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CN-224233534-U - Isolation power supply with wide voltage input and constant voltage output

CN224233534UCN 224233534 UCN224233534 UCN 224233534UCN-224233534-U

Abstract

The utility model relates to the technical field of industrial control input power supplies, in particular to an isolation power supply with wide voltage input and constant voltage output, which comprises a switching power supply control chip and a transformer, wherein the switching power supply control chip comprises an enabling/undervoltage locking input pin, a grounding pin, a feedback pin, a switching output pin and a power supply input pin, a primary side circuit and a secondary side circuit are arranged on two sides of the transformer, the primary side circuit comprises a primary winding leakage inductance peak surge absorption circuit connected with the switching output pin and a primary winding of the transformer connected in series with the primary winding leakage inductance peak surge absorption circuit, the secondary side circuit comprises a secondary winding of the transformer and a power supply output circuit connected with the secondary winding, and a third resistor and a fourth resistor are connected between the feedback pin and the switching output pin. The isolated power supply has the advantages of simple structure, few devices, low cost, small occupied space of a circuit board and convenient control.

Inventors

  • LIU CHENG
  • LI YONGKAI

Assignees

  • 无锡信捷电气股份有限公司

Dates

Publication Date
20260512
Application Date
20250331

Claims (10)

  1. 1. The isolation power supply with wide voltage input and constant voltage output is characterized by comprising a switch power supply control chip (U1) and a transformer (T1), wherein the switch power supply control chip (U1) comprises an enable/undervoltage locking input pin (ENA/UVLO), a grounding pin (GND), a feedback pin (RFB), a switch output pin (SW) and a power supply input pin (VIN), and two sides of the transformer (T1) are respectively provided with a primary side circuit and a secondary side circuit; The primary side circuit comprises a primary winding leakage inductance peak surge absorbing circuit connected with the switch output pin (SW), and a primary winding (Np) of the transformer (T1) connected in series with the primary winding leakage inductance peak surge absorbing circuit; The secondary side circuit includes a secondary winding (Ns) of the transformer (T1), and a power supply output circuit connected to the secondary winding (Ns); The enable/undervoltage locking input pin (ENA/UVLO) is connected with a first resistor (R1) and a second resistor (R2), and is connected with an input voltage through the first resistor (R1); the power input pin (VIN) is connected with an input voltage; a third resistor (R3) and a fourth resistor (R4) are connected between the feedback pin (RFB) and the switch output pin (SW).
  2. 2. The isolated power supply of claim 1, wherein the primary winding leakage inductance spike surge absorption circuit comprises a fourth diode (D4) and a second diode (D2) connected to each other.
  3. 3. The wide voltage input constant voltage output isolated power supply of claim 2, wherein the second diode (D2) is a transient voltage suppression diode (TVS) for preventing voltage spikes.
  4. 4. The isolation power supply with wide voltage input and constant voltage output according to claim 1, wherein the type of the switching power supply control chip (U1) is JW3510SOTA# TRPBF.
  5. 5. The wide voltage input constant voltage output isolated power supply of claim 1, wherein said power supply output circuit comprises a first power supply output circuit and a second power supply output circuit connected to said secondary winding (Ns) for implementing a dual output.
  6. 6. The isolated power supply of claim 5, wherein the first power supply output circuit comprises a first diode (D1) and a first power supply output terminal (9V-1) connected to the secondary winding (Ns), and a fourth capacitor (C4) is further connected in parallel to the first diode (D1).
  7. 7. The isolated power supply of claim 6, wherein a fifth resistor (R5) is further connected in parallel to the first diode (D1).
  8. 8. The wide voltage input constant voltage output isolated power supply according to claim 5, wherein the second power supply output circuit comprises a third diode (D3) and a second power supply output terminal (9V-2) connected with the secondary winding (Ns), and a fifth capacitor (C5) is further connected in parallel with the third diode (D3).
  9. 9. The isolated power supply of claim 8, wherein a sixth resistor (R6) is further connected in parallel to the third diode (D3).
  10. 10. The isolated power supply of claim 1, wherein the power input pin (VIN) is further connected to a first capacitor (C1), a second capacitor (C2) and a third capacitor (C3).

Description

Isolation power supply with wide voltage input and constant voltage output Technical Field The utility model relates to the technical field of industrial control input power supplies, in particular to an isolation power supply with wide voltage input and constant voltage output. Background The switching power supply is a power supply which uses the modern electronic power technology to control the time ratio of the switching on and switching off of a switching tube and maintain the stability of output voltage. As one of the switching power supplies, a Single-ended flyback switching power supply (SEPIC, single-ENDED PRIMARY Inductor Converter) is a common DC-DC converter topology, and is widely used in various electronic devices, especially in occasions where isolation and voltage conversion are required. The working principle is that in the 1-switch conduction stage, when a switching tube (such as MOSFET) is conducted, the primary winding of the transformer starts to store energy. Due to the coupling effect of the transformer, the secondary winding has no energy output at this time, the rectifier diode is in a reverse cut-off state, and the load is supplied with energy by the output capacitor. 2. And in the switch turn-off stage, when the switching tube is turned off, the energy stored in the primary winding of the transformer is released through the secondary winding, and is rectified by the rectifying diode (VD) and filtered by the capacitor C to be output to the load. At this time, the output diode is turned on, and the energy of the transformer supplies power to the load through the diode, and simultaneously charges the capacitor to supplement the previous energy loss. By single ended is meant that the core of the high frequency transformer is only operating on one side of the hysteresis loop. As shown in fig. 1, flyback means that when the switching tube Q1 is turned on, the induced voltage of the primary winding of the high-frequency transformer L3 is positive and negative, the rectifier diode D1 is turned off, and energy is stored in the primary winding. When the switching tube Q1 is cut off, peak leakage inductance energy of the primary coil of the transformer L3 is absorbed by R1 and C1 through D2, and meanwhile energy stored in the primary coil of the transformer L3 is rectified through D1 and filtered through a capacitor C4 and then is output to a load R2 through a secondary coil. Through the description, the MOS tube also needs a driving IC, as shown in the figure 2, the input voltage charges C7 through R3 and R5 to provide the starting voltage of the driving IC, namely the chip U2, and after the IC is started, the power supply voltage is provided by the secondary coil of the transformer L3. The switching frequency of the IC driving MOS tube can be set through resistors R16 and C15, and the frequency is fixed after setting. The 1 foot of U2 regulates and control the switch duty ratio of MOS pipe through the feedback signal of secondary side voltage and the feedback signal of 3 foot through primary side current, prevents to export excessive pressure and overcurrent. The secondary side voltage feedback is shown in fig. 3, the secondary side voltage VCC feeds back a voltage signal to the voltage reference chip D4 through resistors R6, R10, and R11, and then the D4 controls the linear optocoupler U1 to feed back an output voltage signal to the 1 pin of the chip U2. However, the above prior art has the following drawbacks: 1. the peak leakage inductance energy is absorbed through R1 and C1, so that the overvoltage damage of the MOS tube is avoided, but the energy of the primary coil is absorbed during the turn-off period of the MOS tube, and the efficiency is reduced; 2. The driving chip U2 is powered by the secondary coil, so that the volume and the cost of the transformer are increased; The switching frequency of the MOS tube is not variable, so that the switching loss of the MOS tube is increased during light load, and the efficiency is reduced; 4. The external MOS and primary side current feedback increase the area of the cloth plate; 5. The secondary voltage is fed back through the optocoupler and the optocoupler 431, so that the area of the cloth plate is increased, and the cost of the device is also increased. Therefore, a new solution is needed to solve the above technical problems. Disclosure of utility model The utility model aims to solve the problems of the prior art, and provides an isolation power supply with wide voltage input and constant voltage output, which is used for solving the technical problems of complex structure, large cloth area, high cost, low power conversion efficiency and high energy loss of the existing single-ended flyback switching power supply. The above purpose is realized by the following technical scheme: The isolation power supply comprises a switch power supply control chip and a transformer, wherein the switch power supply control chip comprises an enabling/u