When the output is low the driver gate sinks the load current as shown in fig. in high-impedance state, both T3 and T4 in totem-pole arrangement are tured off and as a result the output is open or floating. In TTL with totem-pole output T3 is on when the output is low and T4 is on when the output is high.
the tri-state TTL has three output states, high low and high-impedance. if the output is not in low state, it should definitely in the high state. the output is either in high state or low state.
figure shows the circuit of a TTL NAND gate with open collector output.Ī normal digital circuit has two output states, low and high. this problem of TTL with totem-pole output is overcome in TTL with open collector output. TTL with totem-pole output has a major problem that the two outputs of the two gates cannot be connected together. Here, the outputs of two NAND gates are connected together. using a wired-AND connection, the fan-in of the circuit is increased. In terms of 0 and 1, table (a) can be written as in table (b).Ī wired-AND connection has two or more than two gates connected together. The operation of the circuit is summarized in table (a) TTL with active pull-up is known as TTL with totem-pole output. What is ttl circuit with totem-pole output stage minimize gate and advantages disadvantages or ttl with totem pole output ?įigure shows the circuit of a two-input TTL NAND gate with totem-pole output.
