Compact, Rugged Solutions Lead Power Converter Race

Driven by demands to reduce SWaP, DC-DC and AD-DC converter vendors are focusing on small, efficient devices capable of enduring harsh environments.


For military system designs, reducing SWaP (size, weight and power) is a leading priority. Power conversion technologies play their part in that trend by providing more efficient power conversion combined with ever more compact devices. Power conversion has direct impact the cooling and mobility of defense platforms. Issues like the need to accommodate multi-voltage electronics, operate at wide temperature ranges and serve distributed system requirements all add up to some daunting design challenges.

DC-DC and AD-DC conversion products must juggle a lot of masters to push the limits in power density, voltage range, wide temperature range and advanced filtering schemes. Designs that enable conversion technologies to be compliant to military standards are especially in demand. The need to meet noise and power related standards such as MIL-STD-461, MIL-STD-704 and MIL-STD-1275.

Wide Input Range Solution

Exemplifying those trends is Gaia Converter’s latest ultra wide input voltage range DC/DC converter—announced last month —the High Rel MGDD-40 series, targeting military and airborne applications. The voltage ranges are ideal for complying with MIL-STD-1275, 704 or DO-160 standards without additional front end protection device (Figure 1). The ranges are 9-60 V and 80V /1s and 4.5-33V and 45V /100ms. According to Gaia that performance is achieved thanks to Gaia’s proprietary switching techniques while also keeping efficiency over 90 percent. With two outputs (for parallel, serial or symmetrical operation) of 3.3V, 5V, 12V, 15V and 24V, they can cover a wide variety of needs such as single 5 to 48V output, +/- 15V or 2x24V outputs for example. The MGDD-40 Series have a wide temperature range of -55 to +105 degrees C and are potted to fit rugged military and airborne environmental conditions.

Figure 1. Wide input voltage range allows the MGDD-40 series DC-DC converter to comply with MIL-STD-1275, 704 or DO-160 standards without additional front end protection device.

The MGDD-40 is packaged in a very low profile 0.33- and 1.5-x1.75-inch housing. The units are full featured and protected with zero to full load regulation, trim and on/off capability, adjustable UVLO, soft start, embedded EMI filter as well as over-current and over-temperature protection. They can also be synchronized and/or paralleled for added power or N+1 redundancy. Designed for rugged applications, the MGDDI-40 series do not use any optocoupler.

Reducing Size and Weight

Also following the space-saving trend, last fall Technology Dynamics announced the release of their new COTS TDDC series of 1U DC to DC converter modules (Figure 2). This robust and ruggedized construction allows high performance and superb reliability. With reduced size and weight along with higher efficiency (SWaP), it provides a high-density, space saving solution for applications in the military. The TDDC series delivers up to 1,500W of power and offers DC input voltage range of 18 to 32VDC. The output (24V or 48V) is adjustable and tightly regulated to ±1 percent (load) and ±0.5 percent (line).

Figure 2. The TDDC series of 1U DC-DC converter modules exemplify high power density combined with compact footprint delivering up to 1,500W of power and offers DC input voltage range of 18 to 32VDC.

Features include parallel/redundant operation, inhibit, Power-OK alarms, system reset signaling, active current sharing and programming/monitoring functions. In addition, the converters are fan cooled with a standard operating temperature range of –20 to +75 degrees C, with an option for -40 to +75 degrees C. The unit includes forced current sharing, heavy duty output termination, remote inhibit, OV, OL, OT protection and it is designed to meet MIL-STD-810 and 461 standards. Forced current share makes this IU DC to DC converter ideal for parallel connection. Custom output voltages are available upon request with mechanical and electrical modification readily done. For MIL-STD-461F compliance an external EMI filter is needed. Additional available options include conformal coating, remote voltage adjust, rack mount/panel mount and parallel/redundant operation.

Encapsulated Packages

Meanwhile, Pico Electronics provides its AVP/AVN series of unregulated high voltage DC-DC converters—with output voltages from 6,000 VDC to 10,000 VDC—are produced in an ultra-miniature encapsulated package. 50 different standard models are available. These single output units will operate over the temperature range of -25 to +70 degrees C with no heat sink or electrical derating. For military applications, an operating temperature range -55 to +85 degrees C is available. An optional environmental screening package per MIL-STD-883 is also available.

TDK-Lambda’s HQA120 isolated DC-DC converters are rated at 120W and have been qualified with methods consistent with MIL-STD-883 and MIL-STD-202, making it suitable for use in COTS and harsh environment equipment. Initially available with 12V, 24V and 28V outputs, the encapsulated quarter bricks accept a wide range DC input of 9V to 40V, withstanding a 50V surge for 10 seconds.

Support for High Temp Operations

A key aspect that separates military requirements from that of other markets is the need to function harsh environments like high temperatures. Feeding those needs, VPT’s HTD Series of DC-DC converters specifically designed for harsh and extreme temperature environments including aircraft engine electronics and other industrial applications requiring reliable operation in high temperatures (Figure 3). The HTD isolated 1.5 W DC-DC converter operates from -55 to 155 degrees C and the HTD non-isolated DC-DC converters operate from -55 to 185 degrees C.

Figure 3. The HTD isolated 1.5 W DC-DC converter operates from -55 to 155 degrees C and the HTD non-isolated DC-DC converters operate from -55 to 185 degrees C.

Each model has dual outputs and is designed using thick film hybrid microcircuit technology, bare semiconductor die integrated with passive components and thick film conductors on a ceramic substrate. Within the HTD design, component-attach and die bonding are optimized for high temperature life, and hermetic metal packaging protects internal components for long-term reliability. Each HTD Series product has a low profile of 0.27 inches and measures less than an inch wide at 0.975 x 0.800 inches. The HTD Series of DC-DC converters are available for immediate sale.

Likewise address the need for high-temperature operations is the QMW quarter brick from Calex. Recently UL60950 approved, the devices feature an operating temperature range of -40 to +105 degrees C. The storage temperature is -55 to +125 degrees C. The QMW has an ultra wide 9 to 36V input range making the unit ideal for 12V and 24V battery powered applications. The QMW features remote ON/OFF for battery conservation. Other features include isolated input to output and a fully regulated 12V output with 20.5A of output current max. The unit has a peak efficiency of 93 percent with a fixed switching frequency of 275kHz. The QMW measures 1.54- x 2.39- x 0.50-inches and is designed to meet MIL-STD-810G for functional shock and vibration.

AC-DC Building Blocks

On the AD-DC power supply side, the trend in recent years is toward building block components. The power factor correction piece of that is particularly important. Along those lines, SynQor 3-Phase Power Factor Correction Module provides an essential building block of an AC-DC power supply that make use of full digital control to enable control strategies not possible with conventional designs. The product with part number MPFC 115 3PH-270 FP has a special constant-power output characteristic which helps pulsed-power systems-like radars for example-maintain good input harmonics (Figure 4). Digital control also allows for a data interface allowing the military system developers to view internal voltages, currents, and temperatures-information which would be difficult to obtain otherwise.

Figure 4. The MPFC 115 3PH-270 FP has a special constant-power output characteristic which helps pulsed-power systems-like radar systems maintain good input harmonics.

The MPFC 115 3PH-270 FP make use of SynQor’s robust construction techniques including automated assembly, embedded planar magnetics, and compliant potting materials. The device boasts innovations including minimal inrush current, support for full load current during startup ramp and balanced phase currents with low THD (1.5 percent at full load). It delivers a wide input frequency range of 45- to 800-Hz. The full-brick sized converter delivers 1.5 kW at 270 VDC while switching at 200 kHz, which allows for a groundbreaking improvement in power density. System developers requiring 400 Hz 3-phase for airborne military platforms will find huge weight savings over existing custom solutions. EMI is fully characterized with the available 3-phase half-brick input line filter (SynQor product number MACF 115 3PH-UNV HT).

Another example of innovative AD-DC converter building block technology is Vicor’s family of high density PFM AC-DC front-end modules in the rugged VIA package offer superior cooling performance and versatility in converter mounting. Featuring a universal AC input range (85 – 264 VAC), power factor correction, and a fully isolated 24 VDC or 48 VDC output, and delivering 400 W of isolated, regulated, DC output power at efficiencies up to 93 percent these new modules provide unprecedented power density of 127 W/in3 (8 W/cm3) and best-in-class performance in a diminutive, 9 mm thin VIA package.

Concord, CA
(925) 687-4411

Gaia Converter
Morristown, NJ
(973) 539.0568

Boxborough, MA
(978) 849-0600

TDK-Lambda Americas
San Diego, CA
(619) 628 2885

Technology Dynamics
Bergenfield, NJ
(201) 385-0500

Andover, MA
(978) 749-8359

Blacksburg VA
(425) 353-3010