JPH0365713A - Power unit controller - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a power supply control device using a PNP transistor in its output, such as a low drop type dropper regulator.

BACKGROUND OF THE INVENTION In recent years, low drop type dropper regulators have been released one after another. FIG. 3 is an equivalent circuit diagram of a low drop type dropper regulator. In FIG. 3, Q1 to Q13 are transistors, R1 to RIO are resistors, C1 to C2 are capacitors, Vin is an input voltage terminal,
V out is the output! Insulator 1, G, N, D are ground terminals, V
REF'' VDD is a reference voltage terminal.How this circuit operates as a dropper regulator will be described below.

First, when the output terminal voltage is about to rise, the base voltage of the transistor Qll becomes higher than the base voltage of the transistor Q12 among the transistors Qll and Q12 that constitute the differential amplifier. is on, and transistor Q12 is off. If transistor Qll is on, transistor Q9. constitutes a current mirror circuit. Current flows through QIO. By the way, since transistor Q12 is off, the current from transistor Q10 flows through transistor Q
6, the transistor Q6 is turned on, and a current flows. When current flows through transistor Q6, transistor Q5. Current flows through Q4. The current from transistor Q7 is absorbed by transistor Q4, and no current flows to the base of transistor Q3.

Next, when the output terminal voltage is about to fall, when the output terminal voltage falls, the transistors Q11. Of the transistors Q12, the base voltage of the transistor Q12 is lower than the base voltage of the transistor Qll, so the transistor Qll is off and the transistor Q92 is on. If transistor Qll is off, transistor Q9. No current flows through QIO. Then, the base current of transistor Q6 also does not flow, so transistor Q6 is turned off and transistor Q6
No current flows through.

Therefore, transistor Q5. No current flows through Q4 either.

Current from transistor Q7 is not absorbed by transistor Q4, so current flows into the base of transistor Q3.

Next, the operations of transistors Q1 to Q3 will be described. Transistor Q1 is an output transistor and is several hundred m
Has ability A. As described above, when the output terminal voltage is going to rise, no base current flows into the transistor Q3, but when the output terminal voltage is going to fall, a current flows into the base of the transistor Q3.

Transistor Q3 amplifies this current, but the amplification of transistor Q3-stage is insufficient to drive transistor Q1, and transistor Q2 amplifies it enough to drive transistor Q1. . Transistor Q3 is called a driver. Transistor Q2 is called a driver. In this way, the output terminal voltage tends to fall, the transistor Q1 is driven, current flows, and the output terminal voltage tries to rise, so that the output terminal voltage is kept constant. Also, when the output terminal voltage tries to rise, the transistor Q
1 is no longer driven and no current flows, so the output terminal voltage tends to fall, so the output terminal voltage is kept constant.

Problems to be Solved by the Invention Figure 4 shows the simulation results of the transient response of the output terminal voltage when a rectangular wave is input to the input terminal Vin in a low drop type dropper regulator with the conventional configuration as shown in Figure 3. be. As can be seen from this simulation result, a peak occurs in the output terminal voltage at the instant of the rise of the input rectangular wave. The reason for this is that the response of the output transistor Q1 is slow, and at the moment when the input terminal voltage rises, the base-emitter voltage increases and a large current flows. Therefore, there is a drawback that a peak occurs in the output terminal voltage.

Furthermore, when analyzing this phenomenon, when looking at the base current of the output transistor Q9, C1 is a capacitor for phase compensation, but current may flow transiently in the branch between this capacitor C1 and the resistor R6. . At the moment when the input rectangular wave rises, the base current of the transistor Q1 becomes 1/hpi+, which becomes the base current of the transistor Q2.

This current first goes around the branch of capacitor C1 and resistor R6, and flows to the base of predriver transistor Q3. Thus, current flows through transistor Q3.

In this way, at the moment when the human-powered rectangular wave rises, a current flows to the base of the transistor Q3, so that the collector current also flows, and a peak occurs in the output terminal voltage.

An object of the present invention is to provide a low drop type dropper regulator that improves the occurrence of such peaks.

Means for Solving the Problems To achieve this objective, the present invention provides a PNP
) In a dropper regulator using a transistor, this is a power supply control device in which a transistor cascade-connected to the pre-driver transistor is inserted between the pre-driver transistor and the driver transistor.

According to the present invention, by inserting a cascade-connected transistor, it is possible to prevent the base current of the output transistor from flowing due to the wraparound of the current at the moment of the rise of the input rectangular wave. Also, since the cascade-connected transistor transmits the current determined by the pre-driver transistor to the driver transistor as it is, if the output terminal voltage is to become low due to the addition of the cascade-connected transistor, it will be increased; For example, it has no effect on the action of lowering it. In this way, it is possible to improve the phenomenon in which a peak occurs in the output terminal voltage at the instant of the rise of the input rectangular wave when a rectangular wave is input to the input terminal.

Embodiment The present invention has a circuit configuration as shown in FIG. 1 as an embodiment thereof. In FIG. 1, Q1 to Q13 and Qs are transistors, R1 to RIO are resistors, and 01 to C2 are capacitors. What is different from the conventional circuit shown in FIG. 3 is that a transistor Qs is connected in cascade between the pre-driver transistor Q3 and the driver transistor Q2.

FIG. 2 shows simulation results of the transient response of the output terminal voltage when a rectangular wave is input to the input terminal of the low drop type dropper regulator of the present invention. FIG. 4 shows simulation results for a conventional low drop type dropper regulator. Comparing the two figures, it can be seen that the peak of the output terminal voltage at the moment of the rise of the input rectangular wave is not observed in FIG. 2, and the improvement is very good.

Effects of the Invention As described above, the present invention has the advantage of inserting a transistor connected in cascade to the pre-driver transistor between the pre-driver transistor and the driver transistor. This makes it possible to realize an excellent low-drop type dropper regulator in which the occurrence of a peak in the output terminal voltage at the moment of the rise of a rectangular wave is improved.

[Brief explanation of drawings]

Fig. 1 is an equivalent circuit diagram of a low drop type dropper regulator according to an embodiment of the present invention, Fig. 2 is a transient response simulation characteristic diagram of the same embodiment, and Fig. 3 is an equivalent circuit diagram of a conventional low drop type dropper regulator. 4 are simulation characteristic diagrams of the conventional example. Q1 to Q13, and Qs...transistor,
R1~RIO...Resistance, C1~c2...
・Capacitor.

Claims (1)

[Claims] A power supply control device in which a transistor cascade-connected to the pre-driver transistor is inserted between the pre-driver transistor and the driver transistor in a dropper regulator using a PNP transistor for the output.