Texas Instruments SN74HC377NG4

Overview

SN74HC377NG4 from Texas Instruments is a positive-edge-triggered octal D-type flip-flop with latched clock enable (CLKEN), operating across 2 V to 6 V. It features eight independent single-rail outputs, ±4-mA drive at 5 V, typical propagation delay of 12 ns, and low ICC of 80 µA max - used in synchronous data latching for industrial control registers and digital instrumentation buffers.

For engineers reviewing the SN74HC377NG4 datasheet, SN74HC377NG4 pinout, SN74HC377NG4 application, or SN74HC377NG4 equivalent, key selection criteria include clock-enable latching behavior, 20-pin PDIP package compatibility, 5-V logic-level timing margins, and absence of asynchronous clear - distinguishing it from SN74HC273-family devices.

Technical Context

The SN74HC377NG4 implements eight edge-triggered D flip-flops sharing one CLK input and one latched CLKEN control signal. Its CLKEN input is internally latched to prevent false triggering from noise or glitches on the enable line - unlike common-clear variants such as SN74HC273. Each Q output reflects the corresponding D input state sampled on the rising edge of CLK only when CLKEN is low.

It operates within standard HC logic voltage thresholds: VIH = 3.15 V (at VCC = 4.5 V), VIL = 1.35 V, and supports fan-out of up to 10 LSTTL loads. Input leakage is limited to 1 µA max, and power dissipation capacitance per flip-flop is 30 pF.

Key Specifications

Pinout & Package

SN74HC377NG4 is supplied in a 20-pin plastic dual in-line package (PDIP-N), with 25.40 mm × 6.35 mm body size and through-hole mounting. Pin 1 is marked by a notch or dot; pin numbering follows standard DIP convention (counterclockwise from top-left corner).

Key Features

Applications

Equivalent & Alternatives

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

Compared with SN74HC273N and SN74HCT377N, the SN74HC377NG4 uniquely provides noise-immune clock enable latching without altering pin compatibility - making it optimal for register control in electrically noisy industrial settings where false clocking must be avoided.

Availability

SN74HC377NG4 is available at Aetrix Electronics and suitable for industrial control registers, digital instrumentation buffers, pattern generator stages, and synchronous data acquisition systems requiring stable component supply across extended production lifecycles.

Supply support for SN74HC377NG4 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 U.S.-based semiconductor company specializing in analog, embedded processing, and logic solutions for industrial, automotive, and communications markets.

The SN74HC377NG4 belongs to TI's 74HC logic family, designed specifically for high-noise-margin, low-power, pin-compatible replacements of legacy TTL register functions in commercial and industrial control systems.

FAQ

What is the function of the CLKEN pin on the SN74HC377NG4?

The CLKEN pin on the SN74HC377NG4 is an active-low latched clock enable input. When CLKEN is high, the device ignores clock edges and holds Q outputs constant. When CLKEN is low, rising edges on CLK transfer D-input states to Q outputs. The latching prevents false triggering from transient noise on the enable line - a key distinction from non-latched enable or clear inputs found in similar devices like SN74HC273. This behavior is confirmed in the functional block diagram and timing diagrams of the official SN74HC377 datasheet.

Does the SN74HC377NG4 have an asynchronous reset capability?

No, the SN74HC377NG4 does not include an asynchronous reset (clear) input. Unlike SN74HC273, which features an active-low CLR̅ pin that forces all Q outputs low regardless of clock state, the SN74HC377NG4 relies solely on the latched CLKEN signal for gating clock activity. To reset outputs, the system must drive all D inputs low and apply a clock edge with CLKEN low - resulting in a synchronous reset. This architecture is explicitly documented in the device functional modes table and description section of the TI datasheet.

What is the maximum clock frequency supported by the SN74HC377NG4 at 5 V supply?

At VCC = 5 V, the SN74HC377NG4 supports a maximum clock frequency of 20 MHz under recommended operating conditions, as specified in the timing requirements table (Section 6.5). This limit derives from minimum pulse width (tW) and setup time (tsu) constraints - both 25 ns at 5 V - and is validated across the full commercial temperature range (–40 °C to +85 °C). The 20-MHz rating ensures timing margin compliance for reliable operation in real-world PCB layouts with typical trace parasitics.

Can the SN74HC377NG4 operate reliably at 3.3 V supply voltage?

Yes, the SN74HC377NG4 is fully specified to operate at 3.3 V supply voltage. Its recommended operating range spans 2 V to 6 V, and electrical characteristics including VOH (≥3.15 V), VOL (≤0.33 V), and tpd (≤34 ns) are guaranteed at VCC = 3.3 V per TI's characterization data. Input thresholds scale proportionally, ensuring compatibility with 3.3-V microcontroller GPIOs without level shifting. This capability is confirmed in Section 6.2 (Recommended Operating Conditions) and Section 6.4 (Electrical Characteristics) of the official datasheet.

Is the SN74HC377NG4 pin-compatible with other 20-pin 74HC-series octal flip-flops?

Yes, the SN74HC377NG4 shares identical 20-pin PDIP (N) package dimensions and pinout with SN74HC273N and SN74HCT377N, including matching assignments for D1–D8, Q1–Q8, CLK, CLKEN/CLR̅, VCC, and GND. However, functional differences exist: pin 10 serves as CLKEN (latched) in SN74HC377NG4 but as CLR̅ (asynchronous clear) in SN74HC273N. Direct substitution requires verification of enable/reset logic compatibility - the SN74HC377NG4 cannot be dropped in without modifying surrounding control circuitry.