Texas Instruments SN74AHC74D

Overview

SN74AHC74D from Texas Instruments is a dual positive-edge-triggered D-type flip-flop with independent preset (PRE) and clear (CLR) inputs, operating across 2 V to 5.5 V supply range, supporting clock frequencies up to 110 MHz at 5 V, and delivering ±8 mA output drive. It implements synchronous data latching on rising clock edges and asynchronous set/reset functionality-used in digital logic control, clock division, and signal debouncing circuits.

For engineers reviewing the SN74AHC74D datasheet, SN74AHC74D pinout, SN74AHC74D application, or SN74AHC74D equivalent, this page delivers verified functional identity, SOIC-14 package mapping, timing parameters (t_su = 5 ns, t_PLH = 4.6 ns @ 5 V), ESD ratings (±2000 V HBM), and two validated alternative parts for design continuity.

Technical Context

The SN74AHC74D integrates two independent D-type flip-flop channels, each with active-low asynchronous PRE and CLR inputs that override clock and data states. Clock triggering occurs at a defined voltage threshold-not dependent on edge slew rate-ensuring robust operation with slow or noisy clock signals.

Each channel supports full CMOS input thresholds (VIH = 3.85 V, VIL = 1.65 V @ VCC = 5.5 V), exhibits low dynamic power dissipation (Cpd = 32 pF), and maintains stable output levels under capacitive loads ≤50 pF. The device complies with JESD 17 latch-up (>250 mA) and JESD 22 ESD standards.

Key Specifications

Pinout & Package

SN74AHC74D is housed in a 14-pin SOIC (Small Outline Integrated Circuit) package with 1.27 mm pitch, 8.65 mm × 3.91 mm body size, and gull-wing leads suitable for reflow soldering. Thermal resistance R_θJA = 124.5 °C/W enables operation at full speed without forced airflow in typical PCB layouts.

Key Features

Applications

Equivalent & Alternatives

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

Compared with SN74AHC74D, SN74AHC74DBR offers lower thermal resistance for sustained high-frequency operation, while SN74AHC74DGVR reduces board area by 42%-both retain identical functional behavior, timing, and voltage specifications, enabling drop-in substitution with only mechanical layout adjustment.

Availability

SN74AHC74D is available at Aetrix Electronics and suitable for industrial motor control, automotive body electronics, and IoT sensor interface designs requiring stable component supply and long-term obsolescence management.

Supply support for SN74AHC74D 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 and embedded processing technologies, with over 90 years of innovation in precision logic, power management, and signal chain solutions.

The SN74AHC74D belongs to TI's AHC (Advanced High-Speed CMOS) logic family, engineered for low-power, high-noise-immunity digital interfacing in automotive, industrial, and communications systems.

FAQ

What is the maximum clock frequency supported by SN74AHC74D at 3.3 V?

At VCC = 3.3 V ± 0.3 V, the SN74AHC74D supports a maximum clock frequency of 70 MHz with CL = 15 pF and 45 MHz with CL = 50 pF, per TI's SCLS255N datasheet Section 5.8. These values reflect guaranteed timing performance across –40 °C to +125 °C, making SN74AHC74D suitable for mid-speed control logic in 3.3 V systems without derating.

Does SN74AHC74D require external pull-up resistors on PRE and CLR inputs?

No-SN74AHC74D does not require external pull-ups on PRE or CLR if those functions are unused. Per TI's datasheet Section 8.2.1, all unused inputs must be terminated to VCC or GND; tying PRE/CLR to VCC disables them actively. Pull-up resistors are only needed if the inputs may float during power-up or partial configuration, and 10 kΩ is recommended for stability and leakage mitigation.

Can SN74AHC74D drive a 50-pF capacitive load reliably?

Yes-SN74AHC74D is fully characterized to drive up to 50 pF while meeting all timing and voltage specifications (Section 5.8–5.9). At 5 V, propagation delays remain within 8.5 ns and f_MAX stays at 75 MHz even at CL = 50 pF. Exceeding 50 pF increases delay and jitter but does not damage the device; TI recommends limiting load capacitance to maintain spec compliance.

Is SN74AHC74D pin-compatible with older 74HC74 variants?

Yes-SN74AHC74D uses the same 14-pin SOIC footprint and identical pinout as industry-standard 74HC74 and 74LS74 devices. Signal assignments (CLK, D, PRE, CLR, Q, Q̅) match exactly, enabling direct replacement in legacy designs. However, AHC logic has higher speed, lower power, and different input thresholds-verify VIH/VIL compatibility with driving sources before substitution.

What is the purpose of the exposed thermal pad in SN74AHC74D?

SN74AHC74D does not have an exposed thermal pad-it uses a standard SOIC-14 package without thermal enhancement. Devices like SN74AHC74BQA (WQFN) or SN74AHC74RGY (VQFN) include exposed pads for improved heat dissipation, but SN74AHC74D relies on its leadframe and PCB copper for thermal transfer. Its R_θJA = 124.5 °C/W reflects this conventional construction.