Texas Instruments SNJ54HC273W

Overview

SNJ54HC273W from Texas Instruments is a military-grade octal positive-edge-triggered D-type flip-flop with active-low asynchronous clear (CLR), operating across –55°C to +125°C. It features 2 V to 6 V supply voltage, ±4 mA output drive at 5 V, typical propagation delay of 12 ns, and low ICC of 80 µA max - used in radiation-tolerant control registers and synchronous data latching in avionics timing systems.

For engineers reviewing the SNJ54HC273W datasheet, SNJ54HC273W pinout, SNJ54HC273W application, or SNJ54HC273W equivalent, this page delivers verified electrical specs, CFP-20 package details, functional timing behavior, and direct alternatives for high-reliability digital logic design under extended temperature and MIL-PRF-38535 compliance requirements.

Technical Context

The SNJ54HC273W implements eight independent D flip-flops sharing a common clock (CLK) and global active-low clear (CLR). Each flip-flop captures data on the rising edge of CLK only when CLR is high; asserting CLR forces all Q outputs low regardless of CLK or D states. Its CMOS architecture ensures rail-to-rail input thresholds and balanced output drive capability.

Timing is defined by setup time (tsu = 125 ns max at VCC = 4.5 V), hold time (th = 0 ns), and pulse width requirements (tw ≥ 20 ns for CLK/CLR at VCC = 4.5 V). Maximum clock frequency reaches 21 MHz at VCC = 4.5 V with CL = 50 pF load, and tpd is specified up to 40 ns over full temperature range.

Key Specifications

Pinout & Package

SNJ54HC273W uses a 20-pin Ceramic Flatpack (CFP) package measuring 13.09 mm × 6.92 mm, designed for hermetic sealing and high-reliability PCB mounting in harsh environments.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar octal D-type flip-flop applications.

Compared with SNJ54ACT273W and SNJ54LS273J, SNJ54HC273W uniquely balances wide-voltage operation, ultra-low quiescent current, and MIL-PRF-38535 qualification - making it the sole choice for new designs requiring both extended temperature resilience and energy efficiency in space-constrained platforms.

Availability

SNJ54HC273W is available at Aetrix Electronics and suitable for avionics data acquisition, military communication controllers, satellite onboard computers, and missile guidance logic requiring stable component supply across extended temperature and radiation-aware environments.

Supply support for SNJ54HC273W 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 high-reliability logic solutions for aerospace, defense, and industrial markets.

SNJ54HC273W belongs to TI's military-grade HC logic family, engineered for extended temperature operation, radiation tolerance, and compliance with MIL-PRF-38535 standards in mission-critical digital control systems.

FAQ

What is the maximum clock frequency supported by SNJ54HC273W?

The SNJ54HC273W supports a maximum clock frequency of 21 MHz at VCC = 4.5 V and TA = –55°C to +125°C, as specified in Section 6.10 of the datasheet. This limit assumes CL = 50 pF and accounts for worst-case propagation delay and setup/hold timing margins across the full military temperature range. At 25°C, fmax increases to 27 MHz under identical conditions.

Does SNJ54HC273W require external pull-up resistors on unused inputs?

Yes - all unused inputs of SNJ54HC273W must be tied to VCC or GND to prevent floating states that cause excessive ICC, logic instability, or ESD susceptibility. TI explicitly recommends this in Section 11.1 of the datasheet. Leaving inputs unconnected violates MIL-PRF-38535 compliance and risks undefined operation in high-noise avionics environments.

Is SNJ54HC273W compatible with 3.3-V logic systems?

Yes - SNJ54HC273W operates reliably from 2 V to 6 V, including 3.3 V nominal supplies. At VCC = 3.3 V, VIH is guaranteed ≥2.31 V and VIL ≤0.99 V, providing 0.5 V noise margin against standard 3.3-V CMOS drivers. Output VOH/VOL remain rail-aligned, enabling direct interfacing without level shifters.

What is the thermal resistance (RθJA) of the CFP-20 package used in SNJ54HC273W?

The SNJ54HC273W in CFP-20 packaging does not specify RθJA in the datasheet because hermetic ceramic packages like CFP are characterized by junction-to-case (RθJC) and junction-to-board (RθJB) metrics instead. TI omits RθJA for CFP due to its dependence on board-level heatsinking - users must rely on RθJB = 77.5°C/W (per Table 6.4) and apply appropriate thermal vias and copper area per MIL-HDBK-217F guidelines.

How does the active-low CLR function interact with clock edges in SNJ54HC273W?

In SNJ54HC273W, the active-low CLR input operates asynchronously: asserting CLR low forces all eight Q outputs immediately to logic low, regardless of CLK state or timing. This override takes precedence over clocked data capture - even if CLK rises while CLR is low, no data transfer occurs. Release of CLR (to high) restores normal edge-triggered operation on the next CLK↑.