Eight-way flash integrated circuit

There are many types of integrated circuits currently used for flashing, but most of them are concentrated on three-way and five-way flash types. In many cases, the number of flash channels is too small, and the flash form is monotonous. The eight-way flash integrated circuit can make up for the above. Insufficient.

The pin arrangement of the eight-way flash integrated circuit Y978 is shown in Figure 1. It uses a standard 16-pin dual in-line plastic package. Circuit 1, 8 and VDD, VSS are the power supply and ground of the circuit; 4, 5, 6 are the oscillation input and output of the circuit. The oscillator uses RC oscillation of resistance and capacitance, and the oscillation frequency (ie flash speed). f=1/K.Rx.Cx; where Rx is the oscillation resistance, Cx is the oscillation capacitance, and K is a constant, generally 2.2 to 2.5. It can be seen from the equation that the larger the value of the resistor and capacitor, the slower the flash speed. A satisfactory flash speed can be obtained by selecting an appropriate value. The value of Rx is generally 47kΩ~1.5MΩ, and the range of Cx is InF ~ l0μF. Pin 6 BI is the all-zero input. When the logic zero level (VSS) is input, all eight outputs are zero. The output of the circuit has an output only when a logic high (VDD) is input. The 7-pin L1 is a full-light input control terminal, which can control the output of the circuit to be fully bright. BI, LI is very useful in practical use, it can change more flash patterns in the application. The output terminals 08 to 01 of the circuit correspond to the 9th to 16th pins of the circuit pins, respectively. Figure 2 shows the internal logic block diagram of the Y978 circuit. The output of the circuit uses Bi-CMOS technology, which combines the two technologies of bipolar circuit and MOS circuit. The low power consumption of CMOS technology and the strong load of bipolar circuit. The ability to make the Y978 integrated circuit has low power consumption and large output current.

The output structure in the above figure is an inverting type driver composed of MOS tubes P1, N1, N2 and T. When the input is logic high level, MOS tubes N1 and N2 are turned on, P1 and transistor T are turned off, and the output terminal is Logic low; when the input is low, P1 and T are turned on, N1 and N2 are turned off, and the output is logic high. Since T is a bipolar transistor, it has a large current (up to 35mA) output, which can fully push the general load. The charge and discharge voltage of the point is much higher than the VDD and VSS voltage ranges. Experiments have shown that this voltage is higher than 2VDD and lower than 2VSS. Such a large transient voltage is very likely to damage the 5th pin of the input end of the CMOS circuit, so a protection is added. The resistance R/C, which is from l00kΩ to 1MΩ, acts as a protection input only and does not participate in the oscillator circuit, so its resistance does not affect the oscillation time. The switch K1 is a full-light control input terminal, which is fully illuminated when it is closed, and is disconnected to be in a working state. The switch K2 can control all resets (fully extinguished) of the circuit, and the input terminal is provided with a pull-up resistor inside the circuit. Each output has a current limiting resistor R, which can be calculated based on the operating current. Each channel can be connected to multiple light-emitting diodes (LEDs) as needed. The mode of operation of the LEDs during normal operation is: 01-01 02-01 02 03-02 03 04-03 04 05-04 05 06-05 06 07-06 07 08-All-off-01-01 02......

The circuit can be applied to the taillight display of motor vehicles and various electronic decorations. The LEDs are arranged in various shapes, and the flashing effect may be flashing from the middle to the sides or flashing on one side, or may be arranged in a circulating flow flash. The Y978 flash circuit flashes softly and has no jumping feeling.