The protection circuit for reverse polarity of the op amp power supply voltage is shown in (a) and (b). Figure (a) shows the protection circuit of the single-stage amplifier, and Figure (b) shows the protection circuit of the multi-stage amplifier circuit. If the integrated op amp is not protected by the polarity of the power supply, once the polarity of the power supply voltage is reversed, a destructive current will flow through the chip (generally, the diode inside the chip that is reversed during normal operation will have a large current flowing). The principle of the protection circuit is very simple. For Figure (a), it utilizes the unidirectional conductivity of the diode so that the reverse-connected supply voltage cannot be applied to the integrated op amp. For the figure (b), it is a centralized protection circuit. When the power supply voltage is reversed, the diodes D1 and D2 are turned on, and thus a large current will be generated. If the power supply is connected to the appropriate fuse on the main line, the reverse connection is made. At the moment, the fuse is blown, thus protecting the integrated op amp, while the tube drop of the two diodes is very low (about 0.7V maximum), so the power supply will not cause damage to the device. Since the current flowing through the diode is large when the power is reversed, a power diode having a large current capacity (such as the 1N4001) is generally selected. ShenZhen UHLED Technology Co., LTD. , https://www.uhled.com
Protection of the op amp power supply voltage polarity reverse connection measures and its circuit diagram: There are both single-pole and multi-stage amplifier circuit protection diagrams to protect the diode from burning due to the reverse polarity of the power supply voltage. 