Texas Instruments SN74LVC821ADBRG4

Overview

SN74LVC821ADBRG4 from Texas Instruments is a 10-bit bus-interface D-type flip-flop with 3-state outputs, designed for 1.65 V to 3.6 V operation. It features edge-triggered clocking on the positive CLK transition, buffered OE control for high-impedance output management, and supports mixed-mode signal operation (5-V-tolerant inputs with 3.3-V VCC). It is used in I/O port expansion and bidirectional bus buffering in industrial control and embedded communication interfaces.

For engineers reviewing the SN74LVC821ADBRG4 datasheet, SN74LVC821ADBRG4 pinout, SN74LVC821ADBRG4 application, or SN74LVC821ADBRG4 equivalent, key selection criteria include its 10-bit synchronous latch function, 3.3-V supply compatibility, 5.5-V input tolerance, 7.3 ns max propagation delay at 3.3 V, and SSOP-24 package footprint for space-constrained PCB layouts.

Technical Context

This device implements ten independent edge-triggered D-type flip-flops sharing a common clock (CLK) and output-enable (OE) control. Each flip-flop captures data on the rising edge of CLK and presents true logic at Q outputs, while OE independently places all ten outputs into high-impedance without affecting internal storage.

It incorporates Ioff partial-power-down protection to prevent backflow current when VCC = 0 V, and supports mixed-voltage interfacing via 5.5-V-tolerant inputs - enabling direct connection to legacy 5-V logic while operating from a 3.3-V rail. The design targets low-noise, high-drive bus interface applications requiring precise timing control and bus isolation.

Key Specifications

Pinout & Package

SN74LVC821ADBRG4 is housed in a 24-pin SSOP (Shrink Small Outline Package), DB package type, with 0.65 mm lead pitch and 7.5 mm × 5.6 mm body dimensions. The package is RoHS-compliant, moisture-sensitivity Level-1 rated, and optimized for surface-mount reflow assembly.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar 10-bit bus-interface flip-flop applications.

Compared with SN74LVC821APWR, SN74LVC821ADBRG4 offers lower thermal resistance and smaller footprint in SSOP, while SN74LVCH162374ADGGR adds bus-hold and 16-bit width at the cost of layout complexity - making SN74LVC821ADBRG4 optimal for compact, thermally stable 10-bit bus extension.

Availability

SN74LVC821ADBRG4 is available at Aetrix Electronics and suitable for industrial PLC I/O expansion, embedded microcontroller bus interface, and automotive body control modules requiring stable component supply, long-term lifecycle assurance, and RoHS-compliant sourcing.

Supply support for SN74LVC821ADBRG4 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 connectivity technologies, with decades of experience in industrial, automotive, and communications IC design.

The SN74LVC821A family was developed to deliver high-speed, low-voltage bus interface solutions with robust mixed-signal interoperability - specifically targeting cost-sensitive, space-constrained applications needing reliable 10-bit data latching and 3-state isolation.

FAQ

What is the maximum clock frequency supported by SN74LVC821ADBRG4?

The SN74LVC821ADBRG4 supports a maximum clock frequency of 150 MHz under recommended operating conditions (VCC = 3.3 V, TA = 25°C). This value is derived from the minimum pulse width requirement (tw ≥ 3.3 ns) and confirmed in the Switching Characteristics table of the official TI datasheet SCAS304J. At lower VCC voltages, the achievable frequency decreases due to increased propagation delay.

Does SN74LVC821ADBRG4 support 5-V input signals while operating at 3.3-V VCC?

Yes, SN74LVC821ADBRG4 supports 5-V-tolerant inputs - its VI rating extends to 5.5 V regardless of VCC level. This allows direct connection to 5-V logic families (e.g., TTL, 74HC) while powered from a 3.3-V rail, eliminating external level-shifting components. Input thresholds scale with VCC, ensuring correct logic interpretation across the full 1.65–3.6 V supply range.

What is the purpose of the Ioff feature in SN74LVC821ADBRG4?

The Ioff feature in SN74LVC821ADBRG4 disables output drivers when VCC = 0 V, limiting off-state current to <±10 µA. This prevents damaging back-current flow from live bus lines into a powered-down device - a critical requirement for hot-swap, partial-power-down, and multi-rail system architectures. Ioff is automatically active and requires no external control.

Can SN74LVC821ADBRG4 drive a 50-pF capacitive load reliably?

Yes, SN74LVC821ADBRG4 is characterized to drive 50-pF loads with guaranteed timing performance: tpd ≤ 7.3 ns and tdis ≤ 6.2 ns at VCC = 3.3 V. Its ±24 mA output drive strength ensures fast edge rates and minimal distortion even under heavy capacitive loading, making it suitable for driving long traces, multiple inputs, or unterminated stubs in parallel bus topologies.

Is SN74LVC821ADBRG4 pin-compatible with other members of the SN74LVC821A family?

Yes, SN74LVC821ADBRG4 shares identical pinout and functionality with all SN74LVC821A variants (e.g., SN74LVC821ADW, SN74LVC821APWR), differing only in package type (SSOP-24 vs. SOIC-24 vs. TSSOP-24). All variants use the same DB/DW/PW/DGV pin mapping, allowing drop-in replacement across packages when mechanical constraints permit.