555-pin chip data and circuit diagrams
Any time base circuit 555, the internal structure of the same circuit, the performance is the same. When there are many manufacturers base circuit 555 models, such as MC555, CA
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555, XR555, LM555, etc; domestic models SL555, FX555,5G1555 etc. Typically, the most common is the letter NE555.555 former represents only manufacturers. Timebase circuit 555 is a wider use of precision timers can be used to pulse occurs, as square wave generator, self-excited oscillator, timing circuits, delay circuits, pulse-width modulation circuit, pulse width lack indicating circuit monitoring circuit. The operating voltage is 5 ~ 18V, commonly 10 ~ 15V, maximum output current 200mA, can drive the power switch, relay, LED, LED, doing oscillator, the highest frequency up to 300kHz. 555 time base circuit is relatively simple, the internal integration transistor 21, four crystal diodes and 16 resistors, two voltage comparators, an RS flip-flop, a transistor and a resistor from the three discharge voltage divider. FIG comparator A1 and comparator A2 is lower by two high-gain voltage comparator, VT for the discharge transistor, three resistors R1, R2, R3 resistance is 5k, 3 5 is composed of the time base circuit 555 name of the resulting. 555 8-pin integrated circuit operating voltage input terminal voltage is 5 ~ 18V, with UCC represents; seen from the divider, comparator A1 of 5 feet between R1 and R2, so the voltage is 5 feet fixed on 2UCC/3; comparator A2 is connected between R2 and R3, with the potential of the inverting input of A2 is fixed to the UCC/3. 1 foot to ground. 2 feet for a trigger input; the output of 3 feet, the level of state control output by the flip-flop, and the flip-flop by the comparator 6 feet and 2 feet at a relatively controlled. When the trigger on the high acceptance of the comparator A1 from R pin input, triggers are placed in the reset state, 3 feet output low; 2 feet and 6 feet are complementary, only 2 feet of low-level work, the high level it does not work, that voltage is less than 1Ucc/3, 3 feet high output at this time. 6 feet for the end of the threshold, only the high work, low it does not work, the input voltage is greater than 2 Ucc/3, said the high end of the trigger, 3-pin output low, but there is a precondition, That potential must be greater than 2 feet 1Ucc/3 when effective. 3 feet high potential close to the supply voltage Ucc, the maximum output current to play 200mA. Reset terminal 4 feet, 4 feet when the potential is less than 0.4V, regardless of the status of 2,6 feet, the output of 3 feet output low. 5 feet control terminal. 7 feet, said discharge end, and 3-pin output synchronous output level consistent, but not 7 feet output current, so called solid 3 feet high (or low), 7 feet called unrealistically high.