SN74HC640DW

Buffers, Drivers, Receivers, Transceivers Overview

The SN74HC640DW is an octal bus transceiver from the Texas Instruments HC series, housed in a 20-pin SOIC package. It operates within a supply voltage range of 2 V to 6 V and supports a temperature range of -40 °C to +85 °C. The device features high-current 3-state outputs capable of driving up to 10 LSTTL loads, with maximum output currents of -7.8 mA (high) and 7.8 mA (low). Propagation delay is typically 8 ns at 6 V with a 50 pF load, increasing to 190 ns at 2 V with a 150 pF load.

Buffers, Drivers, Receivers, Transceivers Feature Summary

• Octal configuration providing eight independent bidirectional data channels controlled by direction and output enable pins.
• CMOS input and output levels ensuring compatibility with standard logic families while maintaining low power consumption.
• High-current 3-state outputs designed to drive heavy capacitive loads or multiple downstream devices.

Buffers, Drivers, Receivers, Transceivers Applications

• Asynchronous two-way communication between data buses
• Memory and memory interface control systems
• Driving capacitive loads in digital logic circuits

Buffers, Drivers, Receivers, Transceivers Procurement Notes

Verify the specific ordering suffix against the manufacturer's current Package Option Addendum, as the SN74HC640DW status may differ from active variants like the DWR. Confirm RoHS compliance and lead finish specifications directly from the datasheet documentation before procurement to ensure alignment with assembly requirements.

Buffers, Drivers, Receivers, Transceivers Selection Notes

Select this component for applications requiring wide voltage operation and high-drive capability. Ensure the design accommodates the specified propagation delays under actual load conditions. Unused inputs must be tied to logic high or low states to prevent undefined operational behavior and excessive power consumption.

Buffers, Drivers, Receivers, Transceivers Part Context

This device belongs to the SNx4HC640 family of octal bus transceivers. It shares functional characteristics with other members of the HC series but differs in packaging and thermal metrics. The DW designation specifically identifies the SOIC-20 physical form factor used in surface-mount assemblies.

Buffers, Drivers, Receivers, Transceivers Replacement Considerations

SN74HC640DWR

Buffers, Drivers, Receivers, Transceivers FAQ

How are the data flow directions controlled?

Data transmission direction is determined by the level at the DIR pin. A low level directs data from the B bus to the A bus, while a high level directs data from the A bus to the B bus.

What is the function of the OE pin?

The Output Enable (OE) pin controls the 3-state condition of the outputs. When OE is high, the outputs are disabled, effectively isolating the buses regardless of the DIR pin state.