TTP224 Four-Channel Touch Detector IC

TTP224 is a four-channel touch detector IC that could be used as a 4-touch key driver. It is a useful interface when replaced with a traditional button key. It has a low power consumption with a wide range of operating voltage.

TTP224 has an auto-calibration feature for life and it has a re-calibration period of about 4.0 seconds. The sensitivity can be adjusted using an external capacitor of 0 to 50 pF, 4 input features fewer component counts during the integration in the system.

Pin Description of TTP224

The pinout is shown in the below image-

Features and Specification of TTP224

• Four-channel touch key sensing
• 2.5V - 5.5V Operating Voltage
• Operating current 2.5uA typically in low power mode. Maximum operating current 9.0uA at Fast mode.
• Response time - 100ms at fast mode and 200ms at low power mode.
• Adjustable sensitivity using an external capacitor (0-50 pF)
• Stable touch detection of the human body
• All output modes can be configurable for high or active low by pad options.
• Direct mode and Toggle mode selection pin available
• Auro calibration feature for life. The re-calibration period is about 4.0sec when the key has not been touch.
• Provides one output pin TPQ0D that has no diode protection circuit inbuilt and it is  active low
• Provides fast mode and low power mode selection by pad optional (LPMB pin).
• Provides direct mode or toggle mode, CMOS output, or open-drain output. active high or active low by option (TOG/AHLF/OD pin).

Note: Complete technical details can be found in the TTP224 Datasheet, linked at the bottom of this page.

Alternative Product of TTP224

Alternative product of this touch sensor IC-

1.    ADS7843

2.    TTP226

3.    TTP229

TTP224 Touch Controller IC - Overview

The TTP224 touch controller is the exact non-contact alternative to traditional button switches.

The IC uses an onboard sense pad that uses copper trace as a touch element and the touch sensitivity can be configured using an additional external capacitor ranging from 0 to 50pF. There are three pins, OD, AHLB, and TOG that could be used to configure the output state either high or low or toggle mode enable the option. The output can be made as open-drain using the OD pin configuration. The configurable output is set by those three pins as per the below chart.

Another interesting feature of this TTP224 is the maximum key in a duration time setting. This is set by the MOT1 and MOT0 pin using the below configuration-

Interfacing Diagram and How to Use the TTP224

The below image is showing standard 2.2-5V interfacing of the touch sensor. It requires basic components followed by a sense pad.

As we can see, the sense pad is connected to the input pin and two-slide switches are given to select the configuration of TOG and AHLB. The C1 can be configurable as per the required sensitivity.

Follow the below guidelines for PCB design-related purposes-

1. Place the Sense pads as close as possible to the IC
2. Do not use a mechanical enclosure
3. Use the proper filter and bypass capacitor to reduce noises or ripple in the input supply
4. Place the capacitor C2 as close as possible.
5. Use an X7R or NPO rated capacitor for better accuracy over a wide temperature.

Applications of TTP224

• Appliances control
• Wide range of consumer products
• Replacement of button switches

2D Model of TTP224

The dimensions of TTP224 are given below to help you with selecting the PCB footprint for TTP224.