Texas Instruments SN74CBT3245CDW

Overview

SN74CBT3245CDW from Texas Instruments is an 8-bit high-speed TTL-compatible FET bus switch with bidirectional data flow, near-zero propagation delay (0.15 ns typical at 5 V), 3 Ω typical ON-state resistance, and undershoot protection up to −2 V on A/B ports - used for USB interface isolation and memory interleaving in industrial control backplanes.

For engineers reviewing the SN74CBT3245CDW datasheet, SN74CBT3245CDW pinout, SN74CBT3245CDW application, or SN74CBT3245CDW equivalent, key selection criteria include Ioff partial-power-down support, 0–5-V signal-level compatibility across logic families, low 5.5 pF OFF-state I/O capacitance, and SOIC-20 package thermal performance (θJA = 58°C/W).

Technical Context

The SN74CBT3245CDW 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 ron-induced distortion; when OE is high, both ports enter high-impedance state with Ioff limiting backflow current during partial power-down.

Undershoot-protection circuitry actively monitors A/B port voltages and forces gate cutoff if either port drops below −2 V, preventing false turn-on and latch-up. Control inputs accept TTL or 3.3/5-V CMOS levels, while data I/Os support 0.8-V to 5-V signaling without level-shifting.

Key Specifications

Pinout & Package

SN74CBT3245CDW uses a 20-pin SOIC (DW) package with 7.5 mm × 12.8 mm body, 1.27 mm pitch, and 2.65 mm max height per JEDEC MS-013. Thermal resistance θJA is 58°C/W.

Key Features

Applications

Equivalent & Alternatives

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

Compared with SN74CBT3245CDW, SN74CBTD3384CDW adds dual-supply flexibility but increases ron and complexity, while 74LVC245APW offers lower cost for pure digital buffering but sacrifices analog fidelity, undershoot resilience, and true bidirectional transparency.

Availability

SN74CBT3245CDW is available at Aetrix Electronics and suitable for USB interface isolation, memory interleaving, and industrial backplane bus isolation requiring stable component supply, long-term lifecycle assurance, and RoHS-compliant SOIC packaging.

Supply support for SN74CBT3245CDW 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 SN74CBT3245CDW belongs to TI's CBT (CrossBar Technology) bus switch family, engineered for high-speed, low-distortion signal routing in mixed-voltage digital systems where timing predictability and power-domain isolation are critical.

FAQ

What is the maximum undershoot voltage the SN74CBT3245CDW can tolerate on its A and B ports?

The SN74CBT3245CDW provides active undershoot protection up to −2 V on both A and B ports, as verified in the absolute maximum ratings and undershoot characteristics tables of the SCDS131A datasheet. This ensures reliable operation during ground bounce or ESD transients without false turn-on, making SN74CBT3245CDW suitable for noisy industrial environments where transient immunity is essential.

Does the SN74CBT3245CDW support partial-power-down mode, and how is it implemented?

Yes, the SN74CBT3245CDW supports partial-power-down mode via its Ioff feature, which limits leakage current to 10 µA maximum when VCC = 0 V and I/O voltages range from 0 to 5.5 V. This design prevents damaging back-current flow through the device during power sequencing or hot-swap events, ensuring system-level reliability without requiring external isolation components in the SN74CBT3245CDW signal path.

What is the ON-state resistance (ron) specification for the SN74CBT3245CDW, and how does it affect signal integrity?

The SN74CBT3245CDW has a typical ON-state resistance of 3 Ω at VCC = 4.5 V and IO = 30 mA, with a maximum of 6 Ω across temperature and voltage ranges. This low ron ensures minimal voltage drop (<10 mV at 64 mA), preserving logic thresholds and reducing timing skew - a critical factor for maintaining signal integrity in high-speed parallel buses like those used in memory interleaving or USB 2.0 isolation where SN74CBT3245CDW is deployed.

Can the SN74CBT3245CDW interface between 1.8-V and 5-V logic domains without external level shifters?

Yes, the SN74CBT3245CDW supports 0–5.5 V signaling on its data I/O ports (A and B), allowing direct connection between 1.8-V, 2.5-V, 3.3-V, and 5-V logic families. Its control inputs (OE) accept TTL or 3.3/5-V CMOS levels, and the absence of internal level-shifting circuitry means SN74CBT3245CDW passes analog voltage levels transparently - eliminating need for discrete translators in mixed-voltage system interconnects.

What is the thermal performance of the SN74CBT3245CDW in its SOIC-20 (DW) package?

The SN74CBT3245CDW in the SOIC-20 (DW) package has a specified junction-to-ambient thermal resistance (θJA) of 58°C/W under standard JEDEC test conditions. This value enables reliable operation at full rated current in ambient temperatures up to 85°C when mounted on a 2-layer PCB with moderate copper area, confirming SN74CBT3245CDW suitability for thermally constrained industrial control modules and embedded computing platforms.