JPH0521123Y2 - - Google Patents

Description

[Detailed description of the invention] [Field of industrial application] The present invention relates to a DC stabilized power supply comprising transistors controlled by a constant voltage control circuit connected in series between an input power supply and a DC output terminal. .

[Problems that conventional technology and ideas try to solve]

The input voltage in conventional DC stabilized power supplies is exclusively DC voltage, and AC input must be rectified once. Therefore, the voltage drop of the rectifier diode is added in series to the collector-emitter voltage of the transistor connected in series between the DC input power supply and the DC output terminal, and the power efficiency and voltage utilization rate are reduced by that amount. .

Therefore, an object of the present invention is to provide a DC stabilized power supply that can reduce such power supply circuit loss.

[Means for solving problems]

In order to achieve this purpose, the present invention is constructed as shown in FIG. 1a. That is, Tr1 is the input voltage
Transformer T as AC input power supply supplying Vc
This is a transistor connected in series to 1, and by being a PNP type, it generates a positive and stabilized output voltage Vo at the output terminal. Reference numeral 1 denotes a negative feedback type constant voltage control circuit which is well known per se, to which an output resistor R1 is added according to the present invention. That is, this constant voltage control circuit compares the output voltage Vo and a reference voltage, and controls the collector-emitter voltage Vce through the base of the transistor Tr1 according to the difference. C1 and C2 are smoothing capacitors connected between the output terminal and the base of the transistor Tr1 and a reference potential, respectively.

Incidentally, when generating a negative stabilized output voltage Vo, the transistor Tr1 is made to be an NPN type.

[Effect]

During the period T1 (FIG. 1b) in which the input voltage Vc becomes greater than the base voltage _VB held in the capacitor C2 and can supply a base current, the transistor Tr1 operates in the same way as a normal DC stabilized power supply. In other words, in the constant voltage control circuit 1, the collector-emitter voltage Vce is either the input voltage Vc or the output voltage Vo.
Transistor Tr1 is controlled so as to absorb the changing voltage and keep the output voltage Vo constant.

During the period T2 when the input voltage Vc is lower than the base voltage _VB and no base current flows, the transistor
Tr1 is cut off, and the output voltage Vo is supplied from the capacitor C1. During this time, the base voltage
V _B is discharged with a time constant defined by at least the capacitance of the capacitor C2 and the output resistor R1. In other words,
Without immediately discharging to the constant voltage control circuit 1, the collector-base of the transistor Tr1 is maintained in a cut-off state to prevent a voltage drop due to wasteful discharge of the capacitor C1 to the capacitor C2.

[Example of idea]

In FIG. 2, 2 is a DC-AC converter that generates a rectangular wave voltage with a peak value of approximately 5.5V. Tr2 is a transistor that performs the function of transistor Tr1 in Fig. 1, but transistor Tr2
By using the collector as an emitter to withstand the reverse voltage between the base and emitter (maximum approximately -11V) during cut-off, the reverse breakdown voltage characteristic of the base and collector is utilized. Therefore, the emitter of transistor Tr2 functions as a normal collector.

During the positive pulse period, the constant voltage control circuit 1 outputs +5V as the output voltage Vo, as in the case of Fig. 1, and during the negative pulse period, the transistor Tr
2 is cut off, and power is supplied from the capacitor C1. In this case, the constant voltage control period is longer than when the input voltage is a sine wave, so
A more stable output voltage Vo can be obtained. Also,
If the power source of the DC-AC converter 2 is, for example, a nickel-cadmium battery, compared to configuring the power source only with these batteries, the IC is a DC stabilized power source with fewer circuit elements and low power loss.
A desired voltage suitable for the circuit can be accurately obtained, and the effects of overvoltage at the end of charging the battery can also be avoided.

FIG. 3 shows a DC-AC converter 4 and each part Tr1, R1, 1, C1,
It consists of a stabilized power supply circuit 5 composed of C2.
Output voltage by superimposing 0.2V output DC stabilized power supply
An example will be shown in which +5V is generated as Vo. If this DC power supply circuit is operated with the collector-emitter voltage Vce of the transistor Tr1 close to the saturation voltage, power loss can be reduced to about 1/2 compared to a conventional system including a rectifier diode.

[Effect of idea]

As described above, according to the present invention, it is possible to realize a DC stabilized power supply that does not require a rectifier circuit, and therefore the circuit configuration is simple, power loss is reduced, and voltage utilization efficiency is improved. In particular, when used as a DC stabilized power source for low voltage, the degree of improvement in power efficiency and voltage utilization factor becomes greater.

[Brief explanation of the drawing]

FIG. 1 shows a DC stabilized power supply according to the present invention, a is a circuit diagram thereof, b is an explanatory diagram of its operation, and FIGS. 2 and 3 are circuit diagrams according to an embodiment of the present invention, respectively. .

Claims (1)

[Scope of utility model registration request] A transistor whose base is controlled by a constant voltage control circuit is connected between the AC input power supply and the DC output terminal via an output resistor, and a smoothing capacitor is connected between the DC output terminal and the base and a reference potential, respectively. DC stabilized power supply.