Input under-voltage protection circuit and switching power supply
A technology for input undervoltage and circuit protection, applied in emergency protection circuit devices, DC power input conversion to DC power output, electrical components, etc., can solve the problems of complex control lines, complex circuits, high cost, etc. Simple, avoid the effect of frequent startup
Inactive Publication Date: 2016-03-16
深圳茂硕电子科技有限公司
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Problems solved by technology
The solution of using a dedicated IC is generally high in cost, with fewer optional devices and no alternative materials
[0004] Chinese utility model patent CN201846066U discloses an undervoltage protection circuit with a hysteresis function. Its control circuit is relatively complicated, and an operational amplifier is required to realize undervoltage protection by turning off the switch tube.
There are also some products on the market that require the use of operational amplifiers. Since an additional auxiliary power supply is required to power the operational amplifiers, the circuits of such solutions are generally more complicated and costly.
In addition, there are also some schemes to control the undervoltage protection point through multiple triodes and Zener tubes. Because more devices are used, the circuit is more complicated, and the Zener tubes are greatly affected by temperature and conduction current, and the accuracy poor
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[0026] In order to make those skilled in the art more clearly understand the purpose, technical solutions and advantages of the present invention, the present invention will be further described below in conjunction with the accompanying drawings and embodiments.
[0027] refer to figure 1 As shown, a switching power supply includes a main transformer T1, a power input terminal 10 located on the primary side of the main transformer T1, an input undervoltage protection circuit 20 connected to the power supply input terminal 10, and a primary control circuit connected to the input undervoltage protection circuit 20 30 . The secondary control circuit 40 located on the secondary side of the transformer T1 , and the optocoupler OC1 that transmits the feedback signal (current sampling signal, voltage sampling signal) of the secondary control circuit 40 to the primary control circuit 30 .
[0028] In some embodiments, the AC power at the power input terminal 10 is output after passin...
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The invention discloses an input under-voltage protection circuit. Based on the character that starting voltage of a master controller IC1 is greater than turn-off voltage thereof, voltage for providing power for the master controller IC1 is regulated through the input under-voltage protection circuit composed of an input voltage sampling circuit, a voltage division circuit and a switching tube, and consequently, input under-voltage protection and hysteresis functions are realized. According to the invention, elements, such as an operational amplifier, an extra auxiliary power supply, a plurality of triodes and a special IC, are not needed; circuits are simple, and cost is low; with the hysteresis function, frequent starting of the power supply at a protection point can be avoided in practical application, and performance of the power supply is better. The invention also discloses a switching power supply using the input under-voltage protection circuit.
Description
technical field [0001] The invention relates to the technical field of switching power supplies, in particular to an input undervoltage protection circuit and a switching power supply. Background technique [0002] Switching power supplies are often damaged due to abnormal operating environments in practical applications, and input undervoltage is one of the more common damage factors. Input undervoltage will lead to abnormal conditions such as unstable control loops, overheating of power devices, and saturation of magnetic devices inside the power supply, which may easily cause damage to the power supply. In order to solve this problem, a common solution is to add an undervoltage protection circuit. [0003] Chinese utility model patent CN202334295U discloses an input undervoltage protection circuit device, which focuses on IC design itself, and realizes input undervoltage protection by controlling the internal enabling function of a dedicated IC. Chinese utility model pat...
Claims
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Login to View More IPC IPC(8): H02M3/335H02H7/12
CPCH02M3/33523H02H7/1213
Inventor 邓勇王华轶丁华
Owner 深圳茂硕电子科技有限公司