Multi-output undervoltage and short circuit protection circuit

Abstract

The invention provides a multi-output undervoltage and short circuit protection circuit. The multi-output undervoltage and short circuit protection circuit is applied to a switching power source withmultiple outputs. The multi-output undervoltage and short circuit protection circuit is connected with a rectifying and filtering circuit of one of the output modules of the switching power source andincludes a threshold circuit, a sampling circuit, a comparison circuit, a control circuit and a switching circuit; the input end of the threshold circuit is connected with the same name end of a transformer secondary winding in the output module; the output end of the threshold circuit is connected with the first input end of the comparison circuit; the input end of the sampling circuit is connected with the output positive end of the output module; the output end of the sampling circuit is connected with the second input end of the comparison circuit; the output end of the comparison circuitis connected with the input end of the control circuit; the output end of the control circuit is connected with the input end of the switching circuit so as to control the switching on and switchingoff of the switching circuit; and the output end of the switching circuit is connected with the output negative end of the output module so as to control the switching on and switching off of the output module. The multi-output undervoltage and short circuit protection circuit of the invention has the advantages of simplicity, low cost and high output voltage. According to the multi-output undervoltage and short circuit protection circuit, the outputs can be independent from each other.

Description

technical field [0001] The invention relates to the field of power supplies, in particular to undervoltage and protection circuits for multi-channel output power supplies. Background technique [0002] Nowadays, the power supply has been used in various environments, and its reliability requirements are getting higher and higher. The power supply integrates various protection functions to ensure its reliability, and short-circuit protection and over-current protection are one of the important protection functions. At present, the power supply The internal integrated circuits have integrated short-circuit protection and over-current protection. The over-current protection point of most power supply designs is relatively large. Before the power supply enters the over-current protection, the output voltage will drop, and the power supply does not enter the protection mode at this time. Working with super-rated power, there is a hidden danger of explosion, and the output voltage...

AI Technical Summary

Problems solved by technology

[0002] Nowadays, the power supply has been used in various environments, and its reliability requirements are getting higher and higher. The power supply integrates various protection functions to ensure its reliability, and short-circuit protection and over-current protection are one of the important protection functions. At present, the power supply The internal integrated circuits have integrated short-circuit protection and over-current protection. The over-current protection point of most power supply designs is relatively large. Before the power supply enters the over-current protection, the output voltage will drop, and the power supply does not enter the protection mode at this time. Working with super-rated power, there is a hidden danger of explosion, and the output voltage accuracy is poor. If the power supply is used in high-precision equipment, it is easy to damage the equipment; the power supply detects the output voltage and current, and the integrated circuit judges whether it is short-circuited or over-current. Or over-current, the integrated circuit enters short-circuit protection mode, shuts off the output, prevents the power supply from overheating and explosion, and then protects the power supply from being damaged, so the power supply has a single output or multiple outputs, as long as one of the outputs is undervoltage and short-circuited or over-voltage current, the power supply will enter the protection mode. If there are multiple output power supplies, once one of them is short-circuited or over-current, the power supply will enter the protection mode, and other outputs will also be closed, affecting the output and causing damage to other equipment. Power Reliability

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