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R8C/3JT touch-key


The touch key microcontrollers (MCUs) of the R8C/3JT Group are devices incorporating an electrostatic capacitive touch detector into the R8C/3x Series.
By integrating on a single chip a touch sensor IC for touch detection and a microcontroller for controlling the system based on the signals received, the R8C/3JT Group specifically meets the following five customer needs.
  • More compact system size, and furthermore compact QFN package (5 mm x 5mm, 0.5 mm thick) for thinner devices
  • System control via I/O ports
  • Touch key connection via touch detection input pins (22-input)
  • Reduced power consumption
  • Improved noise tolerance


CPU core: R8C 16-bit CPU core
Minimum instruction execution time:
50nsec (f(Xin)=20 MHz)
Supply voltage:
2.7 to 5.5 V/Max. 20 MHz , 1.8 to 5.5 V/Max. 5 MHz
ROM/RAM: 16 KB/1.5 KB, 24 KB/2 KB, 32 KB/2.5 KB
(RAM: 0.5 KB for touch detection)
Data flash: 1 KB x 4 blocks (Touch setting values can be stored.), with background operation (BGO) function*1
DTC (Data transfer controller): 1 ch
Clock generation circuits: 3 circuits
- XIN-XOUT main clock (oscillation stop detection circuit included)
- High-speed on-chip oscillator (40 MHz Typ.)
- Low-speed on-chip oscillator (125 kHz Typ.)
Voltage detection circuit (LVD):
3 circuits (detection levels selectable)
Power-on reset (POR) circuit
Watchdog timer: 1 ch (supports hardware reset)
Multifunction timer: 3 ch
- 8-bit timer 2 ch (Timer RA, Timer RB)
- 16-bit timer 1 ch (Timer RC)
Serial interface: 2 ch
- Clock synchronous/UART0, UART2 (Simple I2C/SSU*2)
- Hardware LIN (UART & Timer RA)
A/D converter: 10-bit x 12 ch
Touch detector (SCU)*3: 22-input (shared with I/O ports)
(Reduces power consumption by allowing touch detection in wait mode.)
I/O ports: Input/Output: 31, Input only: 1
(Large-current drive capacity is provided. Variable input threshold values: 3 values)
40-pin HXQFN (5 mm x 5 mm x 0.5 mm, 0.4 mm pitch)

Block Diagram

R8C/3JT Group block diagram

*1: A function to read the program ROM area during data flash programming or block erase operation.
*2: Synchronous serial communication unit
*3: Sensor control unit



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