PSU-Polar-3U

3U SpaceVPX Power Supply Card

SpaceVPX VITA 78 28 V Input VITA 62 Aligned >88% Efficiency

DESCRIPTION

The PSU-Polar-3U is a 3U SpaceVPX power supply card that converts the spacecraft 28 V DC bus (18 V – 36 V range, MIL-STD-704F) to the regulated 5 V, 12 V, and 3.3 V rails required by the SpaceVPX backplane utility plane. Aligned with VITA 62, it occupies a standard 3U SpaceVPX slot and delivers power directly via the P0/J0 utility connector without additional cabling. Over-voltage, over-current, over-temperature, and short-circuit protections are implemented on all output rails. The PSU-Polar-3U is radiation-tolerant and qualified for the temperature and vibration environments associated with LEO through GEO missions.

KEY FEATURES

28 V Bus Input: 18 V – 36 V DC input range — MIL-STD-704F spacecraft bus compliant
3 Regulated Outputs: 5 V / 20 A, 12 V / 8 A, 3.3 V / 5 A — all regulated, low-ripple
Full Protection Suite: OVP, OCP, OTP, SCP on all rails — autonomous latch-off and auto-restart
Inrush Limiting: Soft-start with controlled inrush current — meets MIL-STD-461 conducted emissions
Redundant Operation: Two PSU-Polar-3U in parallel provide N+1 redundancy — auto load-sharing
<50 mV Ripple: On all output rails at full load — meets SpaceVPX power quality requirements
>88% Efficiency: At full 5 V load — low thermal dissipation, minimal heat to chassis
VITA 62 Aligned: 3U SpaceVPX power slot — direct backplane P0 / J0 connection, no cabling
Input Isolation: 1,500 V input-to-output isolation — protects backplane from bus transients
Radiation Tolerant: >30 krad (Si) TID; latch-up immune power conversion components
Conduction-Cooled: VITA 48.2 wedge-lock — no airflow required
∼280 g: Low mass — negligible impact on system mass budget

INPUT SPECIFICATIONS

Input voltage: 18 V to 36 V DC (28 V nominal) — MIL-STD-704F Rev F
Input current: ≤12 A at 28 V nominal (full load)
Inrush current: <20 A peak — soft-start controlled
Input isolation: 1,500 V AC input-to-output — protects downstream backplane rail
EMI filter: Input pi-filter; meets MIL-STD-461 CE102 conducted emissions
Reverse polarity: Protected — no damage at −60 V reverse input
Hold-up time: >2 ms at full load (from 28 V input dropout)

OUTPUT SPECIFICATIONS

5 V rail: 5.0 V ±1% / 20 A / 100 W — primary SpaceVPX logic and OBC rail
12 V rail: 12.0 V ±1% / 8 A / 96 W — drive power (PolarStore), SpaceUM, payload
3 V rail: 3.3 V ±1% / 5 A / 16.5 W — auxiliary logic rail
Total output: ~212 W combined peak capability
Efficiency: >88% at full 5 V load; >85% at combined full load
Line regulation: <0.5% over full input voltage range (18 V – 36 V)
Load regulation: <1% from 10% to 100% load on each rail
Ripple / noise: <50 mV pk-pk on all output rails at full load (20 MHz BW)

PROTECTION & COMPLIANCE

Over-voltage protection (OVP): Latching OVP on all rails — trips at 110% of nominal; reset via power cycle
Over-current protection (OCP): Hiccup-mode OCP — folds back output, auto-restarts after fault clears
Short-circuit protection (SCP): Fully protected — no damage at all-rail short circuit
Over-temperature (OTP): Thermal shutdown at +110°C junction — auto-restart at +90°C
Under-voltage lockout (UVLO): Holds off outputs until input exceeds 17 V to prevent brown-out operation
Parallel operation: Current-share control bus supports N+1 redundant parallel PSU-Polar-3U pairs
TID tolerance: >30 krad (Si) — power conversion ICs and passives
Compliance: MIL-STD-704F (power input), MIL-STD-461 CE102 (EMI), VITA 62 (form factor)

MECHANICAL

Form factor: 3U SpaceVPX (VITA 62 aligned)
Slot profile: SLT3-PWR (power slot)
Dimensions: 100 × 160 mm (220 mm depth option)
Connector: VITA-46 MULTIGIG RT2
Cooling: Conduction-cooled, VITA 48.2 wedge-lock
Operating temp.: −40°C to +85°C
Mass: ∼280 g

COMPATIBLE SYSTEMS

SpaceVPX-BP-SS: Slot 1 or 2 power input
SpaceVPX-BP-DS: Single or redundant pair
OBC-Polar VPX: 5 V primary rail consumer
PolarStore-2S/4S: 5 V + 12 V consumers
PolarStore-2N/4N: 5 V + 12 V consumers
SpaceUM-Polar: 5 V consumer