STR81145A是自动识别110V和220V交流电压输入的电压选择器。1.内部原理电路(见图1) 2.各脚工作电压(见表1)其简单工作原理如下:交流输入识别由②脚完成。当220V交流输入时,②脚288V_(DC)经电阻R1和R2分压使稳压管ZD1导通(齐纳击穿),三极管Q1饱和导通,使稳压管ZD2不能导通,三极 The STR81145A is a voltage selector that automatically recognizes 110V and 220V AC voltage inputs. 1. The internal principle of the circuit (see Figure 1) 2. The voltage of each pin (see Table 1) The simple working principle is as follows: AC input recognition by the ② feet to complete. When the 220V AC input, ② feet 288V_ (DC) by the resistor R1 and R2 voltage regulator ZD1 conduction (Zener breakdown), the transistor Q1 is turned on, the regulator ZD2 can not be turned on, the three-pole