Port protection circuit and DSP chip

The invention discloses a port protection circuit and a DSP (Digital Signal Processor) chip, relates to the technical field of port protection, is used for protecting a target port of the chip from being damaged by high voltage, and provides the port protection circuit aiming at the problem that the port protection function is insufficient when a DSP is not powered by a current port protection scheme. Clamping control of port voltage is realized through a switch tube arranged at a target port, and the switch tube is turned on by default; when the chip is not powered, the port voltage is clamped below 0.3 V; therefore, the chip is prevented from being damaged by a voltage signal greater than 0.3 V at the target port, and more comprehensive port protection is realized. When the chip normally supplies power, the chip can freely select whether to control the switching tube to be switched off or not according to needs; when the switching tube is switched off, the normal function of the target port is not influence