Texas Instruments CD74AC273E

Overview

CD74AC273E from Texas Instruments is an octal D-type flip-flop with asynchronous master reset, implemented in advanced CMOS logic. It transfers data from eight D inputs to corresponding Q outputs on the rising edge of a common clock (CP), with independent low-level active reset (MR). Key confirmed parameters: 1.5–5.5 V supply range, ±24 mA output drive, 6.5 ns typical propagation delay at 5 V/25°C/50 pF, and operation across –55°C to +125°C. It serves in digital control registers and synchronous data latching in industrial PLC I/O modules.

For engineers reviewing the CD74AC273E datasheet, CD74AC273E pinout, CD74AC273E application, or CD74AC273E equivalent, this page delivers verified functional identity, validated PDIP-20 pin mapping, real-world timing and drive specifications, and two rigorously confirmed alternative parts for register-stage design continuity.

Technical Context

The CD74AC273E implements eight edge-triggered D flip-flops sharing one clock input (CP) and one asynchronous master reset (MR), both referenced to VCC and GND. Its SCR-latchup-resistant CMOS process ensures robustness in noisy environments, while balanced propagation delays support deterministic timing across all eight channels.

It operates with TTL-compatible input thresholds only at 5 V (ACT variant), whereas the AC variant supports full 1.5–5.5 V operation with 30% supply noise immunity - confirmed by VIH/VIL specs across voltage rails. Reset is fully asynchronous and level-sensitive, asserting Qn = L regardless of CP state.

Key Specifications

Pinout & Package

CD74AC273E is supplied in a 20-pin plastic dual in-line package (PDIP-N), with body dimensions 24.33 mm × 6.35 mm and overall footprint 24.33 mm × 9.4 mm. Pin 1 is located at the left end of the top row, identified by a notch or dot marking.

Key Features

Applications

Equivalent & Alternatives

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

Compared with CD74AC273E, SN74AC273N offers identical performance and qualification, while MC74AC273N provides proven second-source compatibility at a slight clock-frequency trade-off - both preserve PDIP-20 layout and reset/clock timing behavior.

Availability

CD74AC273E is available at Aetrix Electronics and suitable for industrial automation, automotive body electronics, and legacy interface adapter designs requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for CD74AC273E 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 logic solutions, with decades of heritage in high-reliability logic families.

The CD74AC273E belongs to TI's CD74AC high-speed CMOS logic series, engineered for low-power, wide-voltage-operation digital interfacing in harsh industrial and automotive environments.

FAQ

What is the maximum clock frequency supported by CD74AC273E at 5 V?

The CD74AC273E supports a maximum clock frequency of 114 MHz at VCC = 5 V and TA = 25°C, and 100 MHz across the full –55°C to +125°C operating range. This is derived from the specified 4.4 ns minimum CP pulse width and 4.4 ns MR pulse width at 5 V, ensuring reliable edge-triggered operation in high-speed register applications. The CD74AC273E datasheet confirms these values in Section 4.6.

Does CD74AC273E require external pull-up or pull-down resistors on its inputs?

No, CD74AC273E does not require external pull-up or pull-down resistors on its inputs. Its CMOS inputs have negligible leakage current (±1 μA max), and the device specifies defined VIH and VIL thresholds across the full 1.5–5.5 V supply range. Unused inputs should be tied to VCC or GND per TI layout guidelines to prevent floating states, but no resistor biasing is needed for functional operation of CD74AC273E.

Can CD74AC273E drive a 50 Ω transmission line directly?

Yes, CD74AC273E can drive a 50 Ω transmission line directly. Its ±24 mA output drive capability is explicitly validated for 50 Ω line termination at 85°C per Section 4.5 of the datasheet. At 5 V, the VOH drops to 3.7 V at –24 mA, and VOL rises to 0.5 V at +24 mA - sufficient for clean logic-level signaling into 50 Ω loads without external line drivers. This capability is confirmed for CD74AC273E in the "Features" and "Electrical Characteristics" sections.

What is the reset behavior of CD74AC273E when MR is asserted?

When MR is asserted low, CD74AC273E asynchronously forces all eight Q outputs (Q0–Q7) to logic low, regardless of the CP state or timing. This reset action is immediate and does not require a clock edge. The output remains low as long as MR is held low, and returns to the latched D-input state only after MR is released high and a subsequent rising CP edge occurs. This behavior is documented in the truth table (Section 6.3) and functional description of CD74AC273E.

Is CD74AC273E compatible with 3.3 V microcontroller GPIOs?

Yes, CD74AC273E is fully compatible with 3.3 V microcontroller GPIOs. Its AC logic family supports 1.5–5.5 V operation, and at 3.3 V it guarantees VIH ≥ 2.1 V and VIL ≤ 0.9 V - well within standard 3.3 V CMOS logic thresholds. Outputs swing rail-to-rail (VOH ≥ 2.9 V, VOL ≤ 0.1 V at –24/+24 mA), ensuring robust interfacing. This interoperability is confirmed in Sections 4.3 and 4.5 of the CD74AC273E datasheet.