Power supplies and electromagnetic interference (EMI) filters are critical for military operations, and meeting compliance is nonnegotiable. Military equipment must meet strict requirements to ensure safety, durability and reliability. Here, you learn more about MIL-STD-461G and DO-160 requirements and find power supplies and EMI filters to meet your operational needs.
Understanding MIL-STD-461G and DO-160 Standards
Organizations must understand MIL-STD-461G and DO-160 standards to ensure electronic equipment reliability and safety. Both standards help mitigate risks associated with environmental and EMI factors, ultimately enhancing safety and success.
MIL-STD-461G Requirements
MIL-461 standards apply to mission-critical electronics systems used by the United States Department of Defense. This standard aims to ensure electromagnetic compatibility, including how equipment can withstand intended EMI and function with designated tolerances.
MIL-STD-461G is the most recent version of MIL-STD-461, revising MIL-STD-461F to improve upon applicable testing procedures, technical criteria and measurement techniques. These revisions target new EMI concerns that the previous MIL-STD-461F did not account for. MIL-STD-461G offers more testing accuracy with improved test methods and improved clarity for maintaining compliance.
Similar to its predecessor, MIL-STD-461G assesses conducted emissions, conducted susceptibility and radiated emissions.
- Conducted emissions: Based on test methods CE101 and CE102, power supplies may not emit conducted noise above specified limits.
- Conducted susceptibility: Power supplies must operate correctly when subjected to disturbances like audio frequency signals, damped sine waves or impulses injected onto power lines. Unsafe operation, degradation and malfunction are prohibited during testing. These tests include CS101, CS114, CS115 and CS116.
- Radiated emissions: Power supplies must function correctly in strong EM fields and must not radiate excessive EMI according to tests RE101 and RE102.
EMI filters that meet MIL-STD-461G compliance must be able to withstand susceptibility tests without failure or degradation. They must also have an insertion loss high enough to ensure compliance without interfering with normal operation.
DO-160 Requirements
RTCA DO-160, Environmental Conditions and Test Procedures for Airborne Equipment, defines the environmental testing procedures and conditions for airborne equipment. This standard ensures equipment can withstand flight-related conditions, including altitude changes, humidity, vibrations and temperature variations. Adhering to DO-160 allows manufacturers to identify opportunities for stronger equipment reliability and field performance.
DO-160 compliance for power supplies encompasses:
- Temperature variation: Compliant power supplies can operate across various temperatures, ranging from extreme cold to heat. Testing processes expose the power supply to temperature cycles and require manufacturers to monitor equipment performance to ensure verification.
- Altitude: Power supplies must also be able to operate at various altitudes. Air pressure and density vary significantly at different altitudes, so manufacturers must test in several different environments. Testing also assesses the risk of arcing or corona discharge as a result of reduced air pressure.
- Humidity: Testing against humidity determines an equipment's moisture resistance. This metric is crucial because moisture can cause electrical failures and corrosion. Test processes involve exposing the power supply to high humidity levels for extended periods to evaluate performance.
- Operational shocks and crash safety: Equipment in flight can encounter shocks and impacts from turbulence and harsh landings. This testing determines the equipment's ability to withstand sudden impacts and shocks to determine durability and reliability.
- Vibration: Equipment often encounters vibrations during flight. Vibration testing simulates these vibrations to assess durability. Without this durability, the vibrations can cause component failures and mechanical stress.
Power Supplies for Military and Aerospace Applications
Military and aerospace applications demand power supplies with unwavering reliability and strict standard adherence. Consider these key features and examples of compliant power supplies:
Key Features of Compliant Power Supplies
Compliant power supplies must leverage several key features, including:
- High reliability and rugged design: Military and aerospace environments are complex and harsh. These environments involve extreme temperatures, altitude changes, shock, contaminant exposure and more. High reliability and rugged designs are crucial for completing mission-critical applications while minimizing the risks of failure.
- Wide input voltage range: Aircraft power systems often face voltage variations, and military operations must use various power sources with different nominal voltages. A wide input voltage range is essential for maintaining reliable and stable operations despite these fluctuations and input needs.
- Efficient thermal management: Applications in military and aerospace often occur in high-temperature environments. Proximity to heat-generating equipment, direct sunlight exposure and confined spaces can all impact the environmental temperature. Thermal management is crucial for ensuring system longevity in these conditions and meeting DO-160 temperature requirements.
Examples of Compliant Power Supplies
MIL-STD-461G power supply solutions and power supplies for DO-160 include:
- DC/DC converters with EMI filtering: These converters can convert one DC voltage to another. However, these converters can generate significant EMI, making it crucial to integrate internal or external EMI filters.
- Custom-designed power supplies: Demanding applications can rely on custom power supply solutions. A custom approach allows teams to optimize power supply design through tailored PCB layouts, shielded enclosures, integrated EMI filtering and careful component selection.
- Ruggedized: Ruggedized AC-DC power supplies convert AC voltages to DC outputs. These systems can withstand harsh environments and support a wide input voltage range. These supplies are also highly efficient, and their ruggedized construction makes them very durable.
- DC/DC converters: These converters come in isolated and non-isolated designs. Flight control systems and communication systems often use these converters because they are highly efficient and offer a wide input voltage range.
EMI Filters for MIL-STD-461G and DO-160
EMI filters are designed to prevent EMI from disrupting sensitive equipment operation. Compliant filters attenuate or block unwanted noise levels as signals pass through, improve system performance and enhance signal integrity. To meet MIL-STD-461G and DO-160 compliance for EMI filters, consider these types:
- Common-mode filters: Common-mode filters attenuate noise common to return conductors and the signal. This noise often comes from radio transmissions, power line interference and ground loops. These filters allow signals to pass through with minimal disturbance and often leverage capacitors to shunt noise to ground.
- Differential-mode filters: These filters attenuate noise appearing as a voltage difference between return conductors and the signal. This noise often originates from digital circuits, switching power supplies or other equipment sources. Differential-mode filters leverage capacitors and inductors to block high-frequency noise and shunt it to the ground.
- Custom solutions: Custom filters allow you to find high-quality solutions for specialized applications. Custom solutions give you control over selecting filter topology and components to meet integration requirements and compliance.
Challenges and Best Practices to Consider
While meeting industry standards is crucial, there are several common challenges teams must overcome, such as:
- Balancing performance, cost and compliance: Performance is paramount, but teams with budget constraints can face challenges with meeting demands while staying within budget. Additionally, the need for specialized components to maintain compliance and enhance performance can often raise costs.
- Component selection: Teams in these sectors must choose components that meet environmental requirements and electrical performance requirements. Even after choosing the appropriate components and materials, rigorous certification processes can lead to long development cycles.
- Managing space and weight constraints: Military and aerospace applications often demand lightweight, compact solutions. Maintaining compliance while navigating these requirements can be challenging. However, innovative designs and tailored solutions can help ensure you can meet each of these demands.
To ensure compliance, implement these best practices:
- Define performance requirements and compliance standards early.
- Involve compliance testing early in the design phase.
- Use simulation tools for EMI prediction.
- Collaborate with certification bodies.
- Prioritize components with established reliability data.
- Maintain detailed documentation of all component selections, test results and design considerations.
- Use appropriate EMI filters to attenuate radiated and conducted emissions.
- Optimize the PCB layout to minimize EMI.
- Leverage designs with thermal management and environmental protection.
Request Custom EMI Filters and Power Supplies for Your Applications
Astrodyne TDI is dedicated to manufacturing solutions for power and filter applications across demanding industries. We create power technologies that people depend on. As a trusted provider of customized filters and power supplies, you can rely on our team to help you find the right solution to align with MIL-STD-461G and DO-160 standards.
We have decades of experience providing quality power solutions and exceeding expectations. Our exceptional customer service and quality policy ensure we can meet your needs and drive innovation. Reach out to us for expert guidance today.