JPS6326625B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a DC stabilized power supply circuit, which controls the conduction state of a switching element by controlling the level of a switching pulse according to the level of an input voltage, and has a simple circuit configuration. The purpose of this invention is to provide a highly efficient DC stabilized power supply circuit with low switching noise.

FIG. 1 shows a circuit diagram of an example of a conventional switching regulator. In the figure, an unstable DC voltage V _i that enters an input terminal 1 is supplied to a switching element 2 such as a transistor, where it is stopped by a pulse signal P from a pulse width modulation circuit 3, and the switching element 2 is turned off. When the current is smoothed, the current is smoothed by a flywheel diode 4, a smoothing circuit 5, and a smoothing capacitor 6 to continue flowing current to the subsequent stage, and then taken out from an output terminal 7. At this time, the output voltage V _p is supplied to the pulse width modulation circuit 3, and when the level of the output voltage V _p decreases (increases), the pulse width of the pulse signal P increases (shortens) the conduction period of the switching element 1. The output terminal 7 is configured to operate in the direction so as to output a stable voltage V _p from the output terminal 7. When the duty cycle of the pulse signal P is δ, the output voltage V _p is V _p = (1
−δ)V _i .

By the way, if the duty cycle δ of the pulse signal P is set to an extreme value, for example near 0% or 100%, it will be difficult to design pulse width control.
Normally, around 50% is often set as the standard usage state. Therefore, this switching regulator is suitable for obtaining an output voltage V _p that is approximately 1/2 of the input voltage V _i .

However, for example, in a television receiver,
The pulse signal P is synchronized with the period of the horizontal deflection pulse.
When applied to a circuit that determines the switching period of Moreover, since the position of this interference varies depending on the level value of the input voltage V _i , the screen becomes unnatural. Furthermore, devices using batteries have the disadvantage of being uneconomical because they must use a current rated at a voltage V _i that is much higher than the voltage V _p actually used. Furthermore, the pulse width modulation circuit 3 has a complicated structure and cannot be constructed at low cost.

The present invention eliminates the above drawbacks, and the second
An example will be described below with reference to the drawings.

FIG. 2 shows a basic circuit diagram of an embodiment of the DC stabilized power supply circuit according to the present invention, in which the same components as in FIG. 1 are given the same numbers. In the figure, 8 is a standard voltage for output voltage comparison, 9 is an operational amplifier, and 10
is the standard voltage for determining the peak value of the switching pulse signal _Ps , 11 and 12 are clamp diodes, 1
3 is a clamping resistor, 14 is a switching element 2
15 is a horizontal deflection pulse input terminal. The amplitude of the horizontal deflection pulse P _i is set larger than the amplitude of the pulse P _s supplied to the switching element 2 .

This device switches the input voltage V _i entering the input terminal 1 through a switching element 2, a diode 4, a coil 5,
When the voltage is taken out from the output terminal 7 via the capacitor 6, the conduction state of the switching element 2 is controlled according to level fluctuations of the input voltage V _i to obtain an output voltage V _p at a constant level. The horizontal deflection pulse P _i that enters the terminal 15 is supplied to the diodes 11 and 12 via the resistor 13, and the voltage E ₃ and the voltage (E ₂ +
E ₃ ), the base is the voltage E ₃ and the peak-to-peak values of the pulse are the voltage E ₂ as the pulse signal P _s , and the base and peak levels of the pulse signal P _s are the level of the input voltage _Vi . Depending on the output voltage E ₃ of the amplifier 9 depending on the fluctuation, the signal P _s to _{P s} shown in FIG.
It changes like this. In this case, resistance 14, voltage E ₂
is appropriately determined so that signals P _s to _{P s} can be obtained.

That is, as shown in FIG.
Determine the on level l ₁ and off level l ₂ of the input voltage
When V _i is at the standard value (state), the switching element 2 repeats a conductive state (or a state close to a conductive state) and a cutoff state (or a state close to a cutoff state) according to the pulse signal _P s, It operates as a so-called switching regulator. When the input voltage V _i becomes slightly lower from this state, the base level of the pulse signal P _s decreases, and although the base remains at the conduction level of the switching element 2, the pulse part becomes a half-on state. The switching element 2 is repeatedly switched between a conductive state and a non-saturated active state. When the input voltage V _i further decreases from this state, both the base portion and the pulse portion of the pulse signal reach the conduction level of the switching element 2, and the switching element 2 is always in the conduction state. On the contrary, when the input voltage V _i becomes slightly higher than the standard value (states of and ), the base and pulse parts of the pulse signal P _s rise, and the switching element 2 repeats the unsaturated state and cutoff state. , it operates as a so-called series regulator.

These situations are expressed in terms of the relationship between the input voltage vs. output voltage characteristics and the loss of the switching element 2 as shown in FIGS. 4A and 4B, respectively. When the input voltage V _in is low and equal to the standard output voltage V _ps ,
Since the switching element 2 is always conductive, the loss P _p is zero if the circuit operates ideally. When the input voltage V _i is higher than this, the loss P _p increases by the amount that switching element 2 is half-on during the pulse period, and the voltage drop becomes larger than in the case of , and the output voltage It operates to keep V _p constant. When the input voltage V _is is equal to the standard output voltage V _ps (state), the switching element 2 performs a perfect switching operation, so the loss P _p is zero, and the input voltage V _is and output voltage V _ps at this time are The relationship is V _ps = (1-δ) V _is . When the input voltage V _is is higher than this state (states of and ), the switching element 2 repeats the non-saturated active state and cutoff state, so the loss P _p increases uniformly with the input voltage V _is , and the voltage As the drop increases, the output voltage V _p
operates to keep it constant.

That is, the circuit of the present invention does not change the pulse width using the pulse width modulation _circuit 3 as shown in FIG. By doing so, the conduction state of the switching element 2 is varied in order to obtain a constant output voltage level.

Note that if switching element 2 only operates as a series regulator, the loss
P _p increases uniformly from the input voltage _V in which starts voltage stabilization, as shown by the broken line in FIG. 4B.

If the input voltage V _is of the circuit is set to the standard voltage of a battery with discharge characteristics as shown in Figure 5, high efficiency will be maintained under most usage conditions, and the output voltage will vary from the high voltage at the beginning of use to the end of life. Stabilized up to the limit voltage.

FIG. 6 shows a specific circuit diagram of the circuit of the present invention, in which the same components as in FIG. 2 are given the same numbers. In the figure, 16, 17, and 18 are resistors for adjusting the level of the output voltage V _p , and variable resistor 17
If the resistance value from the slider of the variable resistor 17 to the output terminal 7 is R _A , and the resistance value from the slider of the variable resistor 17 to the ground is R _B , the output voltage V _p is V _p = R _A + R _B /R Defined in _B・E ₁ . 19 is a Zener diode for obtaining the standard voltage _E1 , 20 is its bias resistance, 21
is a Zener diode to obtain the standard voltage E ₂ ,
22 is its bias resistor, and 23 and 24 are bypass capacitors. Since the operation and effects of this circuit can be more easily understood than those shown in FIG. 2, their explanation will be omitted.

As described above, the DC stabilized power supply circuit according to the present invention includes a comparison circuit that compares an output voltage with a reference voltage, a pulse generation circuit that generates a switching pulse for switching the active element, and the comparison circuit. The circuit changes the overall level of the switching pulse according to the fluctuation of the input voltage level by the output of repetition with saturated active state,
Since the switching active element is operated in either a repeating state of conduction or a state close to this and a state of cutoff or a state close to this, or a repetition of a non-saturated active state and a cutoff state, the conduction state of the switching active element is controlled by changing the input voltage. A constant level output voltage can be stably obtained simply by controlling according to level fluctuations, there is no need to use a pulse width modulation circuit such as a conventional switching regulator, and the circuit can be configured easily and inexpensively. Also, compared to a switching regulator, interference due to parasitic vibrations during switching can be reduced, and unlike a switching regulator, there is no need to set the switching pulse at around 50%, so for example, When applied to a circuit that determines the switching period of a pulse signal in synchronization with the period of the horizontal deflection pulse of a television receiver, the leading and trailing edges of the switching pulse can be placed at the left and right edges of the receiving screen, resulting in overscanning. Therefore, it can be placed in a position without any influence on the screen, resulting in a more natural screen, and in addition, the ratio of the output voltage to the standard input voltage can be increased, such as with a switching regulator. Since there is no need to set the number of batteries, there is no need to increase the number of batteries, making it suitable for devices that use batteries.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram of an example of a conventional switching regulator, FIG. 2 is a basic circuit diagram of an embodiment of the circuit of the present invention, and FIG. A diagram showing the relationship between the level of the pulse signal and the operating state of the switching element; FIGS. 4A and 4B are an input voltage vs. output voltage characteristic diagram and an input voltage vs. loss characteristic diagram, respectively, for explaining the operation of the circuit of the present invention; FIG. 5 is a discharge characteristic diagram of a battery used in the circuit of the present invention, and FIG. 6 is a specific circuit diagram of the circuit of the present invention. 1... Input voltage terminal, 2... Switching element, 4... Flywheel diode, 5... Smoothing circuit, 6... Smoothing capacitor, 7... Output terminal, 8... Standard voltage for output voltage comparison, 9... ...Operation amplifier, 10... Standard voltage for determining the peak value of the switching pulse signal, 11, 12... Clamping diode, 13... Clamping resistor, 14...
Bias resistance of switching element, 15...Horizontal deflection pulse input terminal.

Claims (1)

[Claims] 1. One end of a load is connected from one end of a DC power source through a series connection of an active element and an inductor, the other end of the load is connected to the other end of the DC power source, and the active element and the inductor are connected to one end of the load. A diode is inserted between the connection point of the inductor and the other end of the DC power supply in a direction such that the active element is conductive when it is in a cut-off state, and the operating state of the active element is controlled. A DC stabilized power supply circuit that controls a DC voltage applied to a DC voltage source, comprising: a comparison circuit that compares an output voltage with a reference voltage; a pulse generation circuit that generates a switching pulse for switching the active element; The output is a circuit that changes the overall level of the switching pulse according to fluctuations in the input voltage level, and changes the active element into a continuous conductive state or a conductive state according to the voltage value of the DC power supply. It is characterized in that it operates in any of the following: repeating a non-saturated active state, repeating a conducting state or a state close to this and a cut-off state or a state close to this, repeating a non-saturated active state and a cut-off state. DC stabilized power supply circuit.