Texas Instruments 74CB3T3306DCURG4

Overview

74CB3T3306DCURG4 from Texas Instruments is a dual 1-bit FET bus switch optimized for bidirectional level translation between 5-V, 3.3-V, and 2.5-V logic domains, featuring 5 Ω typical ON-state resistance, 4.5 pF typical OFF-state I/O capacitance, and 0.25 ns propagation delay at 3.3 V - deployed in USB interface isolation and mixed-voltage memory interconnects.

For engineers reviewing the 74CB3T3306DCURG4 datasheet, 74CB3T3306DCURG4 pinout, 74CB3T3306DCURG4 application, or 74CB3T3306DCURG4 equivalent, key selection criteria include 5-V tolerant I/Os with device powered up or down, Ioff partial-power-down support, VCC operating range (2.3 V to 3.6 V), and VSSOP-8 package compatibility with high-density PCB layouts.

Technical Context

The 74CB3T3306DCURG4 implements two independent FET-based transmission gates, each controlled by an active-low enable (1OE/2OE), enabling bidirectional signal flow with near-zero propagation delay and voltage-tracking output translation that follows VCC. Its architecture supports mixed-mode operation across TTL, LVTTL, and CMOS standards without external level-shifting components.

Each switch exhibits low ON-resistance (5 Ω typ) and minimal parasitic capacitance (4.5 pF OFF, 4 pF ON), ensuring signal integrity in high-speed digital paths. The device integrates undershoot clamp diodes on all data and control inputs and guarantees latch-up immunity exceeding 250 mA per JESD 17.

Key Specifications

Pinout & Package

VSSOP-8 (DCU) package: 2.30 mm × 2.00 mm body, 0.65 mm lead pitch, 1.05 mm A0 cavity depth, Q3 pin-1 quadrant orientation per tape-and-reel standard.

Key Features

Applications

Equivalent & Alternatives

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

Compared with SN74CBT3306CPW and 74LVC2G66GW, the 74CB3T3306DCURG4 uniquely combines dual-channel operation, guaranteed Ioff, and 5-V I/O tolerance in a space-optimized VSSOP-8 package - making it the only option meeting simultaneous requirements for industrial bus isolation, hot-swap safety, and high-density layout.

Availability

74CB3T3306DCURG4 is available at Aetrix Electronics and suitable for USB interface isolation, PCI bus segmentation, and memory interleaving applications requiring stable component supply, long-term industrial lifecycle support, and RoHS-compliant packaging.

Supply support for 74CB3T3306DCURG4 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 delivering analog, embedded processing, and connectivity technologies for industrial, automotive, and consumer applications.

The SN74CB3T3306 product line targets mixed-voltage digital system integration, specifically designed to simplify level translation and bus isolation in resource-constrained, high-reliability embedded platforms.

FAQ

What is the maximum allowable I/O voltage for 74CB3T3306DCURG4 when VCC = 0 V?

The 74CB3T3306DCURG4 supports 0–5.5 V signaling on all I/O pins (1A, 1B, 2A, 2B) regardless of VCC state - including full 5-V tolerance when powered down. This is confirmed by absolute maximum ratings (VI/O = –0.5 V to 7 V) and functional specification of 5-V tolerant I/Os with device powered up or down. No external clamping is required for this condition in the 74CB3T3306DCURG4.

Does 74CB3T3306DCURG4 support true bidirectional signal flow without direction control pins?

Yes, the 74CB3T3306DCURG4 provides inherently bidirectional data flow through its FET-based transmission gate architecture - no direction pin is needed. When 1OE or 2OE is low, the corresponding A–B path conducts equally in both directions, enabling transparent signal pass-through for protocols like I²C, SMBus, or memory address/data lines. This behavior is intrinsic to the 74CB3T3306DCURG4's design.

How does the Ioff feature of 74CB3T3306DCURG4 protect downstream circuitry during partial power-down?

The Ioff feature limits leakage current to ≤20 µA when VCC = 0 V and any I/O pin is driven to 0–5.5 V - preventing destructive backflow current into unpowered sections of the system. This is validated per datasheet electrical characteristics (Ioff = 10–20 µA max) and enables safe hot-swap and power-gating scenarios where the 74CB3T3306DCURG4 remains connected while other rails are off.

Can 74CB3T3306DCURG4 be used to translate 5-V logic down to 1.8-V levels?

No - the 74CB3T3306DCURG4's output voltage is referenced to VCC and cannot generate voltages below VCC. With VCC = 2.3–3.6 V, it supports 5-V-to-3.3-V or 5-V-to-2.5-V translation, but not 5-V-to-1.8-V. For 1.8-V interfaces, a dedicated level translator such as TXS0108E is required. This limitation is inherent to the 74CB3T3306DCURG4's voltage-tracking architecture.

What is the recommended bypass capacitor value and placement for 74CB3T3306DCURG4?

A 0.1-µF ceramic capacitor is recommended directly between VCC and GND pins of the 74CB3T3306DCURG4, placed within 2 mm of the pins to minimize loop inductance. This is specified in Section 10 (Power Supply Recommendations) of the datasheet to suppress high-frequency noise and stabilize the internal FET bias network during fast switching events in the 74CB3T3306DCURG4.