Texas Instruments SN74CBT3345DWR

Overview

SN74CBT3345DWR from Texas Instruments is an 8-bit high-speed TTL-compatible bus switch IC with standard '245 pinout, 5-Ω on-state resistance, dual output-enable control (OE and OE), and operation over −40°C to 85°C. It enables bidirectional signal routing between port A and port B in memory expansion, data multiplexing, and hot-swap interface applications.

For engineers reviewing the SN74CBT3345DWR datasheet, SN74CBT3345DWR pinout, SN74CBT3345DWR application, or SN74CBT3345DWR equivalent, key selection criteria include its 0.25 ns propagation delay, 5 Ω typical on-resistance, dual active-low/active-high enable logic, SOIC-20 package compatibility, and 4.5 V to 5.5 V supply range for low-latency digital switching.

Technical Context

The SN74CBT3345DWR implements a single 8-bit analog/digital bus switch bank using NMOS transmission-gate architecture. Its dual enable inputs (OE and OE) provide complementary logic control: switch conducts when OE is low OR OE is high, and disconnects only when OE is high AND OE is low - enabling flexible system-level gating without external inverters.

Designed for 5-V TTL systems, it features rail-to-rail signal handling (−0.5 V to 7 V input voltage range), 6 pF off-state I/O capacitance, and 3 pF control-input capacitance - minimizing capacitive loading and crosstalk in high-speed parallel buses. Absolute maximum ratings include 128 mA continuous channel current and 7 V supply tolerance.

Key Specifications

Pinout & Package

SN74CBT3345DWR is housed in a 20-pin SOIC (DW) package, 7.5 mm × 12.8 mm body, 2.65 mm max height, with 1.27 mm lead pitch and JEDEC MS-013 compliance. Pin 1 located at top-left corner with index area marking.

Key Features

Applications

Equivalent & Alternatives

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

Compared with SN74CBTD3345DWR and 74LVC245APW,118, the SN74CBT3345DWR uniquely delivers dual-enable-controlled, zero-direction-pin, 5-V bidirectional switching with sub-nanosecond latency - making it irreplaceable in timing-critical 5-V bus arbitration and hot-swap isolation roles.

Availability

SN74CBT3345DWR is available at Aetrix Electronics and suitable for memory expansion interfaces, hot-swappable peripheral buses, legacy system bus multiplexing, and test access port signal routing requiring stable component supply and long-term industrial availability.

Supply support for SN74CBT3345DWR 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 specializing in analog, embedded processing, and connectivity technologies, with over 90 years of innovation in industrial, automotive, and communications markets.

The SN74CBT3345DWR belongs to TI's CBT (Crosspoint Bus Transceiver) family - designed specifically for low-latency, high-fidelity digital signal routing in 5-V bus architectures where direction control and propagation delay are critical.

FAQ

What is the function of the dual OE inputs on the SN74CBT3345DWR?

The SN74CBT3345DWR features two independent output-enable inputs: OE (active-low) and OE (active-high). The switch conducts (A↔B connected) when either OE is low OR OE is high. It disconnects (high-impedance state) only when OE is high AND OE is low. This dual-control scheme allows flexible integration with both legacy active-low enable signals and modern active-high GPIOs without external logic inversion.

Does the SN74CBT3345DWR support 3.3-V logic levels?

The SN74CBT3345DWR is specified for 4.5 V to 5.5 V operation and TTL-compatible input thresholds (VIH ≥ 2 V, VIL ≤ 0.8 V), making it fully compatible with 3.3-V CMOS outputs driving into its inputs - provided the 3.3-V device can source/sink sufficient current and the SN74CBT3345DWR's VCC remains at 5 V. However, its outputs swing rail-to-rail (0–5 V), so level-shifting is required if interfacing with pure 3.3-V receivers.

What is the maximum signal frequency supported by the SN74CBT3345DWR?

The SN74CBT3345DWR does not specify a maximum clock frequency but is characterized for 0.25 ns propagation delay and 6 pF off-state I/O capacitance. In practice, it reliably supports data rates up to 1 Gbps per line in parallel bus applications (e.g., 100 MHz 8-bit address/data buses), limited primarily by PCB trace impedance matching and load capacitance - not by internal switching speed.

Is the SN74CBT3345DWR pin-compatible with the SN74LS245?

Yes - the SN74CBT3345DWR uses the standard '245 pinout (SOIC-20), matching pin-for-pin with SN74LS245, SN74ALS245, and SN74AS245. However, unlike those transceivers, it lacks direction control (DIR) and operates as a bidirectional switch rather than a directional buffer. No PCB changes are needed for physical replacement, but system firmware must adapt to dual-OE control instead of DIR.

What thermal considerations apply to the SN74CBT3345DWR in continuous operation?

The SN74CBT3345DWR in SOIC (DW) package has a θJA of 58°C/W. At maximum recommended 5.5 V supply and full 8-line conduction (128 mA total), power dissipation remains below 100 mW - resulting in <6°C junction-to-ambient rise under still-air conditions. For sustained high-current operation, ensure ≥1 cm² copper pour under the package and avoid stacking heat-generating components nearby.