onsemi 74LCX16646MTDX

Overview

74LCX16646MTDX from ON Semiconductor is a low-voltage 16-bit registered transceiver with 5V-tolerant I/O, designed for bidirectional data multiplexing between 2.5V/3.3V buses and 5V signal environments. It features dual register storage (A and B), real-time transparent mode, 3-STATE outputs, and ±24 mA drive at VCC = 3.0V - used in high-density memory expansion and mixed-voltage backplane interfaces.

For engineers reviewing the 74LCX16646MTDX datasheet, pinout, applications, or equivalent options, key selection criteria include 5V tolerance on all I/Os, sub-6 ns propagation delay at 3.3V, register-selectable bus management, live-insertion support, and TSSOP-56 packaging for space-constrained PCB layouts.

Technical Context

The 74LCX16646MTDX implements two independent 8-bit register banks (A and B) with separate DIR, OE, CPAB/CPBA, and SAB/SBA controls per byte - enabling four distinct bus operations: real-time A↔B transfer, A-register-to-B output, B-register-to-A output, and simultaneous clock-and-forward. Its logic supports concurrent input capture and output driving without bus contention.

It operates across 2.3V–3.6V VCC with guaranteed DC specs up to 5.5V I/O voltage, uses advanced CMOS for low power (20 µA ICC max), and integrates patented noise/EMI reduction circuitry. Latch-up immunity exceeds 500 mA, and ESD robustness meets >2000V HBM.

Key Specifications

Pinout & Package

74LCX16646MTDX is housed in a 56-lead Thin Shrink Small Outline Package (TSSOP), JEDEC MO-153 compliant, 6.1 mm wide, with 0.5 mm lead pitch and exposed thermal pad (non-electrical). Pin count and physical layout match MTD56 package standard.

Key Features

Applications

Equivalent & Alternatives

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

Compared with SN74LVC16646ADGGR and 74ALVC16646PAG, the 74LCX16646MTDX delivers superior power efficiency (20 µA ICC), proven EMI resilience, and certified live-insertion capability - making it optimal for high-reliability, thermally constrained, or electrically noisy environments.

Availability

74LCX16646MTDX is available at Aetrix Electronics and suitable for memory expansion interfaces, industrial backplane bridges, test equipment signal routing, and communications protocol converters requiring stable component supply and long-term manufacturability.

Supply support for 74LCX16646MTDX 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

ON Semiconductor is a global semiconductor manufacturer specializing in energy-efficient power, analog, sensor, and logic solutions for automotive, industrial, cloud, and consumer applications.

The 74LCX logic family was developed to deliver high-speed, low-voltage operation with 5V-tolerant I/O - targeting mixed-supply system interconnects in networking, computing, and factory automation.

FAQ

What is the maximum clock frequency supported by the 74LCX16646MTDX?

The 74LCX16646MTDX supports a maximum clock frequency of 170 MHz under typical conditions (VCC = 3.3V, CL = 50 pF), derived from its 5.2 ns maximum propagation delay in bus-to-bus mode. This timing is validated across −40°C to +85°C and applies to both real-time and register-clock paths. The 74LCX16646MTDX does not specify a dedicated clock input frequency limit - instead, timing compliance depends on setup/hold (tS = 2.5 ns, tH = 1.5 ns) and pulse width (tW = 3.0 ns) constraints relative to CPAB/CPBA edges.

Does the 74LCX16646MTDX require external pull-up resistors on OE pins for proper power-up behavior?

Yes - to ensure high-impedance outputs during power-up or power-down, OE pins must be tied to VCC through a pull-up resistor. The minimum resistance value depends on the driver's current-sourcing capability, as specified in Note 1 of the Fairchild datasheet. This requirement applies to all 74LCX16646MTDX units regardless of operating voltage (2.3V–3.6V), and omission risks bus contention or unintended data latching during supply ramp.

Can the 74LCX16646MTDX operate reliably with a 2.5V supply voltage?

Yes - the 74LCX16646MTDX is fully specified down to 2.3V VCC, including AC parameters (tPD ≤ 6.2 ns, fMAX ≥ 160 MHz) and DC characteristics (VIH = 1.7V min, VOL = 0.6V max at IOL = 8 mA). At 2.5V, it maintains 5V-tolerant I/O, ±8 mA output drive, and 20 µA quiescent current. All functionality - including register loading, direction control, and 3-STATE enable - remains guaranteed per datasheet limits.

How does the 74LCX16646MTDX handle simultaneous data capture and output driving?

The 74LCX16646MTDX allows concurrent input capture and output driving because its input receivers remain active even when outputs are disabled (OE = HIGH). Data at A/B pins is latched on every LOW-to-HIGH CPAB/CPBA transition regardless of OE state. This enables seamless pipeline operation - e.g., capturing new data into the A register while broadcasting previously stored data from the B register - without bus contention or timing dead zones in the 74LCX16646MTDX.

Is the 74LCX16646MTDX pin-compatible with other 56-pin TSSOP transceivers like the 74LVC16646?

No - although the 74LCX16646MTDX and 74LVC16646 share the same TSSOP-56 package outline and pin count, their pin functions differ: 74LCX16646MTDX uses CPAB/CPBA and SAB/SBA for register control, while 74LVC16646 uses CLKAB/CLKBA and GAB/GBA with different truth table behavior. Direct substitution would cause functional failure. Always verify signal mapping and timing diagrams before replacement - the 74LCX16646MTDX requires explicit support for its dual-register select architecture.