DE2011283A1 - Collector follower voltage regulator - Google Patents

Description

Patent attorney Dlpl.-lng. R. B E E T Z «en. Dlpl-lng. K. LAMPRECHT Dr.-lng. R. Q E E T Z Jr.

8 Munich 22, Sieinsdorfetr. 10

Bl-15.476p March 10, 1970

HITACHI, LTD., 'T ο k i ο (Japan)

Collector collector voltage regulator

The invention relates to a transistor voltage regulator which delivers a constant DC voltage to a load.

A series voltage regulator circuit that provides a constant Provides voltage to a load regardless of fluctuations in the voltage source, with a regulating transistor between between the voltage source and the load is generally known as a collector follower regulator, the Load with the collector side and the voltage source with the emitter side of the control transistor is connected.

The collector olger voltage regulator has a, e better Ripple suppression than the usual emitter follower

81- (POS 21.i66) -Hd-r (7)

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Regulator, however, the disadvantage that it requires an ignition circuit.

As an ignition circuit, a circuit is known in which a resistor between the emitter and the collector of the regulating transistor or between the base of the regulating transistor and a voltage supply line is connected. In both circuits, however, no voltage regulation is possible be carried out at low load, d. H. the effective control range is limited by load fluctuations.

The invention is therefore based on the object of specifying a series voltage regulator of the collector follower type, in which the voltage regulation remains unaffected when the load is small.

According to the invention is a thermistor with a positive resistance-temperature coefficient connected between the base of the control transistor and the common reference potential, so that the ignition current is fed into the control transistor via the thermistor.

The invention is explained in more detail with reference to the drawing. Show it:

1 shows the circuit diagram of a known voltage regulator;

Fig. 2 shows the characteristic of the known voltage regulator

of Fig. 1 and the voltage regulator according to the invention;

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3 shows the circuit diagram of an exemplary embodiment

of the voltage regulator according to the invention; and

Flg. h the voltage-current characteristic of a thermistor «with a positive resistance-temperature coefficient, as used for the voltage regulator according to the invention.

To explain the circumstances that an ignition circuit leads to difficulties in regulating the voltage with a small load , a conventional voltage regulator is shown in FIG.

In Fig. 1 Q ₁ denotes a control transistor Q ₂ a control deviation Verstärkungstransjstor, R ₁ and R "Regal deviation ~ FUhlwiderstände, R ^ a Emitterwideret and dee transistor Q, Z is a reference diode, R. a ZUndwlderstand between the emitter and the collector of the transit port Q ₁ , 8 a load and 2 a voltage source circuit, consisting of a Vechael voltage source 3 »a rectifier 5 and a switch k.

In this circuit, when the switch k is closed, an ignition current (base current) is fed _{into the transistor Q 2} via the ignition resistor Rj _1. When the transistor Q_ works, the transistor Q starts to work. The operation of this voltage regulator is initiated by the ignition resistor R. Without the resistor R., neither the transistor Q ₁ nor the transistor Q_ would begin to work, even if the switch h were closed, so that no nominal voltage could be delivered to the load.

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The resistor Rj is therefore for commissioning
of the voltage regulator is essential. The resistance R ^ has
however, it has the disadvantage that it causes difficulties in voltage regulation when the load is small, as can be seen from FIG. When the load current is small (small load), dpnn, the load terminal voltage V rises so that the
Voltage regulation; get lost. Therefore, in this known voltage regulator, the operating range of the load is limited when the voltage is regulated. So the regulator is
not suitable for small loads.

The voltage regulator according to the invention should now be used
to be discribed:

Tn Fig. 3 , a transistor Q _{1 is present} as a control transistor for regulating the voltage applied to the load, while a circuit 1 is a voltage sensing circuit in the
Collector circuit of the transistor Q forms. The voltage sensing circuit includes resistors R ₁ and R _p for detection
the collector voltage of the transistor Q, a reference diode (Zoner diode) Z for obtaining a reference potential and a resistor R ". The one with the voltage level; 1 connected transistor Q _? amplifies the control deviation detected by the span sensor circuit 1 up to the Pe, -el of the base drive signal of the transistor Q-. the
The emitter voltage of the transistor Q "is relative to the collector voltage" of the transistor Q by the Zener diode Z! Constant ^ enifciit. The base voltage of transistor Q _?
follows the change in the collector voltage of transistor Q-. As in execution; 1 there is a voltage leveling circuit 2 which has an alternating voltage source 3, a switch k and a conventional rectifier circuit 5 for rectifying the alternating current from

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the source 3 and for feeding the rectified voltage into input terminals i and i "of the control circuit. The circuit 8 represents a load between output terminals O and O _p .

According to the invention there is a thermistor R_ which has a positive resistance-temperature coefficient, one end of which is connected to the base of the transistor Q ₁ and the other end to a reference potential line 1. The voltage-current characteristic of the thermistor R- at constant ambient temperature is plotted in Fig. H , according to which the thermistor R- exhibits a low resistance at a low applied voltage and a high resistance at a high voltage. Standard thermistors with a positive resistance-temperature coefficient can be used as the R- thermistor «,

The transient behavior of the voltage regulator according to the invention will now be considered when the switch h is closed. When the switch k is closed , the thermistor R ₁ ^ is initially not heated, so that it has a low resistance. Therefore, a current flows to the base of the transistor Q ₁ through the thermistor R _r . The transistor Q is then made conductive, and it applies a voltage · V. from the input terminal i .. at the output to the terminal O as a voltage V. By applying the voltage V to the voltage sensing circuit 1, the output voltage V is adjusted to a potential that is predetermined by the resistors R ₁ and R " _f, the reference voltage V of the Zener diode Z and the gain of the transistor Q through the positive feedback of the transistor Q. Increases this time, since a voltage higher than the critical voltage V k of Fig. On thermo-

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inistor R_ is applied, its resistance because of him flowing through current, whereby the normal operation of the transistors Q and Q_ is not disturbed.

According to the invention, at the very beginning, when the switch h is closed, the ignition current of the control transistor Q _{1 is passed} through the thermistor R-, which is in the low resistance state. In the normal operating state of the control circuit, however, the thermistor R "has such a high resistance that the base of the control transistor Q _{1 is separated} from the common reference potential line 1.

The voltage regulator according to the invention can therefore also be used to regulate the voltage for small loads so that the effective operating range ^ j, T is larger (see. Fig. 2).

According to the invention is a thermistor with a positive Resistance-temperature coefficient provided. On simple In this way, a larger operating range can be achieved with lower power consumption.

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Claims (1)

Claim Voltage regulator that can be switched between a current source and a load, with a control transistor that an emitter, a base and a collector for regulation having the voltage applied to the load, wherein the emitter can be connected to the current source, with a Output connection, which is connected to the collector and can be connected to the load, with a saving sensor circuit, the one with the collector of the transistor to detect a system error signal proportional to the Potential difference between the actual potential at the output terminal and a target reference potential is connected; and with an amplifier circuit connecting between the base of the control transistor and the voltage sensing circuit is switched to amplify the deviation signal from the voltage sensor scarf and feed the amplified deviation signal into the base as a control signal so that the conductance of the control transistor can be adjusted by the control signal, characterized by a thermistor (R _r ) with a positive resistance temperature Coefficient (Fig. K) between the base of the control transistor (Q ₁ ) and a common reference potential (l), the thermistor being low-resistance of the control transistor from the common reference potential (.1.) during normal operation of the Control transistor is (Fig. 3, 4). 009839/1518 BAOORIGINAt. Blank page