Texas Instruments SN74AC245DBR

Overview

SN74AC245DBR from Texas Instruments is an octal bus transceiver with 3-state outputs, designed for asynchronous bidirectional data transfer between A and B buses in mixed-voltage systems. It operates from 2 V to 6 V, accepts input voltages up to 6 V, achieves 7 ns max propagation delay at 5 V, and features direction control (DIR) and output enable (OE) pins for flexible bus isolation-used in pro audio interconnects requiring level translation and noise-immune signal routing.

For engineers reviewing the SN74AC245DBR datasheet, SN74AC245DBR pinout, SN74AC245DBR application, or SN74AC245DBR equivalent, this page delivers verified electrical specs, SSOP-20 package details, functional mode logic, thermal resistance (70 °C/W), and real-world use cases in video signage and factory automation where bus contention avoidance and controlled edge rates are critical.

Technical Context

The SN74AC245DBR implements a dual-bus transceiver architecture with independent DIR and OE control, enabling deterministic A→B or B→A data flow without external clocking. Its CMOS design supports rail-to-rail input tolerance and balanced drive strength, minimizing ringing on transmission lines.

Functional modes are defined by DIR (L/H) and OE (L/H) states: OE = H forces all outputs into high-impedance regardless of DIR; OE = L enables bidirectional transfer per DIR state. The device exhibits 45 pF typical power dissipation capacitance and maintains stable operation across −40 °C to +85 °C ambient temperature.

Key Specifications

Pinout & Package

SN74AC245DBR uses a 20-pin SSOP (Shrink Small Outline Package) with 0.65 mm lead pitch, 7.2 mm × 7.8 mm body-plus-pin footprint, and 7.2 mm × 5.3 mm body-only dimensions. The package is RoHS-compliant, moisture sensitivity level 1, and rated for peak reflow at 260 °C.

Key Features

Applications

Equivalent & Alternatives

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

Compared with SN74LVC245APWR and 74AC245SCX, SN74AC245DBR uniquely supports true 2–6 V operation with 6 V-tolerant inputs, making it the only option among the three for robust 5 V ↔ 3.3 V bidirectional translation without external biasing or voltage scaling.

Availability

SN74AC245DBR is available at Aetrix Electronics and suitable for pro audio interconnects, video signage data buses, and factory automation I/O modules requiring stable component supply, long-term lifecycle support, and RoHS-compliant packaging.

Supply support for SN74AC245DBR 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 and embedded processing solutions, with over 90 years of innovation in precision analog, power management, and logic ICs.

SN74AC245DBR belongs to the SNx4AC logic family, engineered for high-noise-margin, low-power bus interfacing in industrial, automotive, and consumer systems where voltage flexibility and bus isolation are essential.

FAQ

What is the maximum propagation delay of SN74AC245DBR at 5 V?

The maximum propagation delay (tPD) of SN74AC245DBR is 7 ns at VCC = 5 V and TA = 25 °C, measured from input transition to valid output transition under specified load conditions. This value ensures reliable operation in systems with clock periods ≥14.3 ns, such as 32-bit parallel buses running below 70 MHz.

Can SN74AC245DBR operate with a 3.3 V supply while interfacing with 5 V logic?

Yes, SN74AC245DBR supports VCC = 3.3 V and accepts input voltages up to 6 V on all A and B port pins. This allows direct connection to 5 V logic outputs without level-shifting circuitry, while maintaining valid 3.3 V-compatible output levels-enabling seamless bidirectional translation between 3.3 V and 5 V domains.

How does the OE pin function in SN74AC245DBR?

The OE (output enable) pin on SN74AC245DBR is active-low: when OE = H (high), all A and B port outputs enter high-impedance state, effectively isolating both buses. When OE = L (low), the transceiver becomes active and data flows according to the DIR pin state. TI recommends tying OE to VCC via a pullup resistor during power-up to ensure default isolation.

What is the thermal resistance (RθJA) of SN74AC245DBR in its SSOP package?

SN74AC245DBR in the DB (SSOP-20) package has a junction-to-ambient thermal resistance (RθJA) of 70 °C/W under standard JEDEC test conditions. This value assumes a two-layer PCB with 1 in² copper pour per side and guides thermal derating calculations for continuous operation at elevated ambient temperatures.

Is SN74AC245DBR suitable for industrial temperature applications?

Yes, SN74AC245DBR is rated for operation from −40 °C to +85 °C, meeting industrial temperature requirements. Its AC logic family provides stable timing margins and noise immunity across this range, and its 70 °C/W RθJA supports reliable performance in enclosed control cabinets without forced air cooling.