JPS5943608A - Power saving circuit - Google Patents

Abstract

PURPOSE:To attain power saving, miniaturization of circuit and reduction in the fluctuation of power supply voltage at the same time, by interrupting useless current flowing to an IC and its peripheral circuit without switching the power supply. CONSTITUTION:A transistor (TR)Q7 is conductive and a TRQ8 is cut off at the reproduction mode, since a voltage close to a VCC is applied to a terminal 4. Thus, a current flows to TRs Q11, Q14, Q17 and a potential at an output terminal 6 is 3.0V. Since a current of 1mA flows to the Q17, TRs Q5, Q6 connected to the terminal 6 are operative. The potential at the terminal 4 goes nearly to zero at a mode other than the reproduction mode, the Q7 is cut off, the Q8 is conductive and the base potential of the Q11 goes nearly to zero. Thus, the Q14, Q15 are both cut off, the base potential of the Q15 reaches 5V and the potential at the terminal 6 goes nearly to 5V. No current flows to the Q5, since the Q17 is cut off, and the Q5 is cut off. The base current of the Q6 is cut off into inoperative. Thus, the peripheral circuit as well as the IC5 is interrupted for unnecessary current.

Description

[Detailed Description of the Invention] (Field of Application of the Invention) The present invention relates to an electric circuit having two or more modes such as recording and playback, such as a home video tape recorder, and particularly relates to a low-cost, low-power electric circuit. The present invention relates to a power-saving circuit suitable for loading chips that require.

! Prior Art 1 As shown in Figure 1, a conventional home video tape recorder has a power supply circuit that supplies voltage only during playback, and by connecting this playback-only power supply circuit to the playback signal processing circuit, waste is eliminated. This prevented significant power consumption.

However, the configuration shown in Figure 1 requires a power transistor for power switching, resulting in (fl) increased cost, (2) increased board area, (3) increased variation in power supply voltage, (
4) It has the disadvantage of increased power consumption.

Hereinafter, the conventional problems will be explained using FIG. FIG. 1 is a circuit diagram showing the main parts of a conventional playback circuit for a video tape recorder. In Fig. 1, 1 is a DC stabilized power supply;
2 is a switching circuit that supplies voltage to the output terminal 3 only during reproduction, and 4 is a control terminal to which a voltage is applied to make Q2 conductive during reproduction.

5 is a preamplifier IC, and 6 is an output terminal of the preamplifier 5. Transistor Q1 is a power transistor,
Since a base current of 10 to 20% of the collector current is required to sufficiently reduce the saturation resistance during conduction, the TF power consumption in the reproduction mode increases by 0 to 20%.

A consumption current of 10 to 20 mA flows through the preamplifier IC5, and a current consumption of 5 to 10 m flows through the playback 1'AI equalizer Q, Q4.
A current flows. For this reason, Ql and Q2 are designed to kill these circuits except during playback to prevent unnecessary power consumption.
A switching circuit is provided for switching from

The saturation resistance of power transistor Q1 varies to some extent)
Therefore, there is a problem in that this causes variations in the power supply voltage.

(Objective of the Invention) An object of the present invention is to eliminate the drawbacks of the prior art and to provide a power saving circuit that prevents wasteful power consumption without switching the power supply.

, Summary of the Invention: In order to achieve the above object, the present invention connects an IC circuit and a peripheral circuit with direct current, and configures the IC circuit to supply a base current to a transistor of the peripheral circuit during operation,
This IC circuit is provided with input terminals for at least two or more mode control signals such as recording and playback modes, and according to these mode control signals, the circuits are switched so that current flows to unnecessary circuits, and the peripheral circuits are switched. Stop supplying base current to the transistor, cut unnecessary peripheral circuits at the same time, and reduce the current to -1.

1 Examples of the invention] Hereinafter, the present invention will be explained in detail using the drawings.

FIG. 2 shows the use of the present invention in a second circuit of a video tape recorder. FIG. 3 is a circuit diagram showing an embodiment for nine people. FIG. 3 is a circuit diagram showing an embodiment of the main part of the preamplifier 105 used in FIG. 2.

FIG. 2 shows that the preamplifier IC5 is provided with a mode control signal input terminal 4, that the output terminal 6 of the IC is connected to the base of the peripheral transistor Q5, and that Q5.
The feature is that Q6 is an I)ArP) transistor.

Below, FIGS. 2 and 3 will be explained. In regeneration mode, Vcc near voltage and voltage are applied to terminal 4, so Q
7 conducts and Q8 cuts off.

7 Therefore, current flows through Q, Q, and Q, and output 11
L4 17 1 of terminal 6 also has a position of a OJ'''. Since a current of 1 mA flows through 17, Q5 connected to terminal 6.
Q6 becomes operational.

In other than playback mode, the potential of terminal 4 is Ik, which is V, and Q.
7 is cut off, Q8 is passed through, and the base potential of Q and 1 becomes almost zero V. Therefore, Q14Q is also cut off, the base potential of Q15 becomes 57 f'''<Vcc'), and the potential of terminal 6 becomes approximately 5V. Q5 has Q17 canted off, so
No base current flows, resulting in a cutoff. The base current of Q6 is also canted off, and Q6 is also cut off.
Unnecessary current can be cut off not only in C but also in peripheral circuits.

FIG. 4 is a circuit diagram showing a bold part of an embodiment in which the present invention is applied to a post-gradation circuit of a video tape recorder. Fourth
In the figure, F is an IC that includes an FAI demodulation circuit, and 8 is an IC.
A control signal is applied to the mode control terminal for turning on Q18 during playback and turning off Q113 for stations other than the playback station.

Reference numeral 9 designates an output terminal for a video signal subjected to FM processing, and reference numeral 10 designates a DC current input terminal, which is constructed so that the level of the demodulated video signal varies with temperature.

During playback, a voltage of approximately 5V is applied to terminal 8, and Ql8
is turned on, and Q and 9 are turned off. Therefore, in Q20, approximately 1
A current of 00 μA flows through Q21, a current of 1 mA flows through Q21, and Q Q, Q, Q switch 22'.
2! S 24 25 becomes a tinging state. Therefore, the potential of terminal 9 becomes j, around 4V,
Q26 also becomes operational.

On the other hand, in a mode other than the reproduction mode, the potential of the terminal 8 is approximately %ll, Q18 is turned off, and Q17 and Ql are turned on.・This 7E
Both Q and Q are off, so in the end Q22' Q28
20 21 Q and Q are all off, and base 2 is on Q26.
4 25 No current is supplied. Therefore, Q26 is also cut off, and most of the unnecessary current flows. The key points of Fig. 4 are that the base f of terminal 9 and Q26 is directly connected, and that a PNI)) amplicon is used for Q26.

FIG. 5 1 is a circuit diagram showing the bottom of another embodiment in which the present invention is used in a reproducing circuit of a video tape recorder.

In FIG. 5, it is a uJ preamplifier IC, and is characterized by adding a transistor Q27 to 5 in FIG. In case 1 of Fig. 5, during playback, Q7 is on and Q27 * QB is off, so 5 and all (i
i]" The same operation will occur. P) At times other than birth, Q7 is on and Q27 t QB is on. For this reason, Q1
The base potential I'i of the transistor 5 becomes near ''', the base current is no longer supplied to Q3, and both Q3*Q4 are cut-on.

The point of FIG. 5 is not only to cut off the constant current circuit in the IC in the unstable mode, but also to turn on Q27 and turn on the output voltage.

By doing so, it is possible to prevent wasteful current even when using NPNK in peripheral transistors.

FIG. 6 is a circuit diagram showing a main part of another embodiment in which the present invention is applied to an FAi post-tuning circuit for a video tape recorder.

FM demodulation IC12 in Figure 6 Figure (1)
It has a configuration in which Q2p*Q5 (3) is added to IC'7. During playback, the same current as the first current flowing through Q29 flows to the collector of Q50, the base potential of Q26 becomes approximately 1V, and Q26 operates normally. becomes.

Except during playback, VcQ22 e Q25 as in Figure 4.
Q24. Q25 is all cut on, no current flows through Q29, Q5o is also canted off, the base potential of Q26 is zero V, and Q26 is also canted off.

The point in FIG. 6 is that by providing a PNP l-transistor in the ViIC 12, waste current can be prevented even if the external transistor is NPh'.

FIG. 7 is a circuit diagram showing a main part of an embodiment in which the unexploded T3A is used in a recording circuit of a video tape recorder.

In FIG. 7, 12 is a recording IC5, 13 is a control voltage application terminal of IC', and Q29 is turned on during recording.
Q3 (It A voltage is applied that turns off Q3j. 14 is the squelch voltage application terminal, which becomes positive after the user presses the record button.

1-3 seconds until regular recording starts rlJj SQ37
A voltage is applied that turns it on. 15 is a terminal to which a frequency-modulated video signal is applied, 16 is a signal output terminal, and 117 is a terminal to which a low-frequency converted chroma signal, a frequency-modulated sound signal, a pilot signal, etc. are applied. .

First, bug 11 when transitioning from stop mode to recording mode.
Explain the work. When in stop mode, terminal 1
4 are almost at zero potential, Q29゜Q57 is turned off, and Q
3p+ Q51 turns on. For this reason, %Q+Q
3q and Q42 are cut off to reduce the power consumption B' within the IC. In Figure 37, Q50 is turned on, so Q4. The base potential of the IC is about 115V, and the DC potential of the output terminal 6 of the IC is about 115V. Therefore, for foreign signals, almost no current flows through transistors Q49Q46.

When the user presses the record button, the potential at terminal 13 becomes approximately 5V.
rise to At the same time, the potential of the terminal 14 also rises to about 5V, but returns to the original zero when the normal recording state is reached after 1-2 seconds. Therefore, at the same time, without pressing the record button, the IC internal circuit is in the operating state. However, since Q57 is on for l-'-2 seconds, the DC potential of terminal 16 is lower than 9Q, Q
No current flows through the video head 19, and no current flows through the video head 19. After 1 to 2 seconds, Q57 is turned on, so current flows through Q451 and Q46, and the video head 19 starts writing onto the video tape.

In other words, current flows through Q45' Q46 only when terminal U3 is at H voltage and terminal C4 is at Low voltage.
(D current is required, Q45' in unnecessary mode
It is important to cut off Q46.

Next, the case where the pause button is pressed in the recording state will be described. In recording Bose mode, terminal 13 is approximately 51
1. A voltage of about 5V is also applied to the terminal λ4. Therefore, Q451 and Q46 can be cut off even during a recording pause, and power can be reduced.

In modes other than recording mode, terminal 3 is at zero potential.
When Q311Q50 is turned on, the internal circuit of the pIC and the external transistor are cut off.

Q, the collector of Q is Q4. collector of 50
37 The reason why it is connected to the emitter is to reduce the stray capacitance attached to the collector of jiQ41 and widen the bandwidth.

In an IC transistor, the capacitance between the collector and substrate is the largest, and the larger the number of collectors connected to the negative resistance, the narrower the range.

Figure 8? -i This is a circuit diagram showing a bold part of another embodiment of IC3-2 used in FIG. 7. The feature in Figure 8 is the diode Q
, Q and the resistor 1'lI'LR1 are connected to the collector of 46 47 Q50 S Q37 to the collector of Ql. When Q3o+Qsy is completed due to this tl, Q4. sufficiently lower the base potential of terminal 16
By setting the potential to zero and providing Q46 and R1, the bandwidth is secured as shown in FIG. 7 by P and rJ. That is, in the recording mode, diode Q46 is cut off, so the collectors of Q361 and Q57,
Substrate group capacity has no effect. Diode Q46
The use of base and collector junctions so as not to be affected by the floating length is also a consideration from the viewpoint of bandwidth. Resistor R1 is 'h
This is provided to prevent diode Q46 from turning on (due to leakage current of D t Q57).

FIG. 9 is a circuit diagram showing a main part of another embodiment of the IC 12 used in FIG. 7.

In Fig. 9, a signal is applied to the input signal at the base of Q41, outputting it with the opposite polarity, and Q3゜Q57 is applied to the base of Q4o.
collector is connected to cut off unnecessary current.

As shown in FIG. 9, it is also possible to provide the input terminal 5 at the base of Q40. In this case, if the capacitance of the coupling capacitor 20 connected to the terminal 15 is large, QQ turns on,
The transient state that occurs when the power is turned off becomes a problem.

Another way to cut off the external transistors Q45 + Q46 is to connect the collector of ';'50L Q57 to the base of Q44.

[Effects of the Invention] According to the present invention described above, unnecessary current flowing through the IC and peripheral circuits can be cut off without providing a switching circuit in the power supply, resulting in cost reduction, power saving, circuit miniaturization, and power consumption. At the same time, it is possible to reduce variations in U voltage.

[Brief explanation of the drawing]

Figure 1 is a circuit diagram showing an example of a conventional power saving circuit, and Figure 2 is an implementation of the power saving circuit of the present invention. 3 is a circuit diagram showing essential parts of an embodiment of the IC used in FIG. 2, and FIGS. 1
A circuit diagram showing an example of 1 power circuit man 1], Fig. 8,
FIG. 9 is a circuit diagram showing a main part of another embodiment of the IC used in FIG. 7. 5...Integrated circuit (IC) 6...IC output terminal 4...Operation mode control terminal size・)I)βc・ri

Claims (1)

[Claims] It comprises an integrated circuit having two or more operation modes and a transistor circuit whose base is connected to the integrated circuit with direct current, and at least a part of the constant current circuit in the integrated circuit is cut off in at least one operation mode. A power-saving circuit characterized in that, at the same time, supply of base current to a transistor connected to the integrated circuit with direct current is cut off.