DM74AS157M

Overview

The DM74AS157M is a quad 1-of-2 line data selector/multiplexer manufactured by onsemi (formerly Fairchild Semiconductor). It utilizes an advanced oxide-isolated, ion-implanted Schottky TTL process. The device contains inverters and drivers to supply full on-chip data selection to four output gates. It features a separate STROBE input and selects a 4-bit word from one of two sources to route to the outputs. The component operates within a supply voltage range of 4.5V to 5.5V and supports a free air operating temperature range of 0°C to +70°C.

Feature Summary

• Functionally and pin-for-pin compatible with Schottky, low power Schottky, and advanced low power Schottky TTL counterparts.
• Improved AC performance over standard Schottky and low power Schottky variants.
• Includes a separate STROBE input for controlling data routing.

Applications

• Multiplexing dual data buses
• Expanding any data input point
• Implementing general four functions of two variables where one variable is common

Procurement Notes

Verify that the specific ordering code matches the required package type, as the DM74AS157 series is available in multiple configurations including SOIC and PDIP. Confirm the suffix designation if tape and reel packaging is required for automated assembly processes. Ensure compatibility with existing Schottky TTL designs due to functional equivalence.

Selection Notes

Select this component when high-speed switching characteristics are required within a 5V logic environment. The device offers improved AC performance compared to standard Schottky TTL alternatives. It is suitable for designs needing direct replacement for legacy Schottky or low power Schottky multiplexer circuits without requiring schematic modifications.

Part Context

This part belongs to the DM74AS157/158 series of Quad 1 of 2 Line Data Selectors/Multiplexers. The AS157 variant presents true data to the outputs, whereas the AS158 presents inverted data to minimize propagation delay time. Both devices share the same internal architecture and pinout structure defined by the Advanced Schottky TTL technology.

Replacement Considerations

Direct substitute: SN74AS157D (Texas Instruments). Parameter equivalent: SN74AS298AD (Texas Instruments).