Texas Instruments SN74CBT3245CPWR

Overview

SN74CBT3245CPWR from Texas Instruments is an 8-bit high-speed FET bus switch with bidirectional data flow, 3 Ω typical ON-state resistance, near-zero propagation delay (0.15 ns at 5 V), and undershoot protection up to −2 V on A/B ports. It operates from 4 V to 5.5 V and supports mixed-voltage signaling (0.8 V to 5 V) in USB interface and memory interleaving applications.

For engineers reviewing the SN74CBT3245CPWR datasheet, SN74CBT3245CPWR pinout, SN74CBT3245CPWR application, or SN74CBT3245CPWR equivalent, key selection criteria include Ioff partial-power-down support, 5.5 pF typical OFF-state I/O capacitance, TTL/CMOS-compatible control inputs, and TSSOP-20 package compatibility with space-constrained PCB layouts.

Technical Context

The SN74CBT3245CPWR implements eight independent FET transmission gates controlled by a single active-low OE input. When OE is low, A and B ports are connected with minimal signal distortion; when OE is high, both ports enter high-impedance isolation. Internal undershoot-protection circuitry actively clamps transient events below −2 V while maintaining OFF-state integrity.

It features Ioff functionality that prevents backflow current during partial power-down, enabling safe operation in hot-swap and multi-rail systems. The device supports 0–5-V data I/O levels regardless of VCC, allowing level translation between 1.2-V, 1.8-V, 2.5-V, 3.3-V, and 5-V domains without external biasing.

Key Specifications

Pinout & Package

TSSOP-20 (PW) package: 6.95 mm × 4.4 mm × 1.2 mm body, 0.65 mm pitch, exposed pad not present, RoHS-compliant NiPdAu lead finish, MSL Level-1.

Key Features

Applications

Equivalent & Alternatives

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

Compared with SN74CBTD3384CPWR and 74LVC245APW,118, the SN74CBT3245CPWR uniquely combines single-supply operation, −2 V undershoot immunity, and Ioff in a TSSOP-20 footprint-making it optimal for USB, memory, and mixed-voltage isolation where reliability under transient conditions is critical.

Availability

SN74CBT3245CPWR is available at Aetrix Electronics and suitable for USB interface design, memory interleaving architectures, and bus isolation systems requiring stable component supply, long-term lifecycle assurance, and RoHS-compliant packaging.

Supply support for SN74CBT3245CPWR 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 high-reliability components.

The SN74CBT3245CPWR belongs to TI's CBT (Crosspoint Bus Transceiver) family, engineered for ultra-low-latency, low-distortion signal routing in high-speed digital interfaces where timing integrity and power-domain isolation are essential.

FAQ

What is the maximum undershoot voltage the SN74CBT3245CPWR can withstand on its A and B ports?

The SN74CBT3245CPWR provides active undershoot protection up to −2 V on both A and B ports, verified per datasheet SCDS131A. This protection is implemented via internal sensing circuitry that forces the switch into a guaranteed OFF state during transient events, preventing false conduction or latch-up. The SN74CBT3245CPWR maintains this rating across its full operating temperature range (−40°C to 85°C) and does not require external clamping components.

Does the SN74CBT3245CPWR support level translation between different logic families?

Yes, the SN74CBT3245CPWR supports bidirectional level translation across 0.8-V, 1.2-V, 1.5-V, 1.8-V, 2.5-V, 3.3-V, and 5-V logic families. Its data I/Os operate from 0 V to 5.5 V independently of VCC, which is set between 4 V and 5.5 V. This allows the SN74CBT3245CPWR to pass signals between mismatched voltage domains without direction control or external biasing-unlike traditional transceivers.

What is the recommended pull-up configuration for the OE pin during power-up?

TI recommends tying OE to VCC through a pull-up resistor to ensure high-impedance state during power-up or power-down sequences. The minimum resistor value depends on the driver's current-sinking capability; for standard CMOS drivers, 10 kΩ is commonly used. This guarantees the SN74CBT3245CPWR remains disabled until system firmware asserts OE low, preventing bus contention. The SN74CBT3245CPWR datasheet confirms this requirement in Section "Ordering Information".

Can the SN74CBT3245CPWR be used in hot-swap applications?

Yes, the SN74CBT3245CPWR is explicitly designed for hot-swap use via its Ioff feature, which limits current to 10 µA maximum when VCC = 0 V and VI/O = 0–5.5 V. This prevents back-current flow from live backplane traces into a powered-down module. Combined with −2 V undershoot protection and 100 mA latch-up immunity per JESD 78 Class II, the SN74CBT3245CPWR meets core requirements for PCIe add-in cards, modular PLC I/O, and enterprise server mezzanine boards.

What is the thermal performance of the SN74CBT3245CPWR in its TSSOP-20 (PW) package?

The SN74CBT3245CPWR in TSSOP-20 (PW) package has a thermal impedance θJA of 83°C/W, measured per JESD 51-7 on a standard 4-layer JEDEC test board. This value assumes standard copper pour and no thermal vias. For continuous 128 mA per channel operation, junction temperature rise remains within safe limits (<50°C) at ambient ≤70°C. The SN74CBT3245CPWR datasheet specifies absolute maximum ratings including 150°C storage temperature and 100 mA continuous VCC/GND current.