KR20100005867A - Circuit and method for protecting overcurrent - Google Patents

Abstract

PURPOSE: An over current protection circuit and a protection method thereof are provided to reduce dangerous fire of an SMPS(Switching Mode Power Supply) and a peripheral passive device by preventing breakdown of an amplifier IC. CONSTITUTION: A first transistor(310) is turned on when a speaker terminal is shorted. A half-wave rectification diode(360) is connected to a collector terminal of the first transistor. The half-wave rectification diode outputs a high signal. A second transistor(320) is turned on with the high signal of the half-wave rectification diode. A second transistor transmits a low signal to a micro control unit(600). The micro control unit generates a relay off signal in response to a low signal of the second transistor.

Description

Circuit and Method for Protecting Overcurrent

The present invention relates to an overcurrent protection circuit and method, and more particularly, to an overcurrent protection circuit and method for detecting and breaking an overcurrent in an amplifier circuit.

A general amplifier is an apparatus for amplifying an analog signal transmitted as an electric signal, and particularly, an apparatus for amplifying a signal of sound.

1 is a view showing the circuit configuration of a digital amplifier according to the prior art.

As shown in FIG. 1, the speaker terminals are connected to the DIGITAL AMP IC through an LC low pass filter through a relay. Here, the DIGITAL AMP IC is a DIGITAL SANYO STK428-640 series IC, which includes an overcurrent protection circuit inside the IC.

The audio signal input through the Audio In terminal is amplified by Pulse Width Modulation (PWM) in the AMP IC to output a square wave signal, and then converted into an analog output through an LC low pass filter to be relayed and Outputs the amplified audio signal through the speaker.

However, if a connection or speaker short occurs due to a user's error, a micro control unit (hereinafter referred to as 'MCU') is detected through the OCM port before the AMP IC is destroyed by detecting a short inside the AMP IC. Transmits a detection signal (L).

Detecting the low state signal in the high state signal, the MCU protects the AMP IC by blocking the short by sending a relay off signal to the relay for protected mode operation.

However, when the SANYO STK428-640 series digital AMP IC is applying an audio level signal in the 30 mVrms to 95 mVrms range to the audio in terminal, the AMP IC is destroyed when both ends of the speaker are shorted or the two terminals are shorted due to an error.

The SANYO STK428-640 series digital AMP ICs did not detect shorts across the speakers mentioned above, failing to emit a sense signal (L) from the OCM port, and the AMP IC destroyed itself first.

In other words, the SANYO STK428-640 series digital AMP IC is destroyed when the short is applied when the 30mVrms ~ 95mVrms input signal is applied, and the internal circuit of the IC is shorted, causing serious defects.

In order to solve such a problem, the present invention is to provide an overcurrent protection circuit and method for detecting and blocking overcurrent in a SANYO STK428-640 series digital amplifier circuit.

According to an aspect of the present invention, an overcurrent protection circuit may include a first transistor configured to sense a short level of a speaker terminal and turn on to a (+) signal; A half-wave rectifier diode which blocks a (−) region signal in the turned on (+) signal and outputs a high state signal; And converting the signal into a low state signal indicating a malfunction state in a port that receives the high state signal and is turned on and detects a short of an integrated circuit connected to the collector stage due to the turn-on to a micro control unit. And a second transistor for controlling to transmit, wherein the micro control unit controls the relay to an open state by generating a relay off signal and transmitting the relay off signal to the relay when sensing the low state signal.

In the overcurrent protection method according to an aspect of the present invention, when the first transistor turned on by sensing a short level of a speaker terminal is turned on by detecting the short level, a second transistor connected to the first transistor is turned on, A high state signal is converted into a low state signal at a port for detecting a short of an integrated circuit according to the turn-on of the second transistor, and the micro control unit detecting the low state signal is opened by controlling a relay. It is characterized by.

According to an aspect of the present invention, an overcurrent protection device includes: a second resistor, a third resistor, First capacitors are connected in parallel, respectively, and a first resistor connected to one side of the second resistor and the other end of the first transistor is disposed, and when the speaker terminal is shorted to the third resistor. A second diode that sets the level to be sensed is connected in series, and is connected to the collector end of the first transistor through a first diode to a base end of the second transistor, and the collector end of the second transistor is integrated circuit. It is characterized in that it is connected to the port for detecting the short of the circuit).

By the above-described configuration, the present invention can be expected to prevent the destruction of the AMP IC to reduce the unnecessary AS cost generation.

The present invention can prevent the destruction of the AMP IC can reduce the risk of ignition of the peripheral passive element and SMPS power supply.

The present invention can prevent AMP IC destruction and reduce consumer complaints due to quality issues.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art may easily implement the present invention. As those skilled in the art would realize, the described embodiments may be modified in various different ways, all without departing from the spirit or scope of the present invention. In the drawings, parts irrelevant to the description are omitted in order to clearly describe the present invention, and like reference numerals designate like parts throughout the specification.

Throughout the specification, when a part is said to "include" a certain component, it means that it can further include other components, without excluding other components unless specifically stated otherwise. In addition, the terms “… unit”, “… unit”, “module”, “block”, etc. described in the specification mean a unit that processes at least one function or operation, which is hardware or software or a combination of hardware and software. It can be implemented as.

2 and 3 show a circuit configuration and operation of an amplifier including an overcurrent protection circuit according to an embodiment of the present invention.

2 is a view for explaining the operation of the overcurrent protection circuit showing a normal output when a sine wave input according to an embodiment of the present invention.

According to an embodiment of the present invention, the SANYO STK428-640 series digital amplifier may include an AMP IC 100, an LC low pass filter 200, an overcurrent protection circuit 300, a relay 400, a speaker 500, and an MCU. And 600. Hereinafter, in the SANYO STK428-640 series digital amplifier, the AMP IC 100 is described as the AMP IC 100 for convenience of description.

The overcurrent protection circuit 300 is connected in series between the LC low pass filter 200 and the relay 400 so that the first transistor 310, the second transistor 320, the first resistor R1 330, and the first resistor 310 are connected in series. The second resistor (R2) 340, the third resistor (R3) 350, the first diode (D1) 360, the second diode (D2) 370, the first capacitor (C1) 380, the first It consists of two capacitors (C2) 390.

The base terminal of the first transistor 310 is connected in parallel with the first resistor 330 and the relay 400, and the collector terminal of the first transistor 310 is connected with the first diode 360 and is connected to the first terminal. The diode 360 is connected to the base end of the second transistor 320.

In the node A 392 connected to the emitter terminal of the first transistor 310, the second resistor 340, the third resistor 350, and the first capacitor 380 are connected in parallel. Here, the second diode 370 is connected in series with the third resistor 350.

The node B 394 connected to the base end of the second transistor 320 has a first diode 360 and a second capacitor 390 connected in parallel, and the collector end of the second transistor 320 has an AMP IC 100. ) Is connected to the OCM port and MCU (600).

Since the first resistor 330 serves as a load of both ends of the resistor when the both ends of the speaker are short, about 0.1 ohm is suitable, and a low integer should be used as much as possible to reduce the resistance heat generation at the normal output.

The first diode 360 performs half wave rectification and protection and prevents the negative voltage from being applied to the second transistor 320.

The second diode 370 sets a level to be sensed when the both ends of the speaker are shorted, and sets a desired sensing level by the R1 / R2 resistance.

For example, when the second resistor 340 is changed to a low integer, the voltage input to the first transistor 310 is increased, so that the level detected when the both ends of the speaker are short may be set low.

The first capacitor 380 blocks the DC level and passes only AC to the CAP to prevent malfunction.

The first transistor 310 is a transistor that can turn on (Turn-On) at both ends of the speaker. The second capacitor 390 functions to prevent malfunction due to noise or the like.

The second transistor 320 is a final control transistor. When the both ends of the speaker are shorted, the base end of the second transistor 320 becomes high so that the second transistor 320 is turned on and is connected to the collector terminal of the second transistor 320. The OCM port of the connected AMP IC 100 is brought low.

An operation of the overcurrent protection circuit 300 showing a normal output when a sine wave input according to an embodiment of the present invention will be described.

As shown in FIG. 2, the sine wave input to the emitter terminal of the first transistor 310 is turned on only the (−) signal to the collector terminal of the first transistor 310.

At the base end of the second transistor 320, the turned on (−) signal of the collector end of the first transistor 310 is blocked by the first diode 360 so that the node B 394 shows a low ( Low) state.

Therefore, the OCM port of the AMP IC 100 transmits the high state signal in the normal state to the MCU 600 because the second transistor 320 is not turned on.

The audio signal input through the Audio In terminal is amplified by a Pulse Width Modulation (PWM) method in the AMP IC 100 to output a square wave signal, and is passed through the LC low pass filter 200 to analog. The output signal is amplified through the relay 400 and the speaker 500.

3 is a diagram for describing an operation of an overcurrent protection circuit when a sine wave input and a speaker terminal are shorted according to an exemplary embodiment of the present invention.

When the speaker terminal is shorted, the sine wave input to the emitter terminal of the first transistor 310 is shown in FIG. 3 (between the collector terminal of the first transistor 310 and the first diode 360), and a (+) signal. Turn on until

The turned-on (+) region signal of the collector terminal of the first transistor 310 is cut off at the base terminal of the second transistor 320 by the first diode 360, and at node B 394. As shown, the state is high. At this time, the second transistor 320 is turned on because the base terminal is in a high state.

Subsequently, the OCM port of the AMP IC 100 transmits a low state signal to the MCU 600 since the second transistor 320 is turned on.

When the MCU 600 detects a low state signal at a detect pin, the MCU 600 generates a relay off signal and transmits the relay off signal to the relay 400 to control the relay 400 in an open state.

The embodiments of the present invention described above are not implemented only by the apparatus and / or method, but may be implemented through a program for realizing a function corresponding to the configuration of the embodiments of the present invention, a recording medium on which the program is recorded, and the like. Such implementations may be readily implemented by those skilled in the art from the description of the above-described embodiments.

Although the embodiments of the present invention have been described in detail above, the scope of the present invention is not limited thereto, and various modifications and improvements of those skilled in the art using the basic concepts of the present invention defined in the following claims are also provided. It belongs to the scope of rights.

1 is a view showing the circuit configuration of a digital amplifier according to the prior art.

2 is a view for explaining the operation of the overcurrent protection circuit showing a normal output when a sine wave input according to an embodiment of the present invention,

3 is a diagram for describing an operation of an overcurrent protection circuit when a sine wave input and a speaker terminal are shorted according to an exemplary embodiment of the present invention.

Claims (6)

A first transistor that senses a short level of the speaker terminal and is turned on to a (+) signal; A half-wave rectifier diode which blocks a (−) region signal in the turned on (+) signal and outputs a high state signal; And Receives the high state signal and turns it on and converts it into a low state signal indicating a malfunction state at a port that detects a short of an integrated circuit connected to a collector stage due to the turn on, and transmits the signal to a micro control unit. A second transistor for controlling to And when the micro control unit senses the low state signal, generates a relay off signal and transmits the relay off signal to the relay to control the relay to an open state. According to claim 1, When the speaker terminal maintains a normal output without shorting the speaker terminal, only the negative signal is turned on. The second transistor connected to the first transistor receives a high state signal at a port detecting a short of the integrated circuit because the (−) signal is blocked through the half-wave rectifier diode and thus cannot be turned on by receiving a low state signal. Control to transmit to the micro control unit, And when the micro control unit senses the high state signal, generates a relay on signal and transmits the relay on signal to the relay to control the relay to an on state. The method according to claim 1 or 2, And said integrated circuit is destroyed when said speaker terminal is shorted when an audio level signal in a range of 30mVrms and 95mVrms is applied. When a first transistor that is turned on by sensing a short level of a speaker terminal is turned on by sensing the short level, a second transistor connected to the first transistor is turned on and integrated according to the turn-on of the second transistor. And converting a high state signal into a low state signal at a port detecting a short of an integrated circuit, and controlling and opening a relay in the micro control unit detecting the low state signal. The method of claim 4, wherein When the speaker terminal maintains a normal output, the first transistor is turned on only with (-) signal and the (-) signal is blocked by a half-wave rectifier diode so that the second transistor cannot be turned on, and the integrated And the high state signal is transmitted from the port for detecting a short circuit to the micro control unit so that the relay is controlled in an on state. An overcurrent protection circuit comprising a resistor, a transistor, and a diode for detecting and protecting overcurrent, The base terminal of the first transistor sensing a short level of the speaker terminal is connected to a relay, and the second resistor, the third resistor, and the first capacitor are connected in parallel at a contact node A connected to the emitter terminal of the first transistor. A first resistor having one side connected to the second resistor and the other end connected to the base end of the first transistor, A second diode that sets a level to be sensed when the speaker terminal is shorted is connected to the third resistor in series, and is connected to a base end of the second transistor through a first diode at a collector end of the first transistor. And the collector terminal of the second transistor is connected to a port for detecting a short of an integrated circuit.

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