Isolation switch circuit and switch power supply

Abstract

The utility model discloses an isolation switch circuit and a switch power supply. The isolation switch circuit comprises an anti-reverse connection unit, a voltage reduction and stabilization unit, a primary side switch unit and an isolation unit. The input end of the anti-reverse connection unit and the primary side first end of the isolation unit are connected together to serve as the input end of the isolation switch circuit, the output end of the anti-reverse connection unit is connected with the input end of the voltage reduction and stabilization unit, and the output end of the voltage reduction and stabilization unit is connected with the control end of the primary side switch unit. The primary side second end of the isolation unit is connected with one end of the primary side switch unit, the grounding end of the voltage reduction and stabilization unit and the other end of the primary side switch unit are connected together to serve as the first grounding end of the isolation switch circuit, and the secondary side first end of the isolation unit serves as the output end of the isolation switch circuit. And the secondary side second end of the isolation unit is a second grounding end of the isolation switch circuit. The reliability of the circuit can be improved.

Description

Technical Field

[0001] The utility model relates to the technical field of switch power supply control, in particular to an isolation switch circuit and a switch power supply. Background Art

[0002] For switching power supply products, the customer site generally uses an external power-on signal to control the product's on / off, or uses an external dry contact signal to switch the product's working mode. This is especially true in server power supply systems with larger power or more complex systems. External input signals are generally used more frequently. During customer use, negligent operation or unfamiliarity with the technology may cause the external input analog voltage signal to be connected with the opposite polarity or the voltage to be too high. In addition, there is also the condition of unstable signal levels. These anomalies frequently occur in engineering applications. When the switching power supply is subject to these customer-side port risks, there is a risk of damage or failure. Utility Model Content

[0003] In view of this, the technical problem to be solved by the utility model is to propose an isolation switch circuit and a switching power supply, which can avoid damage or failure of the switching power supply caused by reverse connection of the positive and negative poles, excessive high or unstable high and low of the external input analog voltage signal.

[0004] As a first aspect of the present invention, the technical solution of the embodiment of the isolating switch circuit provided is as follows:

[0005] An isolating switch circuit, comprising: an anti-reverse connection unit, a buck stabilizing unit, a primary switch unit and an isolating unit; the input end of the anti-reverse connection unit and the primary first end of the isolating unit are connected together as the input end of the isolating switch circuit, the output end of the anti-reverse connection unit is connected to the input end of the buck stabilizing unit, the output end of the buck stabilizing unit is connected to the control end of the primary switch unit, the primary second end of the isolating unit is connected to one end of the primary switch unit, the ground end of the buck stabilizing unit and the other end of the primary switch unit are connected together as the first ground end of the isolating switch circuit, the secondary first end of the isolating unit is the output end of the isolating switch circuit, and the secondary second end of the isolating unit is the second ground end of the isolating switch circuit;

[0006] When the input end of the isolation switch circuit is connected to the positive pole of the external analog voltage, the anti-reverse connection unit is turned on, and the analog voltage is transmitted to the buck stabilizing unit. The buck stabilizing unit performs buck and stabilization processing on the analog voltage and outputs a voltage signal to control the primary switch unit to be turned on, so that the isolation unit isolates the analog voltage input from the first end of the primary side and outputs it from the first end of the secondary side;

[0007] When the input end of the isolation switch circuit is connected to the negative pole of the external analog voltage, the anti-reverse connection unit is turned off, the buck stabilizing unit does not work, and the primary switch unit is turned off, so that the first end of the secondary side of the isolation unit outputs no voltage.

[0008] Preferably, the anti-reverse connection unit comprises a diode D1, an anode of the diode D1 is an input end of the anti-reverse connection unit, and a cathode of the diode D1 is an output end of the anti-reverse connection unit.

[0009] Preferably, the step-down voltage stabilizing unit includes a resistor R1, a transistor Q1 and a Zener diode ZD1, one end of the resistor R1 and the collector of the transistor Q1 are connected together as the input end of the step-down voltage stabilizing unit, the emitter of the transistor Q1 is the output end of the step-down voltage stabilizing unit, the other end of the resistor R1 and the base of the transistor Q1 are both connected to the cathode of the Zener diode ZD1, and the anode of the Zener diode ZD1 is the ground end of the step-down voltage stabilizing unit.

[0010] Preferably, the primary switch unit includes a MOS tube Q2, a gate of the MOS tube Q2 is a control end of the primary switch unit, a drain of the MOS tube Q2 is one end of the primary switch unit, and a source of the MOS tube Q2 is the other end of the primary switch unit.

[0011] Preferably, the isolation unit includes an optocoupler, the anode of the optocoupler transmitting end is the first end of the primary side of the isolation unit, the cathode of the optocoupler transmitting end is the second end of the primary side of the isolation unit, the collector of the optocoupler receiving end is the first end of the secondary side of the isolation unit, and the emitter of the optocoupler receiving end is the second end of the secondary side of the isolation unit.

[0012] Furthermore, the isolation unit further includes a resistor R2, one end of the resistor R2 is the primary first end of the isolation unit, and the other end of the resistor R2 is connected to the anode of the photocoupler transmitting end.

[0013] Furthermore, the isolation unit further includes a diode D2, an anode of the diode D2 is connected to a cathode of the optocoupler transmitting end, and a cathode of the diode D2 is connected to an anode of the optocoupler transmitting end.

[0014] As a second aspect of the present invention, the technical solution of the embodiment of the switching power supply provided is as follows:

[0015] A switching power supply, comprising: an isolating switch circuit as described in any one of the first aspects above.

[0016] The utility model can improve the reliability of the circuit and has the following advantages and beneficial effects:

[0017] 1) The utility model circuit has an anti-reverse connection unit. When the input end of the isolation switch circuit is connected to the negative pole of the external analog voltage, the anti-reverse connection unit is cut off, the buck regulator unit does not work, and the primary switch unit is cut off, so that the output of the first end of the secondary side of the isolation unit has no voltage output, which can effectively avoid the overcurrent damage of the primary switch unit and the linear regulator unit caused by the reverse connection of the positive and negative poles of the client, resulting in product system failure and permanent failure to work normally;

[0018] 2) The utility model circuit has a step-down and voltage-stabilizing unit, which is used to control the conduction of the primary switch unit after stepping down and stabilizing the analog voltage connected, thereby avoiding damage or failure of the switching power supply caused by the analog voltage being too high or unstable. When the customer connects a voltage that is too high, if there is no step-down and voltage-stabilizing unit, the primary switch unit may be damaged due to withstand voltage. If the voltage is too low or the level is unstable, the primary switch unit will work abnormally, causing abnormal operation inside the system and reducing product reliability.

[0019] 3) The circuit of the utility model has an isolation unit, which can isolate the analog voltage input from the first end of its primary side and output it from the first end of its secondary side. Therefore, when there are interference glitches in the signal connected by the client, the utility model can effectively prevent the influx of differential mode or common mode interference noise. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 A specific isolating switch circuit of the first embodiment of the utility model;

[0021] Figure 2 for Figure 1 Schematic diagram of the first engineering application of the circuit in a switching power supply;

[0022] Figure 3 for Figure 1 Schematic diagram of the second engineering application of the circuit in the switching power supply. DETAILED DESCRIPTION

[0023] In order to make the above-mentioned purposes, features and advantages of the utility model more obvious and easy to understand, the specific implementation methods of the utility model are described in detail below in conjunction with the accompanying drawings. Obviously, the described embodiments are part of the embodiments of the utility model, rather than all the embodiments. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of this application.

[0024] It should be noted that the terms "including" and "having" and any variations thereof described in the specification and claims of the present application are intended to cover non-exclusive inclusions. For example, the inclusion of a series of components, unit circuits or control timings is not necessarily limited to those components, unit circuits or control timings clearly listed, but may include components, unit circuits or control timings that are not clearly listed or inherent to these circuits.

[0025] In addition, the embodiments and features of the embodiments in this application may be combined with each other if there is no conflict.

[0026] It should be understood that, in the specification and the claims, when an element is described as being “connected” to another element, the element may be “directly connected” to the other element, or be “connected” to the other element through a third element; when a step is described as being continued to another step, the step may be directly continued to the other step, or be continued to the other step through a third step.

[0027] First embodiment

[0028] The present embodiment provides an isolation switch circuit, which includes: an anti-reverse connection unit, a buck voltage stabilizing unit, a primary switch unit and an isolation unit; the input end of the anti-reverse connection unit and the primary first end of the isolation unit are connected together as the input end Vcc_OUT of the isolation switch circuit, the output end of the anti-reverse connection unit is connected to the input end of the buck voltage stabilizing unit, the output end of the buck voltage stabilizing unit is connected to the control end of the primary switch unit, the primary second end of the isolation unit is connected to one end of the primary switch unit, the ground end of the buck voltage stabilizing unit and the other end of the primary switch unit are connected together as the first ground end GND1 of the isolation switch circuit, the secondary first end of the isolation unit is the output end A1 of the isolation switch circuit, and the secondary second end of the isolation unit is the second ground end GND2 of the isolation switch circuit;

[0029] When the input end of the isolation switch circuit is connected to the positive pole of the external analog voltage, the reverse connection protection unit is turned on, and the analog voltage is transmitted to the step-down voltage stabilization unit. The step-down voltage stabilization unit performs step-down and voltage stabilization on the analog voltage, and then outputs a voltage signal to control the primary switch unit to be turned on, so that the isolation unit isolates the analog voltage input from the first end of the primary side and then outputs it from the first end of the secondary side.

[0030] When the input end of the isolation switch circuit is connected to the negative pole of the external analog voltage, the anti-reverse connection unit is turned off, the buck regulator unit does not work, and the primary switch unit is turned off, so that the first end of the secondary side of the isolation unit outputs no voltage.

[0031] The utility model circuit has an anti-reverse connection unit. When the input end of the isolation switch circuit is connected to the negative pole of the external analog voltage, the anti-reverse connection unit is cut off, the step-down voltage regulator unit does not work, and the primary switch unit is cut off, so that the output of the first end of the secondary side of the isolation unit has no voltage output, which can effectively avoid the overcurrent damage of the primary switch unit and the linear voltage regulator unit caused by the reverse connection of the positive and negative poles of the client, resulting in product system failure and permanent failure to work normally.

[0032] The utility model circuit has a step-down and voltage-stabilizing unit, which is used to control the conduction of the primary switch unit after stepping down and stabilizing the analog voltage connected, thereby avoiding damage or failure of the switching power supply caused by the analog voltage being too high or unstable. When the customer connects a voltage that is too high, if there is no step-down and voltage-stabilizing unit, the primary switch unit may be damaged due to the withstand voltage. If the voltage is too low or the level is unstable, the primary switch unit will work abnormally, causing abnormal operation inside the system and reducing product reliability.

[0033] The utility model circuit has an isolation unit, which can isolate the analog voltage input from the first end of the primary side and output it from the first end of the secondary side. Therefore, when there are interference glitches in the signal connected by the client, the utility model can effectively prevent the influx of differential mode or common mode interference noise.

[0034] Figure 1 This is a specific isolating switch circuit of the first embodiment of the utility model, see Figure 1 ,in:

[0035] The anti-reverse connection unit includes a diode D1 , an anode of the diode D1 is an input end of the anti-reverse connection unit, and a cathode of the diode D1 is an output end of the anti-reverse connection unit.

[0036] The buck stabilizing unit A1 includes a resistor R1, a transistor Q1 and a zener diode ZD1. One end of the resistor R1 and the collector of the transistor Q1 are connected together as the input end of the buck stabilizing unit. The emitter of the transistor Q1 is the output end of the buck stabilizing unit. The other end of the resistor R1 and the base of the transistor Q1 are connected to the cathode of the zener diode ZD1. The anode of the zener diode ZD1 is the ground end of the buck stabilizing unit.

[0037] The primary switch unit A2 includes a MOS transistor Q2, a gate of the MOS transistor Q2 being a control end of the primary switch unit, a drain of the MOS transistor Q2 being one end of the primary switch unit, and a source of the MOS transistor Q2 being the other end of the primary switch unit.

[0038] The isolation unit includes an optocoupler U1, wherein the anode of the transmitting end of the optocoupler U1 is the primary first end of the isolation unit, the cathode of the transmitting end of the optocoupler U1 is the primary second end of the isolation unit, the collector of the receiving end of the optocoupler U1 is the secondary first end of the isolation unit, and the emitter of the receiving end of the optocoupler U1 is the secondary second end of the isolation unit.

[0039] Furthermore, the isolation unit further includes a resistor R2, one end of the resistor R2 is the primary first end of the isolation unit, and the other end of the resistor R2 is connected to the anode of the photocoupler emitter end.

[0040] Furthermore, the isolation unit further includes a diode D2, an anode of the diode D2 is connected to a cathode of the optocoupler transmitting end, and a cathode of the diode D2 is connected to an anode of the optocoupler transmitting end.

[0041] Figure 1 The circuit works as follows:

[0042] (1) When the input terminal Vcc_OUT of the isolation switch circuit is connected to the positive pole of the external analog voltage and the first ground terminal GND1 of the isolation switch circuit is connected to the negative pole of the external analog voltage

[0043] Diode D1 is turned on, and resistor R1 provides bias current to transistor Q1, making the transistor turned on. Resistor R1 also provides working current to Zener diode ZD1. After Zener diode ZD1 breaks down, cathode voltage is a stable value. Since the cathode of Zener diode ZD1 is connected to the base of transistor Q1, the base voltage of transistor Q1 is stabilized by Zener diode ZD1. Since there is a diode between the base and emitter of transistor Q1, the voltage across the two ends is a stable 0.7V (calculated in silicon tube) when the diode is turned on. The voltage output by the emitter of the diode Q1 is equal to the voltage value of the voltage regulator ZD1 minus 0.7V. By setting appropriate parameters, this voltage can reliably drive the MOS tube Q2 to conduct, avoiding the external analog voltage from being too high to damage the MOS tube Q2. The external analog voltage input at one end of the resistor R2 flows through the path formed by the emitter of the optocoupler U1 and the MOS tube Q2 after being limited by the resistor R2. The collector of the receiving end of the optocoupler U1 outputs an isolated analog voltage, which can be used to realize the product's power on / off control or the switching of the working mode.

[0044] (2) When the first ground terminal GND1 of the isolation switch circuit is connected to the positive pole of the external analog voltage and the input terminal Vcc_OUT of the isolation switch circuit is connected to the negative pole of the external analog voltage

[0045] Diode D1 is cut off, and the step-down voltage regulator unit A1 does not work, and cannot drive the MOS tube Q2 to turn on. There is no path at the transmitter end of the optocoupler U1, and there is no output at the receiver end of the optocoupler U1. An alarm can be set for reverse connection. In this case, the current of the external analog voltage will form a positive voltage at the cathode of the transmitter end of the optocoupler U1 through the body diode of the MOS tube Q2. Since one end of R2 is a negative voltage, a negative voltage is formed at the anode of the transmitter end of the optocoupler U1. At this time, the anode of the transmitter end of the optocoupler U1 presents a negative voltage to the cathode. Since the optocouplers U1 in the current switching power supply industry are similar, the negative voltage withstand voltage of the anode of the transmitter end of the optocoupler U1 to the cathode is generally ≤5V. Therefore, it is necessary to add a clamping diode D2 between the anode and cathode of the transmitter end of the optocoupler U1, so that if the customer's external analog voltage level is high and the negative voltage of the anode to the cathode of the transmitter end of the optocoupler U1 is clamped to about the tube voltage drop (-0.7V) of the diode D2 when it is reversed, to avoid damage to the optocoupler U1 and cause irreversible damage to the switching power supply system.

[0046] Figure 1 The specific circuit has the following characteristics: 1) It is applied to analog control scenarios and can realize the hardware processing of the whole process from signal processing, switching power supply action to protection without digital chip processing;

[0047] 2) It can realize the input of different signals, such as dry contact signals, power on / off signals, mode switching signals and communication signals (low-speed occasions), so it has strong compatibility and low cost;

[0048] 3) It has isolation and signal processing functions, and also has its own protection unit, which can achieve self-protection and report external signal failures, and has the advantages of multi-function and redundancy.

[0049] Second embodiment

[0050] This embodiment provides a switching power supply, which includes the isolation switch circuit described in any one of the first embodiments.

[0051] Since the switching power supply of this embodiment includes the isolation switch circuit described in any one of the first embodiments, it can effectively avoid damage or failure of the switching power supply caused by the reverse connection of the positive and negative poles, excessive high or unstable high and low of the analog voltage signal input from the client, and can also effectively prevent the influx of differential mode or common mode interference noise caused by the analog voltage signal input from the client.

[0052] Figure 2 for Figure 1The first engineering application diagram of the circuit in the switching power supply. The socket terminal CON1 is a 2P interface provided by the switching power supply product to external customers. The function is that the customer connects to the external analog voltage through this interface to control the on / off function of the switching power supply. The customer inserts the external analog voltage into the socket terminal CON1, and the positive terminal of the analog voltage is connected to the PS_ON / OFF port (corresponding to Figure 1 The negative pole is connected to the GND1 interface. At this time, the external high and low level analog voltage signals connected by the customer pass through the isolation switch circuit of the first embodiment, and the corresponding high and low level signals are sent to the secondary side of the optocoupler U1. In this application circuit, the secondary side of the optocoupler U1 is connected to a switch circuit, and the small signal output by the ON port is sent to the control chip or analog IC, so that the customer can freely control the on and off of the switching power supply.

[0053] Figure 3 for Figure 1 The first engineering application diagram of the circuit in the switching power supply. The socket terminal CON1 is a 2P interface provided by the switching power supply product to external customers. The interface function is to control the speed of the fan inside the switching power supply by connecting the external analog pulse voltage through the interface. The customer inserts the external analog voltage into the socket terminal CON1, and the positive terminal of the analog voltage is connected to the FAN_PWM port (corresponding to Figure 1 The negative pole of the Vcc_OUT is connected to the GND1 interface. At this time, the external analog voltage signal connected by the customer passes through the isolation switch circuit of the first embodiment, and the corresponding pulse level is sent to the secondary side of the optocoupler U1. In this application circuit, the secondary side of the optocoupler U1 is connected to the comparator circuit. The function of the comparator circuit is to amplify the pulse signal connected by the customer and improve its signal driving ability. Since there is a switch circuit composed of MOS tube Q2 at the customer input end, and there is a switch circuit composed of MOS tube Q3 after the comparator amplifier circuit, these two switch circuits will perform two reverse processes on the external analog voltage signal connected by the customer, thereby converting the pulse high-level analog voltage connected by the customer into a high-level signal of positive logic, and then sending the high-level signal of positive logic to the speed adjustment foot FAN_SPEED of the fan in the circuit, so as to realize the fan speed inside the customer's freely controllable switching power supply.

[0054] The above are only implementation modes of the present invention. It should be pointed out that the above implementation modes should not be regarded as limitations of the present invention. For ordinary technicians in this technical field, several improvements and modifications can be made without departing from the spirit and scope of the present invention. These improvements and modifications should also be regarded as the protection scope of the present invention.

Claims

1. An isolating switch circuit, characterized in that: include: An anti-reverse connection unit, a buck voltage stabilizing unit, a primary switch unit and an isolation unit; the input end of the anti-reverse connection unit and the primary first end of the isolation unit are connected together as the input end of the isolation switch circuit, the output end of the anti-reverse connection unit is connected to the input end of the buck voltage stabilizing unit, the output end of the buck voltage stabilizing unit is connected to the control end of the primary switch unit, the primary second end of the isolation unit is connected to one end of the primary switch unit, the ground end of the buck voltage stabilizing unit and the other end of the primary switch unit are connected together as the first ground end of the isolation switch circuit, the secondary first end of the isolation unit is the output end of the isolation switch circuit, and the secondary second end of the isolation unit is the second ground end of the isolation switch circuit; When the input end of the isolation switch circuit is connected to the positive pole of the external analog voltage, the anti-reverse connection unit is turned on, and the analog voltage is transmitted to the buck stabilizing unit. The buck stabilizing unit performs buck and stabilization processing on the analog voltage and outputs a voltage signal to control the primary switch unit to be turned on, so that the isolation unit isolates the analog voltage input from the first end of the primary side and outputs it from the first end of the secondary side; When the input end of the isolation switch circuit is connected to the negative pole of the external analog voltage, the anti-reverse connection unit is turned off, the buck stabilizing unit does not work, and the primary switch unit is turned off, so that the first end of the secondary side of the isolation unit outputs no voltage.

2. The isolating switch circuit according to claim 1, characterized in that: The anti-reverse connection unit includes a diode D1 , an anode of the diode D1 is an input end of the anti-reverse connection unit, and a cathode of the diode D1 is an output end of the anti-reverse connection unit.

3. The isolating switch circuit according to claim 1, characterized in that: The step-down voltage stabilizing unit includes a resistor R1, a transistor Q1 and a Zener diode ZD1. One end of the resistor R1 and the collector of the transistor Q1 are connected together as the input end of the step-down voltage stabilizing unit, the emitter of the transistor Q1 is the output end of the step-down voltage stabilizing unit, the other end of the resistor R1 and the base of the transistor Q1 are both connected to the cathode of the Zener diode ZD1, and the anode of the Zener diode ZD1 is the ground end of the step-down voltage stabilizing unit.

4. The isolating switch circuit according to claim 1, characterized in that: The primary switch unit includes a MOS tube Q2, a gate of the MOS tube Q2 is a control end of the primary switch unit, a drain of the MOS tube Q2 is one end of the primary switch unit, and a source of the MOS tube Q2 is the other end of the primary switch unit.

5. The isolating switch circuit according to claim 1, characterized in that: The isolation unit includes an optocoupler, the anode of the optocoupler transmitting end is the first end of the primary side of the isolation unit, the cathode of the optocoupler transmitting end is the second end of the primary side of the isolation unit, the collector of the optocoupler receiving end is the first end of the secondary side of the isolation unit, and the emitter of the optocoupler receiving end is the second end of the secondary side of the isolation unit.

6. The isolating switch circuit according to claim 5, characterized in that: The isolation unit further includes a resistor R2, one end of the resistor R2 is a primary first end of the isolation unit, and the other end of the resistor R2 is connected to the anode of the photocoupler emitter end.

7. The isolating switch circuit according to claim 5 or 6, characterized in that: The isolation unit further includes a diode D2, wherein an anode of the diode D2 is connected to a cathode of the photocoupler transmitting end, and a cathode of the diode D2 is connected to an anode of the photocoupler transmitting end.

8. A switching power supply, characterized in that: The isolating switch circuit comprises the isolating switch circuit as claimed in any one of claims 1 to 7.

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