Voltage-stabilized power supply output system and output method thereof

Abstract

The invention belongs to the field of vehicle-mounted electronic product power supply, and particularly discloses a stabilized power supply output system and an output method thereof.The system comprises a voltage reference chip, a first triode, a second triode, a power MOS tube, a first resistor, a second resistor, a third resistor and a fourth resistor; the third resistor and the fourth resistor are connected in series between the power output end and the ground, the voltage dividing point is connected with the base electrode of the second triode, the emitter electrode is grounded through the first resistor, and the collector electrode is connected with the source electrode of the power MOS tube through the fifth resistor and used for adjusting the voltage stabilizing output voltage limit value according to the normal working voltage limit value of a back-stage load. When the voltage of the input end is smaller than the set voltage-stabilizing output voltage limit value, the output voltage is kept consistent with the input voltage, and when the voltage of the input end is larger than the set voltage-stabilizing output voltage limit value, the output voltage is kept at the set voltage-stabilizing output voltage limit value. The circuit can meet the requirement of a large-power load, and can still work normally when the power supply voltage changes.

Description

Technical Field

[0001] This application pertains to the field of power supply for automotive electronic products, and more specifically, relates to a regulated power supply output system and its output method. Background Technology

[0002] In automotive electronic products, the operating voltage range of some electronic components differs from the supply voltage. Generally, electronic products in a 24V system require an operating voltage range of 9-36V to function properly, while some electronic components can only operate normally at 32V; they will not function properly if the voltage exceeds 32V. Therefore, to ensure that the load is not damaged due to excessive voltage, the power supply needs to be regulated before supplying power to the load.

[0003] In existing technologies, some voltage regulator circuits use transistors to achieve voltage regulation. However, this solution has limited load capacity and can only meet the needs of low-power loads, failing to meet the needs of loads with higher power requirements. Furthermore, if an integrated DC-DC step-down chip is used, the chip will operate abnormally when the supply voltage is lower than the set regulation value, causing subsequent stages to malfunction.

[0004] Therefore, how to provide a regulated power supply output system that can meet the needs of large power loads and still work normally when the supply voltage changes is an urgent problem to be solved. Summary of the Invention

[0005] In view of the shortcomings of the prior art, the purpose of this application is to provide a regulated power supply output system and output method that can meet the needs of large power loads and still work normally when the supply voltage changes.

[0006] To achieve the above objectives, in a first aspect, this application provides a regulated power supply output system, including a voltage reference chip, a first transistor, a second transistor, a power MOSFET, a first resistor, a second resistor, a third resistor, and a fourth resistor; The reference voltage of the voltage reference chip is shorted to its cathode, and its anode is grounded. The cathode is connected to the power input terminal through a current-limiting resistor to provide the reference voltage. The base of the first transistor is connected to the reference terminal of the voltage reference chip, the emitter is grounded through a first resistor, the collector is connected to the gate of the power MOSFET and one end of the second resistor, the second end of the second resistor and the source of the power MOSFET are connected to the power input terminal, and the drain of the power MOSFET serves as the power output terminal. The third and fourth resistors are connected in series between the power output terminal and ground. The voltage divider point is connected to the base of the second transistor. The emitter is grounded through the first resistor, and the collector is connected to the source of the power MOSFET through the fifth resistor. This is used to adjust the regulated output voltage limit according to the voltage limit of the downstream load during normal operation. When the input voltage is less than the set regulated output voltage limit, the output voltage is consistent with the input voltage. When the input voltage is greater than the set regulated output voltage limit, the output voltage is maintained at the set regulated output voltage limit.

[0007] The regulated power supply output system provided in this application has the following effects: It employs a power MOSFET Q1, and through the connection between the power MOSFET Q1, the voltage reference chip U1, and the transistor Q2, the power MOSFET Q1 can control the output voltage based on the comparison between the input voltage and the reference voltage. When the input voltage is less than the set regulated output voltage limit, the synergistic effect of the transistor Q2 and the power MOSFET Q1 ensures that the output voltage remains consistent with the input voltage, thereby guaranteeing that the load can obtain sufficient voltage for normal operation under low input voltage conditions. When the input voltage is greater than the set regulated output voltage limit... When the output voltage is at the limit, resistors R5 and R6 are connected in series between the power output terminal and ground. The voltage divider point is connected to the base of transistor Q3, the emitter is grounded through resistor R4, and the collector is connected to the source of power MOSFET Q1 through resistor R3. This connection method allows transistor Q2 to adjust the conduction level of power MOSFET Q1 according to the voltage change at the voltage divider point, thereby stabilizing the output voltage at the set regulated output voltage limit. This effectively prevents load damage due to excessive input voltage, ensuring that the system can still operate normally when the power supply voltage changes, and meeting the needs of larger power loads.

[0008] As a further preferred embodiment, a filtering circuit is also included, which comprises a first capacitor, a second capacitor, a third capacitor, a fourth capacitor, and a fifth capacitor, for filtering out interference signals at the input and output terminals and stabilizing the power supply.

[0009] As a further preferred embodiment, the first capacitor is connected between the power input terminal and ground to filter out low-frequency interference signals and stabilize the input power supply; the second capacitor is connected between the power input terminal and ground to filter out high-frequency interference signals; the third capacitor is connected in parallel across the third resistor to improve transient response, suppress output ripple, and optimize loop stability; the fourth capacitor is connected between the power output terminal and ground to filter out high-frequency interference signals in the output power supply; and the fifth capacitor is connected between the power output terminal and ground to filter out low-frequency interference signals at the output terminal and stabilize the output power supply.

[0010] As a further preferred embodiment, the voltage reference chip has a reference voltage of 2.5V and an accuracy of 0.5%.

[0011] As a further preferred embodiment, the first transistor and the second transistor are of the same model and have the same parameters and performance; the second resistor and the third resistor are of the same model.

[0012] As a further preferred embodiment, the first transistor and the second transistor are NPN transistors.

[0013] As a further preferred embodiment, the voltage between the collector and emitter of the NPN transistor is 40V, the voltage between the collector and emitter is 60V, and the maximum collector current is 200mA.

[0014] As a further preferred embodiment, the power MOSFET is a PMOS transistor with a drain-source voltage of 60V, a drain current of 20A, and a minimum gate turn-on voltage of 2V.

[0015] As a further preferred option, the formula for calculating the regulated output voltage limit VMAX is: VMAX = (1 + R5 / R6) VREF In the formula, VREF is the reference voltage of the voltage reference chip, and R5 and R6 are the resistance values ​​of the third resistor and the fourth resistor, respectively.

[0016] Secondly, this application provides a regulated power supply output method based on the above-described regulated power supply output system, comprising the following steps: Step 1: The voltage input at the power input terminal is used to provide a reference voltage through a voltage reference chip; Step 2: The base of the first transistor receives the reference voltage, and the conduction state of the first transistor and the power MOSFET is controlled according to the relationship between the input voltage and the set regulated output voltage limit. Step 3: When the input voltage is less than the set regulated output voltage limit, the output voltage remains consistent with the input voltage; Step 4: When the input voltage is greater than the set regulated output voltage limit, the output voltage is maintained at the set regulated output voltage limit.

[0017] It is understandable that the beneficial effects of the second aspect mentioned above can be found in the relevant descriptions in the first aspect mentioned above, and will not be repeated here. Attached Figure Description

[0018] Figure 1 This is a block diagram of the regulated power supply output system provided in the embodiments of this application; Figure 2 This is a specific implementation example of the regulated power supply output provided in the embodiments of this application. Detailed Implementation

[0019] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application.

[0020] It should be understood that, in the description of this application, the terms "first" and "second," etc., are used to distinguish different objects, rather than to describe a specific order of objects.

[0021] like Figure 1 As shown, this application provides a regulated power supply output system that can be applied in automotive electronic products. It mainly includes a voltage reference chip, two transistors, a power MOSFET, and a resistor to achieve regulated power supply output.

[0022] In this application, the basic components of the voltage regulator circuit are described as follows: VIN+ and VIN- are power input ports, and VOUT+ and VOUT- are power output ports.

[0023] Q1 is a power MOSFET, specifically a PMOS power MOSFET. Its main function is to provide operating voltage and current to the downstream load through the input voltage and current. The PMOS can be selected according to the load power.

[0024] Q2 and Q3 are transistors, specifically NPN transistors, and they need to be the same model to maintain consistency in parameters and performance.

[0025] Resistors R2 and R3 are the collector series resistors for transistors Q2 and Q3, respectively, and the models of R2 and R3 must be consistent with the requirements. Resistor R4 is the common series resistor for the emitters of Q2 and Q3.

[0026] Furthermore, the system provided in this application may also include a filtering circuit, which includes capacitors C1 to C5, for filtering out interference signals at the input and output terminals and stabilizing the power supply.

[0027] C1 can be an electrolytic capacitor connected between the power input terminal and ground to filter out low-frequency interference signals and stabilize the power supply at the input terminal.

[0028] C2 can be a ceramic capacitor, connected between the power input terminal and ground, used to filter out high-frequency interference signals.

[0029] C3 can be a ceramic capacitor connected in parallel across resistor R5 to improve transient response, suppress output ripple, and optimize loop stability.

[0030] C4 can be a ceramic capacitor, connected between the power output terminal and ground, used to filter out high-frequency interference signals in the power output terminal.

[0031] C5 is an electrolytic capacitor connected between the power output terminal and the ground, used to filter out low-frequency interference signals at the output terminal and stabilize the power supply at the output terminal.

[0032] The resistor R1 is the current-limiting resistor of the voltage regulator U1. U1 is a low-current precision voltage regulator. The reference voltage terminal voltage of U1 is shorted to its cathode. After operation, the voltage is always the reference voltage terminal voltage.

[0033] Assume that the maximum operating voltage value required by the subsequent load is VMAX. The basic principle of the voltage regulation circuit is explained as follows: (a) When the input voltage VIN < VMAX The input power supply passes through the resistor R1 and then the reference voltage source U1 works, and the stable output voltage is VREF. This voltage value is higher than the BE conduction voltage of the Q2 triode (generally about 0.6V). Then the emitter junction of Q2 is in the conduction state. The voltage at the collector of Q2 is the voltage value after the input power supply passes through the resistor R2. This voltage value is greater than VREF. Then the collector junction of Q2 is in the cut-off state. At this time, Q1 is in the amplification state as a whole. The current at the collector is equal to the base current multiplied by the amplification factor of the triode Q1. There is a voltage drop across the resistor R2. The source voltage of the power MOS transistor Q1 is greater than the gate voltage. Then Q1 is in the conduction state.

[0034] The emitter junction of the Q2 triode is forward-biased. The voltage across the resistor R4 is a fixed value VREF - Vbe, where Vbe is the conduction voltage drop of the triode. The emitter voltage of the Q3 triode is also equal to VREF - Vbe. The voltage at the base of Q3 after the VOUT voltage is divided by the resistors R5 and R6 is less than VREF. Then the emitter junction of Q3 is in the cut-off state. The collector voltage of Q3 is the voltage after the VIN passes through the resistor R3 and is greater than its base voltage. Then the collector junction of Q3 is in the cut-off state, indicating that Q3 is in the cut-off state.

[0035] In this state, Q2 is in the amplification state, Q3 is in the cut-off state, and the output voltage VOUT is equal to VIN.

[0036] (b) When the input voltage VIN > VMAX When the input voltage is greater than VMAX, Q2 is in amplification mode, Q1 is in conduction mode, and the emitter voltage of Q3 is VREF-Vbe. Theoretically, after the input voltage is turned on by Q1, the voltage value after being divided by resistors R5 and R6 is supplied to the base of Q3. The base voltage of Q3 will gradually increase as the input voltage increases until the emitter junction of Q3 is forward biased. Since Q2 and Q3 are the same type of device, the emitter junction conduction voltage of Q3 is Vbe. Therefore, the base voltage of Q3 will stabilize at (VREF-Vbe)+Vbe, that is, the base voltage of Q3 is the same as the base voltage of Q2, which is VREF. This means that even if the input voltage exceeds VMAX, the output voltage will be stabilized at the set value of VMAX. The voltage value of VMAX can be calculated using the following formula: VMAX = (1 + R5 / R6) VREF The above analysis shows that when the input voltage is less than the set VMAX value, the output voltage remains consistent with the input voltage. When the input voltage exceeds the set VMAX value, the output voltage will remain at the VMAX value, ensuring that the downstream load operates within the normal voltage range and achieving the purpose of voltage regulation.

[0037] The regulated power supply output system provided in this application has the following effects: It employs a power MOSFET Q1, and through the connection between the power MOSFET Q1, the voltage reference chip U1, and the transistor Q2, the power MOSFET Q1 can control the output voltage based on the comparison between the input voltage and the reference voltage. When the input voltage is less than the set regulated output voltage limit, the synergistic effect of the transistor Q2 and the power MOSFET Q1 ensures that the output voltage remains consistent with the input voltage, thereby guaranteeing that the load can obtain sufficient voltage for normal operation under low input voltage conditions. When the input voltage is greater than the set regulated output voltage limit... When the output voltage is at the limit, resistors R5 and R6 are connected in series between the power output terminal and ground. The voltage divider point is connected to the base of transistor Q3, the emitter is grounded through resistor R4, and the collector is connected to the source of power MOSFET Q1 through resistor R3. This connection method allows transistor Q2 to adjust the conduction level of power MOSFET Q1 according to the voltage change at the voltage divider point, thereby stabilizing the output voltage at the set regulated output voltage limit. This effectively prevents load damage due to excessive input voltage, ensuring that the system can still operate normally when the power supply voltage changes, and meeting the needs of larger power loads.

[0038] The following is a specific implementation example of this application, such as Figure 2 As shown.

[0039] The key components used in this implementation case are described below: U1 is a power supply voltage regulator reference chip, which is TI's ATL431BQDBZR, packaged in SOT-23, with a reference voltage of 2.5V and an accuracy of 0.5%.

[0040] Q1 is a PMOS power transistor, specifically the NCE60P20K from Xinjieneng, packaged in TO-252. It has a drain-source voltage of 60V, a drain current of 20A, and a minimum gate turn-on voltage of 2V.

[0041] Q2 and Q3 are NPN transistors, specifically Yangjie's MMBT3904, packaged in SOT-23. The voltage between collector and collector is 40V, and the voltage between collector and collector is 60V. The maximum collector current is 200mA.

[0042] R5 is selected as a 56K resistor and R6 as a 4.7K resistor as the voltage regulation limit resistor. Based on the resistance values ​​of R5 and R6, the theoretical regulated voltage can be calculated to be 2.5V. (1 + 56 / 4.7) = 32.3V.

[0043] When the VIN input voltage is 24V, the base voltage of Q2 is 2.5V, and the forward voltage between the base and emitter of Q2 is 0.6V. Therefore, the emitter voltage of Q2 is 2.5 - 0.6 = 1.9V. At this time, the current flowing through R4 is 1.9V / 10K = 190uA. Since Q2 is in amplification mode, the current flowing through the collector is approximately equal to the emitter current. Therefore, the voltage across resistor R2 is 47KΩ. 190uA = 8.9V. Q1 is in the ON state, so the VOUT terminal voltage is 24V. After being regulated and filtered by C4 and C5, the output voltage can directly drive the load. At the same time, the base voltage of Q3 is 24V / (56K+4.7K) = 1.85V < 2.5V, indicating that Q3 is in the OFF state.

[0044] When the VIN input voltage is 36V, Q2 is in amplification mode, there is a voltage drop across R2, Q1 is in conduction mode, the emitter voltage of Q3 is 1.9V, and when the emitter junction of Q3 is forward biased, its base voltage remains unchanged at 2.5V. It will not change because the input port voltage exceeds the limit value. In this way, the output voltage will be fixed at the set limit value, thus protecting the power supply of the downstream load.

[0045] A regulated power supply output device achieves the same output voltage as the input voltage when the input voltage is lower than the set voltage value, and the output voltage is the set value when the input voltage exceeds the limit value. It can safely drive power loads, and has a simple circuit structure and low cost.

[0046] Those skilled in the art will readily understand that the above description is merely a preferred embodiment of this application and is not intended to limit this application. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A regulated power supply output system, characterized in that, It includes a voltage reference chip, a first transistor, a second transistor, a power MOSFET, a first resistor, a second resistor, a third resistor, and a fourth resistor; The reference voltage of the voltage reference chip is shorted to its cathode, and its anode is grounded. The cathode is connected to the power input terminal through a current-limiting resistor to provide the reference voltage. The base of the first transistor is connected to the reference terminal of the voltage reference chip, the emitter is grounded through a first resistor, the collector is connected to the gate of the power MOSFET and one end of the second resistor, the second end of the second resistor and the source of the power MOSFET are connected to the power input terminal, and the drain of the power MOSFET serves as the power output terminal. The third and fourth resistors are connected in series between the power output terminal and ground. The voltage divider point is connected to the base of the second transistor. The emitter is grounded through the first resistor, and the collector is connected to the source of the power MOSFET through the fifth resistor. This is used to adjust the regulated output voltage limit according to the voltage limit of the downstream load during normal operation. When the input voltage is less than the set regulated output voltage limit, the output voltage is consistent with the input voltage. When the input voltage is greater than the set regulated output voltage limit, the output voltage is maintained at the set regulated output voltage limit.

2. The regulated power supply output system as described in claim 1, characterized in that, It also includes a filtering circuit, which comprises a first capacitor, a second capacitor, a third capacitor, a fourth capacitor, and a fifth capacitor, used to filter out interference signals at the input and output terminals and stabilize the power supply.

3. The regulated power supply output system as described in claim 2, characterized in that, The first capacitor is connected between the power input terminal and ground to filter out low-frequency interference signals and stabilize the input power supply; the second capacitor is connected between the power input terminal and ground to filter out high-frequency interference signals; the third capacitor is connected in parallel across the third resistor to improve transient response, suppress output ripple, and optimize loop stability; the fourth capacitor is connected between the power output terminal and ground to filter out high-frequency interference signals in the output power supply; and the fifth capacitor is connected between the power output terminal and ground to filter out low-frequency interference signals at the output and stabilize the output power supply.

4. The regulated power supply output system as described in claim 1, characterized in that, The voltage reference chip has a reference voltage of 2.5V and an accuracy of 0.5%.

5. The regulated power supply output system as described in claim 1, characterized in that, The first transistor and the second transistor are of the same model and have the same parameters and performance; the second resistor and the third resistor are of the same model.

6. The regulated power supply output system as described in claim 1, characterized in that, The first transistor and the second transistor are NPN transistors.

7. The regulated power supply output system as described in claim 6, characterized in that, The NPN transistor has a collector-emitter voltage of 40V, a collector-emitter voltage of 60V, and a collector current of 200mA.

8. The regulated power supply output system as described in claim 1, characterized in that, The power MOSFET is a PMOS transistor with a drain-source voltage of 60V, a drain current of 20A, and a minimum gate turn-on voltage of 2V.

9. The regulated power supply output system as described in claim 1, characterized in that, The formula for calculating the regulated output voltage limit VMAX is: VMAX=(1+R5 / R6) VREF In the formula, VREF is the reference voltage of the voltage reference chip, and R5 and R6 are the resistance values ​​of the third resistor and the fourth resistor, respectively.

10. A method for regulating power supply output based on the regulated power supply output system of claim 1, characterized in that, Includes the following steps: Step 1: The voltage input at the power input terminal is used to provide a reference voltage through a voltage reference chip; Step 2: The base of the first transistor receives the reference voltage, and the conduction state of the first transistor and the power MOSFET is controlled according to the relationship between the input voltage and the set regulated output voltage limit. Step 3: When the input voltage is less than the set regulated output voltage limit, the output voltage remains consistent with the input voltage; Step 4: When the input voltage is greater than the set regulated output voltage limit, the output voltage is maintained at the set regulated output voltage limit.

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