Power-on time sequence control circuit

Abstract

The utility model discloses a power-on time sequence control circuit which is used for a first power supply winding and a second power supply winding, the power-on time sequence is that the first power supply winding is powered on earlier than the second power supply winding, and the circuit comprises a first voltage monitoring unit, a switch control unit, a second voltage monitoring unit and a voltage discharge unit. The output end of the first voltage monitoring unit is connected to the input end of the switch control unit; the switch control unit is connected to the output end of the second voltage monitoring unit; the output end of the second voltage monitoring unit is connected to the first input end of the voltage discharge unit. And a second input end of the voltage discharge unit is connected to a voltage source of the second power supply winding. According to the utility model, through the switch control unit and the voltage discharge unit, when the first power supply winding which needs to be powered on firstly waits to be powered on, the voltage of the second power supply winding is discharged, so that the first power supply winding is powered on later, thereby realizing normal startup logic of a product.

Description

Technical Field

[0001] The utility model relates to the technical field of switch power supplies, in particular to a power-on timing control circuit between auxiliary power supply windings. Background Art

[0002] High-power products often contain a more complex auxiliary power supply system. When the product contains two or more auxiliary power systems, the power-on sequence between the auxiliary power systems is often crucial. If the power-on sequence is disordered, the product will not be able to output normally when powered on, and in severe cases, it may explode.

[0003] Application Case 1: When used between two isolated power supply systems, when the whole machine is powered on normally, when the power supply system of the rear-stage DCDC is powered on before the power supply system of the front-stage ACDC, since the front-stage ACDC is not working properly, the rear-stage DCDC starts to work because it is powered on first, which will cause the product output voltage to be abnormal.

[0004] Application Case 2: When used between different auxiliary windings in the same flyback power supply system, taking the flyback power supply as an example, when the flyback power supply is established, the power-on timing of the secondary winding will not be controlled, and it will be powered on in sequence with the output load size. Summary of the invention

[0005] In view of this, the purpose of the utility model is to provide a power-on timing control circuit to effectively solve the problem of uncertain power-on timing between complex power supply systems, and avoid the risk of abnormal output or even machine damage caused by incorrect power-on timing.

[0006] In order to solve the above technical problems, the technical solution adopted by the utility model is:

[0007] In a first aspect, the utility model provides a power-on timing control circuit, which is used for a first power supply winding and a second power supply winding, and the power-on timing is that the first power supply winding is powered on before the second power supply winding, and the power-on timing control circuit includes a first voltage monitoring unit, a switch control unit, a second voltage monitoring unit and a voltage discharge unit;

[0008] The first voltage monitoring unit is used to monitor the voltage of the first power supply winding, obtain a first voltage, and turn on the switch control unit when the first voltage reaches a first voltage threshold; the output end of the first voltage monitoring unit is connected to the input end of the switch control unit;

[0009] The switch control unit is used to clamp the output end of the second voltage monitoring unit to a low level when the first voltage reaches a first voltage threshold; the switch control unit is connected to the output end of the second voltage monitoring unit;

[0010] The second voltage monitoring unit is used to monitor the voltage of the second power supply winding to obtain a second voltage; the output end of the second voltage monitoring unit is connected to the first input end of the voltage discharge unit.

[0011] The voltage discharge unit is used to be turned on when the first voltage is less than the first voltage threshold and the second voltage is greater than the second voltage threshold, so as to discharge the voltage of the voltage source of the second power supply winding; the second input end of the voltage discharge unit is connected to the voltage source of the second power supply winding.

[0012] Optionally, the first voltage monitoring unit includes a first resistor, a second resistor and a first capacitor, the first end of the first resistor is connected to the voltage source of the first power supply winding, the second end of the first resistor is connected to the ground through the second resistor, the first capacitor is connected in parallel with the second resistor, and the second end of the first resistor is also connected to the input end of the switch control unit.

[0013] Optionally, the switch control unit includes a first switch tube, a control end of the first switch tube is connected to the output end of the first voltage monitoring unit, a first end of the first switch tube is connected to the output end of the second voltage monitoring unit, and a second end of the first switch tube is connected to ground.

[0014] Optionally, the second voltage monitoring unit includes a third resistor, a fourth resistor and a second capacitor, the first end of the third resistor is connected to the voltage source of the second power supply winding, the second end of the third resistor is connected to the ground through the fourth resistor, the second capacitor is connected in parallel with the fourth resistor, and the second end of the third resistor is also connected to the input end of the voltage discharge unit and the switch control unit, respectively.

[0015] Optionally, the voltage discharge unit includes a fifth resistor and a second switch tube, the control end of the second switch tube is connected to the output end of the second voltage monitoring unit, the first end of the second switch tube is connected to the voltage source of the second power supply winding through the fifth resistor, and the second end of the second switch tube is connected to ground.

[0016] Optionally, the first switch tube is an NMOS tube, the control end of the first switch tube is a gate, the first end of the first switch tube is a drain, and the second end of the first switch tube is a source.

[0017] Optionally, the second switch tube is an NMOS tube, the control end of the second switch tube is a gate, the first end of the second switch tube is a drain, and the second end of the second switch tube is a source.

[0018] In the second aspect, the utility model also provides a power-on timing control circuit, which is used for a first power supply winding and a second power supply winding, and the power-on timing is that the first power supply winding is powered on before the second power supply winding. The power-on timing control circuit includes a first resistor, a second resistor, a first capacitor, a first switch tube, a third resistor, a fourth resistor, a second capacitor, a fifth resistor and a second switch tube. The first end of the first resistor is connected to the voltage source of the first power supply winding, the second end of the first resistor is connected to the ground through the second resistor, the first capacitor is connected to the second resistor in parallel, and the second end of the first resistor is also connected to the control end of the first switch tube. The first end of the third resistor is connected to the voltage source of the second power supply winding, the second end of the third resistor is connected to the ground through the fourth resistor, the second capacitor is connected to the fourth resistor in parallel, and the second end of the third resistor is also connected to the control end of the second switch tube and the first end of the first switch tube respectively. The first end of the second switch tube is connected to the voltage source of the second power supply winding through the fifth resistor, and the second end of the first switch tube and the second end of the second switch tube are both connected to the ground.

[0019] In a third aspect, the utility model further provides a power-on timing control circuit, which is used for a first power supply winding and a second power supply winding, and the power-on timing is that the first power supply winding is powered on before the second power supply winding, and the power-on timing control circuit includes a first voltage monitoring unit, a switch control unit, a second voltage monitoring unit and a voltage discharge unit;

[0020] The first voltage monitoring unit is used to monitor the voltage of the first power supply winding to obtain a first voltage, and turn on the switch control unit when the first voltage reaches a first voltage threshold;

[0021] The switch control unit is configured to clamp the output terminal of the second voltage monitoring unit to a low level when the first voltage reaches a first voltage threshold;

[0022] The second voltage monitoring unit is used to monitor the voltage of the second power supply winding to obtain a second voltage;

[0023] The voltage discharge unit is used to discharge the voltage of the voltage source of the second power supply winding when the first voltage is less than the first voltage threshold and the second voltage is greater than the second voltage threshold.

[0024] Compared with the prior art, the utility model has the following advantages and beneficial effects:

[0025] 1) The power-on timing control circuit of the utility model uses a switch control unit and a voltage discharge unit to discharge the voltage of the second power supply winding of the subsequent stage while waiting for the first power supply winding that needs to be powered on first to be powered on, so that it is powered on later than the first power supply winding, thereby realizing the normal startup logic of the product; and the timing control circuit of the utility model cleverly uses the characteristics of the auxiliary power supply system with low power and overcurrent protection, and can use the discharge resistors with different resistance values ​​in the voltage discharge unit to clamp the lagging voltage source at a certain level;

[0026] 2) The power-on timing control circuit between the auxiliary power supply windings of the utility model can be used between two auxiliary power supply systems, and can also be used between different power supply windings of the same auxiliary power supply system. Therefore, it is flexible to use and can be changed according to actual needs;

[0027] 3) The power-on timing control circuit between the auxiliary power supply windings proposed by the utility model has a wide application range and can be used in one power supply system or in multiple power supply systems. The circuit of the utility model is only a bottom unit and can be flexibly increased and configured according to the actual system;

[0028] 4) The power-on timing control circuit of the utility model does not require a digital control chip such as an MCU or a DSP, nor does it require a separate voltage source for power supply. When the system auxiliary power supply is powered on, the control circuit can start to work normally, so it has strong compatibility and a wide range of applications. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 This is a circuit schematic diagram of a power-on timing control circuit of the utility model;

[0030] Figure 2 This is a schematic diagram of a first engineering application of a power-on timing control circuit embodiment of the utility model;

[0031] Figure 3 This is a second engineering application schematic diagram of a power-on timing control circuit embodiment of the utility model. DETAILED DESCRIPTION

[0032] In order to make the technical solutions and advantages of the present invention more clear, the present invention will be described in further detail below with reference to the accompanying drawings.

[0033] In the prior art, the difficulty in designing a power-on timing control circuit is:

[0034] 1) Make reasonable use of the topological characteristics of the auxiliary power supply, i.e., low power and low current, and integrate these characteristics into the control circuit;

[0035] 2) How to ensure the compatibility of the power-on sequence circuit? When the system covers multiple windings or multiple power supply systems, how to control the power-on sequence?

[0036] 3) How can the power-on sequence circuit be reliable and effective without false triggering after the product is operating normally?

[0037] refer to Figure 1 An embodiment of the utility model provides a power-on timing control circuit for a first power supply winding and a second power supply winding, and the power-on timing is that the first power supply winding is powered on before the second power supply winding, wherein the first power supply winding and the second power supply winding can be power supply windings in two independent power supply systems with isolated power supply, or can be two different secondary windings of the same auxiliary power supply.

[0038] The power-on timing control circuit includes a first voltage monitoring unit 100, a switch control unit 200, a second voltage monitoring unit 300 and a voltage discharge unit 400;

[0039] The first voltage monitoring unit 100 is used to monitor the voltage of the first power supply winding, obtain a first voltage, and turn on the switch control unit 200 when the first voltage reaches a first voltage threshold; the output end of the first voltage monitoring unit 100 is connected to the input end of the switch control unit 200;

[0040] The switch control unit 200 is used to clamp the output end of the second voltage monitoring unit 300 to a low level when the first voltage reaches a first voltage threshold; the switch control unit 200 is connected to the output end of the second voltage monitoring unit 300;

[0041] The second voltage monitoring unit 300 is used to monitor the voltage of the second power supply winding to obtain a second voltage; the output end of the second voltage monitoring unit 300 is connected to the first input end of the voltage discharge unit 400.

[0042] The voltage discharge unit 400 is used to turn on and discharge the voltage of the voltage source of the second power supply winding when the first voltage is less than the first voltage threshold and the second voltage is greater than the second voltage threshold; the second input end of the voltage discharge unit 400 is connected to the voltage source of the second power supply winding.

[0043] In this embodiment, the voltage source that is powered on first is connected to the first voltage monitoring unit 100. When the input voltage reaches the first voltage threshold of the voltage monitoring unit, the switch control unit 200 will be turned on to clamp the voltage in the second voltage monitoring unit 300 to a low level, and the voltage discharge unit 400 will not work. Therefore, at this time, the voltage source of the second power supply winding that is powered on later will not be discharged and pulled down by the voltage discharge unit 400, and its normal input is maintained, so that the first power supply winding that is powered on first is powered on first, and the second power supply winding that is powered on later can be powered on; conversely, if the voltage source that is powered on first has not reached the set value of the first voltage monitoring unit 100, the switch control unit 200 will not work. It will work. At this time, if the monitoring value of the second voltage monitoring unit 300 reaches the second voltage threshold, that is, the base voltage in the voltage discharge unit 400 reaches its start-up voltage, it will start to discharge the input voltage monitored by the second voltage monitoring unit 300 through the voltage discharge unit 400. If the voltage monitored by the first monitoring unit 100 has not reached the first voltage threshold at this time, the second voltage monitoring unit 300 and the voltage discharge unit 400 will continue to work, and the voltage of the voltage source of the second power supply winding that is powered on later will be maintained in a dynamic balance, and its level will always be in a state where the back-end load cannot work normally, waiting for the value of the priority power-on voltage source to reach the first voltage threshold of the first voltage detection unit 100. The voltage of the voltage source of the lagging second power supply winding is clamped at a certain level, so that the product cannot be turned on and work until the normal power-on logic of the product is met.

[0044] In one embodiment, the first voltage monitoring unit 100 includes a first resistor R1, a second resistor R2 and a first capacitor C1, the first end of the first resistor R1 is connected to the voltage source of the first power supply winding, the second end of the first resistor R1 is connected to the ground through the second resistor R2, the first capacitor C1 is connected in parallel with the second resistor R2, and the second end of the first resistor R1 is also connected to the input end of the switch control unit 200.

[0045] In one embodiment, the switch control unit 200 includes a first switch tube Q1, a control end of the first switch tube Q1 is connected to the output end of the first voltage monitoring unit 100, a first end of the first switch tube Q1 is connected to the output end of the second voltage monitoring unit 300, and a second end of the first switch tube Q1 is connected to ground.

[0046] It should be noted that the switch tube in the embodiment of the present application may be one or more of a variety of switch tubes such as a metal oxide semiconductor field effect transistor (MOSFET), a bipolar junction transistor (BJT), an insulated gate bipolar transistor (IGBT), a gallium nitride field effect transistor (GaN), a silicon carbide (SiC) power tube, etc., and the embodiment of the present application will not list them one by one. Each switch tube may include a first end, a second end and a control end, wherein the control end is used to control the conduction or disconnection of the switch tube. When the switch tube is turned on, current can be transmitted between the first end and the second end of the switch tube, and when the switch tube is turned off, current cannot be transmitted between the first end and the second end of the switch tube. Taking MOSFET as an example, the control end of the switch tube is the gate, the first end of the switch tube may be the source of the switching device, and the second end may be the drain of the switch tube, or the first end may be the drain of the switch tube, and the second end may be the source of the switch tube.

[0047] In this embodiment, the first switch tube Q1 is an NMOS tube, the control end of the first switch tube Q1 is a gate, the first end of the first switch tube Q1 is a drain, and the second end of the first switch tube Q1 is a source.

[0048] In one embodiment, the second voltage monitoring unit 300 includes a third resistor R1, a fourth resistor R4 and a second capacitor C2, the first end of the third resistor R1 is connected to the voltage source of the second power supply winding, the second end of the third resistor R1 is connected to the ground through the fourth resistor R4, the second capacitor C2 is connected to the fourth resistor R4 in parallel, and the second end of the third resistor R1 is also connected to the input end of the voltage discharge unit 400 and the switch control unit 200, respectively.

[0049] In one embodiment, the voltage discharge unit 400 includes a fifth resistor R5 and a second switch tube Q2, the control end of the second switch tube Q2 is connected to the output end of the second voltage monitoring unit 300, the first end of the second switch tube Q2 is connected to the voltage source of the second power supply winding through the fifth resistor R5, and the second end of the second switch tube Q2 is connected to the ground. The second switch tube Q2 is an NMOS tube, the control end of the second switch tube Q2 is a gate, the first end of the second switch tube Q2 is a drain, and the second end of the second switch tube Q2 is a source.

[0050] In this embodiment, the voltage discharge unit 400 can clamp the voltage of the voltage source of the lagging second power supply winding at a certain level by designing discharge resistors with different powers and different resistance values, namely the fifth resistor R5, which cannot cause the product to over-work when it is turned on.

[0051] In addition, an embodiment of the utility model also provides a power-on timing control circuit, which is used for a first power supply winding and a second power supply winding, and the power-on timing is that the first power supply winding is powered on before the second power supply winding. The power-on timing control circuit includes a first resistor, a second resistor, a first capacitor, a first switch tube, a third resistor, a fourth resistor, a second capacitor, a fifth resistor and a second switch tube. The first end of the first resistor is connected to the voltage source of the first power supply winding, the second end of the first resistor is connected to the ground through the second resistor, the first capacitor is connected to the second resistor in parallel, and the second end of the first resistor is also connected to the control end of the first switch tube. The first end of the third resistor is connected to the voltage source of the second power supply winding, the second end of the third resistor is connected to the ground through the fourth resistor, the second capacitor is connected to the fourth resistor in parallel, and the second end of the third resistor is also connected to the control end of the second switch tube and the first end of the first switch tube respectively. The first end of the second switch tube is connected to the voltage source of the second power supply winding through the fifth resistor, and the second end of the first switch tube and the second end of the second switch tube are both connected to the ground.

[0052] The working principle of this embodiment is consistent with that of the above embodiment, and will not be described in detail here.

[0053] In addition, an embodiment of the utility model further provides a power-on timing control circuit, which is used for a first power supply winding and a second power supply winding, and the power-on timing is that the first power supply winding is powered on before the second power supply winding, and the power-on timing control circuit includes a first voltage monitoring unit, a switch control unit, a second voltage monitoring unit and a voltage discharge unit;

[0054] The first voltage monitoring unit is used to monitor the voltage of the first power supply winding to obtain a first voltage, and turn on the switch control unit when the first voltage reaches a first voltage threshold;

[0055] The switch control unit is configured to clamp the output terminal of the second voltage monitoring unit to a low level when the first voltage reaches a first voltage threshold;

[0056] The second voltage monitoring unit is used to monitor the voltage of the second power supply winding to obtain a second voltage;

[0057] The voltage discharge unit is used to discharge the voltage of the voltage source of the second power supply winding when the first voltage is less than the first voltage threshold and the second voltage is greater than the second voltage threshold.

[0058] The working principle of this embodiment is consistent with that of the above embodiment, and will not be described in detail here.

[0059] In another embodiment, if Figure 2 As shown, Figure 2 In order to apply the power-on timing control circuit between the primary winding power supply Vcc windings of two different flyback power supplies, the flyback power supply Vcc_2 can work normally only when the flyback power supply Vcc_1 works normally.

[0060] In yet another embodiment, Figure 3 As shown, Figure 3 In order to apply the power-on timing control circuit between different power supply windings on the secondary side of the same counter-power supply, it is realized that when winding one is powered on, the rear-end load of winding two can be normally powered to a normal level.

[0061] The above-mentioned implementation examples of the utility model are merely examples for explaining the utility model, and are not intended to limit the implementation methods of the utility model. For ordinary technicians in the relevant field, other different forms of changes and modifications can be made on the basis of the above description. It is impossible to list all the implementation methods here. Any obvious changes or modifications derived from the technical solution of the utility model are still within the scope of protection of the utility model.

Claims

1. A power-on timing control circuit, used for a first power supply winding and a second power supply winding, wherein the power-on timing is that the first power supply winding is powered on before the second power supply winding, characterized in that: The power-on timing control circuit includes a first voltage monitoring unit, a switch control unit, a second voltage monitoring unit and a voltage discharge unit; The first voltage monitoring unit is used to monitor the voltage of the first power supply winding, obtain a first voltage, and turn on the switch control unit when the first voltage reaches a first voltage threshold; the output end of the first voltage monitoring unit is connected to the input end of the switch control unit; The switch control unit is used to clamp the output end of the second voltage monitoring unit to a low level when the first voltage reaches a first voltage threshold; the switch control unit is connected to the output end of the second voltage monitoring unit; The second voltage monitoring unit is used to monitor the voltage of the second power supply winding to obtain a second voltage; the output end of the second voltage monitoring unit is connected to the first input end of the voltage discharge unit; The voltage discharge unit is used to be turned on when the first voltage is less than the first voltage threshold and the second voltage is greater than the second voltage threshold, so as to discharge the voltage of the voltage source of the second power supply winding; the second input end of the voltage discharge unit is connected to the voltage source of the second power supply winding.

2. A power-on timing control circuit according to claim 1, characterized in that: The first voltage monitoring unit includes a first resistor, a second resistor and a first capacitor, the first end of the first resistor is connected to the voltage source of the first power supply winding, the second end of the first resistor is connected to the ground through the second resistor, the first capacitor is connected in parallel with the second resistor, and the second end of the first resistor is also connected to the input end of the switch control unit.

3. A power-on timing control circuit according to claim 1, characterized in that: The switch control unit includes a first switch tube, a control end of the first switch tube is connected to the output end of the first voltage monitoring unit, a first end of the first switch tube is connected to the output end of the second voltage monitoring unit, and a second end of the first switch tube is connected to ground.

4. The power-on timing control circuit according to claim 1, characterized in that: The second voltage monitoring unit includes a third resistor, a fourth resistor and a second capacitor, the first end of the third resistor is connected to the voltage source of the second power supply winding, the second end of the third resistor is connected to the ground through the fourth resistor, the second capacitor is connected in parallel with the fourth resistor, and the second end of the third resistor is also connected to the input end of the voltage discharge unit and the switch control unit, respectively.

5. The power-on timing control circuit according to claim 1, characterized in that: The voltage discharge unit includes a fifth resistor and a second switch tube, the control end of the second switch tube is connected to the output end of the second voltage monitoring unit, the first end of the second switch tube is connected to the voltage source of the second power supply winding through the fifth resistor, and the second end of the second switch tube is connected to the ground.

6. A power-on timing control circuit according to claim 3, characterized in that: The first switch tube is an NMOS tube, the control end of the first switch tube is a gate, the first end of the first switch tube is a drain, and the second end of the first switch tube is a source.

7. A power-on timing control circuit according to claim 5, characterized in that: The second switch tube is an NMOS tube, the control end of the second switch tube is a gate, the first end of the second switch tube is a drain, and the second end of the second switch tube is a source.

8. A power-on timing control circuit, used for a first power supply winding and a second power supply winding, wherein the power-on timing is that the first power supply winding is powered on before the second power supply winding, characterized in that: The power-on timing control circuit includes a first resistor, a second resistor, a first capacitor, a first switch tube, a third resistor, a fourth resistor, a second capacitor, a fifth resistor and a second switch tube. The first end of the first resistor is connected to the voltage source of the first power supply winding, the second end of the first resistor is connected to the ground through the second resistor, the first capacitor is connected in parallel with the second resistor, the second end of the first resistor is also connected to the control end of the first switch tube, the first end of the third resistor is connected to the voltage source of the second power supply winding, the second end of the third resistor is connected to the ground through the fourth resistor, the second capacitor is connected in parallel with the fourth resistor, the second end of the third resistor is also connected to the control end of the second switch tube and the first end of the first switch tube respectively, the first end of the second switch tube is connected to the voltage source of the second power supply winding through the fifth resistor, and the second end of the first switch tube and the second end of the second switch tube are both connected to the ground.

9. A power-on timing control circuit, used for a first power supply winding and a second power supply winding, wherein the power-on timing is that the first power supply winding is powered on before the second power supply winding, characterized in that: The power-on timing control circuit includes a first voltage monitoring unit, a switch control unit, a second voltage monitoring unit and a voltage discharge unit; The first voltage monitoring unit is used to monitor the voltage of the first power supply winding to obtain a first voltage, and turn on the switch control unit when the first voltage reaches a first voltage threshold; The switch control unit is configured to clamp the output terminal of the second voltage monitoring unit to a low level when the first voltage reaches a first voltage threshold; The second voltage monitoring unit is used to monitor the voltage of the second power supply winding to obtain a second voltage; The voltage discharge unit is used to discharge the voltage of the voltage source of the second power supply winding when the first voltage is less than the first voltage threshold and the second voltage is greater than the second voltage threshold.

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