JPH0636635B2 - Semiconductor integrated circuit for remote control signal transmission - Google Patents

Description

The present invention relates to a semiconductor integrated circuit for remote control signal transmission (hereinafter abbreviated as remote control IC).

[Conventional technology]

The remote control IC includes a custom code as an address of each device or device in a part of the transmission code in order to operate only a necessary device or device.

Conventionally, this custom code is set by determining the transmission code by turning on / off an external key matrix switch of the remote control IC, and at the same time reading the presence / absence of an external resistor, diode or the like. There is also a remote control IC with a built-in custom code ROM.

FIG. 6 is a circuit diagram of a conventional example of a type that reads the presence or absence of an external resistor and a diode.

Remote control IC1 ₃ is scanning and for external resistive read block 7 _1, 7 _2, 7 _3, key matrix switch signal reading block 3 _1, 3 _2, diode reading block 10, the scanning terminals 5 _1, 5 _2, It is composed of 5 ₃ , key input terminals 6 ₁ and 6 ₂ and diode reading terminal 9, and externally connected to the key matrix switch 4, custom code setting resistors 8 ₁ and 8 ₂ and diodes 11 ₁ and 11 _2. ing.

FIG. 7 is a timing chart of the circuit of FIG. Here, the transistors TRA ₁ , TRB ₁ , transistors TRA ₂ , TRB ₂ , transistors TRA ₃ , TRB ₃
Block for scanning and external resistance reading respectively
It is a transistor included in 7 ₁ , 7 ₂ and 7 ₃ .

This operation will be described. First, in order to read the on / off state of the key matrix switch 4, the scanning terminal is used.
5 ₁ , 5 ₂ , 5 ₃ are set to high level sequentially and the key input terminals 6 ₁ , 6 ₂
Read the value that appears in. At the same time, the presence / absence of a diode is read from the external diode reading terminal 9. On the other hand, the presence or absence of the external resistors 8 ₁ and 8 ₂ is read by setting the scanning terminals 5 ₁ , 5 ₂ and 5 ₃ to high impedance and turning on the transistor TRC. The ON / OFF data of the key matrix switch 4 thus read is output as a transmission code, and the presence or absence of the external resistors 8 ₁ and 8 ₂ and the diodes 11 ₁ and 11 ₂ is output as a custom code.

On the other hand, in the example in which the custom code ROM is built in the remote control IC, the custom code is read from the ROM and output.

[Problems to be solved by the invention]

Among the conventional remote control ICs described above, the type for reading the presence or absence of the external resistance or diode as shown in FIG. 6 has a drawback that the external resistance and the diode are required. Recent remote control transmitters are made up of a very small number of parts such as remote control ICs, key matrix switches, batteries, infrared LEDs, etc., and are inexpensive. Therefore, even one part will have a large impact on the cost. On the other hand, with built-in ROM,
When setting a custom code, external parts for the custom code are not required, but the ROM is built in, so the chip size becomes large and expensive, and at the same time the ROM is changed by changing the mask for semiconductor manufacturing. Therefore, there is a drawback that the mask cost is also required. On the other hand, in recent years, the number of remote control ICs that use radio waves or power lines as a transmission path has been increasing, and as in the case of infrared transmission up to now, it may cause malfunctions only on a model-by-model basis such as a TV or VTR. It is necessary to set a custom code for each unit. Therefore, built-in ROM
Then, there are some drawbacks that cannot be dealt with quickly.

This problem also applies to the type that reads an external resistance or a diode, and the custom code is determined depending on the mounting position of the resistance or the diode on the substrate, and thus is not suitable for the above-mentioned small-lot production of various types.

[Means for Solving the Problems] A remote control IC of the present invention is provided with a fuse circuit between a signal line and a terminal or between terminals, and one of the transmission codes depends on whether the fuse is cut from the terminal or not. It is characterized by determining a part.

〔Example〕

Next, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a circuit diagram of an embodiment of a remote control IC of the present invention.

The remote control IC ₁₁ has a fuse circuit 12 ₁ connected between a resistor, one of which is connected to a power source, and scan terminals 5 ₁ , 5 ₂ , 5 _3.
For scanning and with / without resistance reading block 2 ₁ , 2
₂ , 2, ₃ Key matrix switch Signal reading block 3
₁ , 3 ₂ , a diode reading block 10, a diode and a fuse circuit 12 ₂ are connected in series between the scanning terminals 5 _{1 to} 5 ₃ and the diode reading block 10, and a diode setting block 13 ₁ , 13 ₂ , 13 ₃ , key It is composed of matrix switch signal reading blocks 3 ₁ and 3 ₂ and key input terminals 6 ₁ and 6 ₂ .

Further, the fuse circuit 12 _1, 12 _2, FIG. 2, as shown in FIG. 3, one end is connected to a diode and a fuse in the power supply terminal is connected, the contact to the signal line (Block 2 ₁ The other end of the fuse is connected to the scanning terminals 5 _{1 to} 5 ₃ ) in the case of 2 ₃ and to the input of the block 10 in the case of blocks 13 _{1 to} 13 ₃ ). Here, VDD is a positive power supply terminal, and VSS is a negative power supply terminal.

Therefore, the power supply terminal connected to the fuse is the positive power supply terminal V
In case of DD, the terminal is grounded, and the scanning terminals 5 _{1 to} 5 ₃
When a positive voltage is applied to the diode, a forward current flows through the diode in the fuse circuit 12 to blow the fuse. If the power supply terminal is the negative power supply terminal VSS, the opposite may be performed. At this time, it is better to set the irrelevant terminals to the same potential as the power supply terminals so that the fuse is not accidentally blown.

In this embodiment, the fuse circuits 12 in blocks 2 ₁ to 2 ₃ are
₁ and the block _131-134 second view type either for the fuse circuit 2 ₂ must be fully independent meaning rather off simultaneously in the _3, must be either the type of FIG. 3 There is. If the fuse blows, the operation of this embodiment is exactly the same as that of the conventional example. On the other hand, the diodes in the diode setting blocks 13 _{1 to} 13 ₃ are not always necessary. Without this diode, when the switch matrix switch 4 is double-pressed, that is, when two switches are pressed at the same time, if there are two or more fuses in the fuse circuit, the two scan signals become high level through the switch matrix switch 4. turn into. However, it is not necessary if it is clear that only one fuse should be attached.

FIG. 5 is a block diagram of another embodiment of the present invention. First
In the illustrated embodiment, it is considered that the fuse circuits 12 ₁ and 12 ₂ in the blocks 2 ₁ to 2 ₃ and the blocks 13 _{1 to} 13 ₃ are cut by using the scan terminals 5 _{1 to} 5 ₃ , but the same as in the conventional example. By providing the external diode reading terminal 9 to the scan terminal 5 ₁
It is possible to cut easily fuse circuit 12 _1, 12 ₂ only applying a current between the 5 ₂ and a diode reading terminal 9. At this time, the fuse circuit becomes a simple fuse circuit as shown in FIG.

On the other hand, in the first view scanning and resistance whether read blocks 2 ₁ to 2 _3, for the transistors TRA and TRB is the presence of the diode between the power supply terminal VDD and VSS, the power supply to the scan terminals 5 ₁ to 5 ₃ Voltage higher than voltage VDD or V
When a voltage lower than SS is applied to cut the fuse circuit, a current of the same magnitude as that flowing in the fuse circuit also flows in the transistors TRA and TRB. Since the fuse circuit is easier to blow due to the value of the current flowing therethrough than other circuits, there is usually no problem, but it is also possible that the transistors TRA and TRB may be blown instead of the fuse circuit due to manufacturing variations. To be Therefore, FIG. 8 shows a block diagram in which there is no problem even in such a case as another embodiment of the present invention.

FIG. 8 is a block for scanning and reading the presence / absence of resistance 18 ₁
To 18 ₃ is obtained by inserting a resistor 19 between the terminals of the fuse circuit that does not result in an intersection and a power supply terminal VDD side to the P-channel transistor TRA and the N-channel transistor TRB. Because of this resistor 19, the scanning terminal 5 ₁
To ₅₃ when trying to cut a fuse circuit by adding a higher voltage and lower voltage than VSS than the power supply voltage VDD, the transistor TRA, the transistor TR accidentally smaller than the current flowing through the always fuse circuit the current flowing through the TRB
It does not cut A and TRB.

On the other hand, this resistor can also serve as a measure against electrostatic breakdown of the transistors TRA and TRB, and does not require a large resistance value and can be configured in a small space.

Although the fuse circuits 12 ₁ and 12 are attached to both the resistor and the diode in these embodiments, there is no problem even if only one of them is used.

〔The invention's effect〕

As described above, according to the present invention, a fuse circuit is provided between a signal line or a terminal and a terminal, and a custom code is determined depending on whether or not the fuse circuit is disconnected from the terminal, that is, in order to determine the custom code. Since the fuse is used and the fuse can be cut from the terminal, the chip size of the remote control IC hardly increases, and external parts such as resistors and diodes and terminals can be reduced. Also, since the fuse can be cut using the terminals, the fuse is cut in the final step, that is, after it is packaged, not in the middle of the semiconductor manufacturing process. It has the effect that it is most suitable for the demands of various types of small-quantity production such as each room unit.

[Brief description of drawings]

FIG. 1 is a block diagram of an embodiment of a semiconductor integrated circuit for remote control signal transmission of the present invention, FIGS. 2 to 4 are circuit diagrams of a fuse circuit 12, and FIG. 5 is another embodiment of the present invention. Block diagram, FIG. 6 is a conventional block diagram, FIG.
FIG. 8 is a timing chart of the conventional example of FIG. 6, and FIG. 8 is a block diagram showing still another embodiment of the present invention. 1 ₁ , 1 ₂ ...... Semiconductor integrated circuit for remote control signal transmission, 2 ₁ to 2 ₃ ...... Scanning and resistance reading block, 18 ₁ -18 ₃ ...... Scanning and resistance reading block, 3 ₁ , 3 ₂ …… Key matrix switch signal reading block, 4 …… Key matrix switch, 5 _{1 to} 5 ₃
...... Scanning terminal, 6 _{1 to} 6 ₂ ...... Key input terminal, 9 ......
External diode reading terminal, 10 ... diode reading block, 11 ₁ , 11 ₂ ... external diode, 12 ₁ , 12 ₂ ...
Fuse circuit, 19 ... Resistor, 13 _{1 to} 13 ₃ ... Diode setting block.

Claims (2)

[Claims] 1. A semiconductor integrated circuit for remote control signal transmission, wherein a fuse circuit is provided between a signal line and a terminal or between terminals and a part of a transmission code is selected depending on whether the fuse is cut from the terminal or not. A semiconductor integrated circuit for remote control signal transmission, characterized in that it is determined. 2. The fuse circuit has a diode and a fuse, one of which is connected to a power supply terminal, and a connection point of the diode and the fuse is the signal line or terminal,
The remote control signal transmitting semiconductor integrated circuit according to claim 1, wherein the other end of the fuse is connected to the other terminal.