JPH0441513Y2 - - Google Patents

Description

[Detailed explanation of the invention] (a) Industrial application field This invention relates to a power supply circuit for a VTR (video tape recorder), and is particularly concerned with an IC (integrated circuit).
The present invention relates to a power supply circuit suitable for

(b) Prior Art The video signal recording and reproducing circuit and the audio signal recording and reproducing circuit used in a VTR are usually integrated into separate ICs. The power consumption of VTR ICs is becoming lower, and the power supply voltage of video signal recording and playback ICs is decreasing.
5V is becoming mainstream. However, the recording amplifier in the video signal recording and reproducing IC and the audio signal recording and reproducing IC require a power supply voltage of 9V in order to widen the dynamic range. For this reason, conventionally, power supply voltages of 5V and 9V are applied to the video signal recording and reproducing IC, and the audio signal recording and reproducing IC
A power supply voltage of 9V was applied to each. or,
The AC bias circuit that supplies AC bias to the audio tape head also requires a 9V power supply voltage.
Normally, the supply of the 9V power supply voltage to the recording amplifier and the AC bias circuit is switched by a recording control signal, since the power supply voltage is required only during recording. For example, the '85
There is ICLA7090 described in "Sanyo Semiconductor Handbook Monolithic Bipolar Integrated Circuit Edition" (published March 20, 1985), pages 962 to 965. Second
The figure shows the ICLA7090 and video signal recording/playback IC.
This is a circuit diagram showing the power supply status between the AC bias circuit and the AC bias circuit. When the VTR is in the playback state, the playback head amplifier in the video signal recording and playback IC1, etc.
A power supply voltage of 5V is applied from the first power supply terminal 3 to the circuit 2 which operates at a voltage of
A voltage of 9V is applied from the second power supply terminal 6.
Furthermore, to the input terminal 7 to which an "H" control signal is applied during recording, an "L" control signal is applied during playback, and transistors 8 and 9 are turned off.
No power supply voltage is applied to the recording amplifier 10 and AC bias circuit 11 in the video signal recording/reproducing IC 1. As a result, the video signal recording and reproducing IC1 and the audio signal recording and reproducing IC4 perform normal reproducing operations.

Next, when the VTR is in the recording state, a power supply voltage of 5V is applied from the first power supply terminal 3 to the IC 1 for recording and reproducing video signals, and a voltage of 9V is applied from the second power supply terminal 6 to the IC 4 for recording and reproducing audio signals. is being applied.
Also, since the "H" control signal is applied to the input terminal 7, the transistors 8 and 9 are turned on, and the recording amplifier 10 and AC bias circuit 11 in the video signal recording/reproducing IC 1 are connected to the second power supply terminal. from 6
A voltage of 9V is applied. As a result, the video signal recording and reproducing IC1 and the audio signal recording and reproducing IC4 perform normal recording operations.

(c) Problems that the invention aims to solve However, in the circuit shown in Figure 2, the power supply circuit consisting of multiple transistors and resistors is
It had to be externally attached to the IC, which was not desirable because it increased the number of parts and board area when manufacturing VTRs.

(d) Means for solving the problems The present invention has been made in view of the above-mentioned points, and includes a circuit that operates at a first power supply voltage and a circuit that operates at a second power supply voltage higher than the first power supply voltage. a first integrated circuit that includes a circuit; a second integrated circuit that includes a circuit that operates at the second power supply voltage; and a power supply circuit that applies the second power supply voltage only when necessary to a circuit that operates with two power supply voltages.

(E) Effect According to the present invention, a power supply circuit is arranged in either the first integrated circuit or the second integrated circuit, and the output voltage of the power supply circuit is required as the power supply voltage for a specific circuit in the first integrated circuit. Only time can supply.

(F) Embodiment Figure 1 is a circuit diagram showing an embodiment of the present invention.
12 is an IC for recording and reproducing video signals; 13 is a circuit that operates with a 5V power supply voltage from the first power supply terminal 14;
15 is a recording amplifier that operates with a power supply voltage of 9V, 1
6 is an AC bias circuit that operates with a power supply voltage of 9V,
17 is an audio signal recording/reproducing IC, 18 is a power input pin to which a 9V power supply voltage from the second power supply terminal 19 is applied, and 20 is a circuit that operates with the 9V power supply voltage applied to the power input pin and 18. , 21 is a control pin to which an "H" control signal is applied from the control input terminal 22 during recording, and 23 is the power input pin 18.
and a switch 25 inserted between the power supply output pin 24 and the power supply output pin 24 is a control circuit that drives the switch 23 in accordance with a control signal applied to the control pin 21. Note that the power input pin 26 is connected to the recording amplifier 15 of the video signal recording/reproducing IC 12.
is connected to the power output pin 24 of the audio signal recording and reproducing IC 17, and the power terminal of the AC bias circuit 16 is also connected to the power output pin 24. Then, the switch 23 and the control circuit 25 perform
Functions as a power supply circuit that generates a 9V power supply voltage.

Next, the operation shown in FIG. 1 will be explained. When the VTR is in the playback state, the video signal recording and playback IC1
The circuit 13, which operates at a voltage of 5V within 2, includes a first
A power supply voltage of 5V from the power supply terminal 14 is applied,
The circuit 20 that operates with a voltage of 9V in the audio signal recording and reproducing IC 17 is supplied with 9V from the second power supply terminal 19.
power supply voltage is applied. Further, a control signal of "L" is applied to the control input terminal 22, and the control circuit 25 sets the switch 23 in the open state shown in the figure.
Therefore, a voltage of 9V is not generated at the power output pin 24, and the recording amplifier 15 and AC bias circuit 1
6 does not work. As a result, for video signal recording and playback
The IC 12 and the audio signal recording/reproducing IC 17 perform normal reproduction operations.

Next, when the VTR is in a recording state, a power supply voltage of 5V is applied from the first power supply terminal 14 to the circuit 13 in the video signal recording/reproducing IC 12, and a power supply voltage of 5V is applied to the power input pin 18 of the audio signal recording/reproducing IC 17. A power supply voltage of 9V is applied from the second power supply terminal 19. or,
Since an "H" control signal is applied to the control input terminal 22, the control circuit 25 puts the switch 23 in the closed state opposite to that shown. Therefore, power output pin 2
A voltage of 4 to 9 V is applied to the recording amplifier 15 and the AC bias circuit 16. As a result, the video signal recording and reproducing IC12 and the audio signal recording and reproducing IC1
7 performs a normal recording operation.

FIG. 3 shows another embodiment of the present invention,
It is characterized in that the switch 27 and the control circuit 28 are arranged within the video signal recording and reproducing IC 12. Third
In the case of the figure, when a control signal of "H" is applied to the control pin 29 in accordance with the recording operation, the control circuit 28
operates and switches the switch 27 to the closed state.
Therefore, a power supply voltage of 9V from the second power supply terminal 19 is applied to the recording amplifier 15 via the power supply input pin 26 and the switch 27, and is further applied to the power supply output pin 3.
Since the voltage is applied to the AC bias circuit 16 through 0, normal recording operation is performed.

The reproduction operation is the same as in the case of FIG. 1 and will be omitted. Components that are the same in FIG. 1 and FIG. 3 are given the same reference numerals, and their explanations will be omitted.

(g) Effects of the invention As described above, according to the invention, it is possible to provide a power supply circuit within the first or second integrated circuit and apply the output voltage of the power supply circuit to the necessary circuits within the integrated circuit. This eliminates the need for an external power supply circuit, making it possible to provide a VTR power supply circuit suitable for IC implementation. In addition, as shown in the embodiment shown in FIG.
If the power supply circuit is built into the audio signal recording/playback IC that is applied with the 9V power supply voltage and recording control signal, just one external pin will be added.
It is possible to achieve IC conversion.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram showing an embodiment of the present invention, FIG. 2 is a circuit diagram showing a conventional VTR power supply circuit,
and FIG. 3 are circuit diagrams showing another embodiment of the present invention. 12...Video signal recording/playback IC, 13...5V
A circuit that operates with a power supply voltage of 15... recording amplifier, 17... audio signal recording/playback IC, 20...
A circuit that operates with a power supply voltage of 9V, 23... switch, 25... control circuit.

Claims (1)

[Scope of utility model registration request] A first integrated circuit that includes a circuit that operates at a first power supply voltage and a circuit that operates at a second power supply voltage higher than the first power supply voltage, and a second integrated circuit that includes a circuit that operates at the second power supply voltage. and a power supply circuit that is disposed in the first or second integrated circuit and applies the second power supply voltage only when necessary to a circuit that operates with the second power supply voltage in the first integrated circuit. circuit.