What are the characterictis and application notes of TTL circuit?
( 1 ) Features
1 ) The input terminal generally has a clamp diode, which reduces the impact of reflection interference.
2 ) Low output resistance, enhanced capacity with capacitive load.
3 ) There is a large noise margin.
4 ) Adopt a + 5V power supply.
In order to perform the function of the device normally, the device should be operated under the recommended conditions. For the 74LS series circuit, the working conditions are :
1 ) The supply voltage should be in the range of 4.75 ~ 5.25V.
2 ) The ambient temperature is 0 ~ 709°C.
3 ) High level input voltage VsH > 2V, low level input voltage VsL < 0.8V.
4 ) The output high level current should be less than 400A, and the output low level current is less than 8 mA.
5 ) the operating frequency is not high, the typical low level to the high level transmission delay time is 15ns, the high level to the low level transmission delay time is 12ns, the maximum operating frequency is about 33 MHz.
( 2 ) Note
1 ) The power supply voltage should be strictly kept in the range of 5V±0.5V, too high to damage the device, too low to work normally. In the test, the DC power supply with good stability and small internal resistance is generally adopted. When using, special attention should be paid to the power supply and ground can not be wrong, otherwise the device will be damaged due to excessive current.
2 ) It is best not to be left vacant when the excess input is suspended, which may not affect the logic function of the and gate ( and the non-gate ), but is vulnerable to interference when left unconnected, for this purpose, the AND gate, and the non-gate redundant input terminals can be directly connected to V, or via a common resistor ( thousands of ohms ) to the Ve. If the front stage driving capability is strong, the redundant input terminal can be connected with the user terminal; there is at least one gate circuit that needs to be directly grounded and has an extended end, the power supply is not allowed to be directly connected to the extended end. If the resistance is grounded through the resistor, the magnitude of the resistance value will directly affect the state of the circuit.
3 ) The output terminal is not allowed to connect directly to the power supply or to the ground, and the output of different output signals is not allowed to be directly connected ( except the open collector gate and the tri-state gate ).
4 ) The load capacity of the circuit, that is, the fan-out coefficient, should be considered, so as to avoid affecting the normal operation of the circuit.
5 ) When working at high frequency, the peak interference of current should be suppressed by shortening the lead wire and shielding the interference source.
6 ) When the edge of the external input signal changes very slowly ( the rising edge or the falling edge is less than 50 ~ 100 ns / V ), the shaping circuit must be added to improve it.
If you want to know more, our website has product specifications for the integrated circuits, you can go to Allicdata Electronics Limited to get more information.