KR100277045B1 - Circuit and component protection device in case of short circuit of switching power supply - Google Patents

Abstract

The present invention relates to a circuit and a component protection device for an output short circuit of a switching power supply for switching power supply (SMPS), in particular, to accurately detect a short signal from multiple output voltages and to prevent damage to circuits and components that occur during an output short circuit. will be.

Conventionally, there is no means to prevent a malfunction due to a momentary short circuit because the switching output voltage is cut off even if the output of the switching power supply is momentarily shorted or a short circuit occurs due to a malfunction. Since there is no means to prevent malfunctions in the production process or oversight, there is a problem of reducing the reliability of the output short circuit protection function of the switching power supply.

In order to solve the above problem, the present invention compares the multiple output voltages of the switching power supplies with a predetermined reference voltage to detect the presence of a short circuit, delays the detected short circuit signal for a predetermined time, and then generates a short circuit according to the level of the signal. Prevents malfunction of the short-circuit protection function and precisely controls the input power supply voltage of the switching power supply, and includes means for enabling or disabling the short-circuit protection function by a microcomputer or an external control signal. It is easy to cope with multiple output of switching power supply, prevent damage and malfunction of parts due to short circuit and enable external control.

Description

Circuit and component protection device in case of output short of switching power supply

The present invention relates to a circuit and a component protection device for an output short circuit of a switching power supply for switching power supply (SMPS), in particular, to accurately detect a short signal from multiple output voltages and to prevent damage to circuits and components that occur during an output short circuit. will be.

As shown in FIG. 1, the circuit and component protection devices in the output short circuit of the conventional switching power supply are

A bridge diode BD1 and a capacitor C1 for rectifying and smoothing the input AC power and outputting the DC power, and the DC power supply are connected to an auxiliary winding of a transformer T1 to supply power to the power control unit 2. A start-up circuit 1 for supplying, a power supply control unit 2 for outputting a driving signal for controlling the output voltage Vo of the switching power supply, and a transistor for switching on and off by the driving signal of the power supply control unit 2; (Q1), the transformer (T1) for converting the DC voltage by the switching of the transistor (Q1) to output to the load-side output voltage (Vo), and the output voltage (Vo) of the transformer (T1) internal reference voltage ( And a comparator 3 for outputting a comparison result output short-circuit signal to the power supply control unit 2 in comparison with Vref).

Reference numerals R1 and R2 are resistors.

Referring to the operation of the circuit and the component protection device when the output short circuit of the conventional switching power supply is configured as described above are as follows.

First, when the input AC power is rectified and smoothed by the bridge diode BD1 and the condenser C1, and then input to the primary side of the transformer T1 and the starter circuit 1 with DC power, the starter circuit 1 It is connected to the auxiliary winding of the transformer (T1) receives the DC power to supply power to the power control unit 2 to drive the power control unit (2).

Then, the power supply control unit 2 outputs a drive signal to the base of the transistor Q1 to drive the transistor Q1 on and off, and to the primary side of the transformer T1 in accordance with the driving of the transistor Q1. The DC power applied is converted into the voltage Vo required for the load and output.

When the switching output voltage Vo of the transformer T1 is short-circuited, the comparator 3 receiving the signal according to the short circuit of the switching output voltage Vo to the inverting terminal (-) has an internal reference voltage Vref. As a result, the resultant signal is output to the power control unit 2 to cut off the power supplied from the starter circuit 1.

Therefore, since the power supply of the power supply control unit 2 is cut off, the transistor Q1 is turned off, and the switching output voltage Vo of the transformer T1 is cut off due to the off of the transistor Q1.

Therefore, the circuit according to the output voltage Vo short of the switching power supply is disconnected by detecting the low voltage according to the output voltage Vo short of the transformer T1 using the comparator 3 and cutting off the output voltage Vo. It is to protect.

However, conventionally, since the switching output voltage is cut off even if the output voltage of the transformer is momentarily shorted or shorted due to a malfunction, there is no means for preventing the instantaneous malfunction of the switching output voltage. Since there is no means for controlling directly, malfunctions can not be prevented in the production process or over-the-counter, thereby reducing the reliability of the output short-circuit protection function of the switching power supply.

In order to solve the above problems, the present invention compares the multiple output voltage of a switching power supply with a predetermined reference voltage to accurately detect a short circuit signal, delays the detected short circuit signal for a predetermined time, and then switches the switching power supply according to the level of the signal. It prevents the short circuit protection function from occurring due to the instantaneous short circuit of the switching output voltage, and activates or stops the short circuit protection function of the switching output voltage by a microcomputer or an external control signal. It is possible to prevent the malfunction of the short-circuit protection function from the instantaneous short-circuit and to allow the external short-circuit protection function to be controlled externally to give the user reliability.

1 is a configuration diagram showing a configuration of a short circuit protection device of a conventional switching power supply.

2 is a block diagram of a circuit and a component protection device at the output short circuit of the switching power supply (SMPS) of the present invention

Figure 3 is a detailed block circuit diagram showing an embodiment of a circuit and component protection device in the output short circuit of the present invention switching power supply

4 (a) to (i) are each sub-output waveform diagram of the circuit and the component protection device when the output of the switching power supply of the present invention.

As shown in FIG. 1, the circuit and component protection devices of the switching power supply (SMPS) of the present invention for achieving the above object are short-circuited.

A reference voltage generating means (10) for making an input power supply voltage (Vcc) into a predetermined reference voltage (Vref),

Short-circuit signal detecting means 20 for comparing the reference voltage (Vref) and the multiple output voltages (Vo1 ~ Von) of the switching power supply to detect the signal (Vs) according to the output voltage short circuit, and

Short-circuit signal delay means 30 for outputting a predetermined signal Vp by delaying the detected short-circuit signal Vs for a predetermined time so as to prevent a malfunction of the short-circuit protection function from an instantaneous short-circuit of the switching output voltages Vo1 to Vo. and,

A latch means 40 for outputting a switching power supply control signal Vc for controlling the power supply voltage Vcc of the switching power supply driving means 50 in an operation state determined according to the delayed short signal Vp;

Switching power supply driving means 50 for controlling the driving of the switching power supply by the switching power supply control signal Vc of the latch means 40;

The short circuit protection control means 60 outputs a short circuit control signal Ve to the short signal delay means 30 according to a microcomputer or an external control signal Vi to activate or stop the short circuit protection function.

The reference voltage generating means 10 includes a reference voltage delay unit 11 for delaying the input voltage voltage Vcc and outputting it as a constant voltage Vcc1 and a delay caused by the reference voltage delay unit 11. The reference voltage generator 12 makes the voltage Vcc1 a predetermined level of the reference voltage Vref.

3 is a detailed circuit block diagram showing an embodiment of the present invention, the configuration of which is as follows.

The reference voltage delay unit 11 is composed of a resistor (R11) and a capacitor (C11) to integrate for the delay of the input power supply voltage (Vcc), the reference voltage generator 12 is a delayed voltage (Vcc1) A diode D11 and a capacitor C12 are provided to divide the resistors R12 and R13 into a reference voltage Vref of a predetermined level.

The short signal detecting means 20 receives an NPN transistor Q11 that is turned on and off in comparison with the emitter side potential by receiving a reference voltage Vref as a base, and an anode of the emitter of the transistor Q11. ) And a plurality of diodes Do1 to Don each having a switching output voltage Vo1 to Von connected to the cathode and outputting a short signal Vs through the collector when the transistor Q11 is turned on. A PNP transistor Q12 is provided.

The short-circuit signal delay means 30 emits a capacitor C13 for charging and discharging the short-circuit signal Vs, and a short-circuit signal Vp delayed for a predetermined time by operating on when the capacitor C13 is discharged. Is provided with a transistor Q13 for outputting

The latch means 40 may include a resistor R18 and a capacitor C15 for integrating the delayed short signal Vp, and a trigger if the level of the integrated short signal is equal to or greater than a threshold voltage Vth. And thyristor SCR1 for blocking the power supply voltage Vcc of the switching power supply driving means 50.

The switching power supply driving means 50 is connected to a transistor Q14 that is turned on and off by receiving a driving signal of the switching power supply, and is connected to a collector of the transistor Q14 to supply power by a switching power supply control signal Vc. Porter coupler (PC1) for controlling the operation of the controller 50a.

Reference numerals R14-R17 and R21-R24 denote resistors, D12 denotes diodes, and C14 denotes capacitors.

Referring to Figures 2 and 4 with respect to the circuit and component protection device when the output short circuit of the switching power supply of the present invention configured as described above is as follows.

First, when the power supply voltage Vcc is input as shown in FIG. 4A, the reference voltage generating means 10 delays the input power supply voltage Vcc by a predetermined time and detects a short circuit signal with a predetermined reference voltage Vref. Output to the means 20.

That is, the reference voltage delay unit 11 of the reference voltage generating unit 10 delays the input power supply voltage Vcc by a predetermined time and then uses the reference voltage generator unit as the delayed voltage Vcc1 as shown in FIG. 12), the delayed voltage Vcc1 is made to be a constant reference voltage Vref in the reference voltage generator 12 as shown in FIG.

Then, the short-circuit signal detecting means 20 compares the reference voltage Vref input from the reference voltage generating means 10 with the multiple output voltages Vo1 to Von of the switching power supply and then outputs the multiple output voltage Vo1 of the switching power supply. When a part of ˜Von is short-circuited, the short-circuit signal Vs according to the comparison result is detected in real time and output to the short-signal delay means 30. See (d) (e) of FIG. 4,

The short signal Vs detected by the short signal detection means 20 is input to the short signal delay means 30 to be delayed for a predetermined time, and the delayed short signal Vp is input to the latch means 40. See (a) of FIG.

Here, the short-circuit signal delay means 30 delays the short-circuit signal Vs for a predetermined time to determine whether the short-circuit signal Vs is in a set time range for short-circuit protection by accurately detecting the short-circuit time.

The latch means 40 outputs a switching power supply control signal Vc for controlling the operation of the switching power supply driving means 50 in an operation state determined by the short-circuit signal Vp delayed for a predetermined time. See, FIG. 4.

Here, when the switching output voltages Vo1 to Vo are momentarily shorted as shown by "t5 to t6" in FIG.

The instantaneous short signal Vs detected from the short signal detecting means 20 (see t5 to t6 in FIG. 4E) is a short signal Vp delayed for a predetermined time by the short signal delay means 30 ( (A) in Fig. 4 (t) through t6) is input to the latch means 40.

At this time, the short-circuit signal Vp delayed by the short-circuit signal delay means 30 for a predetermined time is less than or equal to the set time for the short-circuit protection operation, and the level of the delayed short-circuit signal Vp does not trigger the latch means 40. do.

Therefore, since the latch means 40 is in an off state not triggered, the switching power supply control signal Vc (see t5 to t6 in FIG. 4) of the power supply voltage Vcc is applied to the switching power supply driving means 50. As it is normally supplied, the output voltages Vo1 to Von of the switching power supply are normally output.

On the other hand, when the switching output voltage Vo1 to Vo is shorted for a predetermined time as shown in the section "t7 to t10" of FIG.

The short signal Vs detected from the short signal detecting means 20 (see t7 to t9 in FIG. 4 (e)) is input to the short signal delay means 30, and the short signal Vp delayed for a predetermined time (FIG. 4, see t7 to t9).

At this time, the short-circuit signal Vp delayed by the short-circuit signal delay means 30 for a predetermined time is longer than a set time for the protection operation, and the level of the delayed short-circuit signal Vp is a threshold voltage as shown in FIG. Above (Vth), the latch means 40 is triggered (see t8 in FIG. 4).

Therefore, at the same time as the latch means 40 is triggered, the switching power supply control signal Vc outputted to the switching power supply driving means 50 is turned off (refer to t8 to t10 in FIG. 4), so that the power supply voltage Vcc ( By cutting off t9 to t10 in FIG. 4A, the switching power supply driving means 50 is turned off until the power supply voltage Vcc is supplied again (see t10 to t10 in FIG. 4). Will be maintained.

Therefore, it prevents the malfunction of the protection operation function due to the instantaneous short-circuit from the output voltage (Vo1 to Von) of the switching power supply, and cuts off the input power voltage of the switching power supply in the short-circuit state to prevent damage to circuits and components due to the short circuit. Will be prevented.

On the other hand, the short-circuit protection control means 60 outputs the short-circuit control signal Ve to the short-circuit signal delay means 30 in accordance with a microcomputer or an external control signal Vi to perform the protective function operation regardless of the detection of the short-circuit signal Vs. By enabling or disabling, it prevents malfunctions in the production process and over-run.

That is, when the microcomputer or the external control signal Vi is input to the short-circuit protection control means 60 as shown in FIG. 4 (bar), the short-circuit protection control means as shown in the section "t0 to t4" of FIG. Numeral 60 outputs the short control signal Ve as shown in FIG. 4 to the short signal delay means 30.

Then, as shown in (d) of FIG. 4, the short-circuit signal delay means even if the short-circuit signal Vs is detected in accordance with the short-circuit of the output voltages Vo1 to Von of the switching power supply. 30 is turned off so that it does not affect the operating state of the switching power supply driving means 50, so that the short-circuit protection function is stopped.

In addition, when the microcomputer or the external control signal Vi is off, the short-circuit protection control means 60 is turned off, and as the short-circuit protection control means 60 is turned off, the short-circuit signal delay means 30 operates normally again. The short circuit protection function is activated.

3 is a detailed circuit block diagram showing an embodiment of the present invention, the operation of which is as follows.

First, the reference power supply delay unit 11 of the reference voltage generating unit 10 integrates the input power supply voltage Vcc by the resistor R11 and the capacitor C11 and outputs the delayed voltage Vcc1. See (a) of FIG. 4.

The voltage Vcc1 delayed by the reference voltage delay unit 11 is divided by the resistors R12 and R13 of the reference voltage generator 12, and the divided voltage is applied to the diode D11 and the capacitor C12. By this, it is made into the reference voltage Vref of a predetermined level, and is input to the short circuit signal detection means 20. FIG. See (c) of FIG. 4.

When the reference voltage Vref of the reference voltage generator 12 is input to the base of the transistor Q11 of the short signal detecting means 20, the transistor Q11 cathodes the reference voltage Vref to the emitter. It is compared with the multiple output voltages Vo1 to Von of the switching power source input to the plurality of diodes Do1 to Don connected to each other.

At this time, when the multiple output voltages Vo1 to Von of the switching power supply are normally output, the transistor Q11 is turned off by the emitter potential, and when the transistor Q11 is turned off, the base of the transistor Q11 is turned off. Since the delayed voltage Vcc1 is input to the base of the connected transistor Q12 (PNP type) through a resistor R15 connected to the emitter, the transistor Q12 is turned off.

When the multiple output voltages Vo1 to Von of the switching power supply are shorted, the emitter potential of the transistor Q11 is lowered and the transistor Q11 is turned on for the short time.

Then, the transistor Q12 connected to the collector is turned on by the on operation of the transistor Q11, and the short circuit of the multiple output voltages Vo1 to Vo of the switching power supply is turned on by the on operation of the transistor Q12. The signal Vs according to is output through the collector. See (d) (e) of FIG. 4.

The short signal Vs output through the transistor Q12 is charged in the capacitor C13 through the resistor R16 of the short signal delay means 30, and when the charging is completed, the base of the transistor Q13 is completed. It discharges through to turn on the transistor Q13.

Then, the short-circuit signal Vp, which is delayed for a certain time by the ON of the transistor Q13, is outputted to the latch means 40. See (a) of FIG. 4.

Here, the short signal delay means 30 delays by applying the capacitor C13 and the transistor Q13, so that the operation time for short circuit protection according to the short time of the short signal Vs can be adjusted.

Then, the short signal Vp delayed by the short signal delay means 30 for a predetermined time is integrated by the resistors R18 and R19 and the capacitor C15 of the latch means 40 and then the gate of the thyristor SCR1. G) is applied.

Then, the thyristor SCR1 of the latch means 40 is switched to the switching power supply driving means 50 for controlling the power supply voltage Vcc connected to the anode according to the gate G input level. The control signal Vc is outputted. See, FIG. 4.

At this time, as shown in the section "t5 to t6" of FIG. 4, when the multiple output voltages Vo1 to Von of the switching power supply are momentarily shorted (see (d) of FIG. 4),

The thyristor SCR1 because the short-circuit signal Vp delayed by the short-circuit signal delay means 30 falls short of the set time for short-circuit protection, and the signal Vp level becomes less than or equal to the threshold voltage Vth. Since the switching power supply control signal Vc of the latch means 40 is normally input to the switching power supply driving means 50 at the level of the power supply voltage Vcc. See, FIG. 4.

Accordingly, the switching power supply driving means 50 operates the transistor Q14 operated by the base driving signal, and the port coupler PC1 connected to the collector operates to drive the power control unit 50a normally. Multiple output voltages (Vo1 to Von) of the power supply are normally output.

As described above, when the output voltages Vo1 to Von of the switching power supply are momentarily short-circuited, the short-circuit signal Vs that is momentarily shortened is delayed for a predetermined time, thereby preventing malfunction of the short-circuit protection operation function.

In addition, as shown in the periods t7 to t10 of FIG. 4, when the switching output voltages Vo1 to Von are short-circuited,

Since the short-circuit signal Vp delayed by the short-circuit signal delay means 30 for a predetermined time becomes longer than a predetermined time for the short-circuit protection operation, and the level of the signal Vp becomes equal to or greater than the threshold voltage Vth, the thyristor ( SCR1) will be triggered. See section "t7-t10" in FIG.

Then, the anode-side power supply voltage Vcc flows through the cathode due to the trigger of the thyristor SCR1, so that the switching power supply control signal Vc of the latch means 40 is cut off and switched. The power drive means 50 is turned off. See, FIG. 4.

That is, when the input power supply voltage Vcc of the switching power supply driving means 50 is cut off, the transistor Q14 of the switching power supply driving means 50 is turned off, and when the transistor Q14 is turned off, the porter connected to the collector Since the coupler PC1 is turned off to cut off the power supply controller 50a, the switching output voltages Vo1 to Von are not output until the power supply voltage Vcc is supplied again. See sections t9 to t10 in FIG. 4.

Meanwhile, the short-circuit protection control unit 60 enables or disables the short-circuit protection function according to the microcomputer or the external control signal Vi. See (bar) (g) of FIG. 4.

That is, when the short-circuit protection function is stopped, the high signal of the microcomputer or the external control unit signal Vi is input to the transistor Q15 base of the short-circuit protection control means 60 to turn on the transistor Q15.

Then, by turning on the transistor Q15, the transistor Q13 of the short signal delay means 30 whose base is connected to the collector is turned off, and the short signal Vs detected from the short signal detection means 20 is removed. As a result, the short circuit protection is stopped. See section "t0-t4" in FIG.

Further, when activating the short-circuit protection function, the low signal of the microcomputer or the external control signal Vi is input to the base of the transistor Q15 of the short-circuit protection control means 60, and the transistor Q15 is turned off. Since the transistor Q13 of the short signal delay means 30 operates in accordance with the short signal Vs output from the short signal detection means 20, the short circuit protection function is activated.

As described above, the present invention protects circuits and components by accurately detecting a short circuit signal from multiple output voltages of the switching power supply, and prevents a malfunction of the short circuit protection function even if the output voltage of the switching power supply is momentarily shorted. In addition, it is possible to activate or stop the short-circuit protection function by a microcomputer or an external control signal, thereby preventing the malfunction of the production process or over-run.

Claims (5)

Reference voltage generating means including a reference voltage delay unit for delaying an input power supply voltage for a predetermined time, and a reference voltage generator for making the delayed voltage a predetermined reference voltage; Short-circuit signal detecting means for receiving a reference voltage of the reference voltage generating means and detecting a signal according to a short circuit of the multiple output voltages by comparing with a multiple output voltage of a switching power supply; Short-circuit signal delay means for outputting a delayed short-circuit signal by delaying a short-circuit signal detected from said short-circuit signal detecting means for a predetermined time to prevent malfunction due to a momentary short-circuit of said multiple output voltages; Switching power supply (SMPS) characterized in that it comprises a latch means for outputting a switching power supply control signal for controlling the operation of the switching power supply driving means in an operation state determined according to the level of the short circuit signal delayed by the short circuit signal delay means. Circuit and component protection device in case of output short circuit. The method of claim 1, further comprising: short-circuit protection control means for activating or stopping the output short-circuit protection operation of the switching power supply by controlling the short-circuit signal input to the short-circuit signal delay means according to a microcomputer or an external control signal. Circuit and component protection device in case of short circuit of switching power supply (SMPS). The method of claim 1, wherein the short-circuit detection means is turned on and off by receiving a reference voltage of the reference voltage generating means as a base in real time to detect a short-circuit signal of multiple output voltages of the switching power supply. A plurality of diodes each having an NPN transistor, an anode connected to an emitter of the NPN transistor, and a switching power supply output voltage connected to the cathode thereof, and a short signal outputted through the collector during the on operation of the NPN transistor; Circuit and component protection device in case of output short circuit of switching power supply (SMPS) characterized by including PNP type transistor The short circuit delay means for charging and discharging a short signal detected by the short signal detection means so as to prevent a malfunction of a short circuit protection function due to an instantaneous short circuit of multiple output voltages of the switching power supply. And a transistor for outputting a short-circuit signal delayed for a predetermined time by operating on when the capacitor is discharged. The method of claim 1, wherein the latch means controls the operation of the switching power supply driving means in an operation state determined according to the level of the short circuit signal delayed by the short signal delay means for a predetermined time, wherein the level of the delayed short signal is critical. The circuit and component protection device when the output short of the switching power supply (SMPS) characterized in that it comprises a thyristor that is triggered when the voltage is higher than the power supply of the switching power supply driving means.