Renesas Electronics to Release 16 New Product Types in R8C/Lx Series of MCUs with On-chip LCD Controller and Ultra-low Power Consumption, offering standby currents down to 10 nA

In addition to reduced current consumption, the four groups offer new features that contribute to reduced system power consumption overall, including on-chip flash memory with 1.8 operating voltage (V) and two power-off modes that effectively reduce current consumption during the MCU in standby.

The key differences between the four groups are listed in the table below. A variety of specifications is available with different pin counts and supported LCD sizes, allowing customers to choose the version that best matches their requirements.

Key features of the four groups.

(1) Extremely low power consumption that is among the best in the industry

Through improvements to the fabrication process and other enhancements, the current consumption during operation is only 150 µA per 1 MHz (microamps per megahertz), a reduction of approximately 60 percent compared to the 350 µA per 1 MHz of the first products released in the R8C/Lx Series. In addition, the standby current is less than 10 nA.

The four new groups support the power-off modes (low-power modes) introduced in the first products in the R8C/Lx Series. These power-off modes have received a very favourable response for the fine-grained power control they provide, and now the power consumption has been reduced even more. The standby current in the power-off mode 0 is less than 10nA. This significantly reduces the standby current. Flexibility is increased still further by the ability of the newest MCUs to retain random-access memory (RAM) content and I/O ports status when in a power-off mode. Furthermore the power-off mode 2 newly added on the LAxA group retains the real time clock operation.

These enhancements improve system power efficiency overall and make it possible to extend battery life substantially in applications requiring low power consumption, such as battery-powered devices of various types.

(2) Flash memory that can be erased, programmed, and read using a low voltage of 1.8V

Renesas Electronics’ R8C/Lx MCUs have two types of on-chip flash memory: one primarily for storing programs (programmable flash memory) and one for storing data (data flash memory). The four new groups support erase, program, and read of all flash memory at 1.8V, allowing the flash memory to be accessed over the MCU’s entire operating voltage range of 1.8 to 5.5V. This simplifies the power supply design, enables use of lower voltage, and reduces the system’s overall power consumption by allowing the use of a single power supply.

Data flash (see Note 1 below) is a special type of on-chip flash memory exclusive to Renesas Electronics that is intended for storing data. It helps to reduce the number of external components required by eliminating the need for external EEPROM (electrically erasable and programmable read-only memory) for data storage.

(3) Full-calendar RTC

The first MCUs released in the R8C/Lx Series had a one-week real-time clock (RTC), so additional software processing was required every week. The new MCUs provide a full-calendar RTC and support clock operation without additional software processing. This further reduces the power consumption of clock operation and is suitable for systems in which clock-based standby is used often. These devices also integrate a calibration function, which can correct timing errors caused by inaccuracy in the external 32 kHz oscillator and also an programmable alarm function allowing the device to be kept in a low power mode until needed.

(4) On-chip gain amplifier and temperature sensor

The on-chip gain amplifier offers designers a wider dynamic range of their A/D conversion with the x1, x 2, x4, x6 and x8 software selectable gains. An on-chip temperature sensor offers flexibility for calibration of both internal and external components. These two functions reduce further the external components required to implement many designs.

(5) 32-pin package versions added to product lineup

The available pin counts now range from 32 to 80 pins, allowing customers to choose the package that best meets their requirements. In addition, it is now easy to add LCD capabilities to compact applications previously lacking an LCD display, making it possible for customers to improve the design and functionality of their products.

Product Background

In recent years, MCUs incorporating LCD drivers have come into use in a wide range of fields, both as main MCUs in small-scale systems, such as battery-powered healthcare devices or consumer products with LCD panels, and as sub-MCUs in large-scale systems, such as industrial equipment, electric household appliances, and high-performance office equipment. Demand is growing for reduced power consumption and a wide variety of product types to meet the diverse requirements of products with advanced functionality and battery-powered devices requiring low power consumption.

To meet this demand, Renesas Electronics introduced the R8C/Lx Series of high-performance, low-power MCUs which are now in mass production and have achieved wide adoption in many different markets. Now the second batch of products in the series is appearing, providing environmentally friendly low-power operation and extending the product lineup. The new MCUs retain the advanced functions, performance, and flexibility of the first batch of products in the series, while also achieving ultra-low power consumption rated among the best in the industry.

Product Details

The four groups of MCUs are all built around the Renesas Electronics R8C CPU core, which has a proven track record in the R8C/Lx Series and delivers high performance, excellent functionality and ample flexibility. The R8C is a 16-bit CPU, but the CPU and peripheral functions are linked by an 8-bit bus. The high-speed on-chip oscillator supports a wide range of operating voltages from 1.8 to 5.5V and achieves an accuracy of ± 4 percent. A divider circuit in a later stage is used to produce a variety of oscillation frequencies, allowing adjustment of the serial communication interface (SCI) baud rate and timing adjustment of the timers.

Additionally, the following on-chip peripheral functions are provided.

· Power-on reset function

As in earlier products, a function that resets all of the MCU's internal circuits when the device is powered on is provided. The power-on reset function is designed to respond flexibly even when the power supply voltage rise is gradual.

· Voltage-detection circuits

Voltage-detection circuits are provided for detecting external voltages, unlike previous products that supported only one voltage-detection level. The four new groups are equipped with three circuits providing 20 configurable voltage-detection levels.

· Other

All the new MCUs integrate an I2C bus interface and a synchronous serial communication unit (SSU) to enable communication with a variety of external chips. There is also an on-chip comparator function, making it possible to monitor analogue signals without the use of an A/D converter for a further reduction in power consumption. These products can be used for a wide range of analogue-control applications.

Renesas Electronics’ E8a emulator, an on-chip debugger that uses a single-pin interface, will be offered as a development environment for the new MCUs. Since only a single pin is needed for connection, all of the I/O pins can be use