SN74CBT6845CPW

Overview

The SN74CBT6845CPW is an 8-bit FET bus switch manufactured by Texas Instruments, housed in a 20-pin TSSOP package. It operates within a supply voltage range of 4 V to 5.5 V and supports bidirectional data flow with near-zero propagation delay. The device features active undershoot protection on A and B ports up to -2 V and precharges the B port via a user-selectable bias voltage (BIASV) to minimize live-insertion noise. It provides low ON-state resistance (typical 3 Ω), low input/output capacitance (5.5 pF typical), and supports partial-power-down mode through Ioff isolation.

Feature Summary

• Active undershoot-protection circuitry ensures proper OFF state during undershoot events up to -2 V
• B-port outputs are precharged to a user-selectable bias voltage to minimize signal distortion during live insertion and hot-plugging
• Supports partial-power-down applications by preventing damaging backflow current when powered down
• Bidirectional data flow with TTL-compatible control inputs and low ON-state resistance

Applications

• PCI interface support including hot-plug operations
• Memory interleaving systems
• Bus isolation circuits
• Low-distortion signal gating for digital and analog applications

Procurement Notes

Verify the specific ordering suffix 'PW' corresponds to the TSSOP-20 tube packaging configuration. Confirm that the component meets RoHS compliance standards as indicated in the manufacturer's documentation. Ensure the operating temperature range aligns with system requirements, specifically the -40°C to +85°C specification. Cross-reference the datasheet revision to ensure all electrical characteristics match the design specifications.

Selection Notes

Select this component for high-speed bus switching applications requiring minimal propagation delay and low ON-state resistance. The inclusion of active undershoot protection makes it suitable for environments prone to signal glitches. Verify that the control inputs can be driven by TTL or 5-V/3.3-V CMOS outputs. Ensure the BIASV pin is properly connected to manage live-insertion noise effectively in the target circuit design.

Part Context

This device belongs to the SN74CBT6845C series of high-speed TTL-compatible FET bus switches. It is designed to provide bidirectional data transfer between two ports with a single output-enable input. The series emphasizes low power consumption and robust ESD performance, meeting JESD 22 standards for human-body model and charged-device model testing.

Replacement Considerations

Check for equivalent part numbers within the same family, such as SN74CBT6845CPWR for tape-and-reel packaging. Verify functional compatibility regarding voltage ranges and pin configurations before substitution.