Texas Instruments SN74CBT3245AZQNR

Overview

SN74CBT3245AZQNR from Texas Instruments is an octal FET bus switch IC designed for high-speed TTL-compatible bidirectional data routing between two 8-bit ports (A and B). It features 5-Ω typical on-state resistance, 0.25 ns propagation delay at 5 V, and operates across −40°C to 85°C with supply voltage from 4 V to 5.5 V. It enables low-latency signal isolation in memory expansion and address/data bus multiplexing applications.

For engineers reviewing the SN74CBT3245AZQNR datasheet, SN74CBT3245AZQNR pinout, SN74CBT3245AZQNR application, or SN74CBT3245AZQNR equivalent, key selection criteria include its 5-Ω r_on, 0.25 ns t_pd, standard '245-type pinout, high-impedance isolation when OE is high, and VFBGA ZQN package compatibility with space-constrained PCB layouts.

Technical Context

The SN74CBT3245AZQNR implements eight independent NMOS pass-gate 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 resistive loss and capacitive loading; when OE is high, both ports present >10⁹ Ω isolation impedance. Its architecture avoids latch-up and supports hot-swap capability due to FET-based switching without internal logic states.

It uses TTL-compatible input thresholds (V_IL ≤ 0.8 V, V_IH ≥ 2 V) and operates with rail-to-rail analog signal pass-through - no level-shifting or direction control logic required. The device requires no external biasing beyond V_CC and GND, and OE must be pulled up to V_CC via external resistor during power sequencing to guarantee high-impedance state at startup.

Key Specifications

Pinout & Package

VFBGA package (ZQN), 20-pin, 2.5 mm × 3.5 mm footprint, 0.5 mm pitch, exposed thermal pad. Compliant with JEDEC MO-220, RoHS and green (no Sb/Br) standards.

Key Features

Applications

Equivalent & Alternatives

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

Compared with SN74CBT3245AZQNR, SN74CBTD3384PWR adds voltage translation but increases propagation delay and reduces pin compatibility, while 74LVC245APW,118 introduces direction dependency and eliminates true analog pass-through - neither offers identical 5-V, bidirectional, zero-direction-control functionality in the ZQN package.

Availability

SN74CBT3245AZQNR is available at Aetrix Electronics and suitable for industrial control systems, memory expansion modules, and embedded test equipment requiring stable component supply and long-term lifecycle support.

Supply support for SN74CBT3245AZQNR 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 decades of expertise in high-reliability logic and interface solutions.

The SN74CBT3245AZQNR belongs to TI's CBT (Crossbar Bus Technology) family - engineered for ultra-low-latency, bidirectional signal routing in high-speed digital systems where timing predictability and signal integrity are critical.

FAQ

What is the maximum continuous current per channel for SN74CBT3245AZQNR?

The SN74CBT3245AZQNR supports 128 mA continuous channel current per switch path. This rating applies across the full operating temperature range and ensures reliable conduction without thermal shutdown or parametric shift. The 5-Ω typical on-resistance results in ≤0.64 V drop at 128 mA, making SN74CBT3245AZQNR suitable for driving moderate fan-out loads in 5-V systems.

Does SN74CBT3245AZQNR require external pull-up resistors on the OE pin?

Yes - to ensure high-impedance state during power-up or power-down, OE must be tied to V_CC through an external pull-up resistor. TI specifies the minimum resistor value based on the current-sinking capability of the OE driver; typical values range from 4.7 kΩ to 10 kΩ. Without this, undefined switch states may occur, risking bus contention in SN74CBT3245AZQNR-based designs.

Can SN74CBT3245AZQNR operate with a 3.3-V supply?

No - SN74CBT3245AZQNR is specified only for 4 V to 5.5 V operation. At 3.3 V, the internal FETs fail to fully enhance, resulting in elevated r_on (>20 Ω), increased propagation delay (>1 ns), and potential logic threshold violations. For 3.3-V systems, TI recommends SN74CBTD3384 or LVC-series alternatives instead of SN74CBT3245AZQNR.

Is the ZQN package of SN74CBT3245AZQNR lead-free and RoHS compliant?

Yes - SN74CBT3245AZQNR uses the ZQN (Pb-free) VFBGA package and is RoHS compliant per EU Directive 2011/65/EU, with green (halogen-free) construction and CU-NIPDAU terminal finish. It meets JEDEC moisture sensitivity level (MSL) 3 and is qualified for reflow soldering per J-STD-020.

How does SN74CBT3245AZQNR differ from standard 74LS245 transceivers?

Unlike 74LS245, which is a direction-controlled 3-state transceiver requiring DIR and OE pins, SN74CBT3245AZQNR is a bidirectional FET switch with only one control (OE) and no direction logic. It provides true analog pass-through with 5-Ω r_on and 0.25 ns t_pd, versus LS245's 15–25 ns delay and higher output impedance - making SN74CBT3245AZQNR superior for high-speed, low-skew interconnects.