Блог компании ST LEOAC74PT-D CMOS Dual D Type Positive Edge Triggered Flip Flop For Aerospace Environments

Shenzhen Mingjiada Electronics Co., Ltd. supplies and recycles the ST LEOAC74PT-D CMOS dual D-type positive-edge-triggered flip-flop, suitable for aerospace applications.

I. LEOAC74PT-D Product Overview

The LEOAC74PT-D is a radiation-hardened, plastic-encapsulated CMOS dual D-type rising-edge-triggered flip-flop developed by STMicroelectronics (ST) for the aerospace sector. It forms part of ST’s LEO aerospace-specific product line, strictly adheres to the ST-LEO aerospace specifications, and is specifically designed for harsh space environments such as low Earth orbit (LEO) satellites and airborne avionics. The device integrates two independent D-type flip-flops, supports data latching on the rising edge of the clock, and features asynchronous preset (PRE) and asynchronous clear (CLR) functions. It maintains stable logic timing under space conditions such as radiation, wide temperature ranges, low atmospheric pressure and vibration, making it the preferred choice for on-board data latching, synchronous timing circuits, status registers and interface logic.

Unlike traditional ceramic hermetically sealed aerospace devices, the LEOAC74PT-D utilises a highly reliable plastic-encapsulated solution, balancing miniaturisation, mass production capabilities and overall cost, and is suited to the high-volume networking requirements of commercial space constellations.

II. Core Functional Principles of the LEOAC74PT-D

The device incorporates two mutually independent D-type flip-flops, utilising a clock rising edge (positive edge) triggering mechanism:

At the instant the clock signal CP transitions from a low level to a high level, the level at the D input is captured and transmitted to the Q output; whilst the clock is at a high level, a low level, or during the falling edge, the output state remains unchanged.

Independent asynchronous set (PRE) and asynchronous clear (CLR) functions have the highest priority; they are not controlled by the clock signal and can directly force the output to ‘1’ or clear it, facilitating system power-on initialisation and fault reset control. The two trigger resources are mutually independent and can be configured and used separately, enhancing PCB layout flexibility.

III. Key Electrical and Space-Grade Performance Characteristics of the LEOAC74PT-D

1. Power Supply Specifications

Operating voltage range: 1.65 V to 6 V; absolute maximum rated voltage: 7 V; compatible with mainstream 3.3 V and 5 V on-board power rails, supporting multi-voltage-domain space digital system design.

2. High-Speed Timing Characteristics

Typical propagation delay of 8.5 ns (at 4.5 V with a 50 pF load); high-speed latching capability meets the high-frequency timing requirements of on-board communication payloads and in-orbit processing units. Output drive capability of ±24 mA allows direct driving of on-board logic loads.

3. Wide Operating Temperature Range

Operating temperature: –40 °C to +125 °C; withstands severe day-night temperature fluctuations during satellite operations in orbit and thermal cycling shocks within the onboard equipment bay.

4. Space-Grade Radiation Hardening (Core Advantage)

Total Ionising Dose (TID): 50 krad(Si);

Single-electron-level (SEL) immunity: 62.5 MeV·cm²/mg, ensuring no risk of lock-up whilst in orbit;

Single-electron-transient (SET) characterisation completed, suitable for the radiation environment of low Earth orbit.

5. Space-grade outgassing control (mandatory aerospace specification)

Guaranteed RML < 1% and CVCM < 0.1%, with low outgassing characteristics to mitigate the risk of contamination within optical payloads and vacuum chambers.

6. Packaging and Process Reliability

Packaging: TSSOP-20 thin-profile plastic package;

Bonding: Gold wire bonding; pin surface treatment: NiPdAu (nickel-palladium-gold), eliminating the risk of tin whisker growth and ensuring no risk of pin short-circuits during long-term in-orbit operation; the device weighs only 80 mg, and its lightweight design contributes to reducing satellite payload weight.

7. Quality Specifications

Developed in accordance with the AEC-Q100 standard and compliant with the ST-LEO dedicated space device specification; provides comprehensive batch screening and device traceability, supporting selection for commercial spaceflight models.

IV. Core Advantages of the LEOAC74PT-D Product

Dual-channel integration saves PCB space; a single device achieves two independent timing latches, reducing the number of components and wiring;

A plastic-encapsulated aerospace solution; compared to traditional ceramic hermetic devices, it offers shorter lead times and is suitable for bulk procurement by satellite constellations;

Comprehensive radiation resistance specifications, suited to the space radiation environment of low-Earth orbit satellites;

Low outgassing and lead-free manufacturing processes, meeting reliability requirements for vacuum space environments;

Wide-voltage, low-power CMOS architecture, reducing the load on on-board power supplies;

Independent asynchronous set/reset functions, simplifying the design of system power-up and fault reset logic.

V. Typical Aerospace Applications for the LEOAC74PT-D

On-board digital timing control circuits for low-Earth orbit nanosatellites and CubeSat platforms

Synchronisation registers for satellite communication payloads and on-board data processing units

Logic latch modules for aircraft flight control systems and mission computers

Synchronisation interface circuits for on-board sensor data acquisition

Status register and command sequencing circuits for satellite operations management systems

On-board electronic control systems for small spacecraft and launch vehicles