JPS5831423A - Constant-voltage circuit - Google Patents

Abstract

PURPOSE:To reduce the voltage loss between I/O terminals and stabilize the operation of a control circuit by preventing the control circuit from the generation of oscillation even if p-n-p type transistors for the supply of constant- voltage are used. CONSTITUTION:A circuit for starting and controlling transistors (TRs) consists of a starting circuit 31, a control circuit 32 and a standard voltage circuit 33. When voltage is applied to an electric power source input terminal VIN in the starting circuit 31, a TR39 is turned on and the voltage of an output terminal is increased. When the voltage of the output terminal reaches a prescribed value, the TR39 is turned off. The control circuit 32 consists of an differential amplifier 43 for inputting the voltage obtained by dividing the output voltage through a resistor and standard voltage and plural steps of inversion type amplifier circuits for amplifying the output of the differential amplifier. The voltage of a terminal 18 is kept at a fixed voltage VCC by turning on/off TRs 51, 52.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a constant voltage circuit that can obtain a constant voltage at the output end of a power supply line even if there is a voltage change at the input end of the power supply line.

FIG. 1 is a conventional constant voltage circuit diagram, where 1 is a voltage V that is made constant from the input voltage V□N of the power supply line. .

2 is an operational amplifier for controlling the NPN transistor. Constant voltage property obtained from resistor 3 and constant voltage diode 4, non-inverting input of operational amplifier 2, output voltage V. . , divided by a resistor of 5°6 becomes the inverting input of the operational amplifier 2.

As mentioned above, the conventional constant voltage circuit uses the constant voltage supply transistor (external) IKNPN'll', so the loss voltage between the input and output of the power line is generally 2V or more. , for example V. . When you want to output 5Vt- to 7. ■1) I requires 7v or more. By the way, the reason why an NPN type transistor is used for the transistor 1 is that the output sides of the transistor 1 are in the same phase relationship with each other, so that the configuration is such that oscillation is difficult to occur. On the other hand, if a PNP type transistor is used as the above transistor, the pace and collector output sides will be in an antiphase relationship with each other, which will cause oscillation. It was.

The present invention has been made in view of the above circumstances, and by providing a control circuit for a constant voltage supply transistor that does not cause oscillation even if a PNP type transistor is used, it is possible to By reducing voltage loss, by downsizing the capacitor provided on the output side of the transistor, and by obtaining power for the control circuit from the output end of the transistor, stable operation of the control circuit is possible. The purpose of this invention is to provide a constant voltage circuit.

An embodiment of the present invention will be described below with reference to the drawings. Second
In the figure, 11 is the input voltage vxMt of the power supply twin - the constant voltage V. . ? 12 is a starting and controlling circuit for the transistor 11, and this circuit 12 is constructed of an integrated circuit. The emitter side of the transistor 11 is connected to a terminal 14 of the integrated circuit 12 via a resistor 13. The emitter of the transistor 11 and the paste are connected through a resistor 15, and the paste of the transistor 11 is connected to a terminal 17 of the integrated circuit 12 through a resistor 16. transistor 11
The collector of the transistor 11 is connected to the terminal 18 of the integrated circuit 12, the terminal 18 and the terminal 19 are connected via the oscillation prevention capacitor 10, and the collector of the transistor 11 is grounded via the capacitor 21. This is a detailed diagram of the integrated circuit 12), which is composed of a starting circuit 31, a control circuit 32, and a reference voltage circuit 33. In the starting circuit 31, a resistor 3! is connected between the terminal 18 and the ground terminal 34! i, 36 are connected in series, and the resistor 35.16 is connected to the base of the transistor 310. The terminal of this transistor 37 is grounded, and the collector is connected to a resistor S8.
It is connected to the terminal 14 via. Also, transistor J1
The collector of transistor 390 is connected to the base of transistor 390, and the emitter of transistor 39 is grounded.

In the control circuit 32, a resistor 3s e 40 is connected in a column between the terminals r it s j 4, and a resistor 41
and a constant voltage diode 42 are connected in series. The resistors 39 and 40 are connected to the input terminals of the input stage elements 44 and 450 of the differential amplifier circuit 43, and the resistor 41 and the constant voltage diode 42 are connected to the input terminal of the differential input stage element 4 it e 4F. The emitters, ri, and pace of the differential input stage elements 44 and 45 are:
It is connected to the terminal 18 through the constant current source 48t, and the output terminals of the input stage element 46e47 are connected to the terminal II through the constant current source 49, and the input stage element 45.4'/ The common emitter is connected to the terminal 18 via a constant current source 50. Collector of input stage element 44.46.

is grounded, and the collector a- of the input stage element 46 t 47
'ttL-t'tL) ”)7-)sl 61,6
10-sV octa 11l! be done. The transistor Jj
The emitters of the transistors 47 and 111 are grounded, and the collectors of the transistors 53 and 51 are connected in common. The NIOTS is connected to the pace of the non-inverting amplification element 54, and the collectors of the elements 53 and 54 are grounded.

Element 53. ! Between the emitter of 54 and the pace is a constant current source 5.
5 to the terminal 18, and the voltage of the element 54 is connected to the terminal xtnc* via the constant current source 5C. %, and the transistor 610 is connected in series between terminals 11.34 and 9 resistors i1. Diode 59-62 resistanceits
, and the diode 59, and the collector of the transistor 39 is connected to the terminal 11 and the collector IIC of the transistor 39 via a resistor 63.

In the constant voltage circuit configured in this way, the starting circuit J
1, when a voltage is applied to the power input terminal V□, the resistor 13
The transistor 19 is turned on via the resistor 38. Then, the external transistor 11 is turned on via the resistor 63.16, and the output terminal voltage V. □ is rising. This V. . When the power supply vcc of the integrated circuit 12 reaches a voltage determined by the ratio of the resistors ss and xtt (t-), the transistor 11 is turned on and the transistor 39 is turned off. That is, the starting circuit 31
is used to raise the integrated circuit power supply Vcct, and when this power supply Vcc rises to the level that it reaches Vcct, the transistor 39 will turn off, but since the power supply Vcc is still low, an external transistor 11t
-) Since it is in the on state, the voltage is V. IJ? =VCe continues to rise at a constant voltage (for example, 5V)4. When the transistor S9 is turned off, the transistor 11
is controlled only by control circuit 32.

This control circuit 32 includes a differential amplifier circuit 43 which uses a voltage divided by resistance to Vcc', a reference voltage, and t input, and a cough circuit 43.
The transistor 44 consists of an operational amplifier consisting of multiple stages of non-inverting amplification elements that amplify the output of the transistor 44.
．． 46 (-sha, the same potential is used when the amplifier operates.) The voltage Vcc is stabilized by the reference voltage from the diode 42 and the voltage determined by the resistor 39°400 ratio. For example, when the voltage at terminal 18 rises, When the base voltage of transistors 44 and 45 rises, transistors 51 and 52 turn off, and the base voltage of transistor 530 increases.
The emitter voltages of the transistors 63 and 54 and the collector voltage of the transistor 51 both rise, lowering the voltage at the terminal 18. On the other hand, when the voltage at terminal 18 is about to drop, the pace voltage of transistors 44, 41; turns on, transistors 51, 52 turn on, and the pace voltage of transistor 53, the voltage of each terminal of transistors 53, 54, The collector voltage of transistor 51 decreases, increasing the voltage at terminal 18. In this way, terminal 18 is stabilized at a constant voltage vcc.

In the constant voltage circuit having the above configuration, since the phase is often inverted in the amplifier circuit of the control circuit s2, oscillation occurs. As a result, the constant voltage supply transistor 11 has a PN
A P-type type can be used, and the input end voltage of the power supply line is ν, and the output end voltage is . . The voltage loss between the transistors 7 and 7 can be minimized, and for example, this voltage loss can be made very small to about the saturation voltage of the transistor 11, that is, about O,iv. Furthermore, since this Q circuit has a structure that is difficult to oscillate, the capacitor 21 can be made smaller and can also be built into an integrated circuit. In addition, the power supply voltage of the control circuit 32 is taken from the output end side of the main power supply line, and the power supply voltage vc
Since c is kept constant regardless of the input terminal voltage v4, the control circuit 52t can be operated in a stable state. - Note that the present invention is not limited to the above-mentioned embodiments; for example, the non-inverting amplifier circuit provided in the constant voltage supply transistor 11f integrated circuit may also be used as a non-inverting amplifier circuit.
Various applications are possible, such as regardless of the stage.

As explained above, according to the present invention, since the control circuit does not cause oscillation even if PNPWO is used for the constant voltage supply transistor, the voltage loss between the input and output terminals of the transistor can be reduced, and the output It is possible to provide a constant voltage circuit which has advantages such as the capacitor on the end side can be miniaturized and the power supply for the control circuit is obtained from the output end side of the transistor, so that stable operation of the control circuit is possible. It is.

[Brief explanation of drawings]

Figure 1 is a conventional constant voltage circuit diagram, Figure 2 is a circuit diagram of an embodiment of the present invention, and Figure 3 is a partially detailed diagram of an open circuit. 11...PNP! ) Transistor, 31 - Startup circuit, 32 - Control circuit, 33 - Reference voltage circuit, 39° 40... Voltage division resistor ζ 43 - Differential amplifier circuit, 53.54 - Non-inverting type amplification element.

Claims (2)

[Claims] (1) A PNP transistor inserted between the input and output terminals of the power supply twin, a differential amplifier circuit that inputs a voltage corresponding to the output terminal voltage and a reference voltage and controls the pace of the transistor, and the amplifier circuit. A constant voltage circuit comprising: a non-inverting amplifier circuit inserted between an output terminal and the base of the transistor to amplify the differential amplifier circuit C and the output. (2) PNP inserted between the input and output ends of the power supply line, [
) a differential amplifier circuit that receives a voltage corresponding to the output terminal voltage and a reference voltage as input and controls the pace of the transistor; and a differential amplifier circuit that is inserted between the output terminal of the amplifier circuit and the pace of the transistor. a non-inverting amplifier circuit for amplifying the output of the differential amplifier circuit; means for obtaining a power supply voltage for the amplifier circuit and the differential amplifier circuit from an output end of the power supply line; A constant voltage circuit comprising: a starting circuit that drives to increase the output voltage of the power supply twin.