KR20000007851A - Switching mode power supply having both power source - Google Patents

Abstract

PURPOSE: The power supply removes the surge phenomenon occurred in power on-off or mode conversion, by separating the power supply port into a high voltage port and a low voltage port. CONSTITUTION: The power supply in a display device outputs a PWM(Pulse Width Modulation) pulse, whose duty is determined by a DC voltage from the external, to a switching output part(312, 352) and supplies the DC voltage of different intensity generated in the secondary side to a load circuit according as a switching transformer is switched. The power supply comprises: a low voltage switching mode power supply(350) generating many low voltages on the secondary side according as the DC voltage is inputted from the external; and a high voltage switching mode power supply(310) stopping the high voltage being generated on the secondary side temporarily by generating a high voltage on the secondary side according as the DC voltage is inputted from the external.

Description

Switching mode power supplies with positive power

The present invention relates to a switched mode power supply.

More specifically, by separating the power supply stage of the switching mode power supply into a high voltage stage and a low voltage stage to separate the switching mode power supply having a positive power supply, to eliminate the surge phenomenon occurring during power on-off or mode conversion A switching mode power supply having a positive power supply.

In general, a cathode ray tube display device requires a DC power supply, a device for converting commercial AC power into a predetermined DC power as a means for supplying operating power. Is often driven by a compact, lightweight and highly efficient Switching Mode Power Supply (SMPS).

1 is a block diagram showing an example of such a conventional switching mode power supply.

As shown in the figure, the switching mode power supply controls a pulse width modulation (PWM) signal by controlling a DC voltage rectified from an external AC power and supplies power on and off. And a PWM control unit 110 to which a mode conversion signal is input, a switching output unit 120 driven by an output signal of the PWM control unit 110 to switch the switching transformer 130, and a switching output unit 120. A switching transformer 130 for switching voltages and currents to the secondary coils, and a secondary rectifying smoother for rectifying and smoothing each voltage induced in one or more secondary coils of the switching transformer 130 with DC. And a constant voltage control feedback unit 150 which detects a change in the DC output voltage V1 output from the secondary rectifier smoothing unit 140 and feeds it back to the PWM control unit 110, and controls the entire system. Horizontal PWM Signal and Wave It is connected to the main control unit 180 for outputting the on-off and mode conversion signal, and the first DC output voltage (V1) output from the secondary rectifier smoothing unit 140, the horizontal size PWM signal from the main control unit 180 It is composed of a horizontal size control unit 160 for receiving the horizontal size PWM signal and a horizontal size output unit 170 for outputting the horizontal size signal required by the output signal of the horizontal size control unit 160.

The overall operation of the conventional switching mode power supply configured as described above will be described with reference to FIG.

When the power is supplied, the AC power is rectified and smoothed, and the smoothed DC voltage is supplied to the input terminal Vcc of the PWM control unit IC1 110 through the resistor R1 to supply the voltage. IC1) 110 is operated.

When the PWM controller (IC1) 110 is operated and initially driven, the PWM controller (IC1) 110 applies the PWM signal according to the internal oscillation frequency to the switching output unit (Q1) 120.

As switching output (Q1) 120 consisting of a bipolar transistor (BJT) or a field effect transistor (FET) starts switching by a PWM signal, the switching transformer (T1) 130 also starts switching to at least one Induces voltage to the secondary coil. That is, the output terminal OUT of the PWM control unit IC1 110 turns on and switches on the field effect transistor Q1 and induces the energy accumulated when the field effect transistor Q1 is off to the secondary coil. .

The voltage induced in each of the secondary coils of the switching transformer 130 is rectified and smoothed by the secondary rectifier smoothing unit 140, which is composed of a series connection circuit of a diode and a capacitor, and thus the final DC output voltages V1, V2, and V3. , V4, V5).

V1 (first DC output voltage) having 220 V (volts) among the DC output voltages rectified and smoothed by the secondary rectifying smoother 140 supplies power to the constant voltage control feedback unit 150 and the horizontal size control unit 160. Supply.

The zener diode Dz of the constant voltage control feedback unit 150 is driven by a V1 output voltage of 220 V, and the drive voltage is driven by V4 (fourth DC output voltage) having a DC output voltage of 14 V. IC2 of 150 is operated to control the constant voltage fed back to the PWM controller 110 and output to the secondary rectifying smoother 140.

In addition, the rectified and smoothed V1 is used as an input voltage of the horizontal size control unit 160, thereby operating the field effect transistor Q2 of the horizontal size control unit 160, and thereby the horizontal size output unit 170 Transistor Q3 is operated, and a pulse of about 1200V is generated in the collector Vc of the transistor Q3.

However, the pulse generated at the collector Vc voltage of the transistor Q3 is varied by the horizontal magnitude PWM signal input to the base terminal of the transistor Q3.

In particular, the power on-off signal generated at the time of power on / off output from the main controller 180 or the mode change signal generated at the time of mode conversion of the horizontal size PWM signal is inputted to the PWM controller 110 while suddenly changing the load. Due to the transient caused by surge (Surge) occurs, many parts are damaged.

That is, the duty of the horizontal size PWM signal of the horizontal size control unit 160 becomes excessively large or crushed, and when the driving conditions are not met, the pulse generated in the collector Vc voltage of the transistor Q3 is excessively excessive. As it becomes larger, there is a problem in that the transistor Q3 and surrounding electronic devices are destroyed.

Accordingly, an object of the present invention is to separate the power supply stage of the switching mode power supply into a high voltage stage and a low voltage stage to separate the switching mode power supply having a positive power supply, so that the surge phenomenon occurs during power on-off or mode conversion The present invention provides a switching mode power supply which eliminates damage to electronic components and ensures circuit reliability.

1 is a block diagram of a conventional switching mode power supply;

2 is a circuit diagram illustrating a conventional switching mode power supply device;

3 is a block diagram of a switching mode power supply having a high voltage stage and a low voltage stage power supply to which the present invention is applied;

4 is a circuit diagram of a high voltage stage of a switching mode power supply having a positive power supply to which the present invention is applied;

5 is a circuit diagram of a low voltage terminal of a switching mode power supply having a positive power supply to which the present invention is applied.

Explanation of symbols on the main parts of the drawings

310: high voltage stage switching mode power supply

311,351: PWM control unit 312,352: switching output unit

313,353: switching transformer part 314,354: secondary rectifier smoothing part

315,355: constant voltage control feedback unit 316: horizontal size control unit

317: horizontal output unit 318: main control unit

319: PWM switching unit

350: low voltage switching mode power supply

A feature of the switching mode power supply having a positive power supply according to the present invention for achieving the above object is that a PWM pulse whose duty is determined by a DC voltage input from the outside is initially output to the switching output unit, and when driven, feedback from the output stage. The switching mode power supply of the display device for supplying the DC voltage of the different magnitude generated on the secondary side to the load circuit as the PWM pulse whose duty is determined by the DC voltage is output to the switching output part. A low voltage switching mode power supply for generating a plurality of low voltages on the secondary side as a DC voltage is input from the outside, and a low voltage switching mode power supply separately from the low voltage switching mode power supply to the secondary side as a DC voltage is input from the outside. To generate a high voltage, Words on-off and consists of a mode change signal is input when the high-voltage switching mode in which the release of the high voltage generated in the secondary side to temporarily stop the power supply.

Hereinafter, one preferred embodiment of a switched mode power supply having a positive power supply according to the present invention will be described in detail with reference to FIGS. 3 to 5.

3 is a block diagram of a high voltage terminal and a low voltage terminal of a switching mode power supply having a positive power supply to which the present invention is applied.

As shown, a low voltage switching mode power supply 350 and a low voltage switching mode power supply 350 to generate a plurality of low voltage on the secondary side as the DC voltage is input from the outside is provided separately from the outside High voltage switching mode power supply to generate a high voltage on the secondary side as the voltage is input, and to temporarily stop the high voltage generated on the secondary side when the power on-off and mode conversion signals generated from the main controller 318 are inputted. Device 310.

The high voltage stage switching mode power supply 310 outputs a PWM pulse determined by a DC voltage input from the outside, and inputs a feedback DC output voltage to control a constant pulse width modulation signal to the PWM control unit 311; A switching output unit 312 driven by the output signal of the PWM control unit 311 to switch the switching transformer 313 and a switching transformer switching the switching output unit 312 to induce voltage and current to the secondary coil A secondary side rectification smoother 314 for rectifying and smoothing the first DC output voltage V1 induced by the secondary coil of the switching transformer 313 to DC, and a secondary rectifying smoother ( A constant voltage control feedback unit 315 for detecting a change in the first DC output voltage V1 output from the 314 and feeding it back to the PWM control unit 311, and a power on-off and mode conversion signal from the main control unit 318. PWM control while is input The voltage drop is performed such that the output power of 311 is turned off, and a PWM switching unit 319 having a switching function is included.

The low voltage stage switching mode power supply 350 may further include a PWM control unit 351 for controlling a pulse width modulation signal by a DC voltage rectified from an AC power supplied from the outside, and a PWM control unit 351. A switching output unit 352 driven by an output signal to switch the switching transformer 353, a switching transformer 353 switched by the switching output unit 352 to induce voltage and current to the secondary coil, A secondary rectification smoother 354 for rectifying and smoothing each of the voltages V2, V3, V4, and V5 induced in the one or more secondary coils of the switching transformer 353 to DC, and a secondary rectifying smoother ( 354 receives the second and fourth DC output voltages V2 and V4 to drive a circuit, and detects a change in the second DC output voltage V2 of the secondary rectifier smoothing unit 354 to detect the PWM control unit 351. It is composed of a constant voltage control feedback unit 355 for feeding back.

Referring to the operation principle according to the circuit diagram of Figure 4 and 5 attached to the switching mode power supply having a high voltage stage and a low voltage stage of the present invention configured as described above are as follows.

4 is a circuit diagram of a switching mode power supply having a high voltage stage, and FIG. 5 is a circuit diagram of a switching mode power supply having a low voltage stage.

As shown in the drawing, the present invention is characterized in that a conventional switching mode power supply composed of one PWM control unit and a switching transformer unit is divided into two power supply stages. That is, the high voltage stage outputting a DC voltage of 220V from the secondary rectifying smoother 314 of FIG. 4 and the remaining V2 (90V), V3 (25V), and V4 (14V) from the secondary rectifying smoother 314 of FIG. ) And low power stage to output DC voltage such as V5 (8V), and separate power supply stage into two.

As shown in the figure, the switching mode power supply having the high voltage stage of FIG. 4 includes a PWM switching unit 319, which is a circuit having a switch function, to control the power on / off of the PWM control unit 311.

In addition, although the switching mode power supply having the low voltage terminal of FIG. 5 receives a driving voltage input to the constant voltage control feedback unit 355, a high voltage of 220V has been supplied from the secondary rectifier smoothing unit (140 in FIG. 2). In the present invention, the second rectifier smoothing unit 354 is configured to receive 90 V, which is the second DC output voltage V2.

The operating principle of the switching mode power supply having the high voltage terminal of FIG. 4 is as follows.

The main controller 318 controls the entire system and outputs a power on-off signal, a mode conversion signal, and a horizontal size PWM signal, and the horizontal size control unit 316 is a first direct current output from the secondary rectification smoothing unit 314. It is connected to the output voltage (V1), and receives the horizontal size PWM signal from the main control unit 318 to control the horizontal size PWM signal, the horizontal size output unit 317 is required by the output signal of the horizontal size control unit 316 Outputs a horizontal signal.

The horizontal size PWM signal output from the main controller 320 is input to the mode switching signal generated each time the mode is switched and the power on-off signal generated when the power is turned on and off to the power switching mode unit 318. The input signal is supplied with a driving voltage of 14 V, which is the fourth DC output voltage V4, from the secondary side rectifying smoother 354 of the low voltage stage switching mode power supply 350 to turn on the transistor Q4. .

At the same time, the current fed back from the secondary of the photocoupler IC3 to the primary increases, so that the transistor Q5 of the power switching feedback unit 319 is turned on, and the voltage is 0 V at the CS terminal, which is a control signal of the PWM controller 311. The drop occurs, and the output voltage of the OUT terminal, which is the output terminal of the PWM control unit 311, becomes 0V.

Therefore, when the mode conversion signal is input, the output (OUT terminal) voltage of the PWM controller 311 becomes 0V. After a predetermined time, the transistor Q4 of the power conversion mode unit 318 is turned off when the mode conversion signal is transferred to the normal signal again.

When the transistor Q4 of the power conversion mode unit 318 is turned off, the current fed back from the secondary to the primary in the photo coupler IC3 decreases, and the transistor Q5 of the PWM switching unit 319 is turned off.

Then, the CS terminal, which is a control signal of the PWM controller 311, is restored to the normal operating voltage, and the OUT terminal, which is an output terminal of the PWM controller 311, outputs a normal voltage.

In other words, when the power is turned on or off or the mode is switched, the high voltage terminal supplied with 220V is disconnected, and the power is supplied again after various change conditions such as mode change, thereby preventing damage to the components caused by transient phenomenon and reliability. Stable circuit can be configured.

As described above, the switching mode power supply having the positive power according to the present invention is separated into a switching mode power supply having a positive power by separating the power supply terminal of the power supply into a high voltage terminal and a low voltage terminal, thereby power-on-off By eliminating the surge phenomenon occurring at the time or mode conversion, it prevents the damage of the electronic components, thereby reducing the cost and securing the circuit reliability, thereby improving the performance and quality of the product.

Claims (3)

Initially, the PWM pulse whose duty is determined by the DC voltage input from the outside is output to the switching output unit, and during driving, the PWM pulse whose duty is determined by the DC voltage fed back from the output terminal is output to the switching output unit, whereby the switching transformer In the switching mode power supply of the display apparatus for supplying a different magnitude of the DC voltage generated on the secondary side to the load circuit as the switch, A low voltage switching mode power supply for generating a plurality of low voltages on the secondary side when a DC voltage is input from the outside; And It is provided separately from the low voltage switching mode power supply device and a high voltage is generated on the secondary side as a DC voltage is input from the outside, and a high voltage generated on the secondary side when a power on-off and a mode conversion signal generated from the main controller are input. A switching mode power supply having a positive power source, characterized in that it comprises a high voltage switching mode power supply to be temporarily interrupted. The apparatus of claim 1, wherein the high voltage stage switching mode power supply; A PWM control unit for outputting a PWM pulse determined by a DC voltage input from the outside and inputting a feedback DC output voltage to control a constant pulse width modulation signal; A switching output unit driven by the output signal of the PWM control unit to switch; A switching transformer unit which is switched by the switching output unit to induce voltage and current to a secondary coil; A secondary rectifier smoothing unit rectifying and smoothing the DC output voltage induced in the secondary coil of the switching transformer unit to a DC; A constant voltage control feedback unit which detects a change in the DC output voltage output from the secondary rectifier smoothing unit and feeds it back to the PWM control unit; And And a PWM power supply having a switching function for temporarily stopping the high voltage generated on the secondary side while the power on-off signal and the mode conversion signal outputted from the main controller are input to the PWM controller. Switching mode power supply. The apparatus of claim 1, wherein the low voltage stage switching mode power supply; A PWM control unit for controlling the pulse width modulation signal by the DC power rectifying AC power supplied from the outside; A switching output unit driven by the output signal of the PWM control unit to switch; A switching transformer unit which is switched by the switching output unit to induce voltage and current to a secondary coil; A secondary rectifier smoothing unit rectifying and smoothing one or more voltages induced in the secondary coil of the switching transformer unit by direct current; And And a constant voltage control feedback unit configured to drive a circuit by receiving a DC output voltage from the secondary rectifier smoothing unit, detect a change in the DC output voltage, and return it to a PWM control unit.