JPS611264A - Intermittent control type power source circuit - Google Patents

Abstract

PURPOSE:To operate a switching transistor by completely responding to an intermittent control signal by providing a hysteresis in the conducting and interrupting functions of the transistor by utilizing the unsaturable characteristic of the transistor. CONSTITUTION:A transistor 11 is collector-grounded, and a voltage drop between the collector and the emitter depends upon a base potential.

Description

[Detailed description of the invention] Technical fields> The present invention relates to an intermittent control type power supply circuit.

<Prior Art> A conventional intermittent control type power supply circuit has a configuration as shown in FIG. An alternating current voltage or a non-smooth full-wave or half-wave rectified voltage is applied between the input terminals 1 and 1'. While the instantaneous value of the input terminal is small, the switching transistor is in a conductive state, and if the capacitor 8 is not connected to the output side, a voltage proportional to the input voltage is output between the output terminals 9 and 9'. be done. However, the instantaneous value of the input terminal is
-The moment the voltage on the output side reaches a predetermined value, that is, the moment the output voltage level exceeds the sum of the Zener voltage VIIL and the heath-emitter voltage VBa5 of the transistor 5, the Zener diode 6 becomes energized. Then, transistor 5 becomes conductive. Therefore, the transistor 3 is short-circuited between its base and emitter, and its collector circuit is cut off, so that the switching transistor 2 is cut off and the output voltage is cut off. However, as the output voltage is cut off, the Zener current disappears in the next moment, transistor 5 becomes cut off again, the Hesmi current flows through 1-Lansis transistor 3, and its collector circuit becomes conductive, so the switching transistor 2 also becomes conductive, and an output voltage is generated again. If the output voltage is not generated, the Zener diode becomes conductive again, and the input voltage (instantaneous value) reaches the predetermined value (ii (V
As long as the voltage exceeds ov +VBε→−collector-emitter voltage of the conducting transistor when energized,
The above intermittent action is repeated. FIG. 2 illustrates the above operation when the input is a non-smooth full-wave rectified voltage. When the input voltage changes as shown by the curve ABPCQDP'E in the figure, a voltage virtually equal to the input terminal is output during ABP, but when the change in the input terminal reaches point P, the Zener diode 6 is activated. The switching transistor 2 is cut off, and the output voltage drops to O level. Thereafter, the output voltage repeats intermittent cycles as described above until the change in input voltage reaches point Q. During QDP', a voltage corresponding to ABP and equal to the input voltage is obtained, but
When point P' is reached, the output voltage is again interrupted.

The voltage that changes intermittently in this way is ABP.

A drop part due to the waveform of the input terminal, such as the section QDP', is smoothed by the capacitor 8 on the output side, and a DC voltage is obtained between the output terminals 9 and 9'.

However, in this type of system, the period of intermittent control is determined by the response speed of semiconductor elements such as Zener diodes and transistors, so very high frequency electromagnetic noise is generated from the circuit, which can adversely affect other electronic devices in the vicinity. Not only is this possible, but the period of the intermittent control signal is so short that the switching action of the power transistor used in the switching transistor cannot sufficiently respond to the intermittent control signal, making it impossible to perform class C operation.

Therefore, the average power consumption of the switching transistor increases, which may cause thermal breakdown.

OBJECTS OF THE INVENTION It is an object of the present invention to provide an intermittent controlled power supply circuit in which the switching transistor operates completely in response to an intermittent control signal, eliminating the above-mentioned drawbacks associated with the prior art.

<Configuration of the Invention> In order to achieve the above object, the circuit according to the present invention includes a switching transistor inserted between an input side and an output side, and a Zener diode and a resistor connected in series, which are activated by a voltage on the output side. A DC power supply circuit that outputs an intermittent DC voltage on the output side using the Zener current characteristics of the Zener diode,
An ml collector-emitter circuit of a common collector type transistor is inserted between the Zener diode and one of the positive and negative terminals on the output side, and
! ) It is characterized in that it utilizes the unsaturated characteristics of a run transistor to provide an improved conduction/cutoff function of the isolating transistor described in (-) above.

Example Embodiments of the present invention will be described based on the drawings.

FIG. 3 is a circuit diagram of an embodiment of the present invention. The circuit configuration is that the circuit 10 shown in dotted lines is added to the conventional circuit shown in Figure 1, and the basic operation of oscillation is the same as that shown in Figure 1, except that the detection voltage level has hysteresis. different. The outline of its operation will be explained below.

The collector of the transistor 11 is grounded, and the voltage drop between the collector and emitter depends on the Hess potential.

When the output voltage Vout is less than the specified value, no Zener current flows through the Zener diode 6 as described in FIG. 1, so the transistor 5 is turned off and the transistors 3 and 2 are turned on.

The heath potential VBI+ of transistor II at this time is given by the following equation.

RV + R13 -+11 where Vp171: forward voltage of diode DI71.

VcE3:) Two-luck emitter saturation voltage ratio of transistor 3, RV: Resistance value of volume I2, Rlq: Resistor 13
is the resistance value of Since the collector of the transistor 11 is grounded, its emitter potential is V, II +V8Lll
"v, 11.Here, V8ho+is the base-emitter voltage of transistor 11. Therefore, the voltage detection level VoN when transistor 2 is on is given by the following equation.

V6) 1' VEII 10v, 6 +Voh5 -
-(21 ko, 2 ■ θε5.: base-emitter voltage of transistor 5) 4:,. However, since the relationship R'7<<R7 exists between the value R'7 of the resistor 7' and the value R7 of the resistor 7,
The resistance division ratio was ignored. When Vout becomes larger than the above voltage detection level Vos, a Zener current flows through the Zener diode 6, turning on the transistor 5, and thus turning off the transistor 3.2, stopping the supply of energy to the Vout side. Considering the base potential V'BI+ of the transistor 11 at this time, it is given by:

v′9 II −(Vout −VD 14>Ggo, 1g Cu2(0) is the collector-emitter equivalent resistance of transistor 3 when it is OFF. Therefore, transistor 2
The voltage detection level VIIFF when is off is given by the following equation.

V'FF "V '8 II +VBall"
Since vO6+ VaasV′ell #0, VoFF # VBtII+V l)6 + veEs
-(31 Therefore, the hysteresis of the on voltage and off voltage of transistor 4 is given by equation (2) - (3), so Voy V llFF = f21 equation - (3
) Formula - VeilRV 1R13 - Formula (1), and it can be seen that the hysteresis can be set arbitrarily by selecting the resistance values of the resistors I2 and 13. As described above, the hysteresis characteristic can be set at any continuous point by utilizing the unsaturated characteristic of the common collector type transistor. In addition, since the transistor 11 has a common collector configuration;
- Since the run shifter 11 does not become overdriven due to human input or output voltage fluctuations, there is almost no delay from voltage detection to negative feedback operation to transistor 2, achieving high feedback speed and feedback that are especially required in intermittent control power supply circuits. The biggest feature is that this circuit configuration eliminates delays.

Note that FIG. 4 shows the circuit configuration when a C-type transistor is used for the 1-run shifter 2, and FIG.
r; IqTtt In contrast, the circuit configuration implemented is shown. All circuit operations are the same as in the embodiment shown in FIG. In both figures, the same reference numerals with a or b added to the same reference numerals as those used in FIG. 3G are used for parts corresponding to the circuit components shown in FIG. 3.

<Effects of the Invention> As is clear from the above explanation, according to the present invention, the intermittent cycle can be arbitrarily set, so that it can be adjusted to match the load conditions.
1i switching element can be used, and the v
The problem of J rate reduction and heat generation is solved, and since the intermittent cycle can be adjusted, the amount of noise leaking to the outside can be reduced.

Note that since the transistor 11 has a collector-grounded circuit configuration, there is no overdrive of the transistor, and there is little delay in the operation of the voltage detection/detection circuit in principle.

[Brief explanation of drawings]

FIG. 1 and FIG. 2 are a configuration diagram and an operation explanatory diagram, respectively, of an intermittent control type power supply circuit according to the prior art. FIG. 3 is a circuit configuration diagram of an embodiment of the present invention. 4 and 5 are circuit configuration diagrams in which the above embodiment is modified. 2.2a - Switching transistor 2b - Switching transistor (MO5PH7 type) 3
．． 3a, 3b, 5.5a, 5b, 11. . 11 a, I l b --- Transistor 6.6
a, 6b - Zener diode - 1 7, 7a, 7' - Resistor 8 - Output capacitor 10, ] Oa, l Ob - Intermittent cycle adjustment circuit + 4 Diode

Claims (1)

[Claims] It has a switching transistor inserted between the input side and the output side, and a circuit consisting of a series connection of a Zener diode and a resistor, which is activated by the voltage on the output side, and utilizes the Zener current characteristics of the Zener diode. This is a DC power supply circuit that outputs an intermittent DC voltage to the output side, and a collector-emitter circuit of a common collector transistor is inserted between the Zener diode and one of the positive and negative terminals of the output side. An intermittent control power supply circuit characterized in that the switching transistor has hysteresis in its conduction and cutoff functions by utilizing the unsaturated characteristics of the common collector transistor.