OBC-HYPER-POLAR RT is the radiation-tolerant (RT) product family of the HYPER-POLAR onboard computer. The common platform combines the Microchip PolarFire^® SoC FPGA, RT PolarFire SoC FPGA compute architecture, 4 GB MSS main memory, 8 GB fabric memory, redundant boot storage, high-capacity mass storage and a broad set of serials, SpaceWire, analogue and Gigabit Ethernet interfaces. Baseline and Tiers 0–4 provide cumulative radiation-performance configurations while preserving the common mechanical, software and interface architecture.

The product family provides a cumulative radiation-performance progression. Tiers 0–3 retain our MPFS460T SoC FPGA and progressively harden power, communications, boot, memory, analogue and Ethernet domains. Tier 4 uses our RTPFS460ZT SoC FPGA and provides the highest radiation tolerant compute configuration with nonvolatile configuration Single Event Effect (SEU) immunity. Memory and high-capacity storage are independently protected fault domains, with their published device-specific SEE limits stated explicitly.

Tier 2 uses radiation-tolerant DDR4 for the 4 GB MSS main-memory function. The PolarFire SoC Microprocessor Subsystem (MSS) supports 16/32 data I/Os and 18/36 data I/Os with ECC; the HYPER-POLAR RT MSS configuration uses 32 data I/Os plus 4 ECC I/Os, forming a 36-bit SECDED interface [R4–R5]. The selected 72-bit RT DDR4 memory module has a defined 2:1 width relationship to the 36-bit MSS interface, while 64/72-bit memory operation remains on the fabric DDR controller.

HYPER-POLAR RT separates boot and critical state from bulk mission-data storage. Dual radiation-hardened QSPI NOR devices and SPI MRAM/FRAM carry boot, recovery metadata and critical state. The 512 GB baseline mass-storage domain is independently protected and recoverable. Space eMMC and fabric-attached RTIMS/NAND configurations provide radiation-tolerant storage variants with their published TID/SEE limits and capacity boundaries stated in Tier 3 [R8–R11].

Figure 1 — Functional radiation coverage of the cumulative OBC-HYPER-POLAR RT product tiers.

Tier performance is stated by the functional domains hardened, the manufacturer-published component data and the fault-containment mechanisms provided by the product. Box-level TID values are used only where supported by the applicable component set, shielding basis and qualification evidence.

Product Baseline and Radiation-Relevant Architecture

Compute and Memory Topology

External Interfaces and Fault Domains

PolarFire Architectural Attributes Relevant to Radiation

• PolarFire uses nonvolatile SONOS configuration technology, avoiding the need for continuous configuration-scrubbing burden characteristic of SRAM-configured FPGAs.
• The MSS includes ECC-protected cache/LIM resources and a dedicated external DDR controller. External volatile memory remains a radiation-sensitive system element even when the FPGA configuration itself is robust.
• Fabric logic supports EDAC, memory scrubbing, watchdogs, redundant state machines, interface controllers and fabric-hosted NAND/RTIMS storage control. TMR is applied to protected control logic where required by the RT configuration.
• Power-domain partitioning allows destructive events or persistent SEFIs in external memories/PHYs to be current-limited and recovered by controlled power cycling.

Radiation Performance Criteria and Evidence Basis

Evidence grades used in the component tables: A = QML/RHA or dedicated manufacturer radiation report; B = official manufacturer radiation characterization / space-grade product page; C = space/Hi-Rel device with performance below the CAVU floor or with controlled data not fully public; D = COTS/no radiation claim. “Meets” means the published evidence meets the stated floor for the parameter in question; it does not mean the assembled OBC has undergone equipment-level irradiation.

Procurement-grade discipline. Device family names and marketing grades are not used as substitutes for orderable-level radiation evidence. TI Space EP/SEP establishes a generic lower radiation envelope than the OBC 75 krad/75 MeV component criteria; specific SEP devices are credited with higher performance only when the exact orderable carries corresponding RHA/SEE data [R26]. QML/-SP, SEP and other space grades are therefore controlled by exact orderable, package and manufacturer radiation report.

Figure 2 — Published TID performance of the principal selected radiation-tolerant components.

Figure 3 — Published destructive-SEE/SEL performance of the principal selected radiation-tolerant components.

4mm Aluminum Shielding and Mission-Dose Boundary

The OBC-HYPER-POLAR enclosure uses a confirmed 4 mm aluminium wall. With an aluminium density of approximately 2.70 g/cm³, the nominal wall represents approximately 1.08 g/cm² areal density before local variations caused by machined pockets, fasteners, connector openings or heat-sink features are considered.

Figure 4 — Shielding geometry used as the mechanical input to mission-specific dose-depth analysis.

Figure 4a — Representative TID dose-depth attenuation for the 4 mm aluminium enclosure.

Figure 4b — Representative TID capability margin versus aluminium wall thickness.

The 4 mm aluminium enclosure provides approximately 1.08 g/cm² areal density before local mechanical variations. Figures 4a and 4b reproduce the CAVU product-family representative electron/bremsstrahlung dose-depth basis used in the TCU-RT radiation report: the 4 mm point corresponds to approximately 94 krad in that representative environment and about 1.1× margin against a 100 krad component capability. Absolute mission dose remains dependent on orbit, duration and particle spectrum and is closed by the applicable mission radiation analysis.

Tier Architecture Overview

Cross-Tier Radiation Performance Summary

Controlled Performance Boundaries

1. Commercial MPFS460T remains the compute device in Baseline through Tier 3. These tiers improve fault tolerance but are not equivalent to a fully RHA compute platform.
2. High-density space DDR4 provides 100 krad-class TID capability but the selected 4/8 GB device classes publish SEL thresholds around 61–63 MeV·cm²/mg. HYPER-POLAR RT contains this through SECDED/ECC, protected power islands and autonomous memory recovery.
3. No current space mass-storage component reproduces the baseline dual 256 GB eMMC capacity while simultaneously meeting the full 75 krad/75 MeV component criteria. HYPER-POLAR RT therefore separates critical boot/state from high-capacity mission-data storage and maintains bulk storage as a recoverable fault domain.
4. RTPFS460ZT procurement grade and manufacturer radiation evidence is controlled by the exact Tier 4 orderable and the Microchip screening flow referenced in the product EEE file.
5. Oscillators, level translators, supervisors, small-signal analogue devices and discrete semiconductors are controlled by exact orderable in the product EEE parts list. This report identifies the dominant radiation-performance devices and product-level containment mechanisms.

Tier Capability Matrix

Summary

OBC-HYPER-POLAR RT provides a cumulative, client-selectable radiation-performance product family from the baseline HYPER-POLAR architecture through the maximum-RT Tier 4 configuration. Each tier applies radiation-qualified or radiation-characterized devices to a defined set of functional domains while retaining common OBC interfaces, software architecture and autonomous fault-management behavior.

Tier 0 provides radiation-tolerant power containment. Tier 1 adds command/telemetry, SpaceWire and timing components. Tier 2 provides radiation-hardened boot NVM and the 4 GB MSS RT DDR4/SECDED configuration. Tier 3 adds 8 GB fabric RT DDR4 with ECC/EDAC, precision analogue acquisition, dual rad-hard Gigabit Ethernet PHYs and protected bulk-storage configurations. Tier 4 adds the RTPFS460ZT RT PolarFire SoC and provides the maximum-RT compute configuration.

Across the RT product family, boot and recovery state are separated from high-capacity storage; volatile memories and external PHYs are independently supervised and power-contained; ECC/EDAC, watchdogs, redundant interfaces and golden-boot recovery provide layered mitigation of recoverable SEE mechanisms. Manufacturer evidence and controlled performance boundaries are summarized in the full report.

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For more information, please view the RT PolarFire Device Family Enhancements Compared to PolarFire Devices Application Note.