Texas Instruments SN74CBT3245ADBQRE4

Overview

SN74CBT3245ADBQRE4 from Texas Instruments is an octal FET bus switch IC designed for high-speed TTL-compatible bidirectional signal routing between two 8-bit ports (A and B). It features 5-Ω on-state resistance, 0.25 ns typical propagation delay at 5 V, and operates from −40°C to 85°C with supply voltage range 4 V to 5.5 V. It is used in address/data bus isolation, hot-swap interface buffering, and level-translating I/O expansion.

For engineers reviewing the SN74CBT3245ADBQRE4 datasheet, SN74CBT3245ADBQRE4 pinout, SN74CBT3245ADBQRE4 application, or SN74CBT3245ADBQRE4 equivalent, key selection considerations include its low on-resistance switching, standard '245 pinout compatibility, OE-controlled high-impedance state, and SSOP-20 package thermal performance (θ_JA = 68°C/W).

Technical Context

The SN74CBT3245ADBQRE4 implements eight independent FET-based bilateral analog switches controlled by a single active-low output-enable (OE) input. When OE is low, A1–A8 are electrically connected to B1–B8 with minimal RC delay; when OE is high, both ports present >10⁹ Ω isolation. Its TTL-compatible control inputs accept VIH ≥ 2 V and VIL ≤ 0.8 V, enabling direct interfacing with legacy logic families without level shifters.

No internal clamping diodes are integrated - absolute maximum ratings specify VI and VCC up to 7 V, but recommended operation is strictly 4–5.5 V. The device lacks built-in ESD protection beyond standard HBM (2 kV), requiring external TVS or series resistors in noisy environments. Power-up sequencing requires OE tied to VCC via pull-up resistor to guarantee high-impedance state before logic initialization.

Key Specifications

Pinout & Package

SN74CBT3245ADBQRE4 is housed in a 20-pin SSOP (Shrink Small Outline Package) with 0.65 mm pitch, 7.4 mm × 5.3 mm body, and 2.0 mm max height (JEDEC MO-150 compliant). Pin 1 index is marked by a beveled corner; package is RoHS-compliant with NiPdAu lead finish and MSL Level-1 rating.

Key Features

Applications

Equivalent & Alternatives

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

Compared with SN74CBT3245ADBQRE4, SN74CBTD3384CDWRE4 offers lower power-down current but slightly higher on-resistance, while 74LVC245APW,118 provides direction control and bus-hold at the cost of higher Ron and non-compatible pinout - making SN74CBT3245ADBQRE4 optimal for high-speed, pin-compatible '245 replacements in 5-V systems.

Availability

SN74CBT3245ADBQRE4 is available at Aetrix Electronics and suitable for memory subsystem isolation, hot-swap backplane design, and legacy logic interfacing requiring stable component supply and long-term industrial availability.

Supply support for SN74CBT3245ADBQRE4 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 U.S.-based semiconductor company founded in 1930, specializing in analog, embedded processing, and logic solutions for industrial, automotive, and communications markets.

The SN74CBT3245A family was developed to deliver high-speed, low-distortion bus switching for 5-V digital systems where minimal propagation delay and precise impedance matching are critical - particularly in memory controllers and backplane architectures.

FAQ

What is the maximum continuous current per channel for SN74CBT3245ADBQRE4?

The SN74CBT3245ADBQRE4 supports up to 128 mA total continuous channel current across all eight switches. Per-channel current is not individually rated, but thermal limits require average per-channel current to remain below ~16 mA under sustained operation at 85°C ambient to avoid exceeding the 125°C junction temperature, given its 68°C/W θ_JA.

Can SN74CBT3245ADBQRE4 operate at 3.3 V supply?

No - SN74CBT3245ADBQRE4 is specified only for VCC = 4 V to 5.5 V per its recommended operating conditions. At 3.3 V, the internal FETs fail to fully enhance, resulting in elevated on-resistance (>20 Ω), increased propagation delay (>1 ns), and potential logic threshold violations. For 3.3-V systems, consider SN74CBTD3384 or 74LVC245 alternatives.

Does SN74CBT3245ADBQRE4 have built-in ESD protection on I/O pins?

SN74CBT3245ADBQRE4 meets JEDEC JS-001 HBM Class 2 (±2 kV) but contains no integrated I/O ESD clamps beyond standard process-level protection. External TVS diodes or series resistors are recommended for applications exposed to IEC 61000-4-2 contact discharge (±4 kV–±8 kV), especially in industrial or field-deployed equipment.

Is the pinout of SN74CBT3245ADBQRE4 compatible with standard 74LS245 devices?

Yes - SN74CBT3245ADBQRE4 uses the standard '245-type pinout (A1–A8 on pins 1–8, OE on pin 11, B1–B8 on pins 12–19, GND on pin 9, VCC on pin 10, NC on pin 20), enabling direct PCB-level replacement of 74LS245, 74ACT245, and other '245-family devices in SSOP-20 footprints without layout changes.

How should OE be handled during power-up to ensure safe operation of SN74CBT3245ADBQRE4?

To guarantee high-impedance state at power-up, OE must be held high (≥2 V) before VCC reaches 3 V. TI recommends tying OE to VCC through a pull-up resistor; minimum value is determined by the driver's sink capability - for typical microcontroller GPIO (4 mA sink), a 10-kΩ resistor suffices. Avoid floating OE or connecting it directly to slow-rising control signals.