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capacitive touch switch circuit

TTP223 Capacitive Touch Switch Circuit

Here is a simple capacitive touch switch circuit for electronics hobbyists. Even though the circuit uses smd components, construction of the touch sensor switch is not very hard because the whole circuit can be easily fabricated on a piece of smd prototyping board. At the heart of the circuit is an inexpensive (`20) smd chip TTP223 commonly available in BA-6 package. The TTP223 is a touch pad detector IC which offers one touch key, designed for replacing traditional direct key button switch with diverse pad size. Low power consumption and wide operating voltage are the contact key features for dc or ac application.

capacitive touch switch circuit

The circuit can be interfaced to any microcontroller through the 3-pin header J1. Recommended VCC is regulated 5V, and the available output (OUT) is active-high (H) in case of a finger touch at the touch pad (TP). LED 1 (green) is the power (PWR) indicator, and LED 2 (red) is an optional output status (OUT) indicator. Just bridge the solder jumper JP1 to enable the output status indicator, if necessary.

Prototype built on a general purpose circuit board using traditional (leaded) components with TTP223 mounted on an smd adaptor pcb (SOT-23 to DIP adaptor) was successfully tested using a small (10mm x10mm) copper clad board as the touch pad. If you are using this method, try to keep the length of interconnection wire from touch pad to pin 1 of TTP223 as short as possible.

In some modules, a 1K resistor is inserted between the touch pad and pin 3 of TTP223, but the same is not tested at this time. Note that the total loading of touch pad size and capacitance of connecting line on circuit board can affect the sensitivity. So the sensitivity adjustment must according to the practical application (larger and/or thinner touch pad will increase the overall sensitivity).

14 Comments

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  • philonidhi2000

    Hi,
    I am looking for the Eagle library for TTP223/ TTP224/ TTP229. Please guide.

  • Ninad

    Can you please tell me
    how much current rating required for this TTP223 IC in circuit.
    also tell me is that 2 capacitors are required (100nf & 100uf).

    & what should i do for Dimmer circuit

  • Atul

    I bought for 15/- only from sunrom office as i live near by, I am using it with 5mm Acralic plexiglass sheet, it is working great. I have configured it to ON/OFF application. One touch ON, another touch OFF.

    Earlier have been experimenting with PIC MCU with cap touch sensing but was not good for commercial use and costly too.

    • Ninad

      Can you please tell me how much current rating required for this TTP223 IC in circuit.
      also tell me is that 2 capacitors are required (100nf & 100uf).

    • Ninad

      Dear sir,

      Thanks for replay can you also tell me about multituch IC. “TTP224” is this 4 input 4 output Capacitive tuch IC. if you have any detail about this then please share it with me. also tell me is it like TTP223 IC like ready to use (Inbuilt program)

    • Rocky

      Ninad,
      No need to use any microcontroller for the ic except it needs low power supply see the datasheet.

    • Ninad

      can you tell me do you have any details about TTP223 IC.
      If i buy this TTP223 tuch IC then is it having inbuilt program code or I want to install using microcontroller kit?
      i mean if i buy from sunrom then can i directly use this as a tuch sensor?

    • Rocky

      Hi Atul, thnaks for repply, Iam wondering how did you manage the 10 micro amp current for the ttp223 ic as specified in the datasheet.If possible can you give me yor email id for further contact in details regarding this touch technology.

      Rocky

  • Atul

    In case anybody in India is looking for it.
    I found the IC at below store in India
    http://www.sunrom.com/p/ttp223-ba6

    I went and picked up.

    • Ninad

      Dear sir,

      Thanks for above article. please tell me If i buy this TTP223 tuch IC then is it having inbuilt program code or I want to install using microcontroller kit?
      i mean if i buy from sunrom then can i directly use this as a tuch sensor?

    • rocky

      Hi Atul,
      Can u tell me how the IC is working? Is it sensitive enough to touch via glass panel? If yes qht extra configuration you did?

      Awiatin reply…

      Rocky

  • teng seastres

    Comment

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