Negative power supply circuit

Abstract

The utility model discloses a negative power supply circuit comprising a push-pull circuit which is electrically connected with a charging circuit. The push-pull circuit comprises a first circuit and a second circuit. The first circuit and the second circuit have the same structure and are arranged in parallel; the push-pull circuit is electrically connected with a filtering voltage stabilizing circuit. According to the utility model, the pulse output does not depend on a pulse generation chip, resources such as an IO port of a CPU can be used locally, negative voltage can be generated only by using the triode, the diode and the capacitor, the cost is extremely low, the charging of the main capacitor is continuous, and the energy conversion efficiency is high.

Description

Technical Field

[0001] The utility model relates to the field of electronic circuits, in particular to a negative power supply circuit. Background Art

[0002] IGBT needs negative Vgs voltage to ensure reliable shutdown, and op amps also need positive and negative dual power supplies in some cases. For occasions like these where the negative voltage accuracy is not high, this solution is simple and reliable. If a dedicated negative voltage chip is used, the cost will be high; if the circuit does not have complementary outputs, there is only one capacitor to charge the main capacitor, and the main capacitor has only 50% of the charging time. Under the same conditions, the current provided is small and the ripple is large, so it needs to be improved. Utility Model Content

[0003] In order to solve the above technical problems, the utility model proposes a negative power supply circuit.

[0004] The purpose of the utility model is achieved through the following technical solutions:

[0005] A negative power supply circuit comprises a push-pull circuit, wherein the push-pull circuit is electrically connected to a charging circuit; the push-pull circuit comprises a first circuit and a second circuit; the first circuit and the second circuit have the same structure and are arranged in parallel; the push-pull circuit is electrically connected to a filtering and voltage-stabilizing circuit; the first circuit comprises a first NPN-type triode V1, the base of the first NPN-type triode V1 is electrically connected to one end of a first resistor R1 and the base of a second PNP-type triode V2; the collector of the first NPN-type triode V1 is grounded, the emitter of the first NPN-type triode V1 is electrically connected to the emitter of the second PNP-type triode V2 and the positive electrode of the first electrolytic capacitor C1; the negative electrode of the first capacitor C1 is electrically connected to the positive electrode of a third diode V3, the second circuit and the filtering and voltage-stabilizing circuit; the negative electrode of the third diode V3 is electrically connected to the collector of the second PNP-type triode V2 and is grounded.

[0006] A further improvement is provided that the second circuit includes the first circuit including a sixth PNP transistor V6, the base of the sixth PNP transistor V6 being electrically connected to one end of the fourth resistor R4 and the base of the seventh NPN transistor V7; the collector of the sixth PNP transistor V6 being grounded, the emitter of the sixth PNP transistor V6 being electrically connected to the emitter of the seventh PNP transistor V7 and the positive electrode of the ninth electrolytic capacitor C9; the negative electrode of the ninth electrolytic capacitor C9 being electrically connected to the positive electrode of the eighth diode V8, the negative electrode of the first electrolytic capacitor C1 and the filtering and stabilizing circuit; the negative electrode of the eighth diode V8 being electrically connected to the collector of the seventh PNP transistor V7 and being grounded.

[0007] As a further improvement, the first NPN transistor V1 and the seventh NPN transistor V7 are of the model MMBT4401; the second PNP transistor V2 and the sixth PNP transistor V6 are of the model MMBT4403.

[0008] As a further improvement, the filtering and stabilizing circuit includes a fourth diode V4, the cathode of the fourth diode V4 is electrically connected to the cathode of the first electrolytic capacitor C1 and the cathode of the ninth electrolytic capacitor C9, the anode of the fourth diode V4 is electrically connected to the cathode of the third electrolytic capacitor C3, one end of the fourth capacitor C4 and the second pin of the linear regulator V5; the third pin of the linear regulator V5 is electrically connected to the cathode of the fifth electrolytic capacitor C5 and one end of the sixth capacitor C6; the first pin of the linear regulator V5 is electrically connected to the anode of the third electrolytic capacitor C3, the other end of the fourth capacitor C4, the anode of the fifth electrolytic capacitor C5 and the other end of the sixth capacitor C6 and is grounded.

[0009] As a further improvement, the model of the linear regulator V5 is MC79L05.

[0010] The beneficial effects of the utility model are:

[0011] 1. Negative voltage generation: achieved through transistors, diodes and capacitors, etc. One capacitor is charged, and the other capacitor is charged to the main capacitor through the diode, and the input capacitors are exchanged and charged repeatedly.

[0012] 2. Simple cost: The pulse output does not rely on the pulse generation chip, and can use resources such as the CPU IO port on the spot. Only transistors, diodes and capacitors can be used to generate negative voltage, and the cost is extremely low.

[0013] 3. The main capacitor is charged continuously: Generally, the duty cycle of the pulse output is set to 50%. Since the push-pull structure has two sets of complementary outputs, the main capacitor is charged continuously, and the energy conversion efficiency is high. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] The present invention is further described with reference to the accompanying drawings, but the contents in the accompanying drawings do not constitute any limitation to the present invention.

[0015] Figure 1 It is a schematic diagram of the circuit structure of the utility model. DETAILED DESCRIPTION

[0016] In order to make the purpose, technical solution and advantages of the utility model more clear, the utility model is further described in detail below with reference to the accompanying drawings and examples.

[0017] Example 1

[0018] like Figure 1As shown, V1 is an NPN transistor of model MMBT4401, and V2 is a PNP transistor of model MMBT4403, which are used to control the charging of the electrolytic capacitor C1 or the discharging through the diode V3, wherein the electrolytic capacitor C1 is 100uF, the diode V3 is SS14, and the resistors R1 and R4 are used for the transistor base current limiting; similarly, V6, V7, C9, and V8 constitute the symmetrical part of the push-pull structure; the diode V4 is used to constitute the charging circuit of the electrolytic capacitor C3, wherein the diode model used by V4 is SS14, and the electrolytic capacitor C3 is 100uF; C4 and C6 are filter capacitors; C5 is a 470uF electrolytic capacitor; V5 is a linear regulator of model MC79L05.

[0019] Principle: PWM input is generally a pulse with a duty cycle of 50%. When the voltage is high, transistor V1 is turned on, and electrolytic capacitor C1 is charged through diode V3. At the same time, transistor V7 is turned on, and electrolytic capacitor C9 discharges the energy stored in the previous PWM cycle at a low level to the main electrolytic capacitor C3 through diode V4 and transistor V7. The voltage of C3 is negative at the top and positive at the bottom. At this time, a voltage of approximately -VCC is generated at the negative electrode of electrolytic capacitor C3; when the voltage is low, transistor V2 is turned on, and electrolytic capacitor C1 charges the main capacitor C3 through diode V4 and transistor V7. At this time, a voltage of approximately -VCC continues to be generated at the negative electrode of electrolytic capacitor C3. At the same time, transistor V6 is turned on, and electrolytic capacitor C9 is charged through diode V9; in this cycle, energy flows into the main capacitor C3 at both the high and low levels of the PWM input, so the energy of C3 is continuous. At this time, the conversion of VCC from positive voltage to corresponding negative voltage is completed.

[0020] C4 and C6 are input and output filter capacitors respectively. C5 is a -5V output voltage stabilizing electrolytic capacitor.

[0021] The V5 linear regulator can use the -VCC voltage to generate a more stable -5V voltage for use in some high-precision applications.

[0022] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the utility model rather than to limit the protection scope of the utility model. Although the utility model is described in detail with reference to the preferred embodiments, ordinary technicians in this field should understand that the technical solution of the utility model can be modified or replaced by equivalents without departing from the essence and scope of the technical solution of the utility model.

Claims

1. A negative power supply circuit, characterized in that: The invention comprises a push-pull circuit, which is electrically connected to a charging circuit; the push-pull circuit comprises a first circuit and a second circuit; the first circuit and the second circuit have the same structure and are arranged in parallel; the push-pull circuit is electrically connected to a filtering and voltage-stabilizing circuit; the first circuit comprises a first NPN-type triode (V1), the base of the first NPN-type triode (V1) is electrically connected to one end of a first resistor (R1) and the base of a second PNP-type triode (V2); the collector of the first NPN-type triode (V1) is grounded, the emitter of the first NPN-type triode (V1) is electrically connected to the emitter of the second PNP-type triode (V2) and the positive electrode of the first electrolytic capacitor (C1); the negative electrode of the first capacitor (C1) is electrically connected to the positive electrode of a third diode (V3), the second circuit and the filtering and voltage-stabilizing circuit; the negative electrode of the third diode (V3) is electrically connected to the collector of the second PNP-type triode (V2) and is grounded.

2. The negative power supply circuit according to claim 1, characterized in that: The second circuit comprises a first circuit comprising a sixth PNP-type triode (V6), the base of the sixth PNP-type triode (V6) being electrically connected to one end of a fourth resistor (R4) and the base of a seventh NPN-type triode (V7); the collector of the sixth PNP-type triode (V6) being grounded, the emitter of the sixth PNP-type triode (V6) being electrically connected to the emitter of the seventh PNP-type triode (V7) and the positive electrode of a ninth electrolytic capacitor (C9); the negative electrode of the ninth electrolytic capacitor (C9) being electrically connected to the positive electrode of an eighth diode (V8), the negative electrode of the first electrolytic capacitor (C1) and the filtering and stabilizing circuit; and the negative electrode of the eighth diode (V8) being electrically connected to the collector of the seventh PNP-type triode (V7) and being grounded.

3. The negative power supply circuit according to claim 2, characterized in that: The models of the first NPN transistor (V1) and the seventh NPN transistor (V7) are MMBT4401; the models of the second PNP transistor (V2) and the sixth PNP transistor (V6) are MMBT4403.

4. The negative power supply circuit according to claim 2, characterized in that: The filtering and voltage stabilizing circuit comprises a fourth diode (V4), the cathode of the fourth diode (V4) is electrically connected to the cathode of the first electrolytic capacitor (C1) and the cathode of the ninth electrolytic capacitor (C9), the anode of the fourth diode (V4) is electrically connected to the cathode of the third electrolytic capacitor (C3), one end of the fourth capacitor (C4) and the second pin of the linear voltage stabilizer (V5); the third pin of the linear voltage stabilizer (V5) is electrically connected to the cathode of the fifth electrolytic capacitor (C5) and one end of the sixth capacitor (C6); the first pin of the linear voltage stabilizer (V5) is electrically connected to the anode of the third electrolytic capacitor (C3), the other end of the fourth capacitor (C4), the anode of the fifth electrolytic capacitor (C5) and the other end of the sixth capacitor (C6) and is grounded.

5. The negative power supply circuit according to claim 4, characterized in that: The model of the linear voltage regulator (V5) is MC79L05.

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