Soft start switch circuit

Abstract

The present application relates to the field of power supply technology, and specifically discloses a soft start switch circuit, including a main circuit, a switch device is connected in series in the main circuit, and the main circuit is also connected to a switch state control circuit, the switch state control circuit is connected to the switch device, and the switch device can be controlled to be on and off by the switch state control circuit; the switch state control circuit includes a first resistor, a charging capacitor and a first voltage stabilizing diode, the first end of the first resistor is connected to the signal input end of the main circuit, the second end of the first resistor is connected to the first end of the charging capacitor, the first end of the charging capacitor is also connected to the controlled end of the switch device, the second end of the charging capacitor is connected to the negative electrode of the first voltage stabilizing diode, and the positive electrode of the first voltage stabilizing diode is connected to the main circuit. The soft start of the main circuit can be achieved by the switch state control circuit, thereby reducing the pressure of the previous circuit and avoiding direct impact or damage to the load of the main circuit.

Description

Technical Field

[0001] The present application relates to the technical field of power supply, and in particular to a soft start switch circuit. Background Art

[0002] In traditional technology, the switch control device can directly control the load switch, and once the power is turned on, the switch control device will be turned on to directly supply power to the load. However, in some circuits that require soft start control, if the switch control device is directly turned on, it will cause direct impact or damage to the load. Summary of the invention

[0003] Based on this, it is necessary to provide a soft start switch circuit for the above problem, including a main circuit, a switch device is connected in series in the main circuit, and the main circuit is also connected to a switch state control circuit, the switch state control circuit is connected to the switch device, and the switch state control circuit can control the on and off of the switch device to control the on and off of the main circuit;

[0004] The switch state control circuit includes a first resistor, a charging capacitor and a first voltage-stabilizing diode. The first end of the first resistor is connected to the signal input end of the main circuit, the second end of the first resistor is connected to the first end of the charging capacitor, the first end of the charging capacitor is also connected to the controlled end of the switching device, the second end of the charging capacitor is connected to the cathode of the first voltage-stabilizing diode, and the anode of the first voltage-stabilizing diode is connected to the main circuit.

[0005] In one embodiment, the soft start switch circuit further includes a discharge circuit, and the discharge circuit is connected to the charging capacitor to release the charge stored in the charging capacitor.

[0006] In one embodiment, the discharge circuit includes a first Schottky diode, a second Schottky diode and a second resistor, the positive electrode of the first Schottky diode is connected to the first end of the charging capacitor, the negative electrode of the first Schottky diode is connected to the first end of the second resistor, the second end of the second resistor is connected to the positive electrode of the second Schottky diode, the positive electrode of the second Schottky diode and the second end of the second resistor are both connected to the main circuit, and the negative electrode of the second Schottky diode is connected to the second end of the charging capacitor.

[0007] In one embodiment, the soft start switch circuit further includes a time delay switch, and the time delay switch is connected in parallel to two sides of the first voltage regulator diode.

[0008] In one embodiment, the switch device comprises a MOS tube, and the controlled end of the switch device is a gate of the MOS tube.

[0009] In one embodiment, the switch device includes an N-type MOS tube.

[0010] In one embodiment, a second voltage stabilizing diode is connected in parallel between the gate and source of the MOS tube, the anode of the second voltage stabilizing diode is connected to the source of the MOS tube, and the cathode of the second voltage stabilizing diode is connected to the gate of the MOS tube.

[0011] In one embodiment, the signal input terminal is connected to the main loop via a first switch.

[0012] In one of the embodiments, a load is connected in series in the main circuit.

[0013] In one embodiment, the load comprises a resistor.

[0014] The soft start switch circuit provided in the embodiment of the present application controls the on and off of the switch device through the switch state control circuit, thereby realizing the on and off of the main circuit, wherein the switch state control circuit includes a first resistor, a charging capacitor and a first voltage stabilizing diode, and the current can charge the charging capacitor through the first resistor. When the voltage at the first end of the charging capacitor (i.e., the voltage at the controlled end of the switch device) reaches a certain voltage value, the switch device starts to turn on, the voltage at the controlled end of the switch device continues to increase, and the switch device gradually turns on until it is fully turned on. When the switch device is fully turned on, the main circuit is turned on, thereby realizing the soft start of the main circuit, thereby alleviating the pressure on the previous circuit and avoiding direct impact or damage to the load of the main circuit. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 A schematic diagram of the structure of a soft start switch circuit provided in an embodiment of the present application;

[0016] Figure 2 A schematic diagram of the structure of a soft start switch circuit provided in another embodiment of the present application.

[0017] Description of reference numerals:

[0018] 100, main circuit; VIN, signal input terminal; K1, first switch; R3, load; Q1, switch device; G, gate; S, source; D, drain; D4, second voltage-stabilizing diode; 200, switch state control circuit; R1, first resistor; C1, charging capacitor; D1, first voltage-stabilizing diode; 300, discharge circuit;

[0019] D2, the first Schottky diode; R2, the second resistor; D3, the second Schottky diode; K2, the delay switch. DETAILED DESCRIPTION

[0020] In order to facilitate the understanding of the present application, the present application will be described more fully below with reference to the relevant drawings. The preferred embodiments of the present application are given in the drawings. However, the present application can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to understand the disclosure of the present application more thoroughly and comprehensively.

[0021] In this application, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements, unless otherwise clearly defined. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0022] The terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include at least one of the features. In the description of this application, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0023] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art to which this application belongs. The terms used herein in the specification of this application are only for the purpose of describing specific embodiments and are not intended to limit this application. The term "and / or" used herein includes any and all combinations of one or more of the related listed items.

[0024] In traditional technology, the switch control device can directly control the load switch, and once the power is turned on, the switch control device will be turned on to directly supply power to the load. However, in some circuits that require soft start control, if the switch control device is turned on directly, it will cause direct impact or damage to the load and put pressure on the previous circuit.

[0025] To solve the above problem, in one embodiment, referring to Figure 1 , a soft start switch circuit is provided, comprising a main circuit 100, wherein a switch device Q1 is connected in series in the main circuit 100, and the main circuit 100 is further connected to a switch state control circuit 200, wherein the switch state control circuit 200 is connected to the switch device Q1, and the switch state control circuit 200 can control the on and off of the switch device Q1 to control the on and off of the main circuit 100;

[0026] Reference Figure 2 The switch state control circuit 200 includes a first resistor R1, a charging capacitor C1 and a first voltage-stabilizing diode D1. The first end of the first resistor R1 is connected to the signal input end VIN of the main circuit 100, the second end of the first resistor R1 is connected to the first end of the charging capacitor C1, the first end of the charging capacitor C1 is also connected to the controlled end of the switching device Q1, the second end of the charging capacitor C1 is connected to the cathode of the first voltage-stabilizing diode D1, and the anode of the first voltage-stabilizing diode D1 is connected to the main circuit 100.

[0027] The soft start switch circuit provided in the embodiment of the present application controls the on and off of the switch device Q1 through the switch state control circuit 200, thereby realizing the on and off of the main circuit 100, wherein the switch state control circuit 200 includes a first resistor R1, a charging capacitor C1 and a first voltage stabilizing diode D1, and the current flowing into the main circuit 100 can charge the charging capacitor C1 through the first resistor R1, and when the voltage at the first end of the charging capacitor C1 (that is, the voltage at the controlled end of the switch device Q1) reaches a certain voltage value, the switch device Q1 starts to turn on, and the voltage at the controlled end of the switch device Q1 continues to increase, and the switch device Q1 gradually turns on until it is fully turned on. When the switch device Q1 is fully turned on, the main circuit 100 is turned on, thereby realizing the soft start of the main circuit 100, thereby alleviating the pressure of the previous circuit and avoiding direct impact or damage to the load R3 of the main circuit 100.

[0028] The switch device Q1 may include a controlled end, a first end, and a second end. When the controlled end receives a turn-on signal, the first end and the second end are turned on, that is, the switch device Q1 is turned on, and the main circuit 100 is turned on. When the controlled end receives a turn-off signal, the first end and the second end are disconnected, that is, the switch device Q1 is turned off, and the main circuit 100 is turned off. In this embodiment, the switch state control circuit 200 is connected to the controlled end of the switch device Q1, and can control the turn-on or turn-off of the switch device Q1.

[0029] The switch state control circuit 200 includes a first resistor R1, a charging capacitor C1 and a first voltage regulator diode D1, wherein the charging capacitor C1 may be a ceramic capacitor, and the voltage regulator value of the first voltage regulator diode D1 may be 5V. Figure 2 The switch device Q1 may be a MOS tube, which includes a gate G, a source S and a drain D. The gate G is the controlled end of the switch device Q1, the source S and the drain D are respectively the first end and the second end of the switch device Q1. When the voltage of the gate G reaches the turn-on voltage, the source S and the drain D are connected. When the voltage of the gate G does not reach the turn-on voltage, the source S and the drain D are disconnected.

[0030] Reference Figure 2A second voltage stabilizing diode D4 is also connected in parallel between the gate G and the source S of the MOS tube, the anode of the second voltage stabilizing diode D4 is connected to the source S of the MOS tube, and the cathode of the second voltage stabilizing diode D4 is connected to the gate G of the MOS tube. The second voltage stabilizing diode D4 is a protective voltage stabilizing diode of the MOS tube.

[0031] Further preferably, the switch device Q1 may be an N-type MOS tube. The N-type MOS tube is turned on at a high level, that is, when the current loaded into the main circuit 100 is charged to the capacitor C1 through the first resistor R1, the gate G of the switch device Q1, that is, the voltage of the first end of the charging capacitor C1 increases, and when it increases to the turn-on voltage value of the gate G, the N-type MOS tube is turned on. In this embodiment, the turn-on voltage value of the N-type MOS tube may be 5V.

[0032] In this embodiment, the signal input terminal VIN of the main circuit 100 is connected to the main circuit 100 via the first switch K1. When the main circuit 100 needs to be started, the first switch K1 is turned on, that is, the signal input terminal VIN can load current into the main circuit 100; when the main circuit 100 does not need to be started, the first switch K1 is turned off.

[0033] In this embodiment, a load R3 is further connected in series in the main circuit 100 , wherein the load R3 may be a resistor.

[0034] In one embodiment, the soft start switch circuit further includes a discharge circuit 300, which is connected to the charging capacitor C1 and is used to release the charge stored in the charging capacitor C1. That is, during the period when the main loop 100 is turned off, the charging capacitor C1 can be discharged through the discharge circuit 300.

[0035] Specifically, the discharge circuit 300 may include a first Schottky diode D2, a second Schottky diode D3 and a second resistor R2, the anode of the first Schottky diode D2 is connected to the first end of the charging capacitor C1, the cathode of the first Schottky diode D2 is connected to the first end of the second resistor R2, the second end of the second resistor R2 is connected to the anode of the second Schottky diode D3, the anode of the second Schottky diode D3 and the second end of the second resistor R2 are both connected to the main loop 100, and the cathode of the second Schottky diode D3 is connected to the second end of the charging capacitor C1.

[0036] The first Schottky diode D2 and the second Schottky diode D3 may be selected to have a minimum forward voltage drop of 0.15 V. The resistance of the second resistor R2 is much smaller than the resistance of the first resistor R1.

[0037] During the shutdown of the main circuit 100, the first switch K1 can be disconnected, and the charge stored in the charging capacitor C1 can be released through the first Schottky diode D2, the second resistor R2, and the second Schottky diode D3. Then, the voltage at the first end of the charging capacitor C1, i.e., the controlled end of the switching device Q1, decreases, the switching device Q1 is turned off, and the shutdown process of the main circuit 100 ends.

[0038] The values ​​of the first resistor R1 and the charging capacitor C1 can be adjusted according to actual requirements for the soft start time.

[0039] In one embodiment, the soft start switch circuit further includes a delay switch K2 , and the delay switch K2 is connected in parallel to two sides of the first voltage regulator diode D1 .

[0040] When only soft start is needed and no delay is required, the delay switch K2 can be turned off. At this time, the first switch K1 is turned on, the voltage at the second end of the charging capacitor C1 will quickly rise to 5V, the charging capacitor C1 starts to charge, and the voltage at the first end of the charging capacitor C1, i.e., the controlled end of the switch device Q1, gradually rises, and the switch device Q1 gradually turns on, realizing the soft start of the main circuit. When the main circuit is turned off, the first switch K1 is turned off, the charge of the charging capacitor C1 is released through the first Schottky diode D2, the second resistor R2, and the second Schottky diode D3, the switch device Q1 is quickly turned off, and the main circuit is turned off.

[0041] In practical applications, appropriate delay can be added according to actual needs. Specifically, the voltage stabilization value of the first voltage stabilizing diode D1 can be changed, and the first resistor R1 and the charging capacitor C1 can be used to achieve appropriate delay and soft start. Delayed start can avoid simultaneous start of multiple circuits and reduce the pressure on the previous circuit.

[0042] The soft start switch circuits provided in this embodiment are all constructed using discrete devices, so the circuits are relatively stable and have low cost.

[0043] The technical features of the above-described embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0044] The above-described embodiments only express several implementation methods of the present application, and the descriptions thereof are relatively specific and detailed, but they cannot be construed as limiting the scope of the patent. It should be noted that, for a person of ordinary skill in the art, several modifications and improvements can be made without departing from the concept of the present application, and these all belong to the protection scope of the present application. Therefore, the protection scope of the present application shall be subject to the attached claims.

Claims

1. A soft start switch circuit, characterized in that: The main circuit comprises a switch device connected in series, and the main circuit is also connected to a switch state control circuit, the switch state control circuit is connected to the switch device, and the switch state control circuit can control the on and off of the switch device to control the on and off of the main circuit; The switch state control circuit includes a first resistor, a charging capacitor and a first voltage regulator diode, wherein the first end of the first resistor is connected to the signal input end of the main circuit, the second end of the first resistor is connected to the first end of the charging capacitor, the first end of the charging capacitor is also connected to the controlled end of the switch device, the second end of the charging capacitor is connected to the cathode of the first voltage regulator diode, and the anode of the first voltage regulator diode is connected to the main circuit; The soft start switch circuit further includes a time delay switch, and the time delay switch is connected in parallel to two sides of the first voltage stabilizing diode; The soft start switch circuit further includes a discharge circuit, which is connected to the charging capacitor and is used to release the charge stored in the charging capacitor; The discharge circuit includes a first Schottky diode, a second Schottky diode and a second resistor, the anode of the first Schottky diode is connected to the first end of the charging capacitor, the cathode of the first Schottky diode is connected to the first end of the second resistor, the second end of the second resistor is connected to the anode of the second Schottky diode, the anode of the second Schottky diode and the second end of the second resistor are both connected to the main loop, and the cathode of the second Schottky diode is connected to the second end of the charging capacitor; wherein the first Schottky diode and the second Schottky diode are Schottky diodes with a minimum forward voltage drop of 0.15V.

2. The soft start switch circuit according to claim 1, characterized in that: The switch device comprises a MOS tube, and the controlled end of the switch device is the gate of the MOS tube.

3. The soft start switch circuit according to claim 2, characterized in that: The switch device includes an N-type MOS tube.

4. The soft start switch circuit according to claim 2, characterized in that: A second voltage stabilizing diode is also connected in parallel between the gate and source of the MOS tube, the anode of the second voltage stabilizing diode is connected to the source of the MOS tube, and the cathode of the second voltage stabilizing diode is connected to the gate of the MOS tube.

5. The soft start switch circuit according to claim 1, characterized in that: The signal input terminal is connected to the main circuit via a first switch.

6. The soft start switch circuit according to claim 1, characterized in that: A load is connected in series in the main circuit.

7. The soft start switch circuit according to claim 6, characterized in that: The load includes a resistor.

Images