74HC\/LS\/HCT\/F series chip difference
1, LS is low-power Schottky, HC is high-speed COMS. LS is slightly faster than HC. HCT input and output are compatible with LS, but the power consumption is low. F is for high-speed Schottky circuit;
2, LS is TTL level, HC is COMS level.
3, LS input open circuit for a high level, HC input is not allowed to open circuit, hc generally requires a pull-down resistance to determine the level of the input is invalid. LS does not have this requirement
4, LS output pull-down is strong and weak, HC pull-down is the same.
5, the working voltage is different, LS can only use 5V, while HC is generally 2V to 6V; The operating voltage of HCT is generally 4.5V ~ 5.5V.
6. Different levels. LS is the TTL level, and its low and high levels are 0.8 and V2.4 respectively, while CMOS is 0.3V and 3.6V respectively when the operating voltage is 5V, so CMOS can drive TTL, but the reverse is not possible
7, the driving capacity is different, LS generally high driving capacity is 5mA, low level is 20mA; The average high and low voltage of CMOS is 5mA;
8, CMOS device antistatic ability is poor, prone to latch problems, so the CMOS input foot can not be directly connected to the power supply.