SN74BCT29843DW

Overview

The SN74BCT29843DW is a nine-bit D-type latch with three-state outputs manufactured by Texas Instruments. It utilizes a BiCMOS process featuring CMOS inputs and TTL outputs to reduce standby current. The device operates within a supply voltage range of 4.5 V to 5.5 V and supports an operating temperature range of 0°C to 70°C. Key electrical characteristics include a high-level output current of -24 mA and a low-level output current of 48 mA at VCC = 5 V. Propagation delays from data input (D) to output (Q) are typically 4.5 ns for low-to-high and 5.7 ns for high-to-low transitions under a 50 pF load.

Feature Summary

• Features transparent D-type latches where Q outputs are complementary to noninverting D inputs when latch-enable is high.
• Provides buffered output-enable control to place outputs in normal logic states or high-impedance states without loading bus lines.
• Designed specifically for driving highly capacitive or relatively low-impedance loads using increased drive capability.
• Internal flip-flop operation remains unaffected by the output enable state, allowing data retention or entry while outputs are disabled.

Applications

• Implementing wider buffer registers
• I/O port implementations
• Bidirectional bus drivers with parity
• Working registers

Procurement Notes

Verify the specific package variant during procurement, as the DW suffix denotes a plastic small-outline package. Confirm RoHS compliance status, noting that E4 and G4 suffixes indicate lead-free and green material classifications respectively. Ensure the active status aligns with design requirements, as TI recommends this device for new designs. Cross-reference the pinout diagram for the 24-pin configuration to ensure compatibility with the target PCB footprint.

Selection Notes

Select this component when designing systems requiring nine-bit storage with high-drive three-state outputs. The BiCMOS technology offers a balance of CMOS input compatibility and TTL output drive strength. Consider the propagation delay specifications if timing constraints are critical for the bus interface. Verify that the operating temperature range meets the environmental conditions of the final application.

Part Context

This device belongs to the SN74BCT series, which combines BiCMOS processing with CMOS inputs and TTL outputs. The family is designed to provide improved performance over standard TTL logic while maintaining compatibility. The SN74BCT29843 specifically addresses applications needing wide bus interfacing with reduced power consumption compared to older bipolar technologies.

Replacement Considerations

SN74BCT29843DWE4

FAQ

How does the output-enable input affect internal latch operation?

The output-enable input does not affect the internal operation of the flip-flops. Data can be retained or entered while the outputs are in the high-impedance state.

What is the relationship between the D inputs and Q outputs when latch-enable is high?

When the latch-enable input is high, the Q outputs are complementary to the noninverting data inputs.