Renesas Capacitive Touch Technology Detailed Specifications

Renesas has developed the Capacitive Touch Sensor Unit (CTSU) IP Block in order for designers to implement Capacitive Touch interfaces in their applications when using Renesas MCUs. The CTSU is a stand-alone IP block that, once triggered, can scan multiple sensors without CPU interaction. For detailed information of the CTSU and a description of the capabilities please read the following :

App Note : CTSU Basis of Cap Touch detection (R30AN0218EJ0100)

A block diagram of the CTSU can be seen below :

The specification of the CTSU is as follows :

• Max number of sensors : 36
• Number of CTSU blocks per MCU : 1
• Max input clock : 32MHz (PCLKB)
• Detection method : Switched Capacitor filter technique
• Capacitive sensor load : 10pF to 50pF
• Self-Capacitance support : Yes
• Mutual-Capacitance support : Yes
• Multi-Mode support : Yes (dynamic configuration)
• Dedicated power regulator : Yes (Normal & Low voltage modes)
• Spread Spectrum dithering : Yes
• Scanning frequency : Programmable (per sensor)
• Max overlay thickness : 10mm (sensor size and dielectric material dependant)
• External passive requirement : 10nF (TSCAP) capacitor (1 off per MCU)
• Series damping resistor : 1 per sensor (2Kohms maximum impedance)
• Slider support : Yes (3 to 10 sensors)
• Wheel support : Yes (4 or 8 sensors)
• Proximity support : Yes (mutual capacitive mode)
• Low power : 8uA (R01AN3191EJ0100) (1 sensor, 2MHz SCF, 100ms scan cycle)
• Noise countermeasures : Spread spectrum switching clock, dual frequency scanning and LFSR Phase inversion)
• Standards : Supports IEC 61000 4-3/4-6 Level 3 (5mm acrylic overlay)