Digital Electronics - TTL (Transistor Transistor Logic)

Basic Slide of TTL, 7400 TTL Series,Two Input TTL-NAND Gate , Totem – pole Output Stage of TTL

1. Digital Electronics TRANSISTOR TRANSISTOR LOGIC(TTL) Submitted By Yogendra Yaduwanshi

2. 7400 TTL Series TTL ICs first developed in 1965 and they are known as “standard TTL” . This version of TTL circuit is not available now. TTL family use only transistor to perform the basic logic operations. The standard TTL is improved to a great extent over the year. TTL devices are still used as “glue” logic which connects more complex devices in digital system.

3. Two Input TTL-NAND Gate The first, let us replace transistor Q1 by its equivalent circuits. A and B are the input terminals. The i /p voltage A and B can be either low (zero volts ideally) or High (+ Vcc ideally). A and B both low : If A and B both are connected to ground, then both the B-E junction of the transistor Q1 are forward biased.

4. Totem – pole Output Stage of TTL The arrangement of Q3 and Q4 on the output side of a TTL NAND gate is called the totem-pole arrangement. In this circuit, the three output component Q3,Q4 and diode D1 are stacked one on the top of the other in the form of totem-pole. At any time, only one of them will be conducting.

5. THANKS