CN214591160U

CN214591160U - Micropower DC-DC isolation voltage-stabilizing output circuit

Info

Publication number: CN214591160U
Application number: CN202120564211.3U
Authority: CN
Inventors: 肖永林
Original assignee: Sichan Ai Chance Technology Co ltd
Current assignee: Sichan Ai Chance Technology Co ltd
Priority date: 2021-03-18
Filing date: 2021-03-18
Publication date: 2021-11-02
Anticipated expiration: 2031-03-18

Abstract

The utility model relates to a switching power supply technical field, the utility model discloses micropower DC-DC keeps apart steady voltage output circuit includes Buck circuit unit, keeps apart vary voltage circuit unit and rectification filter circuit unit, Buck circuit unit, keep apart vary voltage circuit unit and rectification filter circuit unit link to each other in order, change direct current voltage into high frequency switching voltage through Buck circuit unit, realize keeping apart and adjusting coupling high frequency switching voltage range through keeping apart the vary voltage circuit unit, export stable direct current voltage after rectification filter circuit unit filters, solved the required DC-DC of communication device and kept apart module power supply circuit output voltage unstability, the unable miniaturization of circuit structure and problem with high costs. The utility model is suitable for a communication device power supply.

Description

Micropower DC-DC isolation voltage-stabilizing output circuit

Technical Field

The utility model relates to a switching power supply technical field, in particular to little power DC-DC keeps apart steady voltage output circuit.

Background

Communication modes such as CAN, RS-485, RS-232, RS-422, SPI, I2C, LAN and the like are adopted in a large number in the applications of automobile manufacturing, large-scale instruments and equipment, industrial control, intelligent families, living community management, robot network interconnection and the like, the communication modes need two or more groups of mutually isolated voltage for power supply, and two circuits are adopted for realizing the two or more groups of mutually isolated voltage at present: the constant-voltage isolation non-stable DC-DC circuit comprises a constant-voltage isolation non-stable DC-DC circuit and a primary side feedback PSR circuit.

The first type is a constant voltage isolation unstable DC-DC circuit, a control chip controls a switch to convert direct current power supply into a high-frequency switching signal, energy is coupled with a secondary stage through an isolation transformer to be rectified to obtain output voltage, and the output voltage linearly changes along with input voltage. For the circuit, the number of transformer windings is large, the winding difficulty is increased, the manufacturing cost is high, and when the input voltage changes, the output voltage is unstable.

Secondly, the primary side feedback flyback PSR circuit realizes constant voltage output by adjusting a PWM mode, and by adopting the circuit, the number of components is large, the cost is high, and the miniaturization cannot be realized.

SUMMERY OF THE UTILITY MODEL

The utility model solves the technical problem that: the micropower DC-DC isolation voltage-stabilizing output circuit solves the problems that a DC-DC isolation module power supply circuit required by a communication device is unstable in output voltage, a circuit structure cannot be miniaturized and the cost is high.

The utility model provides a technical scheme that above-mentioned technical problem adopted: the micro-power DC-DC isolation voltage stabilization output circuit comprises a Buck circuit unit, an isolation voltage transformation circuit unit and a rectification filter circuit unit, wherein the Buck circuit unit, the isolation voltage transformation circuit unit and the rectification filter circuit unit are sequentially connected.

Furthermore, the isolation voltage transformation circuit unit comprises a plurality of secondary windings, the number of the rectification filter circuit units is the same as that of the secondary windings, and each secondary winding is connected with a corresponding rectification filter circuit unit.

Further, the Buck circuit unit comprises a control chip, a first capacitor, a second capacitor, a third capacitor, a fourth capacitor, a first resistor and a second resistor; the IN pin of the control chip is respectively connected with the EN pin of the control chip and one end of the first capacitor as an input voltage anode, the BS pin of the control chip is connected with one end of the second capacitor, the LX pin of the control chip is connected with the other end of the second capacitor as a first output end, the FB pin of the control chip is respectively connected with one end of the third capacitor, one end of the first resistor and one end of the second resistor, the other end of the third capacitor is respectively connected with the other end of the first resistor and one end of the fourth capacitor as a second output end, and the GND pin of the control chip is respectively connected with the other end of the fourth capacitor, the other end of the second resistor and the other end of the first capacitor and is connected with the ground.

Furthermore, the isolation transformation circuit unit comprises a high-frequency switch transformer, the synonym end of the primary winding of the high-frequency switch transformer is connected with the first output end, and the synonym end of the primary winding of the high-frequency switch transformer is connected with the second output end.

Further, the rectifying and filtering circuit unit comprises a first diode, a fifth capacitor and a third resistor; the positive electrode of the first diode is connected with the dotted terminal of the secondary winding of the high-frequency switch transformer, the negative electrode of the first diode is respectively connected with one end of a fifth capacitor and one end of a third resistor to serve as a voltage-stabilizing positive electrode output end, the other end of the fifth capacitor is connected with the dotted terminal of the secondary winding of the high-frequency switch transformer, the other end of the fifth capacitor is connected with the other end of the third resistor, and the other end of the third resistor serves as a voltage-stabilizing negative electrode output end.

The utility model has the advantages that: the utility model discloses micropower DC-DC keeps apart steady voltage output circuit changes direct current voltage into high frequency switching voltage through Buck circuit unit, realizes keeping apart and adjusting coupling high frequency switching voltage range through keeping apart vary voltage circuit unit, exports stable direct current voltage after rectifier filter circuit unit filters, has solved the problem that the required power supply circuit output voltage of communication device is unstable and circuit structure is miniaturized. Compared with the prior art, the utility model, with low costs and circuit structure is miniaturized.

Drawings

Fig. 1 is a schematic diagram of the connection relationship of the micropower DC-DC isolation voltage-stabilizing output circuit of the present invention.

Fig. 2 is a schematic circuit diagram of an embodiment of the micropower DC-DC isolation voltage-stabilizing output circuit of the present invention.

Detailed Description

The utility model discloses micropower DC-DC keeps apart steady voltage output circuit is shown as attached figure 1, including Buck circuit unit, isolation vary voltage circuit unit and rectification filter circuit unit, Buck circuit unit, isolation vary voltage circuit unit and rectification filter circuit unit link to each other in order.

Furthermore, the isolation voltage transformation circuit unit comprises a plurality of secondary windings, the number of the rectification filter circuit units is the same as that of the secondary windings, each secondary winding is connected with a corresponding rectification filter circuit unit, and the number of the secondary windings determines the number of output circuits for stabilizing voltage.

Further, the Buck circuit unit comprises a control chip, a first capacitor C1, a second capacitor C2, a third capacitor C3, a fourth capacitor C4, a first resistor R1 and a second resistor R2; an IN pin 5 of the control chip is respectively connected with an EN pin 4 of the control chip and one end of a first capacitor C1 to serve as an input voltage anode, a BS pin 1 of the control chip is connected with one end of a second capacitor C2, an LX pin 6 of the control chip is connected with the other end of a second capacitor C2 to serve as a first output end Vin, an FB pin 3 of the control chip is respectively connected with one end of a third capacitor C3, one end of a first resistor R1 and one end of a second resistor R2, the other end of the third capacitor C3 is respectively connected with the other end of the first resistor R1 and one end of a fourth capacitor C4 to serve as a second output end, and a GND pin 2 of the control chip is respectively connected with the other end of a fourth capacitor C4, the other end of the second resistor R2 and the other end of the first capacitor C1 to serve as an input voltage cathode.

Furthermore, the isolation transformation circuit unit comprises a high-frequency switch transformer T, the synonym end of the primary winding of the high-frequency switch transformer T is connected with the first output end, and the synonym end of the primary winding of the high-frequency switch transformer T is connected with the second output end.

Further, the rectifier filter circuit unit includes a first diode D1, a fifth capacitor C5, and a third resistor R3; the positive electrode of the first diode D1 is connected with the dotted terminal of the secondary winding of the high-frequency switch transformer T, the negative electrode of the first diode D1 is respectively connected with one end of a fifth capacitor C5 and one end of a third resistor R3 to be used as a voltage-stabilizing positive output terminal + Vout, the other end of the fifth capacitor C5 is connected with the dotted terminal of the secondary winding of the high-frequency switch transformer T, the other end of the fifth capacitor C5 is connected with the other end of the third resistor R3, and the other end of the third resistor R3 is used as a voltage-stabilizing negative output terminal-Vout.

The utility model discloses an embodiment requires input voltage 5-15V, keeps apart steady voltage output 5V 5%/100 mA, and its circuit diagram is as shown in figure 2, including control chip, high frequency switch transformer T, first electric capacity C1, second electric capacity C2, third electric capacity C3, fourth electric capacity C4, fifth electric capacity C5, first resistance R1, second resistance R2, third resistance R3 and first diode D1.

The specific connection relationship is as follows: an IN pin 5 of the control chip is respectively connected with an EN pin 4 of the control chip and one end of a first capacitor C1 as an input voltage anode, a BS pin 1 of the control chip is connected with one end of a second capacitor C2, an LX pin 6 of the control chip is connected with the other end of a second capacitor C2 as a first output end and is connected with a different name end of a primary winding of a high-frequency switch transformer T, an FB pin 3 of the control chip is respectively connected with one end of a third capacitor C3, one end of a first resistor R1 and one end of a second resistor R2, the other end of a third capacitor C3 is respectively connected with the other end of a first resistor R1 and one end of a fourth capacitor C4 as a second output end and is connected with the same name end of the primary winding of the high-frequency switch transformer T, a pin 2 of the control chip is respectively connected with the other end of the fourth capacitor C4, the other end of the second resistor R2 and the other end of the first capacitor C1 and is connected with the ground, a GND terminal of a secondary winding D1 of the high-frequency switch transformer T, the cathode of the first diode D1 is connected to one end of a fifth capacitor C5 and one end of a third resistor R3, respectively, to serve as a voltage-stabilizing positive output terminal + Vout, the other end of the fifth capacitor C5 is connected to the synonym terminal of the secondary winding of the high-frequency switching transformer T, the other end of the fifth capacitor C5 is connected to the other end of the third resistor R3, and the other end of the third resistor R3 serves as a voltage-stabilizing negative output terminal-Vout.

Specifically, the chip adopts SY8113E1, which is internally provided with a MOSFET and a follow current tube and works in a forced continuous conduction mode, wherein VFB is 0.6V. High frequency switch transformer T is

Power ring wound, primary winding

9Ts enameled wire, 10uH +/-20% inductance and secondary winding

The enameled wire 15 Ts. The first capacitance C1 is 4.7 uF. The second capacitance C2 is 100 nF. The third capacitor C3 is 27 pF. The fourth capacitance C4 is 4.7 uF. The fifth capacitance C5 is 4.7 uF. The first resistor R1 is 100K Ω with an accuracy of ± 1%. The second resistor R2 is 22K Ω with an accuracy of ± 1%. The third resistor R3 is 10K omega. The first diode D1 is SS14, whose VF is 0.5V, and minimum load resistance is 10K Ω.

Principle analysis: when the voltage of 5-15V is switched in, the EN pin 4 of the control chip is connected with high level, when the MOSFET in the control chip is switched on, the voltage of the LX pin 6 of the control chip charges the fourth capacitor C4 through the primary winding of the high-frequency switching transformer T, the charging current is in an increasing trend, so that the induced voltage of the primary winding is positive and negative, the voltage V at the upper end of R1 is (R1+ R2)/R2 VFB is 3.33V, the induced voltage of the secondary winding is positive and negative, and no output is generated when the secondary rectification is cut off; when the control chip is in a follow current stage, the current of the primary winding finishes follow current through a follow current tube arranged in the chip, the excitation voltage at two ends of the primary winding is stable 3.33V, the polarity is positive and negative, the induced voltage of the secondary winding is positive and negative, and the formula is combined: V/NP is (Vout + VF)/NS, and a stable output Vout is (R1+ R2) × VFB/(R2 × N) -VF, where a turn ratio N is a ratio of the number of primary winding turns NP and the number of secondary winding turns NS of the high-frequency switching transformer T, and Vout is 3.33V × 15/9-0.5V — 5.05V voltage by calculation, which corresponds to fig. 2.

If high frequency switch transformer T selects the transformer that contains a plurality of secondary winding, every secondary winding connects a rectifier filter circuit unit that corresponds, then the utility model discloses can realize the stable voltage output of multichannel.

Claims

1. The micropower DC-DC isolation voltage-stabilizing output circuit is characterized by comprising a Buck circuit unit, an isolation voltage-transforming circuit unit and a rectification filter circuit unit, wherein the Buck circuit unit, the isolation voltage-transforming circuit unit and the rectification filter circuit unit are sequentially connected, and the Buck circuit unit comprises a control chip, a first capacitor (C1), a second capacitor (C2), a third capacitor (C3), a fourth capacitor (C4), a first resistor (R1) and a second resistor (R2); the IN pin of the control chip is respectively connected with the EN pin of the control chip and one end of a first capacitor (C1) to serve as an input voltage anode (Vin), the BS pin of the control chip is connected with one end of a second capacitor (C2), the LX pin of the control chip is connected with the other end of a second capacitor (C2) to serve as a first output end, the FB pin of the control chip is respectively connected with one end of a third capacitor (C3), one end of a first resistor (R1) and one end of a second resistor (R2), the other end of the third capacitor (C3) is respectively connected with the other end of the first resistor (R1) and one end of a fourth capacitor (C4), and the GND pin of the control chip is respectively connected with the other end of the fourth capacitor (C4), the other end of the second resistor (R2) and the other end of the first capacitor (C1) to be connected with the ground to serve as a second output end.

2. The micropower DC-DC isolating and voltage stabilizing output circuit according to claim 1, wherein the isolating and transforming circuit unit comprises a plurality of secondary windings, the number of the rectifying and filtering circuit units is the same as that of the secondary windings, and each secondary winding is connected with a corresponding rectifying and filtering circuit unit.

3. The micropower DC-DC isolating and voltage-stabilizing output circuit according to claim 1, wherein the isolating transformer circuit unit comprises a high frequency switching transformer (T), the synonym terminal of the primary winding of the high frequency switching transformer (T) is connected to the first output terminal, and the synonym terminal of the primary winding of the high frequency switching transformer (T) is connected to the second output terminal.

4. The micropower DC-DC isolation voltage-stabilizing output circuit according to claim 3, wherein the rectifying and filtering circuit unit comprises a first diode (D1), a fifth capacitor (C5) and a third resistor (R3); the positive electrode of the first diode (D1) is connected with the dotted terminal of the secondary winding of the high-frequency switch transformer (T), the negative electrode of the first diode (D1) is respectively connected with one end of a fifth capacitor (C5) and one end of a third resistor (R3) to serve as a voltage-stabilizing positive output terminal (+ Vout), the other end of the fifth capacitor (C5) is connected with the dotted terminal of the secondary winding of the high-frequency switch transformer (T), the other end of the fifth capacitor (C5) is connected with the other end of the third resistor (R3), and the other end of the third resistor (R3) serves as a voltage-stabilizing negative output terminal (-Vout).