Modular Devices introduces a new line of SSR’s for

lndustrial • Mil/Aero • Naval • Space

The trend in onboard electronic power systems is moving to higher voltage and power requirements across most systems. These include 270V and 540V Mil/Aero platforms, as well as Naval Surface and Subsurface and Space platforms. Recent developments in electric propulsion, directed energy, and photonic-based communications systems across these platforms require high voltage and high current switching with mission reliability.

The majority of commercially available DC SSRs use Silicon FETs and photovoltaic
opto-coupler drive circuitry, but these previously available devices have had two major performance draw backs :

• Higher contact voltage drop in the SSR’s compared to electro-mechanical relays. The higher voltage drop causes higher power dissipation and requires more efforts to cool the SSR to maintain usable junction temperatures.

• The disadvantages in the use of Photo-Voltaic (PV) opto-couplers to provide drive and isolation for the SSR’s are slow response time, limited drive power, and environmental limitations of this type of component.

MDI SOLUTION
Wide Band Gap Semiconductors
Wide Band Gap Semiconductors, such as GaN (Gallium Nitride) and SiC (Silicon Carbide) offer an order of magnitude improvement in DC SSR voltage drop over legacy Silicon-based power devices .

• High operating temperature, higher voltage capabilities, and lower ON resistance .
• Wide band gap semiconductors withstand higher electric fields with lower channel resistances and reduced drive requirements.

RF Coupled SSR Drive
RF Coupled SSR Drive replaces the PV function with a transformer-isolated RF drive and provides a faster, more temperature-stable
and temperature-resistant operation .

The magnetically isolated RF drive can be factory configured to operate from a wide range of control voltages from approximately 3.3 volts to
100 VDC and higher.

Mag Latch Drive
The magnetically isolated SSR can have a mag latch function, meaning it can be energized either by a continuous signal or by a short duration pulse. However, unlike an electromechanical relay, after removal of bias power the DC SSR reverts back to its initial state.

Certain models of the MDI DC SSR can be jumper configured for a latching relay function, or used without the latch .

The MDI SSR’s are packaged in a hermetically sealed case able to withstand severe environments. The units are available with and without mounting flanges.

M/N Description Voltage Rating Current Rating Features Rad Hard MIL/AERO Package

The SSR’s are available in EU (l),M & S ( +85°C), E ( +85°C), LE ( +125°C and 45kRads) and SE (+125°C and lO0kRads) operating and screening grades.

SSR brochure-stacked