The eKT8120 is a low-cost single chip solution for capacitive touch pad. It is an 8-bit RISC microcontroller with Serial Peripheral Interface (SPI), Universal Asynchronous Receiver / Transmitter (UART) and I2C. 
-The eKT8120 supports protocol and I/O mode for customers. Customers can use I/O mode to get a valid message and develop their system very easily, and no longer need to decode the communication package. The capacitive touch pad sensor is covered with a plastic case. 
The typical thickness of the plastic is 1.0mm ~ 1.5mm. It can also auto calibrate the parameters for a wide range of capacitance on the touch pad sensor (5pF~15pF). The system controller converts finger position data to either scrolling data or button presses, depending on finger location and human interface context.

Features

• Operating voltage: 2.6V ~ 5.5V, Ripple < 100mVpp
• Power-on reset time: Stable time for operating < 150ms, the touch pad will send
  "Packet Hello" after initialization
• Interface features: Serial Peripheral Interface (SPI) / Universal Asynchronous Receiver Transmitter (UART)/I2C.
• Operating mode:

  Mode	Description	Current
  Normal	Finger on touch pad Higher scan rate	<1.5 mA
  Idle	Finger leaves touch pad Lower scan rate Scan rate in idle mode can be adjusted by changing the external RC value.	<200 µA
  Sleep	No scan	<20 µA

• Application mode:
  Mode 1: one scroll bar + six buttons (FUNMODE_SEL =0)
  Mode 2: two scroll bars + four buttons (FUNMODE_SEL =1)
• Useful Information
  Scrolling information (S1/S2) and key buttons information can be acquired through
  I/O transition or protocol decode.
• Sensitivity: Sensitivity can be adjusted from 0 to 6 for different thickness of the
  plastic cover (protocol mode only). The default label is "2".
• Package type: QFN40