totem pole output for ttl logic families

examples of saturated bipolar logic families are thus the speed of saturated bipolar logic family is low. In saturated bipolar logic families, transistors work in saturation region. bipolar logic families are further classified as on the basis of operations of transistors in ICs. In bipolar logic families, transistors and diodes are used as ked elements. the examples of unipolar families include PMOS, NMOS and CMOS. In unipolar logic families, unipolar devices are the ked elements. Logic families The set of compatible ICs with the same logic levels and same supply voltages fabricated to perform the various logic functions is known as logic family.īased on the fabrication technology, logic families are classified into two types

The operation is the same as the 2-input TTL NAND gate.What is differentiate between unipolar and bipolar logic families ? definition meaning characteristics of logic families pdf, classification and comparison ? It is the same as that we discussed in the 2-input TTL NAND gate circuit, except that here, the input transistor Q 1 has three emitters instead of two. The following figure shows the circuit of the standard 3-input TTL NAND gate. Circuit of standard 3-input TTL NAND Gate With Q 2 turned ON, transistor Q 4 will also be turned ON.īoth the transistors at the output side will conduct and so the output at terminal will have LOW value, which is considered as logic 0. The diode D C at the collector-base junction is forward biased. When both the inputs A and B are high, both the diodes at the emitter-base junction will be reverse biased. The same operation will take place as explained above. When any one input, either A or B is low, the diode with low input will be forward biased. Since Q 3 is an emitter follower, the output at the terminal will also be HIGH, which is at logic 1. With Q 2 open, the transistor Q 4 will also cut off. The supply voltage gets dropped in the resistor R 1 and it will not be sufficient to turn ON the transistor Q 2. So the current due to the supply voltage +V CC = 5 V will go to the ground through R 1 and the two diodes D A and D B. When both inputs A and B are low, both the diodes are forward biased.

Diode D C represents the collector-base junction of transistor Q 2. In the figure, diodes, D A and D B represent the 2-input emitter junction of transistor Q 1.

Totem pole output for ttl logic families