Standards for power requirements and form factors for equipment designs do not exist for space applications. Major satellite manufactures establish their own power bus standards, the main power line that regulates the power from the solar panels and delivers regulated voltage to all the payload and system equipment. Most have a unique input/output voltage range, voltage level and dynamic behavior, telecommand (TC) and telemetry (TLM) interfaces among the subsystems that are also distinctive. The converters' output voltages and powers while dictated by the types of load are often unique from one payload design or program to the next. The distinction or lack of standards is believed to be due to the competitive nature of the industry. Each manufacturer attempts to gain a competitive edge on functional performances and overall power conversion efficiency resulting in unique designs and the lack of similarity in power converters.

IR's Mx design platform is created with these diverse input, output, and functional requirements in mind. In addition to insistence for high efficiency and functional performances, the space industry when making any make/buy decisions for a DC-DC converter for new equipment designs, demands design documentation/analyses and flight heritage to mitigate program risks that may cause slippage in delivery schedule and added costs.

This design platform targets low RF power design applications requiring power up to 15 W. The platform is developed for sensitive RF equipment onboard a spacecraft, i.e., receivers, transmitters, beacons, low-noise amplifiers (LNAs), and up/downconverters. It is designed for continuous operations in radiation environments that are presented to commercial, military and scientific missions operating in long-term geosynchronous (GEO), medium earth (MEO) and low earth (LEO) orbits.

Mx series is a radiation-hardened multiple outputs DC-DC converter design platform that can be adapted to most satellite input and output power requirements. The design topology allows simple component changes in the primary section to accommodate different bus voltages. While most design applications require power up to 15 W, the platform has adequate design margin to accommodate slightly higher combined output power than 15 W. The platform includes TC/TLM design that can be readily adapted to most major satellite interface requirements. It also includes a hold-up capacitor bank and electrical circuitry to insure proper turn-on and turn-off timing among the outputs, a critical biasing sequence for GaAs FET devices commonly used for RF power amplifiers.

Two standard assembly outlines exist. While MA platform is for output power up to 5 W, MB with a slightly larger outline is for output power of up to 15W. Open board PCBstyle construction is chosen to facilitate design adaptation and design changes as needed. Proprietary design simulation tools and design analysis templates are created to quickly and accurately provide performance projection and design trade offs where decision in design changes can be made with a high level of confidence. The platform offers RF equipment designers the ability to react and incorporate last-minute design adjustments with little or no impact to program schedule.

In addition to deliverable hardware, i.e., engineering model (EM), engineering qualification model (EQM), protoeflight model (PFM), and flight model (FM), almost all space programs require extensive design, qualification and program documentations. These items typically include preliminary/critical design review meetings, thermal analysis, stress analysis, reliability analysis, worst case analysis, failure mode effect analysis, radiation susceptibility analysis, acceptance and qualification test procedures/reports, monthly program reports, updated program schedule, weekly status update, and dedicated program management function.

These deliverable items, program review and design review meetings can incur substantial costs and impact program schedule and may become the pacing items when design changes occur. The Mx design configuration and the proprietary simulation and design tools are primed to lessen these impacts.

Performances and functional features of Mx series can be summarized as follows:

• accommodates most major power buses, 28 V, 50 V, 70 V, and 100 V;

• integrated input filter to ensure EMC/EMI compatibility to most satellite power buses;

• no limitation on number of outputs though most requirements are triple output configuration;

• each output can be configured to meet output voltage levels up to 15 V and any current level up to 1 A;

• guaranteed voltage accuracy and regulation to within 1% begin-of-life and 2% end-of-life accounting for temperature, radiation and aging effects;

• no cross regulation and crosstalk as each output is independently regulated;

• two design patents are deployed to maximize efficiency performance;

• efficiency is in the range of 65 to 75% depending on output voltage, current and power;

• each output uses linear regulator enabling output noise to be less than 1 mV(RMS);

• conducted susceptibility (CS) rejection is as high as 100 dB as a result of a two-stage regulation design;

• outputs are orderly sequenced during power-up and power-down to insure proper biasing for RF amplifier devices;

• isolated on/off tele-command and on/off status telemetry with a latching relay;

• two established assembly outlines for differing output powers; and

• components are space flight qualified class S.

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