CN110837287B

CN110837287B - Restart circuit

Info

Publication number: CN110837287B
Application number: CN201910987849.5A
Authority: CN
Inventors: 尹显泓; 王国云; 冯刚
Original assignee: Mornsun Guangzhou Science and Technology Ltd
Current assignee: Mornsun Guangzhou Science and Technology Ltd
Priority date: 2019-10-17
Filing date: 2019-10-17
Publication date: 2021-03-02
Anticipated expiration: 2039-10-17
Also published as: CN110837287A

Abstract

The invention provides a restart circuit which is used for controlling a power supply module to be quickly restarted. The restarting circuit can automatically turn off the control IC after detecting that the power supply power module is undervoltage or the CTRL pin is turned off, so that the IC can be initialized immediately after being turned on and turned off frequently and the CTRL pin is turned off, and the IC is prevented from entering a protection state, thereby avoiding the problem that the restarting time sequence is different from the first starting time sequence. The circuit has the advantages of high precision, high reliability, low temperature drift, simple circuit design, realization without a voltage-stabilizing power supply circuit and cost reduction.

Description

Restart circuit

Technical Field

The invention relates to the field of switching power supplies, in particular to a restart circuit.

Background

In the application of the switching power supply, a CTRL pin is usually used for remotely controlling the on and off of the switching power supply, or the frequent on and off of the switching power supply is controlled by frequent actions of an input voltage.

In the application of controlling the switching power supply to be frequently turned on and off through the frequent action of the input voltage, when the input is powered off, the switching power supply cannot immediately stop working due to the residual charge of the input capacitor. At this time, the energy of the input capacitor is still transmitted to the output load by the switching power supply, and the voltage of the input capacitor drops sharply. Before the voltage of the input capacitor is reduced to the threshold value of the undervoltage protection, the switching power supply cannot stop working; when the residual voltage of the input capacitor is reduced to an undervoltage protection point, the main power circuit of the switching power supply stops working, and the energy of the input capacitor is not transmitted to the output load any more and only consumed by the IC power supply circuit. Since the power consumption of the IC power supply circuit is very small compared to the main power circuit, the input capacitor residual voltage remains relatively high and decreases very slowly. When the computer is frequently turned on and off, the undervoltage detection pin of the IC enters an undervoltage protection state, and the power supply pin of the IC is still sufficient in voltage, so that the internal logic of the IC can enter a protection mode. Usually, after the under-voltage protection pin recovers under voltage, the IC outputs the duty ratio again after a certain timing protection period or after delayed blanking, and the main power circuit works again. If the interval of the startup and shutdown is long enough for undervoltage protection of the undervoltage protection pin, the IC power supply pin continues to consume the residual voltage of the input capacitor completely, after the IC stops working, the IC is shut down, the internal logic is initialized by restarting, and the restart delay is normal. Therefore, the application has the problems of too long time and inconsistent time sequence with the first startup.

In the application of using the CTRL pin to remotely control the power on and off, a general specific implementation method is to pull down the under-voltage protection pin of the main control IC, so that the under-voltage protection pin enters an under-voltage protection state. At the moment, the input voltage is unchanged, the power supply of the main control IC is still sufficient, and the interior of the IC can enter an undervoltage protection mode. When the CTRL pin returns to the high level, the undervoltage protection also returns, and after a long protection period (generally 0 to 2 seconds), the IC outputs the duty cycle again, and the main power circuit resumes operation. The application has a problem that the restart delay time is too long.

In the above two applications, the start-up delay is long (usually between 0S and 2S, and the start-up delay should normally be in the order of tens of milliseconds at the first time of start-up), and the power-on timing is different from the timing at the first time of start-up. In order to solve the problems of long restarting time and inconsistent time sequence in the application of the two switching power supplies, the design optimization is made, so that the restarting speed is greatly improved and is improved from the second order of magnitude to the millisecond order of magnitude.

Disclosure of Invention

In view of the above, the present invention provides a restart circuit, which utilizes an IC design with an under-voltage protection function to solve the problem of a delay time of a restart time of a switching power supply. Meanwhile, the circuit is realized without power supply of a voltage stabilizing circuit, has a built-in reference voltage source, and is convenient to design and use and low in cost. Compared with the design of using the operational amplifier, a plurality of peripheral circuits can be saved, and the cost is low.

The invention is realized by the following technical scheme:

a restart circuit comprises a first diode D1, a second diode D2, a third diode D3, a first integrated circuit IC1, a first switching tube Q1, a first resistor R1, a second resistor R2, a fourth resistor R4, a fifth resistor R5, a Vin pin port, a CTRL pin port and a Vcc auxiliary power supply control port;

the cathode of the third diode D3 is connected to the CTRL pin, and the anode of the third diode D3, one end of the first resistor R1, and one end of the second resistor R2 are connected, and the connection point is electrically connected to the reference terminal of the first integrated circuit IC 1; one end of the fourth resistor R4 is connected with the cathode of the first integrated circuit IC 1; the base electrode of the first switch tube Q1 is connected with the connection point of one end of the fourth resistor R4 and the cathode of the first integrated circuit IC1, the collector electrode of the first switch tube Q1 is connected with the Vcc auxiliary power supply control port, and the emitter electrode of the first switch tube Q1 is connected with the cathode of the second diode D2; one end of a fifth resistor R5 is connected with one end of a third resistor R3, the other end of the fifth resistor R5 is connected with the cathode of a first diode D1, and the anode of the first diode D1 is connected with the Vcc auxiliary power supply control port; the other end of the first resistor R1 and the other end of the fourth resistor R4 are connected with a Vin pin port; the anode of the second diode D2, the other end of the second resistor R2, and the anode of the first integrated circuit IC1 are grounded.

Preferably, the first integrated circuit IC1 is a precision tunable reference voltage source integrated circuit TL 431.

Preferably, the first integrated circuit IC1 is a precision tunable reference voltage source integrated circuit AZ 431.

Preferably, the first switching tube Q1 is a triode or a MOS tube.

Preferably, the second diode D2 is a zener diode.

Preferably, the device further comprises a third resistor R3, one end of the third resistor R3 is connected to the anode of the third diode D3, a connection point between one end of the first resistor R1 and one end of the second resistor R2, and the other end of the third resistor R3 is connected to the reference end of the first integrated circuit IC 1.

Preferably, the second diode D2 is replaced by a sixth resistor R6.

Preferably, the circuit further comprises a first capacitor C1, one end of the first capacitor C1 is connected to the base of the first switch Q1, and the other end of the first capacitor C1 is grounded.

Preferably, the device further comprises a second capacitor C2, one end of the second capacitor C2 is connected to the anode of the third diode D3, a connection point between one end of the first resistor R1 and one end of the second resistor R2, and the other end of the second capacitor C2 is connected to the other end of the second resistor R2.

Interpretation of terms:

electrically coupling: the connection mode includes direct or indirect connection, and also includes connection modes such as inductive coupling, for example, the connection mode described in the present invention is "the anode of the third diode D3, one end of the first resistor R1 and one end of the second resistor R2 are connected, and the connection point is electrically connected with the reference end of the first integrated circuit IC 1", and is direct connection, and when the third resistor R3 is further connected between the connection point and the reference end of the first integrated circuit IC1, the connection mode belongs to indirect connection.

The working principle of the scheme provided by the invention is explained in detail in the specific embodiment, and the working principle of the scheme is integrated, so that the defects in the prior art are overcome, and the scheme has the following beneficial effects:

the invention can automatically turn off the control IC after detecting that the power supply power module is undervoltage or the CTRL pin is turned off, so that the IC can be initialized immediately after being frequently turned on and turned off and the CTRL pin is turned off, and the IC is prevented from entering a protection state, thereby preventing the restart time sequence from being different from the time sequence of the first startup;

the circuit has the advantages of high precision, high reliability, low temperature drift, simple circuit design, realization without a voltage-stabilizing power supply circuit and cost reduction.

Drawings

FIG. 1 is a timing diagram of input and output voltages of a fast restart circuit;

FIG. 2 is a schematic diagram of an embodiment of the present invention;

FIG. 3 is a schematic diagram of a second embodiment of the present invention;

fig. 4 is a timing diagram of the input voltage and output voltage of the fast restart circuit.

DETAILED DESCRIPTION OF EMBODIMENT (S) OF INVENTION

Example one

Fig. 2 shows a schematic diagram of a first embodiment of the invention. The restart circuit comprises a first diode D1, a second diode D2, a third diode D3, a first integrated circuit IC1, a first switching tube Q1, a first resistor R1, a second resistor R2, a third resistor R3, a fourth resistor R4, a fifth resistor R5, a Vin pin port, a CTRL pin port and a Vcc auxiliary power supply control port;

the cathode of the third diode D3 is connected with the CTRL pin, the anode of the third diode D3, one end of the first resistor R1, one end of the second resistor R2 and one end of the third resistor R3 are connected with each other, and four ports are connected with each other; the other end of the first resistor R1 is connected with a Vin pin port, the other end of the second resistor R2 is grounded, the other end of the third resistor R3 is connected with a reference end of a first integrated circuit IC1, one end of the fourth resistor R4 is connected with the Vin pin port, the other end of the fourth resistor R4 is connected with a cathode of the first integrated circuit IC1, and an anode of the first integrated circuit IC1 is grounded; one end of a fifth resistor R5 is connected with one end of a third resistor R3, the other end of the fifth resistor R5 is connected with the cathode of a first diode D1, and the anode of the first diode D1 is connected with the Vcc auxiliary power supply control port; the base of the first switch tube Q1 is connected to the connection point of the other end of the fourth resistor R4 and the cathode of the first integrated circuit IC1, the collector of the first switch tube Q1 is connected to the Vcc auxiliary power supply control port, the emitter of the first switch tube Q1 is connected to the cathode of the second diode D2, and the anode of the second diode D2 is grounded.

The specific working principle of the embodiment is as follows:

when the input voltage is powered down or the CTRL pin is at a low level, the output of the power module is cut off. The voltage sampled by the first resistor R1 and the second resistor R2 will decrease, resulting in a decrease in the voltage at the reference terminal of the first IC 1. Since the voltage of the reference terminal of the first integrated circuit IC1 is lower than the internal reference voltage, the cathode and the anode of the first integrated circuit IC1 assume an open state, and the potential at the V2 point becomes a high potential. When the voltage V2 goes high, the first switch Q1 is controlled to turn on, pulling the Vcc auxiliary power control port low. The Vcc auxiliary power control port supplies Vdd power to the master IC, so the master IC will be turned off due to insufficient Vdd power and will not enter the under-voltage protection mode.

When the input voltage rapidly rises above the threshold voltage or CTRL is high again, the voltage sampled by the first and second resistors R1 and R2 will increase, resulting in an increase in the voltage at the reference terminal of the first integrated circuit IC 1. Because the voltage of the reference end of the first integrated circuit IC1 is higher than the internal reference voltage, the cathode and the anode of the first integrated circuit IC1 are in a short-circuit state, the potential of the V2 point becomes low potential, and further the first switching tube is controlled to be turned off, the Vcc auxiliary power supply control port can be restored to about 12V designed for voltage stabilization, and the Vdd power supply of the main control IC is ensured to be normal.

The master IC has also stopped working after the last power main was turned off. When the computer is started again, the IC is equivalent to reinitialization power-on, so that the condition that the computer enters an undervoltage protection mode is avoided. The quick restart of the power module after the CTRL is closed and the input voltage is in power failure is realized. The timing diagrams of the input voltage and the output voltage of the power module without the circuit are shown in fig. 1, and the timing diagrams of the input voltage and the output voltage of the power module with the circuit are shown in fig. 4, so that the delay of the startup timing sequence is obviously reduced.

Example two

As shown in fig. 3, a schematic circuit diagram of a second embodiment of the present invention is different from the first embodiment in that: the two ends of the second resistor R2 are connected with the second capacitor in parallel, and the control end of the first switch tube Q1 is connected with the first capacitor in parallel, so that the anti-interference capability of the circuit such as false triggering and oscillation in dynamic overshoot can be improved. Meanwhile, the second diode D2 is replaced by the sixth resistor R6, so as to pull the Vcc auxiliary power control port low, and still achieve the same effect as the first embodiment. Other specific working principles are the same as those of the first embodiment.

The embodiments of the present invention are not limited thereto, and according to the above-mentioned contents of the present invention, the specific implementation circuit of the present invention can be modified, replaced or changed in various other forms without departing from the basic technical idea of the present invention.

Claims

1. A restart circuit, characterized in that: the circuit comprises a first diode D1, a second diode D2, a third diode D3, an adjustable reference voltage source integrated circuit, a first switch tube Q1, a first resistor R1, a second resistor R2, a fourth resistor R4, a fifth resistor R5, a Vin pin port, a CTRL pin port and a Vcc auxiliary power supply control port;

the cathode of the third diode D3 is connected with the CTRL pin, the anode of the third diode D3, one end of the first resistor R1 and one end of the second resistor R2 are connected, and the connection point is electrically connected with the reference end of the adjustable reference voltage source integrated circuit; one end of a fourth resistor R4 is connected with the cathode of the adjustable reference voltage source integrated circuit; the base electrode of the first switch tube Q1 is connected with the connection point of one end of the fourth resistor R4 and the cathode of the adjustable reference voltage source integrated circuit, the collector electrode of the first switch tube Q1 is connected with the Vcc auxiliary power supply control port, and the emitter electrode of the first switch tube Q1 is connected with the cathode of the second diode D2; one end of a fifth resistor R5 is connected with one end of a third resistor R3, the other end of the fifth resistor R5 is connected with the cathode of a first diode D1, and the anode of the first diode D1 is connected with the Vcc auxiliary power supply control port; the other end of the first resistor R1 and the other end of the fourth resistor R4 are connected with a Vin pin port; the anode of the second diode D2, the other end of the second resistor R2 and the anode of the adjustable reference voltage source integrated circuit are grounded.

2. The restart circuit of claim 1, wherein: the adjustable reference voltage source integrated circuit is a precision adjustable reference voltage source integrated circuit TL 431.

3. The restart circuit of claim 1, wherein: the adjustable reference voltage source integrated circuit is a precise adjustable reference voltage source integrated circuit AZ 431.

4. The restart circuit of claim 1, wherein: the first switching tube Q1 is a triode or a MOS transistor.

5. The restart circuit of claim 1, wherein: the second diode D2 is a zener diode.

6. The restart circuit of claim 1, wherein: the voltage regulator further comprises a third resistor R3, one end of a third resistor R3 is connected with the anode of the third diode D3, one end of the first resistor R1 is connected with a connection point of one end of the second resistor R2, and the other end of the third resistor R3 is connected with a reference end of the adjustable reference voltage source integrated circuit.

7. The restart circuit of claim 1, wherein: the second diode D2 is replaced by a sixth resistor R6.

8. The restart circuit of claim 1, wherein: the circuit also comprises a first capacitor C1, one end of the first capacitor C1 is connected with the base electrode of the first switch tube Q1, and the other end of the first capacitor C1 is grounded.

9. The restart circuit of claim 1, wherein: the LED driving circuit further comprises a second capacitor C2, one end of the second capacitor C2 is connected with the anode of the third diode D3, a connection point of one end of the first resistor R1 and one end of the second resistor R2, and the other end of the second capacitor C2 is connected with the other end of the second resistor R2.