Texas Instruments SN74CBT3245CPW

Overview

SN74CBT3245CPW from Texas Instruments is an 8-bit high-speed TTL-compatible FET bus switch with bidirectional data flow, near-zero propagation delay (0.15 ns typical at 5 V), 3 Ω typical ON-state resistance, and undershoot protection up to −2 V on A/B ports - used for USB interface isolation and memory interleaving in mixed-voltage systems.

For engineers reviewing the SN74CBT3245CPW datasheet, SN74CBT3245CPW pinout, SN74CBT3245CPW application, or SN74CBT3245CPW equivalent, key selection criteria include Ioff partial-power-down support, 0–5-V signal level compatibility across 0.8 V to 5 V logic families, and TSSOP-20 package thermal performance (θJA = 83°C/W).

Technical Context

The SN74CBT3245CPW implements eight independent FET-based analog/digital switches controlled by a single active-low OE input. Its internal undershoot-protection circuitry actively clamps A/B port voltages down to −2 V while maintaining OFF-state isolation, preventing false turn-on during signal transients.

It supports full 0–5-V signaling across all I/Os, accepts TTL- or CMOS-level control inputs (VIH ≥ 2 V, VIL ≤ 0.8 V), and features Ioff current limiting (<10 µA at VCC = 0) to prevent backflow during partial power-down - critical for hot-swap and multi-rail system designs.

Key Specifications

Pinout & Package

TSSOP-20 package (PW), 6.6 mm × 4.4 mm × 1.2 mm max height, exposed pad not present, JEDEC MO-153 compliant, 0.65 mm lead pitch.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar bus switch applications.

Compared with SN74CBTD3384CPW and 74LVC245APW, the SN74CBT3245CPW provides superior transient immunity, lower ON-resistance, and true bidirectional zero-delay operation - making it optimal for USB, memory, and analog signal gating where simplicity and robustness are prioritized over voltage translation.

Availability

SN74CBT3245CPW is available at Aetrix Electronics and suitable for USB interface isolation, memory interleaving, bus isolation, and low-distortion signal gating requiring stable component supply and long-term industrial availability.

Supply support for SN74CBT3245CPW includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.

Manufacturer

Texas Instruments is a global semiconductor leader focused on analog, embedded processing, and connectivity technologies, with over 90 years of innovation in high-reliability components.

The SN74CBT3245CPW belongs to TI's CBT (Crossbar Bus Technology) family, designed specifically for high-speed, low-distortion, bidirectional signal routing in mixed-voltage digital and analog systems.

FAQ

What is the maximum undershoot voltage the SN74CBT3245CPW can tolerate on its A and B ports?

The SN74CBT3245CPW provides active undershoot protection up to −2 V on both A and B ports, verified per test conditions in the SCDS131A datasheet. This protection operates independently of VCC status and ensures the switch remains fully OFF during negative transients, preventing unintended conduction or latch-up. The SN74CBT3245CPW achieves this via integrated clamp circuitry that senses and responds to sub-ground excursions without requiring external components.

Does the SN74CBT3245CPW support partial-power-down operation, and how is it implemented?

Yes, the SN74CBT3245CPW supports partial-power-down via its Ioff feature, which limits current to ≤10 µA when VCC = 0 V and VI/O = 0–5.5 V. This prevents damaging back-current flow from live I/Os into a powered-down domain - essential for hot-swap and multi-rail systems. The SN74CBT3245CPW maintains high-impedance isolation even with VCC unpowered, eliminating need for external isolation circuitry.

What is the typical ON-state resistance of the SN74CBT3245CPW, and how does it affect signal integrity?

The SN74CBT3245CPW has a typical ON-state resistance (ron) of 3 Ω at VCC = 4.5 V and IO = 30 mA. This low ron ensures minimal voltage drop (<90 mV at 30 mA), preserves signal rise/fall times, and reduces insertion loss in high-speed digital and analog paths. Measured directly between A and B terminals, this value is confirmed across temperature and supply voltage ranges in the SN74CBT3245CPW electrical characteristics table.

Can the SN74CBT3245CPW interface between different logic families such as 1.8-V and 5-V systems?

Yes, the SN74CBT3245CPW supports 0–5.5 V signaling on all data I/Os (A1–A8, B1–B8), enabling seamless interoperability between 0.8-V, 1.2-V, 1.5-V, 1.8-V, 2.5-V, 3.3-V, and 5-V logic families without level shifters. Its control inputs accept TTL- or CMOS-level signals (VIH ≥ 2 V, VIL ≤ 0.8 V), and the SN74CBT3245CPW maintains full functionality across its 4–5.5 V VCC range - ideal for mixed-voltage board design.

What package type and thermal characteristics apply to the SN74CBT3245CPW?

The SN74CBT3245CPW uses the TSSOP-20 (PW) package: 6.6 mm × 4.4 mm × 1.2 mm max height, 0.65 mm lead pitch, JEDEC MO-153 compliant. Its thermal impedance is θJA = 83°C/W (free-air), measured per JESD 51-7. This value reflects standard PCB mounting with no thermal pad - consistent with the PW package's construction, which lacks an exposed thermal die pad unlike QFN variants.