一种小型化DC / DC隔离变换器

Abstract

本实用新型涉及隔离变换器，具体涉及一种小型化DC / DC隔离变换器；包括与PWM控制电路相连的直流电源输入电路、UVLO电路、辅助电源电路、功率开关电路、电流采样电路和输出电压采样反馈电路，以及与隔离变换器电路相连的第二路整流滤波电路、第三路整流滤波电路；直流电源输入电路、辅助电源电路和功率开关电路与隔离变换器电路相连；输出电压采样反馈电路通过第一路整流滤波电路与隔离变换器电路相连；第二路整流滤波电路上设有第二路稳压电路；第三路整流滤波电路上设有第三路稳压电路。本实用新型选用DC‑DC降压变换器电路和稳压电路相结合的架构，在相同绝缘条件下，电压降低使得爬电现象减少，提高了安全性和适应范围。

Claims

1. A miniaturized DC / DC isolated converter, characterized in that: It includes a PWM control circuit (6) and an isolation converter circuit (8), a DC power input circuit (1), a UVLO circuit (2), an auxiliary power supply circuit (3), a power switch circuit (4), a current sampling circuit (5) and an output voltage sampling feedback circuit (7) connected to the PWM control circuit (6), and a second rectifier filter circuit (10) and a third rectifier filter circuit (12) connected to the isolation converter circuit (8); The DC power input circuit (1) is connected to the UVLO circuit (2); The power switching circuit (4) is connected to the current sampling circuit (5); The DC power input circuit (1), auxiliary power circuit (3) and power switch circuit (4) are connected to the isolation converter circuit (8); The output voltage sampling feedback circuit (7) is connected to the isolation converter circuit (8) through the first rectifier filter circuit (9); The second rectifier and filter circuit (10) is provided with a second voltage regulator circuit (11); the third rectifier and filter circuit (12) is provided with a third voltage regulator circuit (13).

2. The compact DC / DC isolated converter of claim 1, wherein: The DC power input circuit (1) includes a positive input terminal Vi+ and a negative input terminal Vi-; A capacitor C3 is connected in series between the positive input terminal Vi+ and the negative input terminal Vi-. The negative input terminal Vi- is grounded, and the positive input terminal Vi+ is connected to the UVLO circuit (2). The UVLO circuit (2) includes a Zener diode Z1; The anode of Zener diode Z1 is grounded, the cathode of Zener diode Z1 is connected to the PWM control circuit (6) and one end of resistor R2, and the other end of resistor R2 is connected to the positive input terminal Vi+. A capacitor C5 and a resistor R6 are connected across the two ends of the Zener diode Z1; The auxiliary power supply circuit (3) includes a Zener diode Z2; The anode of the Zener diode Z2 is grounded, and the cathode of the Zener diode Z2 is connected to the anode of the rectifier diode D1 and one end of the resistor R9. The cathode of the rectifier diode D1 is connected to the PWM control circuit (6). The other end of the resistor R9 is connected to one end of the capacitor C8, one end of the resistor R10, and the cathode of the rectifier diode D2. The other end of capacitor C8 and resistor R10 is grounded, and the anode of rectifier diode D2 is connected to the isolation converter circuit (8).

3. The compact DC / DC isolated converter of claim 1, wherein: The power switching circuit (4) includes a MOSFET Q1; The drain of MOSFET Q1 is connected to the isolation converter circuit (8) and the current sampling circuit (5); The gate of MOSFET Q1 is connected to the PWM control circuit (6) and one end of resistor R16, and the other end of resistor R16 is connected to the source of MOSFET Q1 and the current sampling circuit (5).

4. The miniaturized DC / DC isolated converter of claim 3, wherein: The current sampling circuit (5) includes a resistor R17; One end of resistor R17 is connected to the source of MOSFET Q1 and the PWM control circuit (6), and the other end of resistor R17 is grounded.

5. The miniaturized DC / DC isolation converter according to claim 4, characterized in that: The PWM control circuit (6) includes a PWM control chip U1; The first pin of the PWM control chip U1 is connected to the positive input terminal Vi+ through resistor R1 and grounded through capacitor C2; The second and sixth pins of the PWM control chip U1 are grounded; The third pin of the PWM control chip U1 is connected to the output voltage sampling feedback circuit (7) and one end of the capacitor C6. The other end of the capacitor C6 is grounded through the resistor R8. The fourth pin of the PWM control chip U1 is connected to the cathode of the rectifier diode D1 and grounded through capacitor C1; The fifth pin of the PWM control chip U1 is connected to the gate of the MOSFET Q1 through resistor R4; The seventh pin of the PWM control chip U1 is connected to the cathode of the Zener diode Z1 through resistor R3; The eighth pin of the PWM control chip U1 is connected to one end of resistor R5 and capacitor C4. The other end of resistor R5 is connected to the source of MOSFET Q1, and the other end of capacitor C4 is grounded. The ninth pin of the PWM control chip U1 is grounded through resistor R7; The tenth pin of the PWM control chip U1 is grounded through capacitor C7.

6. The compact DC / DC isolated converter of claim 5, wherein: The output voltage sampling feedback circuit (7) includes an optocoupler U2 and a voltage regulator U3; The first pin of the optocoupler U2 is connected to one end of resistors R11 and R14; the other end of resistor R11 is connected to the first rectifier and filter circuit (9); the other end of resistor R14 is connected to the second pin of optocoupler U2, the cathode of voltage regulator U3, and one end of capacitor C11; the other end of capacitor C11 is connected to the reference terminal of voltage regulator U3, one end of resistors R13 and R15; the other end of resistor R15 is grounded; and the other end of resistor R13 is connected to the first rectifier and filter circuit (9) through resistor R12. The anode of voltage regulator U3 is grounded; The third pin of optocoupler U2 is grounded, and the fourth pin of optocoupler U2 is connected to the third pin of PWM control chip U1.

7. The compact DC / DC isolated converter of claim 2, wherein: The isolation converter circuit (8) includes a transformer T1; The first pin of the transformer T1 is connected to the anode of the rectifier tube D2; The second pin of transformer T1 is grounded; The third pin of transformer T1 is connected to the drain of MOSFET Q1 and one end of capacitor C26. The other end of capacitor C26 is grounded through resistor R24. The fourth pin of transformer T1 is connected to the positive input terminal Vi+; The fifth pin of transformer T1 is grounded through capacitor C12; The sixth pin of transformer T1 is connected to the third rectifier and filter circuit (12); The seventh pin of transformer T1 is connected to the first rectifier and filter circuit (9); The eighth pin of transformer T1 is connected to the second rectifier and filter circuit (10); The ninth pin of transformer T1 is grounded.

8. The compact DC / DC isolated converter of claim 7, wherein: The first rectifier and filter circuit (9) includes a Schottky diode D3; The anode of Schottky diode D3 is connected to the seventh pin of transformer T1. The cathode of Schottky diode D3 is connected to the +12V / 0.25A output terminal, resistors R11 and R12, and grounded through capacitors C9, C10, C25 and C27.

9. The compact DC / DC isolated converter of claim 7, wherein: The second rectifier and filter circuit (10) includes a Schottky diode D4; The anode of Schottky diode D4 is connected to the eighth pin of transformer T1, and the cathode of Schottky diode D4 is connected to the second voltage regulator circuit (11) and grounded through capacitors C13, C14 and C17. The second voltage regulator circuit (11) includes a voltage regulator U4; The first pin of the voltage regulator U4 is connected to the fifth pin and the cathode of the Schottky diode D4; The second pin of regulator U4 is connected to the +5V 1 / 0.2A output terminal, one end of resistor R20 and capacitor C18, and grounded through capacitors C15 and C16; the other end of resistor R20 and capacitor C18 is connected to the fourth pin of regulator U4, and connected to one end of resistor R19, the other end of resistor R19 is grounded through resistor R18. The third pin of voltage regulator U4 is grounded.

10. The miniaturized DC / DC isolation converter according to claim 7, characterized in that: The third rectifier and filter circuit (12) includes a Schottky diode D5; The anode of Schottky diode D5 is connected to the sixth pin of transformer T1, and the cathode of Schottky diode D5 is connected to the third voltage regulator circuit (13) and grounded through capacitors C23, C24 and C20. The third voltage regulator circuit (13) includes a voltage regulator U5; The first pin of voltage regulator U5 is connected to the fifth pin and the cathode of Schottky diode D5; The second pin of voltage regulator U5 is connected to the +5V2 / 0.2A output terminal, one end of resistor R21 and capacitor C19, and grounded through capacitors C21 and C22; the other end of resistor R21 and capacitor C19 is connected to the fourth pin of voltage regulator U5, and connected to one end of resistor R22, and the other end of resistor R22 is grounded through resistor R23. The third pin of voltage regulator U5 is grounded.

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