test temperature calibration, but uses a two-measurement
method to eliminate the need for absolute temperature calibration and for achieving 2°C accuracy. This mode
requires a second conversion with an address of A2 = 1, A1 = 1, and A0 = 1, with a 91 times larger current. The
voltage difference between the first and second conversion using 91 times the bias current is represented by
Equation 1:
ΔV =
kT
× ln(N)
q
(1)
where:
N = the current ratio = 91
k = Boltzmann's constant = 1.3807 × 10-23 J/K (joules/kelvin)
q = the electron charge = 1.6022 × 10-19 C (coulombs)
T = the temperature in kelvin (K)
This method can provide improved absolute temperature measurement, but at a lower resolution of 1.6°C/LSB.
The resulting equation that solves for T is:
T=
q - DV
k × ln(N)
(2)
where:
ΔV = VBE(TEMP1) - VBE(TEMP0) (in mV)
\ T = 2.573 × ΔV (in K)
or T = 2.573 × ΔV - 273 (in °C)
NOTE
The bias current for each diode temperature measurement is only on for three clock
cycles (during the acquisition mode) and, therefore, does not add any noticeable increase
in power, especially if the temperature measurement only occurs occasionally.
Battery Measurement
An added feature of the TSC2046E is the ability to monitor the battery voltage on the other side of the voltage
regulator (dc/dc converter), as shown in Figure 7. The battery voltage can vary from 0V to 6V, while maintaining
the voltage to the TSC2046E at 2.7V, 3.3V, etc. The input voltage (VBAT) is divided down by four so that a 5.5V
battery voltage is represented as 1.375V to the ADC. This design simplifies the multiplexer and control logic. In
order to minimize the power consumption, the divider is only on during the sampling period when A2 = 0, A1 = 1,
and A0 = 0 (see Table 1 for the relationship between the control bits and configuration of the TSC2046E).
DC/DC
Converter
Battery
0.5V +
to
5.5V
2.7V
+VCC
0.125V to 1.375V
VBAT
ADC
7.5kΩ
2.5kΩ
Figure 7. Battery Measurement Functional Block Diagram
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Pressure Measurement
Measuring touch pressure can also be done with the TSC2046E. To determine pen or finger touch, the pressure
of the touch needs to be determined. Generally, it is not necessary to have very high performance for this test;
therefore, the 8-bit resolution mode is recommended (however, calculations shown here are in the 12-bit
resolution mode). There are several different ways of performing this measurement. The TSC2046E supports two
methods. The first method requires knowing the X-plate resistance, measurement of the X-Position, and two
additional cross panel measurements (Z1 and Z2) of the touch screen, as shown in Figure 8. Using Equation 3
calculates the touch resistance:
RTOUCH = R X-Plate ×
ö
X-Position æ Z2
– 1÷÷
ç
4096 çè Z1
ø
(3)
The second method requires knowing both the X-Plate and Y-Plate resistance, measurement of X-Position and
Y-Position, and Z1. Equation 4 calculates the touch resistance using the second method:
RTOUCH =
ö
R X-Plate × X-Position æ 4096
– 1÷÷ – R Y-Plate
çç
4096
è Z1
ø
Measure
X−Position
Y-Position ö
æ
ç1 –
÷
4096 ø
è
(4)
Measure
Z1−Position
Y+
X+
X+
Y+
Y+
X+
Touch
Touch
Touch
X−Position
Z1−Position
Z2−Position
X−
Y−
X−
X−
Y−
Y−
Measure
Z2−Position
Figure 8. Pressure Measurement Block Diagram
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Digital Interface
See Figure 9 for the typical operation of the TSC2046E digital interface. This diagram assumes that the source of
the digital signals is a microcontroller or digital signal processor with a basic serial interface. Each
communication between the processor and the converter, such as SPI, SSI, or Microwire™ synchronous serial
interface, consists of eight clock cycles. One complete conversion can be accomplished with three serial
communications for a total of 24 clock cycles on the DCLK input.
Control Byte
The control byte (on DIN), as shown in Table 3, provides the start conversion, addressing, ADC resolution,
configuration, and power-down of the TSC2046E. Figure 9, Table 3 and Table 4 give detailed information
regarding the order and description of these control bits within the control byte.
Initiate START—The first bit, the S bit, must always be high and initiates the start of the control byte. The
TSC2046E ignores inputs on the DIN pin until the start bit is detected.
Addressing—The next three bits (A2, A1, and A0) select the active input channel(s) of the input multiplexer (see
Table 1, Table 2, and Figure 2), touch screen drivers, and the reference inputs.
MODE—The mode bit sets the resolution of the ADC. With this bit low, the next conversion has 12-bit resolution,
whereas with this bit high, the next conversion has 8-bit resolution.
SER/DFR—The SER/DFR bit controls the reference mode, either single-ended (high) or differential (low). The
differential mode is also referred to as the ratiometric conversion mode and is preferred for X-Position,
Y-Position, and Pressure-Touch measurements for optimum performance. The reference is derived from the
voltage at the switch drivers, which is almost the same as the voltage to the touch screen. In this case, a
reference voltage is not needed as the reference voltage to the ADC is the voltage across the touch screen. In
the single-ended mode, the converter reference voltage is always the difference between the VREF and GND pins
(see Table 1 and Table 2, and Figure 2 through Figure 5, for further information).
Table 3. Order of the Control Bits in the Control Byte
BIT 7 (MSB)
BIT 6
BIT 5
BIT 4
BIT 3
BIT 2
BIT 1
BIT 0 (LSB)
S
A2
A1
A0
MODE
SER/DFR
PD1
PD0
Table 4. Descriptions of the Control Bits within the Control Byte
16
BIT
NAME
7
S
DESCRIPTION
6-4
A2-A0
Channel Select bits. Along with the SER/DFR bit, these bits control the setting of the multiplexer input,
touch driver switches, and reference inputs (see Table 1 and Figure 13).
3
MODE
12-Bit/8-Bit Conversion Select bit. This bit controls the number of bits for the next conversion: 12-bits
(low) or 8-bits (high).
2
SER/DFR
Single-Ended/Differential Reference Select bit. Along with bits A2-A0, this bit controls the setting of the
multiplexer input, touch driver switches, and reference inputs (see Table 1 and Table 2).
1-0
PD1-PD0
Power-Down Mode Select bits. See Table 5 for details.
Start bit. Control byte starts with first high bit on DIN. A new control byte can start every 15th clock
cycle in 12-bit conversion mode or every 11th clock cycle in 8-bit conversion mode (see Figure 13).
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CS
t ACQ
DCLK
1
DIN
S
8
A2
A1
A0
MO D E
SER/
DFR
8
1
1
8
PD1 PD0
(START)
Idle
Conversion
Acquire
Idle
BUSY
DOUT
11
10
9
8
7
6
5
4
3
2
1
(MSB)
0
Zero Filled...
(LSB)
(1)
Drivers 1 and 2
(SER/DFR High)
Off
Drivers 1 and 2(1, 2)
(SER/DFR Low)
Off
On
Off
On
Off
NOTES: (1) For Y−Position, Driver 1 is on X+ is selected, and Driver 2 is off. For X−Position, Driver 1 is off, Y+ is selected, and Driver 2 is on. Y− will turn on when power-down mode is entered and PD0 = 0.
(2) Drivers will remain on if PD0 = 1 (no power down) until selected input channel, reference mode, or p ower−down mode is changed, or CS is high.
Figure 9. Conversion Timing, 24 Clocks-per-Conversion, 8-Bit Bus Interface
No DCLK Delay Required With Dedicated Serial Port
If X-Position, Y-Position, and Pressure-Touch are measured in the single-ended mode, an external reference
voltage is needed. The TSC2046E must also be powered from the external reference. Caution should be
observed when using the single-ended mode such that the input voltage to the ADC does not exceed the internal
reference voltage, especially if the supply voltage is greater than 2.7V.
NOTE
The differential mode can only be used for X-Position, Y-Position, and Pressure-Touch
measurements. All other measurements require the single-ended mode.
PD0 and PD1—Table 5 describes the power-down and the internal reference voltage configurations. The internal
reference voltage can be turned on or off independently of the ADC. This feature can allow extra time for the
internal reference voltage to settle to the final value prior to making a conversion. Make sure to also allow this
extra wake-up time if the internal reference is powered down. The ADC requires no wake-up time and can be
instantaneously used. Also note that the status of the internal reference power-down is latched into the part
(internally) with BUSY going high. In order to turn the reference off, an additional write to the TSC2046E is
required after the channel has been converted.
Table 5. Power-Down and Internal Reference Selection
PD1
PD0
PENIRQ
DESCRIPTION
0
0
Enabled
Power-Down Between Conversions. When each conversion is finished, the converter enters a
low-power mode. At the start of the next conversion, the device instantly powers up to full power. There
is no need for additional delays to ensure full operation, and the very first conversion is valid. The Yswitch is on when in power-down.
0
1
Disabled
Reference is off and ADC is on.
1
0
Enabled
Reference is on and ADC is off.
1
1
Disabled
Device is always powered. Reference is on and ADC is on.
PENIRQ Output
The pen-interrupt output function is shown in Figure 10. While in power-down mode with PD0 = 0, the Y-driver is
on and connects the Y-plane of the touch screen to GND. The PENIRQ output is connected to the X+ input
through two transmission gates. When the screen is touched, the X+ input is pulled to ground through the touch
screen.
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In most of the TSC2046E models, the internal pullup resistor value is nominally 50kΩ, but this value may vary
between 36kΩ and 67kΩ given process and temperature variations. In order to assure a logic low of 0.35 (+VCC)
is presented to the PENIRQ circuitry, the total resistance between the X+ and Y- terminals must be less than
21kΩ.
IOVDD
+V CC
Level
Shifter
50kΩ
or
90kΩ
+VCC
TEMP0
Y+
PENIRQ
High except
when TEMP0,
TEMP1 activated.
X+
TEMP1
TEMP
DIODE
Y−
On
Y+ or X+ drivers on,
or TEMP0, TEMP1
measurements activated.
Figure 10. PENIRQ Functional Block Diagram
The -90 version of the TSC2046E uses a nominal 90kΩ pullup resistor that allows the total resistance between
the X+ and Y- terminals to be as high as 30kΩ. Note that the higher pullup resistance causes a slower response
time of the PENIRQ to a screen touch, so user software should take this into account.
The PENIRQ output goes low due to the current path through the touch screen to ground, initiating an interrupt to
the processor. During the measurement cycle for X-, Y-, and Z-Position, the X+ input is disconnected from the
PENIRQ internal pull-up resistor. This disconnection is done to eliminate any leakage current from the internal
pull-up resistor through the touch screen, thus causing no errors.
Furthermore, the PENIRQ output is disabled and low during the measurement cycle for X-, Y-, and Z-Position.
The PENIRQ output is disabled and high during the measurement cycle for battery monitor, auxiliary input, and
chip temperature. If the last control byte written to the TSC2046E contains PD0 = 1, the pen-interrupt output
function is disabled and is not able to detect when the screen is touched. In order to re-enable the pen-interrupt
output function under these circumstances, a control byte needs to be written to the TSC2046E with PD0 = 0. If
the last control byte written to the TSC2046E contains PD0 = 0, the pen-interrupt output function is enabled at
the end of the conversion. The end of the conversion occurs on the falling edge of DCLK after bit 1 of the
converted data is clocked out of the TSC2046E.
It is recommended that the processor mask the interrupt that PENIRQ is associated with whenever the processor
sends a control byte to the TSC2046E. This masking prevents false triggering of interrupts when the PENIRQ
output is disabled in the cases discussed in this section.
16 Clocks-per-Conversion
The control bits for conversion n + 1 can be overlapped with conversion n to allow for a conversion every 16
clock cycles, as shown in Figure 11. This figure also shows possible serial communication occurring with other
serial peripherals between each byte transfer from the processor to the converter. (16 clocks cycles are possible,
provided that each conversion completes within 1.6ms of starting. Otherwise, the signal that is captured on the
input sample-and-hold may droop enough to affect the conversion result.) Note that the TSC2046E is fully
powered while other serial communications are taking place during a conversion.
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CS
DCLK
1
DIN
8
8
1
1
8
1
S
S
Control Bits
Control Bits
BUSY
DOUT
11 10 9
8
7
6
5
4
3
2
1
11 10 9
0
Figure 11. Conversion Timing, 16 Clocks-per-Conversion, 8-Bit Bus Interface
No DCLK Delay Required With Dedicated Serial Port
Digital Timing
Figure 9, Figure 12, and Table 6 provide detailed timing for the digital interface of the TSC2046E.
CS
tCL
t CH
tCSS
tBD
tBD
tCSH
tDO
DCLK
tDH
t DS
PD0
DIN
tBDV
tBTR
BUSY
tDV
tTR
DOUT
11
10
Figure 12. Detailed Timing Diagram
Table 6. Timing Specifications (1)
SYMBOL
(1)
DESCRIPTION
MIN
TYP
MAX
UNIT
tACQ
Acquisition Time
1.5
µs
tDS
DIN Valid Prior to DCLK Rising
100
ns
tDH
DIN Hold After DCLK High
tDO
DCLK Falling to DOUT Valid
50
200
ns
ns
tDV
CS Falling to DOUT Enabled
200
ns
200
ns
tTR
CS Rising to DOUT Disabled
tCSS
CS Falling to First DCLK Rising
tCSH
CS Rising to DCLK Ignored
tCH
tCL
tBD
DCLK Falling to BUSY Rising/Falling
200
ns
tBDV
CS Falling to BUSY Enabled
200
ns
tBTR
CS Rising to BUSY Disabled
200
ns
100
ns
10
ns
DCLK High
200
ns
DCLK Low
200
ns
TA = −40°C to +125°C, +VCC = 2.7V, +VCC ≥ IOVDD ≥ 1.5V, CLOAD = 50pF
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15 Clocks-per-Conversion
Figure 13 provides the fastest way to clock the TSC2046E. This method does not work with the serial interface of
most microcontrollers and digital signal processors, as they are generally not capable of providing 15 clock
cycles per serial transfer. However, this method can be used with field-programmable gate arrays (FPGAs) or
application- specific integrated circuits (ASICs). Note that this effectively increases the maximum conversion rate
of the converter beyond the values given in the specification tables, which assume 16 clock cycles per
conversion.
Power−Down
CS
DCLK
1
DIN
15
S A2 A1 A0
MOD E
SER/
DFR
1
15
S A2 A1 A0
PD1 PD0
SER/
MODE
DFR
1
S A2 A1 A0
PD1 PD0
BUSY
DOUT
11 10
9
8
7
6
5
4
3
2
1
0
11 10
9
8
7
Figure 13. Maximum Conversion Rate, 15 Clocks-per-Conversion
Data Format
The TSC2046E output data is in Straight Binary format, as shown in Figure 14. 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
FS − 1LSB
0V
Input Voltage(2) (V)
NOTES: (1) Reference voltage at converter: +REF − (−REF); see Figure 2.
(2) Input voltage at converter, after multiplexer: +IN − (−IN); see Figure 2.
Figure 14. Ideal Input Voltages and Output Codes
8-Bit Conversion
The TSC2046E provides an 8-bit conversion mode that can be used when faster throughput is needed and the
digital result is not as critical. By switching to the 8-bit mode, a conversion is complete four clock cycles earlier.
Not only does this shorten each conversion by four bits (25% faster throughput), but each conversion can
actually occur at a faster clock rate. This faster rate occurs because the internal settling time of the TSC2046E is
not as critical—settling to better than 8 bits is all that is needed. The clock rate can be as much as 50% faster.
The faster clock rate and fewer clock cycles combine to provide a 2x increase in conversion rate.
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Power Dissipation
There are two major power modes for the TSC2046E: full-power (PD0 = 1) and auto power-down (PD0 = 0).
When operating at full speed and 16 clocks-per-conversion (see Figure 11), the TSC2046E spends most of the
time acquiring or converting. There is little time for auto power-down, assuming that this mode is active.
Therefore, the difference between full-power mode and auto power-down is negligible. If the conversion rate is
decreased by slowing the frequency of the DCLK input, the two modes remain approximately equal. However, if
the DCLK frequency is kept at the maximum rate during a conversion but conversions are done less often, the
difference between the two modes is dramatic.
Figure 15 shows the difference between reducing the DCLK frequency (scaling DCLK to match the conversion
rate) or maintaining DCLK at the highest frequency and reducing the number of conversions per second. In the
latter case, the converter spends an increasing percentage of time in power-down mode (assuming the auto
power-down mode is active).
1000
Supply Current (µA)
fCLK = 16 ⋅fSAMPLE
100
f CLK = 2MHz
Supply Current from
+ V C C and IOVDD
10
TA = 25°C
+VCC = 2.7V
IOVDD = 1.8V
1
1k
10k
100k
1M
fSAMPLE (Hz)
Figure 15. Supply Current vs Directly Scaling the Frequency of DCLK with Sample Rate or Maintaining
DCLK at the Maximum Possible Frequency
Another important consideration for power dissipation is the reference mode of the converter. In the single-ended
reference mode, the touch panel drivers are ON only when the analog input voltage is being acquired (see
Figure 9 and Table 1). The external device (for example, a resistive touch screen), therefore, is only powered
during the acquisition period. In the differential reference mode, the external device must be powered throughout
the acquisition and conversion periods (see Figure 9). If the conversion rate is high, it could substantially
increase power dissipation.
CS also puts the TSC2046E into power-down mode. When CS goes high, the TSC2046E immediately goes into
power-down mode and does not complete the current conversion. The internal reference, however, does not turn
off with CS going high. To turn the reference off, an additional write is required before CS goes high (PD1 = 0).
When the TSC2046E first powers up, the device draws about 20µA of current until a control byte is written to it
with PD0 = 0 to put it into power-down mode. This current draw can be avoided if the TSC2046E is powered up
with CS = 0 and DCLK = IOVDD.
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Layout
The following layout suggestions provide the most optimum performance from the TSC2046E. Many portable
applications, however, have conflicting requirements concerning 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 means less bypassing for the converter power and less concern regarding grounding. Still,
each situation is unique and the following suggestions should be reviewed carefully.
For optimum performance, care should be taken with the physical layout of the TSC2046E 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 can 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 DCLK input.
Because of the SAR architecture sensitvity, power to the TSC2046E should be clean and well bypassed. A 0.1µF
ceramic bypass capacitor should 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 +VCC or IOVDD and the power supplies is high.
Low-leakage capacitors should be used to minimize power dissipation through the bypass capacitors when the
TSC2046E is in power-down mode.
A bypass capacitor is generally not needed on the VREF pin because the internal reference is buffered by an
internal op amp. If an external reference voltage originates from an op amp, make sure that it can drive any
bypass capacitor that is used without oscillation.
The TSC2046E architecture offers no inherent rejection of noise or voltage variation in regards to using an
external reference input. This is of particular concern when the reference input is tied to the power supply. Any
noise and ripple from the supply appears directly in the digital results. Whereas high-frequency noise can be
filtered out, voltage variation bacause of line frequency (50Hz or 60Hz) can be difficult to remove.
The GND pin must be connected to a clean ground point. In many cases, this is the analog ground. Avoid
connections which 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. Although resistive touch screens have fairly low resistance, the interconnection
should be as short and robust as possible. Longer connections are a source of error, much like the on-resistance
of the internal switches. Likewise, 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 (such as in
applications that require a backlit LCD panel). This EMI noise can be coupled through the LCD panel to the touch
screen and cause flickering of the converted data. Several things can be done to reduce this error; for instance,
using a touch screen with a bottom-side metal layer connected to ground to shunt the majority of noise to
ground. Additionally, filtering capacitors from Y+, Y-, X+, and X- pins to ground can also help. Caution should be
observed under these circumstances for settling time of the touch screen, especially operating in the
single-ended mode and at high data rates.
22
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Copyright © 2010, Texas Instruments Incorporated
Product Folder Link(s): TSC2046E-Q1
PACKAGE OPTION ADDENDUM
www.ti.com
10-Dec-2020
PACKAGING INFORMATION
Orderable Device
Status
(1)
Package Type Package Pins Package
Drawing
Qty
Eco Plan
(2)
Lead finish/
Ball material
MSL Peak Temp
Op Temp (°C)
Device Marking
(3)
(4/5)
(6)
TSC2046EQPWRQ1
ACTIVE
TSSOP
PW
16
2000
RoHS & Green
NIPDAU
Level-1-260C-UNLIM
-40 to 125
T2046EQ
(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)
RoHS: TI defines "RoHS" to mean semiconductor products that are compliant with the current EU RoHS requirements for all 10 RoHS substances, including the requirement that RoHS substance
do not exceed 0.1% by weight in homogeneous materials. Where designed to be soldered at high temperatures, "RoHS" products are suitable for use in specified lead-free processes. TI may
reference these types of products as "Pb-Free".
RoHS Exempt: TI defines "RoHS Exempt" to mean products that contain lead but are compliant with EU RoHS pursuant to a specific EU RoHS exemption.
Green: TI defines "Green" to mean the content of Chlorine (Cl) and Bromine (Br) based flame retardants meet JS709B low halogen requirements of
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