Texas Instruments SN74ALVCH162721DLR

Overview

SN74ALVCH162721DLR from Texas Instruments is a 3.3-V, 20-bit edge-triggered D-type flip-flop with 3-state outputs, bus-hold inputs, and integrated 26-Ω output series resistors. It operates from 1.65 V to 3.6 V, supports up to 150 MHz clock frequency, and is rated for -40°C to 85°C. It serves as a high-density data latch and bus interface in low-voltage memory address/data buffering systems.

For engineers reviewing the SN74ALVCH162721DLR datasheet, SN74ALVCH162721DLR pinout, SN74ALVCH162721DLR application, or SN74ALVCH162721DLR equivalent, key selection criteria include its 20-bit parallel register function, clock-enable control logic, OE-gated 3-state output drive capability, bus-hold input retention, and DL-package thermal impedance of 74°C/W.

Technical Context

This device implements 20 independent D-type flip-flops sharing a common clock (CLK) and clock-enable (CLKEN) input, where data is latched on the positive CLK edge only when CLKEN = L. The buffered output-enable (OE) controls all 20 Q outputs simultaneously, placing them in high-impedance state without affecting internal storage.

Each input features active bus-hold circuitry eliminating external pullup/pulldown resistors; each output integrates a 26-Ω series resistor to suppress overshoot/undershoot and enable direct bus driving without interface components. All I/Os are 3.3-V tolerant with VIH/VIL thresholds scaled to VCC (e.g., VIH = 2.0 V at VCC = 3.0 V).

Key Specifications

Pinout & Package

SN74ALVCH162721DLR uses a 56-pin Shrink Small-Outline Package (SSOP), DL variant, with 300-mil body width, 0.5-mm lead pitch, and 74°C/W junction-to-ambient thermal resistance.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar 20-bit latch/register applications.

Compared with SN74ALVCH162721DLR, SN74ALVCH162244DLR omits clocked storage entirely, while SN74LVC16374DLR trades bus-hold and integrated damping for broader voltage support and higher drive - making SN74ALVCH162721DLR optimal for noise-sensitive, space-constrained 3.3-V industrial bus interfaces requiring zero-external-component reliability.

Availability

SN74ALVCH162721DLR is available at Aetrix Electronics and suitable for industrial automation, test equipment, and FPGA-based embedded systems requiring stable component supply, long-lifecycle assurance, and RoHS-compliant packaging.

Supply support for SN74ALVCH162721DLR 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 specializing in analog, embedded processing, and logic solutions for industrial, automotive, and communications markets.

The SN74ALVCH162721DLR belongs to TI's Widebus™ family of high-density logic devices, engineered specifically for low-voltage, high-speed parallel data path management in memory and interconnect subsystems.

FAQ

What is the recommended power-up sequence for SN74ALVCH162721DLR?

TI specifies that OE should be tied to VCC through a pullup resistor during power-up to guarantee outputs remain in high-impedance state until system initialization completes. For SN74ALVCH162721DLR, minimum pullup resistance is determined by the driver's current-sinking capability - typically 4.7 kΩ suffices for most 3.3-V microcontroller GPIOs. This prevents bus contention before firmware configures CLKEN and OE states.

Does SN74ALVCH162721DLR support mixed-voltage operation between D inputs and Q outputs?

Yes. SN74ALVCH162721DLR supports mixed-voltage operation: D inputs accept 1.65 V–3.6 V logic levels, and Q outputs swing rail-to-rail within the same VCC range. Input thresholds scale with VCC (e.g., VIH = 2.0 V at VCC = 3.0 V), enabling interoperability with 1.8-V or 2.5-V sources while driving 3.3-V loads - no level shifters needed when VCC = 3.3 V.

How does the bus-hold circuitry in SN74ALVCH162721DLR function during power-down?

The bus-hold circuitry in SN74ALVCH162721DLR remains active down to VCC ≈ 0.5 V, retaining the last-valid logic state on floating D inputs during gradual power-down. This prevents undefined transitions and metastability in downstream logic. TI confirms bus-hold current remains within ±75 µA at VCC = 3 V, ensuring reliable hold without excessive leakage or latch-up risk in SN74ALVCH162721DLR.

Can SN74ALVCH162721DLR be used in place of SN74ALVCH162722DLR?

No. SN74ALVCH162721DLR and SN74ALVCH162722DLR differ fundamentally: the former is a 20-bit D-type flip-flop with common CLK/CLKEN/OE, while the latter is a 20-bit transparent latch with G (gate) control. Their timing models, pinouts, and functional behavior are incompatible - substituting SN74ALVCH162721DLR for SN74ALVCH162722DLR would break edge-triggered vs. level-sensitive operation and cause data corruption.

What is the maximum capacitive load SN74ALVCH162721DLR can drive while maintaining 150-MHz operation?

TI characterizes SN74ALVCH162721DLR for 150-MHz operation with CL = 30 pF (per Figure 1–3). At 3.3 V, it maintains tpd ≤ 6.7 ns and timing margins (tsu/th) under this load. Driving >50 pF increases propagation delay nonlinearly and risks violating setup/hold windows - for heavier loads, derate clock frequency or add series damping. The integrated 26-Ω resistor optimizes performance specifically for ≤30-pF routing.