從太陽能或電池充電的雙模式USB移動(dòng)電源設(shè)計(jì)

　　有時(shí)候，智能手機(jī)、平板電腦和其他移動(dòng)設(shè)備是否真的知道，當(dāng)你移動(dòng)到一個(gè)方便的墻上插頭的時(shí)候，卻恰恰選擇了那一刻用完了果汁？我最近使用一款嶄新的Android智能手機(jī)的經(jīng)驗(yàn)，它迅速成為我職業(yè)和個(gè)人生活中不可或缺的一部分，我發(fā)現(xiàn)自己在忙碌的一天中幾乎沒有精力了。而不是回到我的舊翻蓋手機(jī)，我決定解決這個(gè)問題，使用絕對綠色解決方案在一個(gè)曬手機(jī)USB充電站的形式。我們的目標(biāo)是建立一個(gè)緊湊的電源包，它正好放在我隨身攜帶的一個(gè)小的實(shí)用袋的底部，它裝有一個(gè)穩(wěn)壓USB電源和一個(gè)容量足夠的電池，可以裝幾個(gè)智能手機(jī)或中型平板電腦。為了確保最大的靈活性，我希望電池的充電電路能夠從任何可用的USB端口或一個(gè)小型光伏陣列中提取它的汁液。

　　Component selection

　　For simplicity’s sake， I decided to base the power pack on one of the new crop of single-chip maximum power point tracking （MPPT） solar charge controllers， such as STMicroelectronics’ SPV1040 and Texas Instruments’ BQ24650. In the end， I decided on ST’s SPV 1040 because of the flexibility it offers in terms of input voltage （0.3 to 5.5 V） and its high levels of integration and efficiency （Figure 1）。 The part integrates a high-efficiency， PWM-based step-up converter with a MPPT controller that optimizes its input impedance to match the solar panel’s characteristics， which vary according to how much solar input it is receiving. Besides being able to extract the most power from whatever solar panel I find for the project， a charger based on the SPV1040 can be easily adapted to accept power inputs from an alternate USB source. It also has protection circuits that disable the PWM converter if either a selectable current threshold （up to 1.8 A） is reached or a programmed temperature limit （up to155°C） is exceeded.