SN74F138NSR

The SN74F138NSR belongs to the family of logic-signal switches, multiplexers, decoders, and is specifically designed for purpose of emulation and logic expansion. This 3-to-8 line decoder/demultiplexer receives an enable input and three binary address inputs, and provides eight mutually exclusive outputs. The device features an active-low enable input such that all outputs are ON when enable is LOW, except a low impedance ON the output selected by the binary address input. All outputs are OFF when enable is HIGH, independent of the address inputs.

The SN74F138NSR parts are characterized for operation over the full military temperature range of -55°C to 125°C, and the SN74F138NSR can be used with either active-low or active-high enable inputs. Dependant upon the enable input, this 3-8 decoder can be used to construct various types of logic diagrams utilizing various logic inputs and logic layers. In addition, this logic switch offers superior noise margin and EMI-tolerant logic levels.

The SN74F138NSR decoders can be used in wide variety of different applications, and are often used in telecom and military applications. In telecom applications, the SN74F138NSR is used to decode addresses and signal data, while in military applications, it is used to decode addresses, signal data, and provide some level of lockout control. This type of decoder is also often used in audio and video processing systems, such as cable, satellite, and broadcast systems.

Working Principle

The SN74F138NSR has three inputs - A, B, and E – and eight outputs, Y1 through Y8. The logic states of A and B select the address, i.e. the address for which the output is the logical “1”. There are eight different addresses in pick from, of which a single address is active at any given time. The E input is used to enable the decoder. When E is at a logical “1” all outputs are forced into the OFF state, this is known as “enabled OFF”. The decoder is enabled when E is a logical “0”, at which point the logic levels of A and B choose the desired address.

The SN74F138NSR is powered using 5.0V and has two operating temperature range-40°C to 85°C and -55°C to 125°C. The power supply current is very low and it can operate from 400ns to 600 ns depending upon clock frequency. The decoder can operate up to a maximum of 6MHz. The decoder also features an active low enable input, which means that all outputs are on when the enable is low, except for the one selected by the binary address input.

The SN74F138NSR is a fast and reliable decoder ideal for many applications, due to its small package size and low power consumption. The device offers a wide range of addressable outputs, enabling multiplexing and provides the customer with an efficient and flexible solution for a multitude of different functions. The SN74F138NSR is an excellent way to control a wide variety of signals, due to its wide temperature range, low power consumption and robust design.