Non-isolated voltage-stabilized power supply

Abstract

The utility model discloses a non-isolated voltage-stabilized power supply, which relates to the field of power supplies and comprises an input filter circuit used for filtering input direct current and then outputting voltage to a chip starting circuit, and the output voltage is supplied to a driving circuit through a current detection circuit; the chip starting circuit is used for starting a chip to work after voltage is input, and the model of the chip is UCC28C43DR; compared with the prior art, the utility model has the beneficial effects that the circuit is simple, a large transformer in an isolated power supply is not arranged, an absorption circuit for generating peak voltage aiming at parasitic parameters of the MOS tube and the transformer is not arranged, the size is reduced, and the cost is also reduced; the mutual inductor current detection is adopted to replace a traditional power resistor, the loss of a power supply is reduced, the efficiency is high, and the proper switching frequency can be flexibly set to reduce the interference of switching noise; a slope compensation circuit is added so as to stabilize the entire power supply loop when the duty cycle exceeds 50%.

Description

TECHNICAL FIELD

[0001] The utility model relates to the field of power supply, specifically a non-isolated regulated power supply. BACKGROUND

[0002] At present, there are many kinds of regulated power supply, including isolated regulated power supply, LDO, etc. The isolated regulated power supply needs to use an isolation transformer to realize energy conversion, which will affect the power supply efficiency, and the leakage inductance and other parasitic parameters of the transformer will affect important indicators such as ripple noise. LDO belongs to linear voltage regulation, which is more suitable for small signal and small power, but it is not suitable for high-power products, and the efficiency is low and the device generates a lot of heat.

[0003] In summary, the existing regulated power supply has low conversion efficiency and high loss, which needs to be improved. UTILITY MODEL CONTENT

[0004] The utility model aims at providing a non-isolated regulated power supply to solve the problems raised in the above background technology.

[0005] To achieve the above-mentioned purpose, the utility model provides the following technical scheme:

[0006] A non-isolated regulated power supply comprises:

[0007] An input filter circuit is used to filter the input DC voltage and output the voltage to the chip start-up circuit. The output voltage is supplied to the drive circuit through the current detection circuit.

[0008] A chip start-up circuit is used to start the chip after voltage input and make the chip work. The chip model is UCC28C43DR.

[0009] A drive circuit is used to receive the PWM signal of the chip, control the conduction state of the switch (specifically MOS tube Q1), and change the output voltage size.

[0010] A current detection circuit is used to detect the current size flowing through the switch and feed back to the chip.

[0011] An output voltage stabilizing circuit is used to sample the output voltage of the drive circuit, feed back to the chip, change the duty cycle of the PWM signal output by the chip, and construct the output voltage stabilization of the drive circuit.

[0012] The input filter circuit is connected to the chip start-up circuit and the current detection circuit. The chip start-up circuit is connected to pin 7 of the chip. The current detection circuit is connected to the drive circuit and pin 3 of the chip. Pin 6 of the chip is connected to the drive circuit. The drive circuit is connected to the output voltage stabilizing circuit. The output voltage stabilizing circuit is connected to pin 2 of the chip.

[0013] As a further scheme of the utility model: the chip starting circuit includes resistance R6, resistance R7, resistance R10, resistance R11, voltage stabilizing tube ZD4, capacitor C6, capacitor C7, one end of resistance R6 connects one end of resistance R7, input filter circuit, the other end of resistance R6 connects the other end of resistance R7, one end of resistance R10, one end of resistance R11, the other end of resistance R10 connects the other end of resistance R11, the negative pole of voltage stabilizing tube ZD4, one end of capacitor C6, one end of capacitor C7, the 7th pin of chip, the other end of capacitor C6 is grounded, the other end of capacitor C7 is grounded, the positive pole of voltage stabilizing tube ZD4 is grounded.

[0014] As a further scheme of the utility model: the driving circuit includes transformer T1, voltage stabilizing tube ZD1, MOS tube Q1, one end of the input end of transformer T1 is connected with the 6th pin of chip through resistance R15 and capacitor C8 in proper order, the other end of the input end of transformer T1 is grounded, one end of the output end of transformer T1 is connected with one end of resistance R17 and one end of capacitor C9, the other end of capacitor C9 is connected with one end of resistance R16, the other end of resistance R16 is connected with one end of resistance R26, the negative pole of voltage stabilizing tube ZD1 and the G pole of MOS tube Q1, the D pole of MOS tube Q1 is connected with current detection circuit, the S pole of MOS tube Q1 is connected with the other end of the output end of transformer T1, the other end of resistance R17, the other end of resistance R26, the positive pole of voltage stabilizing tube ZD1, the negative pole of fast recovery diode D5 and one end of inductor L4, the positive pole of fast recovery diode D5 is grounded, the other end of inductor L4 is connected with one end of capacitor C18 and one end of capacitor C25, and is connected with output voltage stabilizing circuit, the other end of capacitor C18 is grounded, and the other end of capacitor C25 is grounded.

[0015] As a further scheme of the utility model: the current detection circuit includes current transformer TR1, resistance R37, resistance R14, resistance R5 and diode D2, the first end of current transformer TR1 is connected with input filter circuit, the second end of current transformer TR1 is connected with driving circuit, the third end of current transformer TR1 is grounded, the fourth end of current transformer TR1 is connected with the positive pole of diode D2 and one end of resistance R5, the other end of resistance R5 is grounded, the negative pole of diode D2 is connected with one end of resistance R37 and one end of resistance R14, the other end of resistance R37 is grounded, the other end of resistance R14 is connected with the 3rd pin of chip.

[0016] As a further scheme of the utility model: the output voltage stabilizing circuit includes resistance R21, resistance R22, resistance R23, resistance R18, resistance R20, triode Q2, capacitor C13, capacitor C31, one end of resistance R21 is connected with one end of resistance R22, one end of capacitor C31, driving circuit, the other end of capacitor C31 is grounded, the other end of resistance R21 is connected with the other end of resistance R22, one end of resistance R19, one end of capacitor C11, one end of resistance R23, 2nd pin of the chip, the other end of resistance R23 is grounded, the other end of capacitor C11 is connected with the other end of resistance R19, 1st pin of the chip, one end of capacitor C13 is grounded, the other end of capacitor C13 is connected with one end of resistance R18, 4th pin of the chip, base of triode Q2, the other end of resistance R18 is connected with one end of capacitor C10, collector of triode Q2, 8th pin of the chip, the other end of capacitor C10 is grounded, one end of resistance R20 is connected with the emitter of triode Q2, the other end of resistance R20 is connected with 3rd pin of the chip.

[0017] Compared with the prior art, the utility model has the advantages that: the utility model circuit is simple, without big transformer in the isolation power supply, without the absorption circuit for the spike voltage generated by the parasitic parameters of MOS tube and transformer, which reduces the volume and cost; the current detection of mutual inductor (current transformer TR1) is used to replace the traditional power resistor, which reduces the power loss and improves the efficiency, and the appropriate switching frequency can be set to reduce the interference of switching noise (resistance R18 and capacitor C13); the slope compensation circuit (triode Q2, resistance R20) is added to stabilize the entire power loop when the duty cycle exceeds 50%. BRIEF DESCRIPTION OF DRAWINGS

[0018] Figure 1 It is a kind of non-isolated voltage stabilizing power supply circuit.

[0019] Figure 2 The circuit diagram of the traditional current sampling circuit. DETAILED DESCRIPTION

[0020] The technical solutions in the embodiments of the utility model will be clearly and completely described in combination with the drawings in the embodiments of the utility model. Apparently, the described embodiments are only part of the embodiments of the utility model, not all the embodiments. Based on the embodiments in the utility model, all other embodiments obtained by those skilled in the art without creative labor belong to the protection scope of the utility model.

[0021] Please refer to Figure 1 A kind of non-isolated voltage stabilizing power supply, comprising:

[0022] Input filter circuit, for filtering the input DC, output voltage to the chip start-up circuit, the output voltage through the current detection circuit to the drive circuit;

[0023] Chip start-up circuit, for starting the chip work after voltage input, the chip model is UCC28C43DR;

[0024] Drive circuit, for receiving the PWM signal of the chip, controlling the on-off state of the switch (specifically MOS tube Q1), changing the output voltage size;

[0025] Current detection circuit, for detecting the current size flowing through the switch, feeding back to the chip;

[0026] Output voltage stabilizing circuit, for sampling the output voltage of the drive circuit, feeding back to the chip, changing the duty cycle of the PWM signal output by the chip, to build the output voltage stabilizing of the drive circuit;

[0027] The input filter circuit is connected with the chip start-up circuit and the current detection circuit, the chip start-up circuit is connected with the No. 7 pin of the chip, the current detection circuit is connected with the drive circuit and the No. 3 pin of the chip, the No. 6 pin of the chip is connected with the drive circuit, the drive circuit is connected with the output voltage stabilizing circuit, and the output voltage stabilizing circuit is connected with the No. 2 pin of the chip.

[0028] In specific embodiments, please refer to Figure 1 The input filter circuit includes a capacitor C3, the input VIN+ voltage is connected with the capacitor C3 for filtering, and the electrolytic capacitor C3 can also store energy. Assuming that the input is suddenly powered off, the energy stored in the capacitor C3 can continue to maintain the output voltage, especially in the case of data saving after the power-off of the electronic product.

[0029] In the embodiment, please refer to Figure 1 The chip start-up circuit includes resistors R6, R7, R10, R11, a voltage stabilizing tube ZD4, capacitors C6 and C7, one end of the resistor R6 is connected with one end of the resistor R7 and the input filter circuit, the other end of the resistor R6 is connected with the other end of the resistor R7, one end of the resistor R10 and one end of the resistor R11, the other end of the resistor R10 is connected with the other end of the resistor R11, the negative electrode of the voltage stabilizing tube ZD4, one end of the capacitor C6 and one end of the capacitor C7, the No. 7 pin of the chip, the other end of the capacitor C6 is grounded, the other end of the capacitor C7 is grounded, and the positive electrode of the voltage stabilizing tube ZD4 is grounded.

[0030] When the voltage VIN+ is powered on, the starting current is generated by the chip starting circuit and the electrolytic capacitor C6 is charged, so that the chip starts. The ZD4 stabilizes the voltage of the 7th pin of the chip at a certain value, preventing the chip from being damaged by excessive voltage. The capacitor C7 is a bypass capacitor between the 7th pin of the chip and the ground to reduce the interference of noise on the 7th pin of the chip. It should be noted that when selecting the starting resistor, the power loss and the starting time need to be balanced. The current flowing through the starting resistor at the minimum input voltage must be higher than the VDD (7th pin) current (maximum 100 μA) under the UVLO (under voltage lockout) condition. Generally, a starting current of 250 μA is provided under low voltage input condition. The starting resistors R6, R7, R10 and R11 can be composed in series and parallel to meet the rated power under high voltage input.

[0031] In the embodiment, please refer to Figure 1 The driving circuit includes a transformer T1, a Zener diode ZD1, and a MOS transistor Q1. One end of the input end of the transformer T1 is connected to the 6th pin of the chip through the resistor R15 and the capacitor C8 in sequence. The other end of the input end of the transformer T1 is grounded. One end of the output end of the transformer T1 is connected to one end of the resistor R17 and one end of the capacitor C9. The other end of the capacitor C9 is connected to one end of the resistor R16. The other end of the resistor R16 is connected to one end of the resistor R26, the negative electrode of the Zener diode ZD1, and the G electrode of the MOS transistor Q1. The D electrode of the MOS transistor Q1 is connected to the current detection circuit. The S electrode of the MOS transistor Q1 is connected to the other end of the output end of the transformer T1, the other end of the resistor R17, the other end of the resistor R26, the positive electrode of the Zener diode ZD1, the negative electrode of the fast recovery diode D5, and one end of the inductor L4. The positive electrode of the fast recovery diode D5 is grounded. The other end of the inductor L4 is connected to one end of the capacitor C18 and one end of the capacitor C25, and the output voltage stabilizing circuit. The other end of the capacitor C18 is grounded. The other end of the capacitor C25 is grounded.

[0032] When the chip starts, the 6th pin of the chip generates a PWM driving voltage, which drives the N-type MOS transistor Q1 through the capacitor C8, the resistor R15, the driving transformer T1, the capacitor C9, and the resistor R16. The resistor R17 stabilizes the driving voltage. The resistor R16 is a driving resistor, which can affect the turn-on and turn-off speed of the N-type MOS transistor Q1. The selection of the resistance value of the resistor R16 needs to balance the EMI (electromagnetic interference) and the switching loss. The resistor R26 discharges the voltage of the junction capacitor between the G electrode and the S electrode of the MOS transistor Q1, preventing the MOS transistor Q1 from being mistakenly turned on. The Zener diode ZD1 stabilizes the voltage of the G electrode of the MOS transistor at a certain value, preventing the G electrode of the MOS transistor from being damaged by excessive voltage.

[0033] In the embodiment, please refer to Figure 1The current detection circuit comprises a current transformer TR1, a resistor R37, a resistor R14, a resistor R5 and a diode D2, the first end of the current transformer TR1 is connected to the input filter circuit, the second end of the current transformer TR1 is connected to the driving circuit, the third end of the current transformer TR1 is grounded, the fourth end of the current transformer TR1 is connected to the anode of the diode D2 and one end of the resistor R5, the other end of the resistor R5 is grounded, the cathode of the diode D2 is connected to one end of the resistor R37 and one end of the resistor R14, the other end of the resistor R37 is grounded, and the other end of the resistor R14 is connected to the No. 3 pin of the chip.

[0034] When the voltage VIN+ is powered on, the MOS tube Q1 is turned on, the primary winding of the current transformer TR1 is connected in series on the circuit, a certain current will flow, then the secondary winding of the current transformer TR1 generates an induced current, the current flows through the diode D2 and the resistor R37, and a voltage is generated at the cathode of the diode D2, when the voltage enters the No. 3 pin of the chip through the resistor R14, once the maximum amplitude voltage 1V of the No. 3 pin of the chip is exceeded, the chip will enter the protection mode, and the capacitor C12 is a filter capacitor, which forms a low-pass filter with the resistor R14 and is used to provide immunity to suppress the front peak, without a large transformer in the traditional isolated power supply, and without an absorption circuit for the peak voltage generated by the parasitic parameters of the N-type MOS tube and the transformer, the volume is reduced and the cost is reduced.

[0035] Taking the input 60V of the power supply, the output 24.5V / 8A (196W), the efficiency 88%, the turns ratio 1:100 of the current transformer TR1 and the voltage drop 0.7V of D2 as an example, the current flowing through the primary winding of the current transformer TR1 is 24.5*8 / (0.88*60) = 3.71A, the current flowing through the secondary winding of the current transformer TR1 is 3.71 / 100 = 0.0371A, the maximum voltage at the cathode of the diode D2 is 1V, and R37 is 1 / 0.0371 = 26.95Ω.

[0036] Please refer to Figure 2 In the traditional current sampling circuit, the resistor R32 is a current detection resistor, assuming that the resistance value of the resistor R32 is 0.3Ω, the output power is 196W, and the main current is also 3.71A, so the power consumed by the resistor R32 is 3.71*3.71*0.3 = 4.13W. In the utility model, the current transformer TR1 is used as part of the current detection circuit, and the actual power consumption of the current detection resistor R37 in the utility model is 0.0371*0.0371*26.95 = 0.037W, which greatly reduces the power consumption and improves the efficiency of the power supply.

[0037] In the embodiment, please refer to Figure 1The output voltage stabilizing circuit comprises resistors R21, R22, R23, R18, R20, a transistor Q2, a capacitor C13 and a capacitor C31. One end of the resistor R21 is connected to one end of the resistor R22, one end of the capacitor C31 and the driving circuit. The other end of the capacitor C31 is grounded. The other end of the resistor R21 is connected to the other end of the resistor R22, one end of the resistor R19, one end of the capacitor C11, one end of the resistor R23, the 2nd pin of the chip and the ground. The other end of the resistor R23 is grounded. The other end of the capacitor C11 is connected to the other end of the resistor R19 and the 1st pin of the chip. One end of the capacitor C13 is grounded. The other end of the capacitor C13 is connected to one end of the resistor R18, the 4th pin of the chip and the base of the transistor Q2. The other end of the resistor R18 is connected to one end of the capacitor C10, the collector of the transistor Q2 and the 8th pin of the chip. The other end of the capacitor C10 is grounded. One end of the resistor R20 is connected to the emitter of the transistor Q2. The other end of the resistor R20 is connected to the 3rd pin of the chip.

[0038] After the voltage VIN+ is powered on, the chip starts, the MOS tube Q1 is turned on, a voltage is output through the energy storage inductor L4, and then fed back to the 2nd pin of the chip. The MOS tube Q1 is in a switching state, and the switching frequency is determined by the resistor R18 and the capacitor C13 to flexibly set a suitable switching frequency to reduce the interference of switching noise. Assuming that the resistance of the resistor R18 is 9.1K and the capacitance of the capacitor C13 is 4.7nF, the switching frequency = 1.72 / (9.1*4.7) = 40KHz. The size of the output voltage is determined by the resistors R21, R22, R23 and the 2nd pin of the chip. The comparison voltage of the 2nd pin of the chip is 2.5V, and the output voltage =

(R21 / / R22) / R23+1

[0039] In addition, large signal subharmonic instability may occur when the duty cycle exceeds 50%, in which the rising primary side inductor current slope may not match the falling secondary side current slope. Subharmonic oscillation back leads to an increase in output voltage ripple, and may even limit the power handling capability of the converter. Therefore, slope compensation is needed to stabilize the entire loop when the duty cycle exceeds 50%. The specific slope compensation circuit comprises a resistor R20 and a transistor Q2. The slope compensation is achieved by injecting part of the oscillator waveform into the actual detected primary current. The two signals are added at the connection of the current detection input chip 3 pin of the filter capacitor.

[0040] The 8th pin of the chip generates a 5V reference voltage. The capacitor C10 is a bypass capacitor of the 8th pin of the chip to ground, which can reduce the interference of noise on the 8th pin of the chip.

[0041] The utility model discloses a working principle is: input filter circuit is used to filter after input direct current, and the output voltage is given chip starting circuit, and the output voltage is supplied to drive circuit through current detection circuit;Chip starting circuit is used to start the chip work after voltage input, and the chip model is UCC28C43DR;Drive circuit is used for receiving the PWM signal of chip, and the conduction condition of switch (specifically MOS pipe Q1) is controlled, and the output voltage size is changed;Current detection circuit is used for detecting the current size of flowing through switch, and feedback is given to chip;Output voltage stabilizing circuit is used for sampling the output voltage of drive circuit, and feedback is given to chip, and the duty cycle of the PWM signal of chip output is changed, and the output voltage stabilizing of drive circuit is constructed.

[0042] It is apparent for those skilled in the art that the utility model is not limited to the details of the above-mentioned exemplary embodiments, and the utility model can be realized in other specific forms without departing from the spirit or basic characteristics of the utility model. Therefore, no matter from which point of view, the embodiments should be regarded as exemplary and non-restrictive.

[0043] In addition, it should be understood that, although the present specification is described in terms of embodiments, not every embodiment contains only one independent technical solution, and the description of the specification is only for the sake of clarity, and those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can be combined appropriately to form other embodiments that those skilled in the art can understand.

Claims

1. A non-isolated regulated power supply, characterized in that, This non-isolated regulated power supply includes: The input filter circuit filters the input DC current and outputs the voltage to the chip startup circuit. The output voltage is then supplied to the drive circuit through the current detection circuit. The chip startup circuit is used to start the chip after a voltage input. The chip model is UCC28C43DR. The drive circuit is used to receive the PWM signal from the chip, control the conduction status of the switch, and change the output voltage. The current detection circuit is used to detect the magnitude of the current flowing through the switch and feed it back to the chip; The output voltage regulator circuit is used to sample the output voltage of the drive circuit and feed it back to the chip to change the duty cycle of the PWM signal output by the chip, thereby constructing the output voltage regulation of the drive circuit. The input filter circuit is connected to the chip startup circuit and the current detection circuit. The chip startup circuit is connected to pin 7 of the chip. The current detection circuit is connected to the drive circuit and pin 3 of the chip. Pin 6 of the chip is connected to the drive circuit. The drive circuit is connected to the output voltage regulator circuit. The output voltage regulator circuit is connected to pin 2 of the chip.

2. The non-isolated regulated power supply according to claim 1, characterized in that, The chip startup circuit includes resistors R6, R7, R10, and R11, a Zener diode ZD4, capacitors C6 and C7. One end of resistor R6 is connected to one end of resistor R7 and the input filter circuit. The other end of resistor R6 is connected to the other end of resistor R7, one end of resistor R10, and one end of resistor R11. The other end of resistor R10 is connected to the other end of resistor R11, the negative terminal of Zener diode ZD4, one end of capacitor C6, one end of capacitor C7, and pin 7 of the chip. The other end of capacitor C6 is grounded, the other end of capacitor C7 is grounded, and the positive terminal of Zener diode ZD4 is grounded.

3. The non-isolated regulated power supply according to claim 1, characterized in that, The driving circuit includes a transformer T1, a Zener diode ZD1, and a MOSFET Q1. One input terminal of the transformer T1 is connected to pin 6 of the chip via a resistor R15 and a capacitor C8. The other input terminal of the transformer T1 is grounded. One output terminal of the transformer T1 is connected to one end of a resistor R17 and one end of a capacitor C9. The other end of the capacitor C9 is connected to one end of a resistor R16. The other end of the resistor R16 is connected to one end of a resistor R26, the negative terminal of the Zener diode ZD1, and the gate terminal of the MOSFET Q1. The drain terminal of the MOSFET Q1 is connected to the current detection circuit. The source terminal of the MOSFET Q1 is connected to the other output terminal of the transformer T1, the other end of a resistor R17, the other end of a resistor R26, the positive terminal of the Zener diode ZD1, the negative terminal of a fast recovery diode D5, and one end of an inductor L4. The positive terminal of the fast recovery diode D5 is grounded. The other end of the inductor L4 is connected to one end of a capacitor C18, one end of a capacitor C25, and the output voltage regulator circuit. The other end of both capacitors C18 and C25 are grounded.

4. The non-isolated regulated power supply according to claim 1, characterized in that, The current detection circuit includes a current transformer TR1, resistors R37, R14, and R5, and a diode D2. The first terminal of the current transformer TR1 is connected to the input filter circuit, the second terminal of the current transformer TR1 is connected to the drive circuit, the third terminal of the current transformer TR1 is grounded, the fourth terminal of the current transformer TR1 is connected to the positive terminal of the diode D2 and one end of the resistor R5, the other end of the resistor R5 is grounded, the negative terminal of the diode D2 is connected to one end of the resistor R37 and one end of the resistor R14, the other end of the resistor R37 is grounded, and the other end of the resistor R14 is connected to pin 3 of the chip.

5. The non-isolated regulated power supply according to claim 1 or 3, characterized in that, The output voltage regulator circuit includes resistors R21, R22, R23, R18, and R20, transistor Q2, capacitors C13 and C31. One end of resistor R21 is connected to one end of resistor R22, one end of capacitor C31, and the driver circuit. The other end of capacitor C31 is grounded. The other end of resistor R21 is connected to the other end of resistor R22, one end of resistor R19, one end of capacitor C11, one end of resistor R23, and pin 2 of the chip. The other end of resistor R23 is connected to... One end of capacitor C11 is grounded, the other end of resistor R19 is connected to pin 1 of the chip, one end of capacitor C13 is grounded, the other end of capacitor C13 is connected to one end of resistor R18, pin 4 of the chip, and the base of transistor Q2, the other end of resistor R18 is connected to one end of capacitor C10, the collector of transistor Q2, and pin 8 of the chip, the other end of capacitor C10 is grounded, the emitter of transistor Q2 is connected to one end of resistor R20, and the other end of resistor R20 is connected to pin 3 of the chip.

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