TTP223 Capacitive Touch Sensor PCB

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.

• Operating voltage 2.0V~5.5V
• Operating current @VDD=3V, no load, SLRFTB=1
• The response time max about 60mS at fast mode, 220mS at low power mode @VDD=3V
• Sensitivity can adjust by the capacitance(0~50pF) outside
• Have two kinds of sampling length by pad option(SLRFTB pin)
• Stable touching detection of human body for replacing traditional direct switch key
• Provides Fast mode and Low Power mode selection by pad option(LPMB pin)
• Provides direct mode、toggle mode by pad option(TOG pin)
  Open drain mode by bonding option, OPDO pin is open drain output, Q pin is CMOS output
• All output modes can be selected active high or active low by pad option(AHLB pin)
• Have the maximum on time 100sec by pad option(MOTB pin)
• Have external power on reset pin(RST pin)
• After power-on have about 0.5sec stable-time, during the time do not touch the key pad, And the function is disabled
• Auto calibration for life
• Re-calibration period is about 4.0sec, when key has not be touched