KR20000013383A - Transistor circuit with faster speed of switching - Google Patents

Abstract

PURPOSE: Voltage ringing can be reduced effectively without delay with a transistor off. A circuit with a better switching speed is provided in a transistor in which circuits after a speed-up condenser and a resistor for reducing ringing can be operated independently. CONSTITUTION: With the second transistor (Q2) off, the resistor for reducing ringing (RP) does not delay the second transistor going off, because the resistor for ringing (RP) is placed between the secondary winding of a transformer and a speed-up condenser (CS). With the second transistor (Q2) on, the whole electric current from the transformer to the speed-up condenser is supplied for the base terminal of the second transistor without being divided by the resistor for ringing (RP), because the resistor for ringing (RP) is placed between the transformer and the speed-up condenser (CS). This is the same as saying the current from the speed-up condenser (CS) to the base terminal does not subject itself to the resistor for ringing (RP). Thus the independent operation improves the speed of switching.

Description

Switching Speed Improvement Circuit of Transistor Circuit

The present invention relates to a switching circuit using a transistor.

More specifically, in a switching circuit in which a transformer output signal is applied to a base terminal and driven, and a speed-up capacitor is connected in series between the base terminal and the output terminal of the transformer, a resistance for reducing voltage ringing is paralleled to the output terminal of the transformer. Transistor circuits that can reduce voltage ringing without incurring time lag in the transistor's off operation and allow circuit design after the speed-up capacitor to be independent of the resistors that attenuate voltage ringing. It relates to a switching speed improvement circuit of.

In general, in a switching circuit using a transistor, a speed-up capacitor is used to shorten the on / off switching time of the transistor, and the switching speed is improved by using a resistive element to reduce the ringing voltage that may occur when the transistor is turned off. Doing.

1 is a circuit diagram illustrating an example of a switching speed improvement circuit of a conventional transistor circuit.

As illustrated, the switching speed improvement circuit of the conventional transistor circuit includes a first transistor Q1 and a collector output of the first transistor Q1, the emitter terminal of which is first grounded and switched by receiving a pulse input signal as a base terminal. A transformer (TRANS) in which a primary winding (Np) is connected in series between a terminal and a first power supply (B1 +), and in series with an output terminal of a secondary winding (Ns) of a transformer (TRANS) whose one end is second grounded. A second transistor Q2 connected to the base resistor Rb, the other end of the base resistor Rb, and the base terminal, and connected in series between the collector output terminal of the second transistor Q2 and the second power source B2 +. A speed-up capacitor Cs connected in parallel with the collector resistor Rc, the base resistor Rb, and a ringing damping resistor Rp connected to the base terminal of the second transistor, one end of which is connected to the second ground. It is composed.

Here, the emitter terminal of the second transistor Q2 is second grounded, and the output signal of the entire circuit is output from the collector terminal of the second transistor.

The operation of the switching speed improvement circuit of the conventional transistor circuit configured as described above is as follows.

The first transistor Q1 is switched on / off according to the pulse input signal applied to the base terminal to interrupt the current flowing in the primary winding Np of the transformer TRANS connected in series with the collector terminal. A pulse for switching the second transistor Q2 to the output terminal of the secondary winding Ns is induced and output.

The pulse generated from the output terminal of the transformer secondary winding Ns is applied to the base of the second transistor Q2 through the base resistor Rb used for current limiting, thereby turning on the second transistor Q2. Switch on / off.

The collector resistor Rc limits the amount of current flowing when the second transistor Q2 is turned on, and the final output signal of the circuit is output from the collector terminal of the second transistor Q2.

In the second transistor Q2 circuit which performs this operation, the speed-up capacitor Cs is connected in parallel with the base resistor Rb, which is a carrier when switching the second transistor Q2 due to the characteristics of the transistor as a switching element. This is because the conversion speed of the on / off is limited because there is a time delay due to accumulation and carrier diffusion of the base region.

However, when the second transistor Q2 is turned off, the base terminal and the emitter terminal are equivalently operated like a condenser. Thus, in the state of including the coil component such as the transformer secondary winding Ns as in the circuit described above. When the speed-up capacitor Cs speeds up the switching time of the second transistor Q2, ringing occurs in the voltage between the base of the second transistor Q2 and the emitter terminal.

The resistor Rp connected between the base terminal and the emitter terminal of the second transistor Q2 is a ringing damping resistor used to attenuate such voltage ringing quickly and further improve the on / off switching time.

However, the switching speed improvement circuit of the conventional transistor circuit having the configuration and function as described above has the following problems.

That is, since the ringing damping resistor Rp is located between the speed-up capacitor Cs and the base terminal, the time when the second transistor Q2 is turned off is affected by the ringing damping resistor Rp.

This is because the speed-up capacitor Cs must withdraw the current not only from the base terminal of the second transistor Q2 but also from the ringing damping resistor Rp.

In addition, when the second transistor Q2 is turned on because the ringing damping resistor Rp is located after the speedup capacitor Cs, the current flowing from the transformer TRANS to the speedup capacitor Cs is reduced by the ringing damping resistor (Cs). Divided by Rp) and supplied to the base terminal of the second transistor Q2.

This means that the current supplied from the speed-up capacitor Cs to the base terminal is dependent by the presence of the ringing damping resistor Rp, and it is easy to determine the value of each component after the speed-up capacitor Cs in circuit design. Did not do it.

Accordingly, an object of the present invention is a transistor switching circuit in which a transformer output signal is applied to a base terminal and driven, and a speed-up capacitor is connected in series between the base terminal and the output terminal of the transformer. In addition, the present invention provides a circuit for improving the switching speed of a transistor circuit that can effectively attenuate the circuit and the circuit after the speed-up capacitor and the ringing damping resistor can operate independently of each other.

1 is a circuit diagram showing an example of a switching speed improvement circuit of a conventional transistor circuit;

2 is a circuit diagram showing an embodiment of a switching speed improving circuit of a transistor circuit according to the present invention;

3 is a circuit diagram illustrating another embodiment in which the switching speed improvement circuit of the transistor circuit according to the present invention is applied to a horizontal deflection circuit of a display device using a cathode ray tube.

Explanation of symbols on the main parts of the drawings

B1 +: first power source B2 +: second power source

Q1: first transistor Q2: second transistor

TRANS: Transformer Rp: Resistor for ringing attenuation

Rb: Base Resistance Rc: Collector Resistance

Cs: Speed up capacitor Np: Primary winding

Ns: secondary winding

A characteristic of the switching speed improvement circuit of the transistor circuit according to the present invention for achieving the above object is to receive the output signal of the transformer connected to the output terminal of the first transistor switched by the pulse input signal to the base terminal through a resistor In a circuit in which a second transistor is switched and a speed-up capacitor which improves the switching speed of the second transistor is connected in parallel with a resistor, the second transistor is connected in parallel across the secondary winding of the transformer and is generated when switching the second transistor. The resistive element which attenuates the voltage ringing of a base terminal is comprised.

Hereinafter, preferred embodiments of the switching speed improvement circuit of the transistor circuit according to the present invention will be described in detail with reference to FIGS. 2 and 3.

2 is a circuit diagram illustrating an embodiment of a switching speed improving circuit of a transistor circuit according to the present invention.

As shown, one embodiment of the switching speed improvement circuit of the transistor circuit according to the present invention except that the ringing damping resistor Rp in its configuration is connected in parallel to the secondary winding of the transformer TRANS. 1 is the same as FIG.

Therefore, only the differences unique to the present invention, which are different from those of FIG.

First, when the second transistor Q2 is turned off in FIG. 2, the ringing damping resistor Rp is located between the secondary winding of the transformer TRANS and the speed-up capacitor Cs. ), The off time of the second transistor Q2 is not delayed.

This is because the speed-up capacitor Cs has conventionally subtracted not only the base terminal of the second transistor Q2 but also the current from the ringing damping resistor Rp. This is because you only need to subtract the current.

Here, the voltage ringing damping action of the ringing damping resistor Rp is such that the ringing damping resistor Rp is located between the speed-up capacitor Cs and the base terminal of the second transistor Q2, as shown in FIG. It is almost the same as the case.

In addition, when the second transistor Q2 is turned on, the current flowing from the transformer TRANS to the speedup capacitor Cs because the ringing damping resistor Rp is located between the transformer and the speedup capacitor Cs. Are not divided by the ringing damping resistor Rp (see FIG. 1), and are all supplied to the base terminal of the second transistor Q2.

This means that the current supplied from the speed-up capacitor Cs to the base terminal is not dependent even if the ringing damping resistor Rp is present, which is the value of each component after the speed-up capacitor Cs in circuit design. Independent circuit setting facilitates circuit design, and reduces interference between circuits after the ringing attenuation resistor (Rp) and the speed-up capacitor (Cs), thereby allowing for a strong design even in tolerance.

3 is a circuit diagram illustrating another embodiment in which the switching speed improvement circuit of the transistor circuit according to the present invention is applied to a horizontal deflection circuit of a display device using a cathode ray tube.

As illustrated, another embodiment in which the switching speed improvement circuit of the transistor circuit according to the present invention is applied to a horizontal deflection circuit of a display device using a cathode ray tube is provided in which the first transistor Q1 is switched by a horizontal synchronization signal Hsync. The second transistor Q2, which is switched by receiving the output signal of the transformer HDT connected to the output terminal to the base terminal through the resistor Rb, interrupts the current flowing through the horizontal deflection coil H-DY of the display device. In a horizontal deflection circuit of a display device in which a speed-up capacitor Cs for improving the switching speed of the second transistor Q2 is connected in parallel with the resistor Rb, the secondary winding of the transformer HDT is wound. And a resistive element Rp connected in parallel to both ends of Ns to attenuate voltage ringing of the base terminal generated during switching of the second transistor Q2.

That is, FIG. 3 shows that the circuit of FIG. 2 is applied to a horizontal deflection circuit of a display device using a cathode ray tube. The basic operation is the same as that of FIG.

However, in the process of being applied to the horizontal deflection circuit of the display device using the cathode ray tube, the first transistor Q1 is switched to the horizontal synchronization signal Hsync instead of the pulse input signal, and the first power source B1 + of FIG. After being stabilized by R1 and condenser C1, it is supplied to the primary winding Np of the transformer HDT which is used exclusively for the horizontal deflection circuit.

In addition, the output signal from the collector terminal of the second transistor Q2 is directly supplied to the horizontal deflection coil H-DY to horizontally deflect the electron beam of the cathode ray tube.

In FIG. 3, the coil L connected in series between the second transistor Q2 and the second power source B2 + is for linearity correction and is connected in parallel to the collector terminal and the emitter terminal of the second transistor Q2. The capacitor C2 is a resonant capacitor, and the capacitor C3 connected in series between the other end of the horizontal deflection coil H-DY connected to the collector terminal of the second transistor Q2 and the second ground is S-shaped. It is for correction.

The diode D1 connected in parallel with the resonant capacitor C2 is a damping diode.

As described above, according to the switching speed improvement circuit of the transistor circuit according to the present invention, in a switching circuit in which a transformer output signal is driven by being applied to a base terminal and a speed-up capacitor is connected in series between the base terminal and the output terminal of the transformer. By placing a resistor to attenuate the voltage ringing at the front of the speed-up capacitor, it is possible to attenuate the voltage ringing without incurring a time delay during the off operation of the transistor, while the circuit design after the speed-up capacitor reduces the voltage ringing. Independent of and, it is easy to determine the value of each circuit component, as a result has the effect that the circuit design can be made effectively.

Claims (2)

The second transistor is switched by receiving the output signal of the transformer connected to the output terminal of the first transistor switched by the pulse input signal to the base terminal through the resistor, and the speed-up capacitor for improving the switching speed of the second transistor is In a circuit connected in parallel with a resistor, And a resistive element connected in parallel to both ends of the secondary winding of the transformer to attenuate voltage ringing of the base terminal generated during switching of the second transistor. The second transistor switched by receiving the output signal of the transformer connected to the output terminal of the first transistor switched by the horizontal synchronizing signal to the base terminal through a resistor intercepts the current flowing through the horizontal deflection coil of the display device. In a horizontal deflection circuit of a display device, in which a speed-up capacitor for improving the switching speed of two transistors is connected in parallel with the resistor, And a resistive element connected in parallel to both ends of the secondary winding of the transformer to attenuate voltage ringing of the base terminal generated during switching of the second transistor.