JPH04113404A - Series regulator circuit - Google Patents

Abstract

PURPOSE:To stabilize the output voltage by keeping the load power of a transistor TR within a fixed level by adding a series regulator and actuating this regulator according to the difference of potentials. CONSTITUTION:A TR 9 is turned on when the difference of potentials is large between a DC power supply 1 and the output voltage together with a high load voltage level of a TR 3. Then a base current is supplied to a TR 12 through a resistance 11 and the TR 12 turned on. Both a TR 6 and a constant voltage diode 7 are biased by a resistance 8 and the TR 6 functions as a series regulator. That is, another series regulator is added in place of a power loss reducing resistance. This added series regulator does not work usually and then works when the difference of potentials increases between the input and output voltage levels. As a result, the output voltage is kept at a constant level without causing burning damage of the TR.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an improvement in a series regulator circuit that steps down an unstable DC power source and converts it into a stable DC power source.

[Prior Art] FIG. 2 is a diagram showing a conventional series regulator circuit. In the figure, (1) is an unstable DC power supply that is the primary power supply of the series regulator circuit, (2) is the load of the series regulator circuit, (3) is a transistor that is the series control element of the series regulator circuit, and (4) is A constant voltage diode (5) is a transistor (3) a constant voltage diode for setting the output voltage of the series regulator circuit.
4) is a resistor for applying a bias, and (13) is a resistor for reducing power loss of the transistor (3).

Next, the operation will be explained. The resistor (5) biases the transistor (3) and the constant voltage diode (4),
Even if the voltage of the DC power supply (1) fluctuates, the 2 series regulator circuit outputs a voltage value obtained by subtracting the base-emitter voltage of the transistor (3) from the Zener voltage of the constant voltage diode (4).

When the potential difference between the voltage of the DC power supply (1) and the output voltage of the series regulator circuit is large, the loss of the transistor (3), which is a series control element, increases and burns out. Therefore, a resistor (13) is provided, and the voltage drop across the resistor (13) allows the above potential difference to be shared between the resistor (]3) and the transistor (3), thereby reducing the power loss of the transistor (3). Therefore, the resistance value of the resistor (13) needs to be appropriately set depending on the flowing current value.

[Problems to be Solved by the Invention] Since the conventional series regulator circuit is configured as described above, the input voltage fluctuates greatly (in the case of an increase in the loss of the transistor of the series control element or the output voltage of the series regulator circuit). There were some problems that could not be solved with a single power loss resistor, such as a drop in power.

This invention was made to solve the problem mentioned in 1. When the input voltage of the DC power supply fluctuates greatly, the load on the series control element is reduced by another series regulator instead of the voltage drop caused by the resistor. share the voltage,
The purpose is to obtain a series regulator that can always provide a constant output.

[Means to solve the problem] The series regulator circuit according to this invention is as follows.

Instead of a resistor for reducing power loss, another series regulator is added.1 Normally, this series regulator is not operated, but when the potential difference between input and output becomes large, this added series regulator is operated, and the series control element This prevents the loss of the transistor for use from increasing.

[Function] The series regulator circuit according to the present invention maintains the output voltage constant without burning out the transistor of the series control element even if the voltage of the DC power supply varies greatly.

[Example] Below, an example of the present invention will be described with reference to the drawings. In Figure 1, (1) is an unstable DC power source that is the primary power source of the series regulator circuit, (2) is the load of the series regulator circuit, (3) is the transistor that is the series control element of the series regulator circuit, and (4) is the load of the series regulator circuit. ) is a constant voltage diode for setting the output voltage of the series regulator circuit, (5) is a transistor (3) and a constant voltage diode (
4) is a resistor for providing a bias, (6) is a transistor which is a series control element of the added series regulator according to the present invention, (7) is a constant voltage diode similar to (6), and (8) is a transistor (6). and constant voltage diode (
7) is a resistor for maintaining the bias, (9) is a transistor for detecting an increase in the burden voltage of transistor (3), and (H4) is for setting the detection point of the burden voltage of transistor (3). constant voltage diode, (11)
is a resistor to limit the base current of the transistor (1, 2), and (1, 2) are transistors to operate the added series regulator.

Here, the following symbols are defined for explanation.

Output voltage V□' of Vo series regulator circuit: Output voltage D7・V of added series regulator,! : Zener voltage of constant voltage diode (7).・vz: Zener voltage T3 of constant voltage diode (10) VC: 6: Voltage between collector and emitter of transistor (3) T6・vBl,: Voltage between base and emitter of transistor (6) T9・Vr3L: Transistor ( Voltage T between the base and emitter of 9), VCE: Voltage between the collector and emink of transistors C1 and 2) ■ The potential difference between the DC type 1 (1) and the output voltage is small, so the burden on transistor (3) When the voltage is small, the seventh-order relationship holds true.

(T 9-V 11.ri+(D,.-V 2)> (
According to the above relationship, 7 transistors (9
) is in the OFF state, no base current is supplied, and the transistor (42) is also in the OFF state. The constant voltage diode (7) does not operate, and the transistor (
6) becomes a saturated state of 1V or less. Therefore, if the potential difference is small, the transistor (6) will be in a low voltage ON state.
Transistor (3) stabilizes the output voltage and takes up all the potential difference.

If the potential difference between the DC power supply (1) and the output voltage is large (if the burden voltage of the transistor (3) is large), a quadratic relationship holds true.

(Tg・V 13 E) +(n +.・■, ri≦(
T3・VC4,) In the above relationship, take the transistor (9
) becomes an ON state, and a base current is supplied to the transistor (shi,) through the resistor (], i), and the transistor (shi,) becomes an ON state. The transistor (6) and constant voltage diode (A) are biased by the resistor (8),
Transistor (6) operates as a series regulator. The output voltage of this series regulator is as follows.

Vo'-(D7fz)+CT+,4cE)(Ta・Vs
r:> And transistor (3) bears the following voltage (T3・VCE) = Vo' Vo = (T9・
VBE) -1-(D+ o・v7) In a state where the potential difference is large, 8 Transistor <9) is.

The above-mentioned substantially constant voltage is shared, and the transistor (6) shares the remaining potential difference to compensate for the voltage fluctuation of the DC power supply (1).

Note that the Zener voltage of the constant voltage diode (7) sets the output voltage (v0') of the added series regulator, but must be set in a linear relationship in order to operate two circuits.

V O' ≧Vo4- (Tg・VBJ→-(D+o-
Vz) This is because when the potential difference is large, the series regulator operates stably by the transistors (1, 2).

In this way, when the potential difference between the voltage of the DC power supply C],) and the output voltage of the series regulator is small, the transistor (6) of the added series regulator is saturated to a low voltage, and the output voltage is adjusted by only two transistors (3). stabilize. 17. If the potential difference is large, the voltage burden on the transistor (3) is almost constant. The transistor (6) is operated 1-1 with the 7-Leads regulator, and the potential difference is shared between each transistor. Therefore, even if the input power varies greatly, the power burden on the transistor can always be kept below a certain level.

In the above embodiment, the components for detecting the overload of the shared voltage of the transistor (3) were composed of the transistor (9) and the constant voltage diode (10), but the components that detect the overload of the shared voltage of the transistor (3) are the transistor (9) and the constant voltage diode (10). It goes without saying that the configuration functions similarly.

Further, although the above embodiment has a two-stage series regulator configuration, depending on the magnitude of the potential difference and the allowable loss of the transistor, a plurality of configurations with two or more stages can have the same effect as the above embodiment.

[Effects of the Invention] As described above, according to the present invention, since a series regulator is added and operated according to the potential difference, the power burden on the transistors does not increase beyond a certain level (
Output voltage can be stabilized.

[Brief explanation of drawings]

FIG. 1 shows a series regulator circuit according to an embodiment of the present invention. FIG. 2 shows a conventional series regulator circuit. In the figure, (j) is the DC power supply, (2) is the load, and (3)
is a transistor, (4) is a constant voltage guide, (5) is a resistor, (6) is a transistor, (7) is a constant voltage diode, (8) is a resistor, (9) is a transistor, <10> is a constant voltage diode, (IJ,) is resistance, (shi,)
is a transistor, and (1, 3) is a resistor. In the drawings, the same reference numerals indicate the same or equivalent parts.

Claims (2)

[Claims] (1) A first transistor whose collector is connected to a DC power supply and whose emitter is connected to a load; a first constant voltage diode whose cathode is connected to the base of the first transistor; and a voltage regulator between the DC power supply and the base of the first transistor. In a series regulator circuit consisting of a resistor, a DC power supply and a first
a second transistor provided between the transistors;
a second voltage regulator diode with its cathode connected to the base of the transistor; a third transistor connected to the anode of the second voltage regulator diode; a resistor connected between the DC power source and the base of the second transistor; a third voltage regulator diode whose anode is connected to the emitter of the first transistor; a fourth transistor whose base is connected to the cathode of the third voltage regulator diode; and a fourth transistor whose emitter is connected between the first transistor and the second transistor; A series regulator circuit comprising a resistor connected between the collector of a fourth transistor and the base of a third transistor. (2) The cathode of the third voltage regulator diode is connected between the first transistor and the second transistor, the emitter is connected to the anode of the third voltage regulator diode, and the base is connected to the emitter of the first transistor. The series regulator circuit according to claim 1, characterized in that the series regulator circuit comprises a fourth transistor.