/> The R8C/3NT group integrates on a single chip a capacitive touch sensor circuit and a flash MCU. It features (1) a wafer process package (WPP) that is formed on the wafer before it is cut into individual chips, resulting in a compact package size [3 × 3 millimetres (mm)], which is approximately 64 percent smaller than that of Renesas Electronics’ R8C/3JT Group; and (2) improved communication functions that enable connection of the multiple sensors required in devices with advanced functionality. The R8C/3NT group will contribute to the production of more compact portable products.

Recently, touch keys have come into use on portable devices such as mobile phones due to aesthetic design considerations and to improve resistance to moisture and dust. Now, touch panels have been adopted for a wide variety of applications. In future, more new products incorporating touch key functions and delivering even more sophisticated applications are expected to appear. The MCU used to control the touch key is typically separate from the system’s main control MCU, and is paired with an external touch sensor IC chip. However, the need to reduce space and cost has led to a demand for flash MCU products with on-chip touch sensor circuits.

Renesas Electronics already mass-produces flash MCUs with on-chip capacitive touch sensor circuits for use in applications including electric household appliances such as white goods, AV equipment, office equipment, and mobile devices. The new R8C/3NT group has specifications that have been further refined for mobile devices and features an ultra-compact WPP package.

Key features of the R8C/3NT Group of MCUs:



(1) Ultra-compact size of 3 mm × 3 mm

The use of a wafer process package (WPP) enables a mounting area of 3 mm × 3 mm (package thickness: 0.64 mm), which is among the smallest in the industry for a flash MCU designed for touch panel applications. This contributes to more compact system size overall.

(2) Enhanced communication functions

To ensure the smooth transfer of data to and from external sensors and IC chips, the R8C/3NT incorporates an I2C bus interface and a four-channel synchronous serial communication unit (SSU) module with chip select. The new MCUs also incorporate a maximum of 128KB of flash memory, over 3.5 times more than the existing MCUs, making it easier to connect multiple sensors.

In contrast to Renesas Electronics’ existing R8C/3GC touch panel control MCU (with no on-chip touch panel circuit), the R8C/3NT has the following enhancements:

2-1) Mounting area approximately 42 percent smaller than a two-chip configuration with a conventional touch sensor IC chip (compared to existing Renesas Electronics products).

2-2) The capacitive touch sensor circuit has five channels and enables the implementation of touch keys, track wheel, and slider controls. This makes it possible to design systems that are aesthetically more attractive and also more resistant to moisture and dust.

2-3) The CPU processing time associated with the touch sensors is reduced dramatically, and it is possible to reduce system power consumption by about 10 percent in comparison with software implementations of touch sensor control using existing Renesas Electronics products.

The R8C/3NT retains the data transfer controller, data flash (Note 1) with background operation, power-on reset, voltage detection function, and high-speed on-chip oscillator from the earlier R8C/3GC, making it suitable for a variety of sophisticated applications employing multiple sensors.

The R8C/3NT group of MCUs comprises four product versions with ROM sizes ranging from 48 KB to 128 KB.

Furthermore, by using an operation tool called a workbench with a graphical user interface (GUI), essential design tasks such as electrode design, sensitivity adjustment, threshold value setting, and signal monitoring can be performed easily, contributing to a reduction in design man-hours and development costs. Settings can be written to the data flash to allow for fine tuning of individual models. This makes it possible for customers to incorporate highly accurate touch sensor solutions into their products.