Texas Instruments SN74CBT3244PWRG4

Overview

SN74CBT3244PWRG4 from Texas Instruments is an octal FET bus switch organized as two independent 4-bit bidirectional low-impedance switches, featuring 5 Ω typical ON-state resistance, 6 pF typical OFF-state I/O capacitance, and sub-nanosecond propagation delay (0.25 ns typical), used for high-speed signal routing between microprocessors and peripherals in test equipment and factory automation control boards.

For engineers reviewing the SN74CBT3244PWRG4 datasheet, SN74CBT3244PWRG4 pinout, SN74CBT3244PWRG4 application, or SN74CBT3244PWRG4 equivalent, key selection considerations include its TTL/CMOS-compatible control inputs, 4.5 V to 5.5 V supply range, 0–5 V data-level tolerance, active-low dual OE control, and TSSOP-20 package compatibility with standard '244 pinout.

Technical Context

The SN74CBT3244PWRG4 implements eight independent analog/digital bus switches using NMOS transmission-gate topology, with two groups (1A/1B and 2A/2B) each controlled by a dedicated active-low output-enable input (1OE, 2OE). Each switch conducts bidirectionally with near-zero propagation delay and flat on-resistance over voltage and temperature.

Its design supports mixed-voltage signaling: data I/Os tolerate 0 V to 5 V regardless of VCC (4.5–5.5 V), enabling level-shifting between 1.8 V, 2.5 V, 3.3 V, and 5 V domains without external circuitry. Control inputs accept TTL thresholds (VIL ≤ 0.8 V, VIH ≥ 2 V) and are compatible with both 3.3 V and 5 V logic families.

Key Specifications

Pinout & Package

TSSOP-20 package (5.00 mm × 4.40 mm body, 1.2 mm max height), lead pitch 0.65 mm, 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 SN74CBT3244PWRG4, SN74CBTD3384PWR offers broader voltage flexibility but requires PCB redesign, while 74LVC244APW,118 provides lower-cost buffering at the expense of bidirectionality and 5 V interoperability-making SN74CBT3244PWRG4 optimal for legacy 5 V bus isolation with minimal layout impact.

Availability

SN74CBT3244PWRG4 is available at Aetrix Electronics and suitable for multi-processor communications, test and measurement systems, and factory automation control boards requiring stable component supply and long-term industrial lifecycle support.

Supply support for SN74CBT3244PWRG4 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 company founded in 1930, specializing in analog, embedded processing, and digital signal technologies for industrial, automotive, and communications markets.

The SN74CBT3244PWRG4 belongs to TI's CBT (Crossbar Bus Transceiver) family, designed specifically for high-speed, low-distortion bus switching in instrumentation, control, and test environments where signal fidelity and timing predictability are critical.

FAQ

What is the function of the 1OE and 2OE pins on the SN74CBT3244PWRG4?

The 1OE and 2OE pins are active-low output-enable inputs controlling two independent 4-bit switch groups. When pulled low, they connect corresponding A and B ports (e.g., 1A1 ↔ 1B1); when high, they place those ports in high-impedance isolation. For reliable power-up behavior, TI recommends tying both OE pins to VCC via pullup resistors to ensure default isolation until firmware asserts them low. This behavior is explicitly defined in the SN74CBT3244PWRG4 functional modes section.

Can the SN74CBT3244PWRG4 operate with a 3.3 V supply voltage?

No, the SN74CBT3244PWRG4 requires a minimum VCC of 4.5 V and operates only within 4.5 V to 5.5 V. It is not rated for 3.3 V operation. However, its data I/O pins tolerate 0–5 V signals regardless of VCC-so it can interface with 3.3 V or lower logic families as long as VCC remains at 4.5–5.5 V and proper level-shifting or clamping is applied to control inputs if driven by 3.3 V sources. This limitation is specified in the Recommended Operating Conditions table of the SN74CBT3244PWRG4 datasheet.

Is the SN74CBT3244PWRG4 pin-compatible with the 74LS244?

Yes, the SN74CBT3244PWRG4 uses the industry-standard '244 pinout across all packages including TSSOP-20, making it a direct physical and functional replacement for 74LS244 and 74ACT244 in existing designs. Pin mapping matches exactly: 1OE/2OE correspond to 1G/2G, and all A/B I/O positions align. This compatibility is confirmed in TI's SN74CBT3244PWRG4 datasheet Feature Description and Pin Configuration sections.

What is the maximum continuous current per channel for the SN74CBT3244PWRG4?

The SN74CBT3244PWRG4 supports a maximum continuous channel current of ±64 mA per switch, as specified in the Absolute Maximum Ratings table. Exceeding this value risks thermal overstress or parametric shift. The device's 5 Ω typical ON-resistance results in only ~320 mV drop at 64 mA, preserving signal swing integrity. This rating applies under recommended operating conditions and must be verified against board-level thermal performance in the final layout.

Does the SN74CBT3244PWRG4 require external bypass capacitors?

Yes, TI specifies a 0.1 µF ceramic bypass capacitor between VCC (pin 20) and GND (pin 10), placed as close as possible to the SN74CBT3244PWRG4 package. This is mandatory to suppress supply noise and maintain signal integrity at high frequencies. Layout guidelines emphasize minimizing trace inductance-failure to implement proper decoupling may cause erratic switching behavior or increased jitter, especially above 50 MHz. This requirement appears in Section 9.2.1 (Design Requirements) of the SN74CBT3244PWRG4 datasheet.