Military Power Supplies and DC-DC Converters – A Guide to MIL-STD Standards

When an engineer selects a power supply for a commercial system, the starting point is relatively straightforward: input voltage, output voltage, power, efficiency, and size.

In a military system, these are only the beginning.

A power supply installed in a military ground vehicle, airborne system, communications system, radar, or electro-optical system must operate in an environment where the input power is not necessarily clean and stable DC.

Voltage surges, spikes, conducted interference, vibration, shock, extreme temperatures, and strict size and weight constraints can all be part of the system requirements.

Therefore, the right question is not simply:

“Which power supply provides the voltage and power I need?”

But rather:

“Which power supply will continue to operate in the military environment in which my system is expected to perform?”

This is where MIL-STD requirements come into play.

A Military Power Supply Is Much More Than a Voltage Converter

Consider a system installed in a military ground vehicle that receives a 28VDC input and requires 12VDC to power its electronics.

On paper, the task looks simple:

28VDC → DC-DC Converter → 12VDC

In a real-world system, however, the DC-DC converter may also need to withstand disturbances and abnormal conditions coming through the platform’s electrical power system.

The actual power architecture may therefore include:

Input Protection → Surge & Spike Protection → EMI Filtering → DC-DC Conversion → Load

When each of these functions requires separate components and circuits, the overall solution begins to occupy more space, add weight, and increase system integration complexity.

This is where one of the key advantages of compact military power solutions becomes particularly important:

Integrating power conversion, filtering, and the required protection circuitry into a single solution.

Rather than viewing the DC-DC converter as a standalone component, it is often more useful to consider it as part of a complete Power Conditioning solution.

Four Key MIL-STD Families to Know

When designing or selecting power supplies and DC-DC converters for military and aerospace systems, four MIL-STD families are particularly important:

MIL-STD-1275 – Defines the characteristics of 28VDC input power supplied to equipment connected to military ground vehicle electrical systems.

MIL-STD-704 – Defines the characteristics of electrical power supplied to equipment aboard aircraft.

MIL-STD-461 – Defines requirements related to EMI/EMC, including electromagnetic emissions and susceptibility.

MIL-STD-810 – Defines environmental test methods that may include vibration, shock, temperature, and other environmental conditions, depending on the application.

Each standard addresses a different aspect of the challenge.

Together, they demonstrate why the term Military Power Supply describes much more than simply a power supply with a wide operating temperature range.

MIL-STD-1275 – Why 28VDC in a Military Vehicle Is Not Simply 28VDC

One of the key standards for power supplies used in military ground vehicles is MIL-STD-1275.

The standard defines the operating voltage limits and transient characteristics of 28VDC electrical power supplied to equipment connected to military ground vehicle electrical systems.

This is an important distinction: when a system specification states 28VDC Input, it does not mean that the equipment will receive a clean and constant 28 volts at all times.

A military vehicle electrical system is a dynamic environment. Engine starting, loads being connected or disconnected, charging systems, and various electrical loads sharing the same power bus can create voltage conditions that connected electronics must be able to handle.

MIL-STD-1275 therefore defines more than just a nominal 28VDC value. It also addresses voltage limits and electrical transients that equipment may encounter at its input.

The current active revision is MIL-STD-1275F, published in September 2022, which superseded MIL-STD-1275E.

What Does This Mean for the Power Supply?

Suppose our system requires 12VDC.

A commercial DC-DC converter might be specified as:

Input: 18-36VDC
Output: 12VDC

On paper, it appears suitable for a 28VDC system.

But this specification alone does not mean that the converter is suitable for a military ground vehicle.

The more important question is:

What happens when the input voltage temporarily moves outside normal operating conditions?

Is the converter protected?

Will it continue to operate as required?

Will it recover and return to normal operation after the event?

And will additional external protection and filtering circuits be required for the complete system to meet the project requirements?

Therefore, when selecting a MIL-STD-1275 Power Supply or a Military DC-DC Converter for 28VDC Vehicles, it is important to evaluate the entire power input solution, not just the input voltage range of the DC-DC converter.

MIL-STD-704 – When the 28VDC Comes from an Aircraft

This is where the distinction becomes even more important.

Aircraft also use 28VDC electrical systems. As a result, two different projects may appear to have exactly the same requirement:

Input Voltage: 28VDC

But one may be intended for a military ground vehicle and the other for an aircraft.

These are not necessarily the same electrical requirements.

MIL-STD-704 defines the characteristics of electrical power supplied to utilization equipment aboard aircraft. In other words, it defines the electrical power environment that airborne equipment is expected to encounter at its input.

The standard is not limited to 28VDC. The MIL-STD-704 family also addresses other types of electrical power used in aircraft, including various AC and DC power systems.

For 28VDC utilization equipment, dedicated test guidance is also provided within the MIL-HDBK-704 series.

Same Voltage, Different Electrical Environment

This is an important misconception to avoid at the beginning of a project:

28VDC does not automatically mean the same electrical environment.

A DC-DC converter designed for a 28VDC military ground vehicle power bus is not automatically suitable for a 28VDC aircraft power system, and vice versa.

MIL-STD-1275 addresses the 28VDC electrical power environment for equipment connected to military ground vehicle electrical systems.

MIL-STD-704 addresses the characteristics of electrical power supplied to utilization equipment aboard aircraft.

Therefore, before selecting a power supply or DC-DC converter, it is important to know not only the input voltage, but also which platform supplies that power and which standard the system is required to meet.

In some systems, the requirement can be even more complex: the same product may need to operate across more than one type of platform or meet requirements originating from more than one electrical power environment.

In such cases, selecting the Power Front End becomes an important part of the overall system design, rather than simply a matter of choosing a voltage converter.

MIL-STD-461 – When the Challenge Goes Beyond Input Voltage

So far, we have focused mainly on what reaches the power supply through the platform’s electrical power system.

But military systems face another important challenge: EMI – Electromagnetic Interference.

Military electronic systems can operate in electromagnetically dense environments. Power supplies, communication systems, computers, motors, radars, RF systems, and other electronic equipment may operate in close proximity and may share common power sources.

Therefore, converting voltage is only part of the job.

We also need to consider how the power supply and the overall system behave in the presence of electromagnetic interference.

This is where MIL-STD-461 comes into play. The standard establishes requirements for controlling the electromagnetic interference characteristics of equipment and subsystems.

In simple terms, we need to consider the relationship in both directions:

What interference does the equipment generate and introduce into the surrounding environment or power lines?

And:

What happens to the equipment when it is exposed to interference from the environment or through its power lines?

This leads to two important concepts:

Emissions – Electromagnetic interference generated by the equipment itself.

Susceptibility – The equipment’s response to external electromagnetic interference.

Conducted vs. Radiated EMI

Electromagnetic interference can reach equipment in different ways.

Conducted EMI refers to interference that travels through conductors, such as power supply lines.

Radiated EMI refers to electromagnetic energy that propagates through the electromagnetic field and is received by the equipment.

From a power supply perspective, conducted EMI is particularly important because the power supply is directly connected to the platform’s power lines.

It effectively sits at the interface between the platform power source and the electronics we need to power.

What Is CS101?

One of the well-known requirements within MIL-STD-461 is CS101 – Conducted Susceptibility, Power Leads.

CS101 evaluates the ability of equipment to withstand disturbances coupled onto its power input leads over the frequency range specified by the requirement.

In simple terms:

A controlled disturbance is applied to the equipment’s power input, and the equipment is evaluated to determine whether it continues to operate as required.

This is particularly important when designing a military power supply.

A DC-DC converter may perform very well in terms of input voltage, output voltage, efficiency, and power, while the complete system may still require additional filtering to meet the project’s EMI/EMC requirements.

Therefore, when a requirement such as MIL-STD-461 CS101 applies, the Power Front End should be evaluated as a complete system.

Why Is the Input Filter So Important?

An Input Filter can be viewed as an electrical interface between two environments:

Platform Power Bus ↔ Filter / Protection ↔ DC-DC Converter ↔ Sensitive Electronics

On one side is the electrical power system of the vehicle or platform.

On the other side is the sensitive electronics that need to be powered.

Between them, the design must manage both power quality and electromagnetic interference.

In a conventional solution, a system engineer may select a DC-DC converter and then design the additional circuitry required around it:

Protection Circuit

Surge / Transient Protection

EMI Filter

DC-DC Converter

Additional components may also be required depending on the specific project requirements.

Each of these elements may be necessary on its own.

But together, they require space.

They add components to the BOM, require additional PCB area or wiring, affect thermal management, and increase integration and testing effort.

This brings us to one of the most important considerations in modern military power supply design:

Can All of This Be Integrated Into the Power Supply?

In suitable applications, yes.

Instead of treating a Military DC-DC Converter simply as a “box that converts 28VDC to 12VDC,” the power solution can be designed to incorporate Input Protection and Filtering functions according to the requirements of the product and the project.

This can mean fewer external components, a smaller footprint, less wiring, and reduced integration complexity for the system designer.

In a space-constrained military system, these advantages can be significant.

MIL-STD-810 – When the Challenge Comes from the Environment, Not the Power Line

So far, we have focused mainly on the electrical environment of the power supply: input voltage, transients, and EMI.

But a military power supply does not operate only in a challenging electrical environment.

It may be installed in an off-road vehicle, mobile system, aircraft, electro-optical system, or other equipment that must continue to operate under harsh environmental conditions.

This is where MIL-STD-810 comes into play.

Unlike MIL-STD-1275 or MIL-STD-704, which address the electrical power environment, MIL-STD-810 focuses on environmental test methods intended to tailor equipment testing to the conditions it is expected to encounter throughout its service life.

Depending on the product and application, relevant requirements may include:

• Vibration
• Shock
• High Temperature
• Low Temperature
• Humidity
• Altitude
• Dust and Sand
• Other environmental conditions depending on the project

Not every power supply is required to undergo all of these tests.

For this reason, it is important to avoid broad statements such as “MIL-STD-810 compliant” without identifying the specific Methods, Procedures, and test conditions required for the project.

Why Is Vibration Particularly Important for a Power Supply?

A power supply contains electronic components, magnetic components, connectors, solder joints, and sometimes components with significant mass.

In an environment subject to continuous vibration, mechanical design becomes an integral part of the electrical design.

This is why, in military applications, rugged design is about much more than simply using an enclosure that looks strong.

The product must be considered as a complete system:

Electronics + PCB + Components + Connectors + Mechanical Structure + Thermal Design

All of these elements must work together in the environment for which the product is intended.

Size, Weight and Power – Why Every Millimeter Matters

In military and aerospace system design, the term SWaP – Size, Weight and Power is frequently used.

The concept is straightforward: achieve the required performance while minimizing size and weight and using available power as efficiently as possible.

For a military power supply, these requirements create an inherent design challenge.

On one hand, we want a compact converter.

On the other hand, we may also want to integrate:

• DC-DC Conversion
• Input Protection
• Filtering
• Isolation, when required
• Thermal Management
• Mechanical Protection
• Connectors

And all of these functions must operate within the required temperature range and environmental conditions.

This makes Power Density an important consideration in military power supply design.

But high power density alone is not enough.

The heat still needs to go somewhere.

High Efficiency Is Also a Thermal Consideration

Power supply efficiency is more than just an electrical specification.

Every watt entering the power supply that does not reach the load ultimately becomes primarily heat that must be dissipated.

Consider a simple example.

A system delivers 200W to the load.

At 80% efficiency, the power supply requires 250W at its input, resulting in approximately 50W of power loss.

At 90% efficiency, it requires approximately 222W at its input, reducing the losses to approximately 22W.

In this example, a ten-percentage-point improvement in efficiency reduces the power that must be dissipated as heat by more than half.

In a compact, sealed, or fanless system, that can make a significant difference.

A High Efficiency Military Power Supply can therefore provide benefits beyond reduced power consumption, including:

• Less heat generation
• Reduced cooling requirements
• The possibility of a more compact enclosure
• Improved thermal conditions for nearby components
• Easier implementation of fanless systems

Some Gilgal Power Systems solutions offer high-efficiency power conversion, depending on the specific model, power level, and operating conditions.

Conduction Cooling – When a Fan Is Not the Answer

In commercial equipment, thermal challenges can sometimes be addressed by adding a fan.

In a military system, however, a fan is not always desirable or even practical.

A fan adds a mechanical component, consumes power, may introduce dust and contaminants into the system, and requires an appropriate airflow path.

In sealed systems, this option becomes even more limited.

For this reason, many military power solutions are designed to transfer heat through Conduction Cooling to the enclosure, chassis, or other system structure.

In such a design, the enclosure is not simply packaging.

It becomes part of the thermal management system.

Metal Shielding – The Enclosure Is Part of the Electromagnetic Design

A metal power supply enclosure can serve another important function: Shielding.

In a densely integrated military system, power supplies, computers, communication equipment, RF systems, sensors, and sensitive electronics may all operate in close proximity.

A metal enclosure around the power converter can form part of the strategy for reducing electromagnetic coupling between the power supply and its surroundings.

Depending on the product design, some power solutions may use metal shielding around five or six sides of the converter.

However, it is important to emphasize:

Metal Shielding alone does not guarantee compliance with MIL-STD-461.

Meeting EMI/EMC requirements depends on the complete design:

Filtering + PCB Layout + Grounding + Shielding + Cabling + Connectors + Mechanical Design

Metal shielding should therefore be considered one part of the overall solution, not a substitute for proper EMI design.

Connectors Matter Too

A connector may appear to be a relatively small detail in a power supply specification, but at the system level it can have a significant impact on ease of integration.

Selecting commonly available connectors that are appropriate for the application can simplify:

• Harness Design
• Assembly
• Maintenance
• Replacement
• System Integration

For a custom product, it may also be possible to adapt the connector type, pinout, and other mechanical parameters to the specific requirements of the system.

This can be a significant advantage when the power supply needs to fit into an existing system, rather than requiring the system to be redesigned around the power supply.

How to Select a Military Power Supply or DC-DC Converter

Now that we understand the differences between MIL-STD-1275, MIL-STD-704, MIL-STD-461, and MIL-STD-810, we can return to the practical question:

How do you select the right power supply for your system?

A common mistake is to start with only three parameters:

Input Voltage → Output Voltage → Power

These are, of course, essential specifications, but in a military project they are not enough.

The right selection process begins by defining the environment in which the power supply will operate.

1. What Is the Target Platform?

Is the power supply intended for a:

• Military ground vehicle
• Aircraft
• Ground-based system
• Communication system
• Electro-optical system
• Radar system
• Mobile system
• Sealed system
• Other military application

The platform directly influences the electrical, environmental, vibration, cooling, and EMI requirements.

2. What Is the Input Voltage?

Do not consider only the nominal voltage.

For example:

Nominal Input: 28VDC

The actual input voltage range and the abnormal conditions that the product may need to withstand must also be considered.

Especially in military ground vehicle applications, 28VDC is the beginning of the discussion, not the end.

3. What Output Voltage and Power Are Required?

The following parameters should be defined:

Output Voltage

Output Current

Required Power

It is also important to determine whether the system requires a single output or multiple outputs.

For example:

28VDC Input → 12VDC / 200W

Or the system may require several output voltages for different loads.

4. Which MIL-STD Requirements Apply?

This is one of the most important pieces of information.

For example:

MIL-STD-1275

MIL-STD-704

MIL-STD-461

MIL-STD-810

However, simply specifying the name of a standard may not be sufficient.

Where applicable, the requirement should be defined as precisely as possible:

Revision + Requirement + Method + Procedure

depending on the relevant standard and project requirements.

Simply stating “MIL-STD required” is not a complete technical specification.

5. What Are the EMI/EMC Requirements?

If MIL-STD-461 applies, it is important to understand which specific requirements are relevant to the system.

For example, if CS101 is required, this should be considered during the design of the Power Front End rather than discovering at the end of system integration that an additional filter is needed.

The same principle applies to other EMI/EMC requirements.

6. What Are the Environmental Conditions?

Depending on the application, relevant parameters may include:

• Operating Temperature
• Storage Temperature
• Vibration
• Shock
• Humidity
• Altitude
• Dust / Sand
• Sealing Requirements

These conditions should be defined according to the actual application.

7. How Will the Heat Be Dissipated?

A forced-air-cooled system, a sealed system, and a system based on Conduction Cooling require different thermal approaches.

It is therefore important to understand from the beginning:

How will the power supply be mounted, and how will heat be transferred away from it?

Especially at higher power levels and in compact enclosures, thermal management is a key factor in selecting the right power supply.

8. How Much Space and Weight Are Available?

In a densely integrated military system, a more compact solution can save much more than just the physical volume of the power supply itself.

If protection and filtering functions are integrated into the power supply, it may also be possible to reduce:

• PCB Area
• External Components
• Wiring
• Connectors
• Weight
• Integration Effort

For this reason, it is important to compare the complete power solution, not only the dimensions of the DC-DC converter module.

9. Which Connectors Are Required?

Connector type, pinout, current ratings, environmental conditions, and system maintenance requirements should all be considered.

Using common and application-appropriate connectors can significantly simplify system integration and field maintenance.

Standard or Custom?

Not every project requires a new design.

When an existing standard product meets the electrical, mechanical, and environmental requirements, using it can reduce development time and cost.

However, military systems often have requirements that do not fit a standard configuration.

These may include a special input voltage, multiple outputs, a customer-specified connector, a unique mechanical envelope, height restrictions, specific cooling requirements, or a particular combination of MIL-STD requirements.

In these cases, a Custom Military Power Supply or a modified version of an existing solution may be considered to meet the specific system requirements.

Gilgal Power Systems – Military Power Expertise

Gilgal Power Systems specializes in the development and manufacture of power conversion solutions for military, aerospace, and industrial applications.

Depending on the product family and application requirements, solutions include:

• Military Power Supplies
• DC-DC Converters
• Rugged Power Supplies
• Input Protection Circuits
• Active Filters
• Sealed Power Solutions
• Custom Power Solutions

Experience in military applications makes it possible to approach the power supply not simply as a voltage converter, but as an integral part of the system’s Power Front End.

One of the key advantages is the ability to integrate power conversion with the required Protection and Filtering functions within a compact solution.

Instead of starting with a commercial converter and building an entire system of external protection and filtering around it, suitable applications can begin with a power solution designed from the outset for the military operating environment.

Conclusion – A Military Power Supply Is a System, Not Just a Voltage Converter

Selecting a military power supply is about much more than:

28VDC IN → 12VDC OUT

The complete picture needs to be considered:

Electrical Environment

Surges & Transients

Protection

EMI / EMC

Filtering

Temperature

Vibration & Shock

Thermal Management

Size & Weight

Mechanical Integration

Standards such as MIL-STD-1275, MIL-STD-704, MIL-STD-461, and MIL-STD-810 help define different aspects of the environment in which the system is expected to operate.

The more of the required functions that can be integrated into a compact, purpose-designed power conversion solution, the greater the potential to reduce external components and simplify system integration.

Looking for a Military Power Supply for a New Project?

Amironic represents Gilgal Power Systems in Israel, providing military power supplies, DC-DC converters, filters, and protection circuits for defense applications.

To evaluate the most suitable solution, it is recommended to provide:

Input Voltage • Output Voltage • Power • MIL-STD Requirements • Temperature • Mechanical Requirements • Connectors

Based on the project requirements, either a standard product or a custom power solution can be evaluated for the application.