Texas Instruments 74LVC8T245DBQRG4

Overview

74LVC8T245DBQRG4 from Texas Instruments is an 8-bit dual-supply non-inverting bus transceiver enabling bidirectional voltage-level translation between 1.65V and 5.5V domains. It features independent VCCA (1.65–5.5V) and VCCB (1.65–5.5V) rails, 3-state outputs controlled by DIR and OE pins referenced to VCCA, and Ioff support for partial-power-down operation. It is used in mixed-voltage interconnects such as 1.8V microcontroller-to-5V peripheral interfaces.

For engineers reviewing the 74LVC8T245DBQRG4 datasheet, 74LVC8T245DBQRG4 pinout, 74LVC8T245DBQRG4 application, or 74LVC8T245DBQRG4 equivalent, key selection criteria include configurable dual-rail operation, glitch-free power sequencing, VCC isolation behavior, ±32mA output drive at 5V, and SSOP-24 package compatibility with industrial temperature range (–40°C to +85°C).

Technical Context

The 74LVC8T245DBQRG4 implements asynchronous bidirectional data flow via DIR-controlled directionality and OE-gated 3-state outputs. Its input circuitry remains active regardless of OE state, requiring all A/B port pins to be held HIGH or LOW to prevent excess ICC/ICCZ. Control inputs (DIR, OE) are referenced solely to VCCA, decoupling logic thresholds from VCCB.

VCC isolation ensures all I/Os enter high-impedance when either VCCA or VCCB falls below 100mV or floats-critical for hot-swap and power-rail sequencing in multi-voltage systems. The device supports robust partial-power-down via Ioff, limiting leakage to ±2μA per pin when either supply is at 0V while the other remains active.

Key Specifications

Pinout & Package

74LVC8T245DBQRG4 uses a 24-pin SSOP (Shrink Small Outline Package) with 0.65mm pitch, body size 8.65mm × 6.0mm, and exposed thermal pad not present (DBQ variant). Pin 1 = VCCA; Pins 23–24 = VCCB; Pins 11–13 = GND; Pin 22 = OE (active-low, VCCA-referenced); Pin 2 = DIR (VCCA-referenced); A-port pins 3–10; B-port pins 14–21.

Key Features

Applications

Equivalent & Alternatives

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

Compared with SN74AVC8T245RHLR and TXS0108EJRVR, the 74LVC8T245DBQRG4 uniquely supports full 1.65V–5.5V dual-rail operation with ±32mA push-pull outputs and explicit DIR control - making it the only option among the three capable of robust 5V↔1.8V translation in industrial control backplanes.

Availability

74LVC8T245DBQRG4 is available at Aetrix Electronics and suitable for industrial PLC backplanes, embedded computing memory expansion, flat-panel display timing bridges, and network-attached storage SATA adapters requiring stable component supply across extended temperature and mixed-voltage conditions.

Supply support for 74LVC8T245DBQRG4 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 interface technologies.

The SN74LVC8T245 belongs to TI's LVC logic family, designed specifically for low-voltage, high-speed bidirectional bus interfacing in mixed-supply systems - emphasizing voltage translation flexibility, power sequencing resilience, and industrial reliability.

FAQ

What voltage ranges does the 74LVC8T245DBQRG4 support on its A and B ports?

The 74LVC8T245DBQRG4 supports 1.65V to 5.5V independently on both VCCA (A port) and VCCB (B port), enabling translation between any pair of standard logic voltages including 1.8V↔3.3V, 2.5V↔5V, and 3.3V↔5V. This full-range compatibility is confirmed in Section 5.3 of the TI SCES584D datasheet under Recommended Operating Conditions.

How does the VCC isolation feature work in the 74LVC8T245DBQRG4?

The 74LVC8T245DBQRG4 enters high-impedance on all I/Os when either VCCA or VCCB falls below 100mV or is left floating - even if the other supply remains active. This behavior is implemented in hardware and requires no external circuitry. It is explicitly documented in Section 7.3.5 and Table 7-1 of the TI datasheet as a core safety feature for multi-rail systems.

Can the 74LVC8T245DBQRG4 operate with different supply voltages on VCCA and VCCB simultaneously?

Yes - the 74LVC8T245DBQRG4 is expressly designed for asymmetric dual-supply operation. For example, VCCA can be set to 1.8V while VCCB is 5V, or VCCA = 3.3V and VCCB = 2.5V. This capability is foundational to its role as a voltage translator and is validated across all switching characteristics tables (Sections 5.7–5.10) in the TI datasheet.

What is the maximum output drive strength of the 74LVC8T245DBQRG4?

The 74LVC8T245DBQRG4 delivers ±32mA output current when powered at 5V (Section 5.3, IOH/IOL specifications), with reduced but still robust drive at lower voltages (e.g., ±24mA at 3V, ±8mA at 2.5V). This push-pull capability allows direct driving of multiple CMOS inputs or parallel outputs without external buffers.

Is the 74LVC8T245DBQRG4 compatible with partial-power-down modes?

Yes - the 74LVC8T245DBQRG4 incorporates Ioff circuitry that limits leakage current to ±2μA per pin when either VCCA or VCCB is at 0V (Section 5.6, Ioff specification). This prevents damaging backflow current into powered-down sections of the system, a requirement verified per JESD78 Class II latch-up testing.