Baltazar Mercado
Sr Manager, Global Systems and Solutions
Published: March 17, 2023

Solar chargers today are designed to charge home device and vehicle batteries such as cars, boats, RVs, and more. The goal is to have a power source that is reliable, maintenance free, and with no moving parts or need for refueling. Solar power provides the answer, which is why almost all modern satellites are solar powered.

Solar has proven to provide a host of benefits that fit into four easy to understand statements. 1. It's clean, quiet, easy to use, and safe, 2. Provides electrical independence (off grid), 3. maximizes battery life, and 4. Is low maintenance and reliable. The Smart Solar Battery Charger solution (Figure 1) from Renesas is a fully realized design that covers all these benefits in a compact system.

Smart Solar Battery Charger
Figure 1: Smart Solar Battery Charger solution

At the heart of this solution is the Renesas RL78/G23 low power MCU (41uA/MHz) allowing for plenty of processing power at low power to run the MPPT algorithm to maximize power usage from the solar power. This solution also allows for programmable charge rates to support various modes such as fast-charge and trickle-charge to extend battery life. The RL78/G23 group has the industry’s leading lowest power consumption with 210nA at stop (4KB SRAM retention), and a snooze mode sequencer which significantly reduces power consumption during intermittent operation.

On the power side the DC/DC Buck RAA211820, the buck/boost controller ISL81601 and RJK1003DPP MOSFETs allow us to use voltage inputs of up to 60V and adjustable output voltages of 0.8V to 60V while also allowing the system to monitor the battery status and protecting it from damage due to over-charging. Key to this architecture is the buck-boost architecture which supports the battery being charged even when the solar panel's voltage is below the battery voltage.

This winning combination from Renesas is just one application for charging in remote locations with no AC power available. To find out more about this winning combination and others please visit to help you get to market more quickly.

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