Texas Instruments SN74HCS72DR

Overview

SN74HCS72DR from Texas Instruments is a dual D-type negative-edge-triggered flip-flop with Schmitt-trigger inputs, asynchronous clear and preset, and CMOS push-pull outputs. It operates from 2 V to 6 V, delivers ±7.8-mA output drive at 5 V, and features typical supply current of 100 nA - enabling reliable toggle switching and noise-immune wake-up control in automotive CAN standby circuits.

For engineers reviewing the SN74HCS72DR datasheet, SN74HCS72DR pinout, SN74HCS72DR application, or SN74HCS72DR equivalent, key selection criteria include its hysteresis-enabled slow-input tolerance (ΔVT = 0.6–1.6 V), –40°C to +125°C operation, dual-channel independent timing, and SOIC-14 package compatibility with industrial and automotive power-enable designs.

Technical Context

This device implements two independent, fully asynchronous D-type flip-flops, each with Schmitt-trigger inputs providing hysteresis (ΔVT up to 1.6 V at 6 V) to reject noise and support unlimited input edge rates. The PRE and CLR inputs are active-low and override clock/data behavior regardless of CLK state.

Each channel responds only on the falling edge of CLK; data at D is latched into Q/Q when setup (tsu ≥ 3 ns at 6 V) and hold (th ≥ 2 ns at 6 V) times are met. Output drive strength (±7.8 mA at 6 V) and low ICC (≤2 µA max) enable direct interfacing with CAN transceiver enable inputs while maintaining sub-µA system standby current.

Key Specifications

Pinout & Package

SN74HCS72DR is housed in a 14-pin SOIC (D) package measuring 8.70 mm × 3.90 mm, with standard JEDEC MS-012AC footprint and Level-1 moisture sensitivity rating (260°C peak reflow).

Key Features

Applications

Equivalent & Alternatives

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

Compared with SN74HCS72PWR, SN74HCS72DR offers identical logic behavior but larger SOIC-14 footprint for easier hand-soldering and thermal dissipation; compared with SN74LV72A, it adds essential hysteresis and lower ICC for noise-prone, ultra-low-power applications - making SN74HCS72DR the only choice for automotive wake-up and industrial sensor conditioning.

Availability

SN74HCS72DR is available at Aetrix Electronics and suitable for automotive CAN subsystems, industrial sensor interfaces, momentary switch debouncing, and low-power state machine control requiring stable component supply across extended temperature ranges.

Supply support for SN74HCS72DR 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 personal electronics markets.

SN74HCS72DR belongs to the HCS family of high-speed CMOS logic devices designed specifically for noise-immune, low-power operation in harsh environments - emphasizing Schmitt-trigger robustness, wide VCC range, and extended temperature qualification.

FAQ

What is the maximum clock frequency supported by SN74HCS72DR?

The SN74HCS72DR supports a maximum clock frequency of 105 MHz at VCC = 6 V, 95 MHz at 4.5 V, and 31 MHz at 2 V. These values are guaranteed across the full operating temperature range (–40°C to +125°C) and measured with CL = 50 pF load. At 5 V operation, typical fmax is ~100 MHz, enabling use in high-speed control logic where precise edge-triggered timing is required. The SN74HCS72DR's performance scales predictably with supply voltage due to its CMOS architecture.

Does SN74HCS72DR require external pull-up or pull-down resistors on unused inputs?

Yes - all unused inputs on SN74HCS72DR must be externally biased to VCC or GND to prevent floating states that cause increased ICC, erratic switching, or localized heating. TI's layout guidelines explicitly require this, especially for Schmitt-trigger inputs which may oscillate if left unconnected. Tying unused PRE, CLR, D, or CLK pins to VCC (for inactive-high functions) or GND (for active-low functions) ensures deterministic operation and avoids undefined logic levels. The SN74HCS72DR datasheet confirms this in Section 11.1.

Can SN74HCS72DR be used to replace SN74HC72 in existing designs?

SN74HCS72DR is not a direct replacement for SN74HC72 due to fundamental architectural differences: SN74HCS72DR features Schmitt-trigger inputs (ΔVT = 0.6–1.6 V), while SN74HC72 uses standard CMOS inputs with no hysteresis. This means SN74HCS72DR tolerates slow/noisy signals that would cause metastability in SN74HC72. Electrical parameters like ICC, VOH/VOL, and propagation delay also differ. Therefore, SN74HCS72DR can be substituted only after verifying signal integrity, timing margins, and noise immunity requirements - the SN74HCS72DR is not pin-compatible in functional behavior despite identical pinout.

What is the purpose of the complementary Q and Q̅ outputs on SN74HCS72DR?

The complementary Q and Q̅ outputs on SN74HCS72DR provide simultaneous active-high and active-low logic states from the same flip-flop stage, eliminating the need for external inverters in enable/control applications. For example, one output can assert an EN signal to a CAN controller while the other disables a companion transceiver - simplifying PCB routing and reducing component count. This feature is intrinsic to the SN74HCS72DR's dual D-type architecture and is electrically guaranteed across temperature and voltage, supporting robust power sequencing in automotive systems.

How does the Schmitt-trigger input of SN74HCS72DR improve noise immunity in CAN wake-up applications?

The Schmitt-trigger input of SN74HCS72DR provides hysteresis (ΔVT = 0.6–1.6 V) that prevents multiple toggles when sensing slow-rising or noisy CAN RX wake pulses. Unlike standard CMOS inputs, it requires distinct high-to-low and low-to-high thresholds - so a noisy signal crossing VT+ then VT− repeatedly won't trigger spurious edges. In CAN standby mode, this ensures SN74HCS72DR asserts power enable only once per valid wake pattern, even with EMI-induced ringing on the RX line. This behavior is verified in TI's Application Report SLLA309.