今天的太陽能充電器被設計成給家用設備和車輛電池充電，例如汽車、船、房車等等。目標是有一個可靠的、免維護的、沒有移動部件或不需要加油的電源。太陽能提供了答案，這就是為什么幾乎所有的現代衛(wèi)星都是太陽能驅動的。

事實證明，太陽能提供了一系列的好處，這些好處可以用四個簡單易懂的陳述來概括。1.它干凈、安靜、易用、安全。2.提供電氣獨立性(離網)，3.最大限度地延長電池壽命。4.維護成本低且可靠。瑞薩的智能太陽能電池充電器解決方案(圖1)是一個完全實現的設計，在一個緊湊的系統(tǒng)中涵蓋了所有這些優(yōu)勢。

圖1:智能太陽能電池充電器解決方案

系統(tǒng)優(yōu)勢：
-MPPT算法最大化太陽能電池板的電力利用率
-降壓-升壓架構即使太陽能電池板的電壓低于電池電壓,也能為電池充電
-可編程充電速率,支持快速充電和涓流充電等多種模式
-輸入電壓可達60V，可調節(jié)輸出電壓范圍為0.8V至60V
-監(jiān)控電池狀態(tài)并保護電池免受過度充電造成的損壞

這個解決方案的核心是Renesas瑞薩晶振RL78/G23低功耗MCU (41uA/MHz)允許以低功耗運行MPPT算法，以最大限度地利用太陽能。該解決方案還支持可編程充電速率，以支持各種模式，如快速充電和涓流充電，從而延長電池壽命。這RL78/G23group擁有業(yè)界領先的最低功耗，停止時功耗為210 na(4KB SRAM保持能力)，還有一個貪睡模式序列器，可顯著降低間歇操作期間的功耗。

在動力方面，DC/DC巴克RAA211820，降壓/升壓控制器ISL81601和RJK1003DPPMOSFETs允許我們使用最高60V的電壓輸入和0.8V至60V的可調輸出電壓，同時還允許系統(tǒng)監(jiān)控電池狀態(tài)，防止電池因過度充電而損壞。這種架構的關鍵是降壓升壓架構，即使太陽能電池板的電壓低于電池電壓，該架構也支持電池充電。

使用太陽能的綠色能源為電池充電是一個非常受歡迎的應用。然而,由于輸出電壓的廣泛變化取決于指向面板的太陽能量、溫度和面板上的負載,太陽能電池會產生挑戰(zhàn)。瑞薩的這一成功組合只是在沒有交流電源的偏遠地區(qū)充電的一個應用。

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.

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.