Diodes Incorporated PI74LVC4245ALEX

Overview

PI74LVC4245ALEX from Pericom Semiconductor is an 8-bit non-inverting dual-supply bidirectional bus transceiver with 3-state outputs, enabling asynchronous level translation between 5V (A-port) and 3.3V (B-port) buses. It features independent VCCA (4.5–5.5V) and VCCB (2.7–3.6V) rails, DIR-controlled data direction, active-low OE for high-impedance isolation, and operates across –40°C to +85°C.

For engineers reviewing the PI74LVC4245ALEX datasheet, PI74LVC4245ALEX pinout, PI74LVC4245ALEX application, or PI74LVC4245ALEX equivalent, key selection criteria include dual-rail voltage tolerance, propagation delay (≤6.1 ns), 3-state output control timing, and industrial temperature compliance in TSSOP-24 packaging.

Technical Context

The PI74LVC4245ALEX implements a true bidirectional translation architecture using separate A- and B-port I/O structures, each referenced to its own supply rail. Direction control is managed solely by the DIR input, while OE independently places both ports into high-impedance state regardless of DIR state.

It supports simultaneous 5V ↔ 3.3V translation without external biasing or pull-ups. Propagation delays are asymmetric: A→B tPHL/tPLH ≤5.7 ns, B→A tPHL/tPLH ≤6.1 ns (CL = 50 pF, VCCA = 5V, VCCB = 3.3V), and enable/disable times (tPZL/tPLZ ≤8 ns) ensure clean bus arbitration during state transitions.

Key Specifications

Pinout & Package

PI74LVC4245ALEX is packaged in a Pb-free, green 24-pin TSSOP (173-mil width, JEDEC MO-153), with 0.65 mm lead pitch and exposed thermal pad (not electrically connected). Pin numbering follows standard TSSOP convention: Pin 1 (top-left corner, dot-marked) is OE; pins 2–9 and 16–23 are bidirectional I/O; pins 10/11 (GND), 12 (DIR), 24 (VCCA), and 15 (VCCB).

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar bidirectional level translation applications.

Compared with SN74LVC4245APWR and 74AVCH4245BQX, the PI74LVC4245ALEX delivers tighter propagation delay control (≤6.1 ns), verified industrial latch-up immunity (>200 mA), and optimized drive strength for 3.3V bus loading - making it the preferred choice for deterministic timing and robustness in harsh industrial settings.

Availability

PI74LVC4245ALEX is available at Aetrix Electronics and suitable for industrial PLC backplane interfaces, automotive body control modules, test equipment digital I/O subsystems, and programmable logic controller I/O expansion requiring stable component supply and long-term lifecycle support.

Supply support for PI74LVC4245ALEX 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

Pericom Semiconductor (acquired by Diodes Incorporated in 2016) specialized in high-speed interface, timing, and signal integrity solutions for communications, computing, and industrial markets.

The PI74LVC4245ALEX belongs to Pericom's LVC-level translation transceiver product line, engineered specifically for reliable, low-latency bidirectional voltage translation in mixed-supply embedded systems with stringent industrial reliability requirements.

FAQ

What are the power sequencing requirements for PI74LVC4245ALEX?

Pericom specifies strict power-up order: connect GND first, then ramp VCCA (control side) ahead of or concurrently with VCCB, and assert OE before DIR transitions. Violating this sequence risks bus contention or excessive supply current due to undefined I/O states during rail ramping.

Can PI74LVC4245ALEX translate between 5V and 1.8V logic levels?

No. The B-port is rated only for 2.7V to 3.6V operation. Applying 1.8V to VCCB violates the recommended operating conditions and may cause incorrect logic thresholds, increased leakage, or permanent damage. For 1.8V interfaces, use SN74LVC4245APWR or similar wider-range alternatives.

Is the PI74LVC4245ALEX pin-compatible with other 24-pin TSSOP bus transceivers?

Yes - it matches standard 24-pin TSSOP mechanical dimensions and pinout (JEDEC MO-153), including identical placement of VCCA, VCCB, GND, OE, DIR, and bidirectional I/Os. However, electrical behavior (e.g., drive strength, timing, supply ranges) differs from non-LVC families like ABT or ALVC, so functional substitution requires validation.

Does PI74LVC4245ALEX require external pull-up or pull-down resistors on DIR or OE?

Yes. Neither DIR nor OE has internal biasing. OE must be pulled HIGH via external resistor (e.g., 10 kΩ to VCCA) to maintain high-impedance state during power-up; DIR requires explicit logic-level control or pull-up/down to define initial data direction, as floating inputs risk metastability and excessive current draw.