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Touch screen interfaces are a highly effective medium of operating personal devices (like smartphones, tablets, etc.) or public informational devices (ATMs and ticket vending machines, for example) because of their highly interactive and user-friendly nature. Touch screen switch panels are also gaining popularity and can be seen in the control panel of cars, smart washing machines, and many other appliances. A variety of touch screen light switch is being used today in different types of applications, each having their own advantages and drawbacks. The two main types of touch screens used today are the resistive touch screens and the capacitive touch screens.
The resistive touch screen senses a touch when the pressure applied by the touch leads to contact between the two conductive layers of the screen. A capacitive touch screen, on the other hand, detects a touch when static charge from the screen is transferred to the human skin or stylus. Due to low prices, the resistive touch screens are preferred over other touch screens in areas where image quality can be compromised for low prices.
When a touch screen is touched at a given point on the touch screen, it creates an analog signal that containing some noise, which needs to be filtered and converted into digital signals, which is known as Data Acquisition. Also, when a touch screen is pressed, it leads to vibrations in the conductive layers and inductive and capacitive effects due to the drivers. The reading can be taken only when the voltage has settled. The time elapsed until this happens is called the settling-time. This settling-time also needs to be taken into account while taking the readings. Be
cause of such challenges, sensing and interpreting the touch signals requires a very advanced and sophisticated system which is generally called Touch Screen Controllers. These systems are available in the form of small chips (ICs).As soon as the screen is touched, a series of processes are triggered inside the touch screen controllers. First of all, a few readings for the X-coordinate of the touched region are taken. After this, several readings are taken for the Y-coordinates as well. Similar happens for Z-values (if the system supports three-dimensional analysis). After this is done, the values of X, Y, and Z readings are averaged to reduce the noise in the signal. Then, the touch screen controller checks if the variation between different readings doesn’t fall outside a particular range or else, the readings are discarded and the whole process is repeated from the beginning.
The whole process involved in determining the position of the touch is carried out by the intelligent touch screen controller and no involvement is required from the CPU but the CPU just receives the final result and then processes it.
Data Acquisition - Touch Screen Controllers
Image |
Part Number |
Manufacturer |
Description |
Package |
Stock |
Quantity |
Resolution (Bits) | Interface | Voltage Reference | Voltage - Supply | Current - Supply | Operating Temperature | Mounting Type | Package / Case | Supplier Device Package |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
|
Analog Devices Inc. |
IC ADC 12BIT CTLR TOUCH 16CSP
|
Package: 16-VQFN Exposed Pad, CSP |
Stock263 |
|
12 b | SPI | External | 1.6 V ~ 3.6 V | - | -40°C ~ 85°C | Surface Mount | 16-VQFN Exposed Pad, CSP | 16-LFCSP-VQ (4x4) | |
|
Microchip Technology |
IC SCREEN CNTRL 10BIT 32MLF
|
Package: 32-VFQFN Exposed Pad |
Stock150 |
|
10 b | I2C | External, Internal | 1.8 V ~ 5.5 V | - | - | Surface Mount | 32-VFQFN Exposed Pad | 32-MLF? (5x5) | |
|
Semtech Corporation |
IC TOUCH SCREEN 12BIT 20QFN
|
Package: 20-WFQFN Exposed Pad |
Stock221 |
|
12 b | I2C, Serial | Internal | 2.3 V ~ 3.6 V | - | -40°C ~ 85°C | Surface Mount | 20-WFQFN Exposed Pad | 20-QFN (4x4) | |
 
|
Analog Devices Inc. |
IC ADC 12BIT CTRLR TOUCH 12WLCSP
|
Package: 12-UFBGA, WLCSP |
Stock971 |
|
12 b | SPI | External | 1.6 V ~ 3.6 V | 10nA | -40°C ~ 85°C | Surface Mount | 12-UFBGA, WLCSP | 12-WLCSP (1.51x2.01) | |
|
Maxim Integrated |
IC TOUCH SCREEN CTRLR LP 20TQFN
|
Package: 20-WFQFN Exposed Pad |
Stock416 |
|
12 b | I2C, Serial | - | 1.7 V ~ 3.6 V | - | -40°C ~ 105°C | Surface Mount | 20-WFQFN Exposed Pad | 20-TQFN (4x4) | |
|
NXP |
IC CTLR TOUCH SENSOR 8-TSSOP
|
Package: 16-TSSOP (0.173", 4.40mm Width) |
Stock107 |
|
- | - | - | - | - | - | Surface Mount | 16-TSSOP (0.173", 4.40mm Width) | 16-TSSOP | |
|
Maxim Integrated |
IC CTRLR TOUCH-SCREEN 12-TQFN
|
Package: 12-WQFN Exposed Pad |
Stock429 |
|
12 b | SPI | - | 1.7 V ~ 3.6 V | - | -40°C ~ 85°C | Surface Mount | 12-WQFN Exposed Pad | 12-TQFN (4x4) | |
|
IDT, Integrated Device Technology Inc |
IC TOUCH SCREEN CTLR 28-SSOP
|
Package: 28-SSOP (0.154", 3.90mm Width) |
Stock10,104 |
|
12 b | Parallel | - | 3 V ~ 5.5 V | 5mA | - | Surface Mount | 28-SSOP (0.154", 3.90mm Width) | 28-QSOP | |
|
NKK Switches |
TOUCH SCREEN
|
Package: - |
Stock308 |
|
- | Serial, USB | - | - | - | -20°C ~ 70°C | - | - | - | |
|
Microchip Technology |
IC TOUCH CTRLR 64TQFP
|
Package: 64-TQFP |
Stock188 |
|
- | I2C, USB | - | 2.3 V ~ 3.6 V | - | -40°C ~ 85°C | Surface Mount | 64-TQFP | 64-TQFP (10x10) | |
|
|
Semtech Corporation |
IC SCREEN CNTRL 12BIT 19WLCSP
|
Package: 19-UFBGA, WLCSP |
Stock155 |
|
12 b | I2C, Serial | Internal | 2.3 V ~ 3.6 V | 120µA | -40°C ~ 85°C | Surface Mount | 19-UFBGA, WLCSP | 19-WLCSP (2.07x2.07) | |
|
Microchip Technology |
IC CTRLR TOUCH SENSE 20QFN
|
Package: 20-VFQFN Exposed Pad |
Stock332 |
|
10 b | I2C, Serial, SPI | - | 2.5 V ~ 5 V | 17mA | -40°C ~ 85°C | Surface Mount | 20-VFQFN Exposed Pad | 20-QFN (4x4) | |
|
Microchip Technology |
IC TOUCH CTLR PROJECTED 28SSOP
|
Package: 28-SSOP (0.209", 5.30mm Width) |
Stock162 |
|
- | I2C | - | 1.8 V ~ 3.6 V | 1.17mA | -40°C ~ 85°C | Surface Mount | 28-SSOP (0.209", 5.30mm Width) | 28-SSOP | |
|
|
Semtech Corporation |
IC SCREEN CNTRL 12BIT 12WLCSP
|
Package: 12-UFBGA, WLCSP |
Stock301 |
|
12 b | SPI | Internal | 1.65 V ~ 3.7 V | 105µA | -40°C ~ 85°C | Surface Mount | 12-UFBGA, WLCSP | 12-WLCSP (2x1.5) | |
|
|
Microchip Technology |
IC CTLR TOUCH SENSE 20QFN
|
Package: 20-VFQFN Exposed Pad |
Stock345 |
|
10 b | UART | - | 2.5 V ~ 5 V | 17mA | -40°C ~ 85°C | Surface Mount | 20-VFQFN Exposed Pad | 20-QFN (4x4) | |
|
|
Analog Devices Inc. |
TOUCH SCREEN CONTROLLER
|
Package: 16-VQFN Exposed Pad, CSP |
Stock349 |
|
12 b | SPI | External | 1.6 V ~ 3.6 V | - | -40°C ~ 85°C | Surface Mount | 16-VQFN Exposed Pad, CSP | 16-LFCSP-VQ (4x4) | |
|
Cypress Semiconductor Corp |
IC SCREEN CNTRL 32BIT 44QFN
|
Package: 44-UFQFN Exposed Pad |
Stock969 |
|
32 b | I2C, SPI | - | 1.71 V ~ 5.5 V | - | - | Surface Mount | 44-UFQFN Exposed Pad | 44-QFN (5x5) | |
|
Microchip Technology |
IC CTRLR TOUCH SENSE 20SSOP
|
Package: 20-SSOP (0.209", 5.30mm Width) |
Stock2,583 |
|
10 b | UART | - | 2.5 V ~ 5 V | 17mA | -40°C ~ 85°C | Surface Mount | 20-SSOP (0.209", 5.30mm Width) | 20-SSOP | |
|
|
Microchip Technology |
IC TOUCH SCREEN CTRLR 20-QFN
|
Package: 20-VFQFN Exposed Pad |
Stock589 |
|
10 b | I2C, Serial, SPI | - | 2.5 V ~ 5 V | 17mA | -40°C ~ 85°C | Surface Mount | 20-VFQFN Exposed Pad | 20-QFN-EP (4x4) | |
|
Microchip Technology |
IC TOUCH SCREEN CTRLR 20-SOIC
|
Package: 20-SOIC (0.295", 7.50mm Width) |
Stock2,255 |
|
10, 12 b | Serial, UART, USB | Internal | 3.3 V ~ 5 V | 25mA | -40°C ~ 85°C | Surface Mount | 20-SOIC (0.295", 7.50mm Width) | 20-SOIC | |
|
|
Cypress Semiconductor Corp |
IC SCREEN CNTRL TRUETOUCH 84BGA
|
Package: - |
Stock260 |
|
- | - | - | - | - | - | - | - | - | |
|
|
Cypress Semiconductor Corp |
IC SCREEN CNTRL TRUETOUCH 56QFN
|
Package: - |
Stock183 |
|
- | - | - | - | - | - | - | - | - | |
|
|
Cypress Semiconductor Corp |
IC SCREEN CNTRL TRUETOUCH 48QFN
|
Package: - |
Stock310 |
|
- | - | - | - | - | - | - | - | - | |
|
|
Cypress Semiconductor Corp |
IC SCREEN CNTRL TRUETOUCH
|
Package: - |
Stock316 |
|
- | - | - | - | - | - | - | - | - | |
|
|
Cypress Semiconductor Corp |
IC SCREEN CNTRL TRUETOUCH
|
Package: - |
Stock188 |
|
- | - | - | - | - | - | - | - | - | |
|
|
Cypress Semiconductor Corp |
IC SCREEN CNTRL TRUETOUCH
|
Package: - |
Stock313 |
|
- | - | - | - | - | - | - | - | - | |
|
|
Cypress Semiconductor Corp |
IC SCREEN CNTRL TRUETOUCH
|
Package: - |
Stock424 |
|
- | - | - | - | - | - | - | - | - | |
|
|
Cypress Semiconductor Corp |
IC SCREEN CNTRL TRUETOUCH 84BGA
|
Package: - |
Stock297 |
|
- | - | - | - | - | - | - | - | - | |
|
|
Cypress Semiconductor Corp |
IC SCREEN CNTRL PSOC 70BGA
|
Package: - |
Stock479 |
|
- | - | - | - | - | - | - | - | - | |
|
|
Cypress Semiconductor Corp |
IC SCREEN CNTRL PSOC 48QFN
|
Package: - |
Stock114 |
|
- | - | - | - | - | - | - | - | - |
