Texas Instruments SN74AHC74NSR

Overview

SN74AHC74NSR from Texas Instruments is a dual positive-edge-triggered D-type flip-flop with independent asynchronous clear (CLR) and preset (PRE) inputs, operating across 2 V to 5.5 V supply range, supporting clock frequencies up to 110 MHz at 5 V, with 4 mA output drive capability and ±2000 V HBM ESD rating - used in digital logic state retention, clock division, and switch debouncing circuits.

For engineers reviewing the SN74AHC74NSR datasheet, SN74AHC74NSR pinout, SN74AHC74NSR application, or SN74AHC74NSR equivalent, key selection considerations include its 14-pin SO (NS) package, dual-channel edge-triggered behavior, asynchronous control inputs, guaranteed setup/hold timing (5 ns min pulse width at 5 V), and compatibility with mixed-voltage 3.3 V/5 V systems.

Technical Context

The SN74AHC74NSR implements two independent D-type flip-flops sharing no internal coupling; each channel features separate CLK, D, PRE, CLR, Q, and Q̅ terminals. Triggering occurs on the rising edge of CLK only when both PRE and CLR are high; low assertion on either PRE or CLR forces immediate Q/Q̅ output states regardless of CLK or D.

Its CMOS AHC-family design ensures rail-to-rail output swing, low static current (≤20 µA at 5.5 V), and input thresholds scaled to VCC (VIH = 0.7×VCC, VIL = 0.3×VCC), enabling robust noise immunity in industrial environments where slow or noisy edges may be present on control lines.

Key Specifications

Pinout & Package

SN74AHC74NSR uses a 14-pin SO (Small Outline) package (NS), 5.3 mm × 10.2 mm body, 1.27 mm pitch, with gull-wing leads and exposed pad not present. Pin 1 is marked by notch or dot; device orientation follows JEDEC MS-012.

Key Features

Applications

Equivalent & Alternatives

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

Compared with SN74LVC74APWR and MC74HC74ADTR2G, the SN74AHC74NSR delivers optimal balance of speed (110 MHz), noise immunity (VCC-scaled thresholds), and wide supply flexibility (2–5.5 V), making it the preferred choice for new designs requiring robust 5 V operation and moderate frequency performance.

Availability

SN74AHC74NSR is available at Aetrix Electronics and suitable for industrial automation, automotive body electronics, and consumer appliance control systems requiring stable component supply across extended temperature ranges and multi-year production cycles.

Supply support for SN74AHC74NSR 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 delivering analog, embedded processing, and logic solutions for industrial, automotive, and communications markets.

The SN74AHC74NSR belongs to TI's advanced high-speed CMOS (AHC) logic family, engineered for low-power, high-noise-immunity digital interfacing and state retention in harsh electromagnetic environments.

FAQ

What is the maximum clock frequency supported by the SN74AHC74NSR?

The SN74AHC74NSR supports a maximum clock frequency of 110 MHz when operated at VCC = 5 V with a 15 pF load. At 3.3 V, the maximum frequency drops to 70 MHz. These values are specified under recommended operating conditions and assume proper layout, decoupling, and signal integrity - exceeding them risks setup/hold violations or metastability.

Does the SN74AHC74NSR require external pull-up or pull-down resistors on unused inputs?

Yes, all unused inputs of the SN74AHC74NSR must be terminated to either VCC or GND to prevent floating states that cause increased power consumption, oscillation, or undefined outputs. TI recommends 10-kΩ resistors for default HIGH (pull-up) or LOW (pull-down) biasing - especially critical for PRE, CLR, and CLK lines in noise-prone environments.

Can the SN74AHC74NSR operate reliably at 2.0 V supply voltage?

Yes, the SN74AHC74NSR is fully specified down to 2.0 V supply voltage, with guaranteed functionality including 5 ns minimum clock pulse width, 5 ns setup time, and 4 mA output drive at 2 V. However, propagation delay increases significantly (tPLH/tPHL ≈ 14 ns typical), and noise margins shrink - verify timing closure in 2 V designs using worst-case data from Section 5.6–5.9 of the datasheet.

Is the SN74AHC74NSR pin-compatible with older 74HC74 or 74LS74 devices?

No, the SN74AHC74NSR is not pin-compatible with 74LS74 (which uses different pin assignments for PRE/CLR) and differs electrically from 74HC74 despite identical 14-pin SO packaging - AHC offers faster speed, lower power, and VCC-scaled input thresholds. Direct replacement requires validation of timing, drive strength, and voltage translation in the target system.

What thermal considerations apply to the SN74AHC74NSR in continuous operation?

The SN74AHC74NSR in NS (SO) package has a junction-to-ambient thermal resistance (RθJA) of 76 °C/W. At 125 °C max ambient and 5 V supply, total power dissipation must remain below ~165 mW to keep junction temperature ≤150 °C. With typical Cpd = 32 pF and f = 10 MHz, dynamic power is ~1.6 mW - thermal derating is rarely needed unless driving heavy capacitive loads or operating in sealed enclosures above 85 °C.