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16-bit MCUs

Low-power 16-bit MCU families with on-chip CAN

Renesas (Japan) has released the RL78/F13 and RL78/F14 micro-controller families. These chips are suitable for automotive applications requiring low-power consumption and functional safety features.

BOTH AUTOMAKERS AS WELL AS ECU MANUFACTURERS are concerned with miniaturization, lower weight, and less power consumption in automotive electronics. Another trend is striving to assure safety as well. The Japanese chipmaker addresses these market needs by introducing dedicated MCUs meeting these requirements.
There are 60 products in the RL78/F13 Group and there are 31 products in the FL78/F14 family.
The RL78/F13 MCUs have been designed for use in body control ECUs such as power window and side mirror control as well as motor control ECUs such as electric water pumps and cooling fans. The RL78/F14 MCUs are intended for body control ECUs such as BCM (body control module) and HVAC (heating, ventilation, and air conditioning) control that require especially large memory capacities. All these MCUs provide CAN connectivity. Additionally, they feature LIN interfaces.

To support needs such as the ability to change ROM sizes due to difference in system specifications to supporting reuse in a completely different system, the new MCUs all integrate the same CPU core, peripheral functions including the above mentioned support of CAN and LIN. For example, the RL78/F13 MCUs have internal flash memory sizes from 16 KiB to 128 KiB and packages from 20 pins to 80 pins. The RL78/F14 MCUs have internal flash memory with capacities from 48 KiB to 256 KiB plus RAM capacities of up to 20 KiB, and packages from 30 pins to 100 pins.

The QFN (Quad Flat No-leads) package responds to needs for even more compact ECUs. When compared to the company's existing 32-pin SSOP (Shrink Small Outline Package), the QFN package can reduce mounting areas by approximately 69 percent. The new QFN packages have indentations on the pin-side surface to improve solder wettability during mounting. This makes it possible to mount the MCUs without making any changes to the factory production line. The adoption of this QFN package allows the size of the printed circuit board to be reduced.

Furthermore, while there is increasing demand for unification of mechanics and electronics in which MCUs are directly mounted in actuators to achieve further system miniaturization, since ambient temperatures can reach high levels in applications such as water pumps, it was difficult to use existing MCUs in such applications. Since the launched MCUs can operate in ambient temperatures of up to 150 °C, they can be directly mounted in actuators, thus contributing to further system miniaturization.

By adopting a lower current consumption process, standby mode current consumption of the MCUs are reduced by 50 percent from the 1 µA to 500 nA. The micro-controllers also contribute to lower system power consumption with a function that allows A/D conversions to be performed without activating the CPU.
Last but not least, the MCUs provide a set of hardware functions that support functional safety as defined by ISO 26262. For example, there is a test function that verifies that the A/D converter is operating correctly by converting a reference voltage or the power supply voltage and comparing the result to a standard value. Another function prevents software runaway by detecting stack overflow with an interrupt. An additional safety function detects if an external clock oscillator has stopped by comparing it to an internal oscillator.

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