The Renesas RA8M1 MCU plays a crucial role in the Feather SOM and custom carrier board solution. This solution is divided into two parts: the Feather SOM and the custom carrier board. The Feather SOM utilizes the Renesas RA8M1 MCU as its core, which is the first 32-bit microcontroller based on the Arm® Cortex®-M85 (CM85) core. This MCU is renowned for its groundbreaking performance with over 3000 CoreMark scores and a running frequency of up to 480MHz. With features like complete determinism, low latency, and real-time operations, it can meet the demands of even the most stringent applications. In addition to the powerful CM85 core, the RA8M1 MCU integrates large storage memory, multiple external interfaces, and a variety of peripherals that, after optimization, can meet the requirements of various high-performance scenarios. Furthermore, this MCU also includes Secure Element-like features, providing advanced encryption security IP, immutable storage, and anti-tampering protection to ensure security in the design and implementation of IoT applications.
To meet customers' flexible power supply needs, the Feather SOM offers two power supply options: LiPo battery and USB. For LiPo battery support, the solution incorporates the ISL9205 charging IC to ensure the safety and stability of the battery. The ISL9205 is an integrated single-cell lithium battery charger that can operate at input voltages as low as 2.5V. It includes temperature protection features where the thermal foldback function reduces charging current when the chip temperature exceeds 100°C, preventing overheating and extending the lifespan of the device and battery.
On the other hand, for USB power supply, the solution employs the ISL80102 LDO (Linear Voltage Regulator). This device operates within an input voltage range of 2.2V to 6V, offering an adjustable output voltage from 0.8V to 5.5V, with customization options available for voltage settings. The external capacitors on the soft-start pins of the chip help reduce the impact of surge currents. Compared to similar devices, the ISL80102 utilizes a BiCMOS process, providing excellent analog performance and overall value.
In the custom carrier board aspect, the solution includes the ISL9008A and RAA214023 linear regulators for power support. The RAA214023 is a low-noise, high PSRR (Power Supply Rejection Ratio), low-dropout regulator with an input voltage range of 2.7V to 5.5V and a maximum load current of 2A. Without the need for traditional external feedback resistors, the output voltage can be programmed between 0.8V to 3.95V through PCB layout.
The ISL9008A can provide a continuous load current of 150mA with low standby current. The device achieves a PSRR of 65dB, with output noise less than 45µVRMS. Its quiescent current is 46µA (typical) in unloaded conditions, with a shutdown current of 0.5µA, making it an ideal choice for portable wireless devices. In this solution, Renesas utilizes the ISL9008A to provide a stable power source for the audio decoder DA7212. The DA7212 is a high-performance, low-power audio codec with enhanced Automatic Level Control (ALC) and robust speaker drivers, ensuring faster response times and finer gain resolution for stable audio quality during recordings.
By combining the exceptional performance of the RA8M1 MCU with the flexibility of the Feather platform, Renesas offers developers an easy-to-use modular system to drive the development of various innovative applications.