V28A5M175BG2

FAQFrequently Asked Questions

• Can the V28A5M175BG2 DC-DC converter operate reliably with a 12V industrial power supply that has significant ripple and transients? The V28A5M175BG2 accepts input voltage from 9V to 36V, which covers 12V supplies, but ripple and transient performance depends on input filtering. The converter includes UVLO (Under-Voltage Lock-Out) protection to prevent operation during voltage sags. For industrial supplies with >2V peak-to-peak ripple or fast transients, add a 100µF low-ESR bulk capacitor and a 10µF ceramic capacitor at the input, placed within 2 inches of the V28A5M175BG2 input pins. This combination attenuates common-mode noise and stabilizes the input rail during load transients, ensuring the UVLO threshold is not inadvertently crossed.
• What are the isolation voltage specifications and creepage/clearance requirements when integrating the V28A5M175BG2 into a 48V telecom application? The V28A5M175BG2 provides 3 kV isolation between input and output. This meets basic reinforced isolation requirements per IEC 60950-1 for circuits up to 300V peak input. However, in 48V telecom systems, the critical concern is the output return path isolation. The V28A5M175BG2 output is galvanically isolated from the input, but the converter housing and input return must be kept at the same potential as the primary ground reference. Maintain minimum 5mm creepage distance between the isolated 5V output circuitry and primary-side components. If your application requires double isolation (270V isolation rating), the V28A5M175BG2 single stage does not qualify; consider Vicor's multi-stage isolated modules or complementary isolation transformers.
• The V28A5M175BG2 draws 35A at 5V output—how do I properly route the output traces and connector pins to avoid voltage droop and thermal stress? 35A output current requires careful PCB design. Use multiple output traces (minimum 2oz copper weight) or a thick busbar rated for continuous 35A with <5mΩ resistance. Keep output trace length <3 inches from the V28A5M175BG2 to the load; longer runs risk 1.5V+ droop at full current. The V28A5M175BG2 output pins must terminate to a solid 5V power plane immediately beneath or adjacent to the package. Use four-point or six-point sense connections if available to compensate for wire and connector resistance. At maximum load, the 35A current generates I²R losses in the output path—verify that output connectors are rated for continuous 35A at your ambient temperature to prevent contact degradation.
• Can I replace a Meanwell RSP-150-5 (150W, 5V) with the V28A5M175BG2 in an existing design? The V28A5M175BG2 offers 175W continuous power at 5V (35A) compared to Meanwell RSP-150-5's 150W (30A), so power capacity is higher. However, key differences exist: the V28A5M175BG2 is isolated with 3 kV isolation and operates over -55°C to +100°C, while the Meanwell is non-isolated and typically rated to 50°C or 60°C. The V28A5M175BG2 requires 9V–36V input (no low-voltage operation below 9V), whereas the Meanwell accepts 85–264V AC input. Mechanically, the V28A5M175BG2 is a Full Brick module with through-hole mounting, not DIN-rail compatible. Electrically, you must account for 3 kV isolation in your output circuit topology; if your design assumes a non-isolated return path to input ground, additional isolation conditioning may be required. Performance-wise, the V28A5M175BG2's 76.8% efficiency is competitive for DC input modules, though lower than many 150W Meanwell units under light load. Direct replacement is not plug-and-play; validate input voltage source, output grounding scheme, and thermal environment.
• What happens if I exceed 35A output current or apply a short circuit to the 5V output of the V28A5M175BG2? The V28A5M175BG2 includes Over-Voltage Protection (OVP) but relies primarily on current limiting for short-circuit events. Under sustained short circuit or load >35A, the output will attempt to current-limit, but prolonged overdraw can cause thermal runaway in the converter's output stage. The V28A5M175BG2 is not rated for indefinite short-circuit tolerance. Implement external circuit protection: place a 50A polyfuse or electronic circuit breaker on the 5V output line, set to trip at 40–45A. Alternatively, use a dedicated 5V supply supervisor IC to monitor output voltage and trigger a shutdown signal to the V28A5M175BG2 if voltage sags below 4.7V, preventing sustained fault current. Without external protection, exceeding 35A for >10 seconds risks permanent damage to internal output rectifiers and control circuitry.
• Is the V28A5M175BG2 suitable for battery-backed 12V automotive or mobile power applications? The V28A5M175BG2 is designed for fixed DC input supplies in the 9V–36V range, not battery-backed mobile or automotive duty. Automotive 12V supplies exhibit cold-crank transients (voltage sag to <5V for 100–500ms) and load-dump spikes (up to 40–60V for microseconds). The V28A5M175BG2's UVLO will disable the converter during cold crank, and OVP may be insufficient to protect against load-dump transients. For automotive or battery-backed applications, use TVS diodes and bulk ceramic capacitors to clamp input voltage to <40V, and select a converter rated for cold-crank survival or add a boost circuit to maintain input >9V. The V28A5M175BG2 also operates from -55°C to +100°C, which covers cold-start survival, but the converter is optimized for ITE (Commercial) applications with stable 12V or 24V rails, not dynamic battery systems.
• How does the V28A5M175BG2 efficiency of 76.8% affect thermal design in a compact 1U rackmount chassis? At full 175W output with 76.8% efficiency, the V28A5M175BG2 dissipates ~52W as heat (175W ÷ 0.768 = 228W input; 228W − 175W = 53W loss, approximately). In a compact 1U enclosure (1.75 inches tall), this heat must be managed. The V28A5M175BG2 Full Brick package (4.6" × 2.2" × 0.62") requires forced-air convection; passive operation will exceed the +100°C maximum junction temperature within minutes. Establish an air intake directly over the V28A5M175BG2 with a 30–40 CFM axial fan, ensuring ≥6 inches of airflow across the module. Alternatively, mount the V28A5M175BG2 on a heatsink with ≥0.5°C/W thermal resistance. If ambient is +50°C and you require full 175W output, the internal junction may reach 50°C + (53W × 0.5°C/W) ≈ +76°C, staying within the +100°C max. Calculate margin conservatively; derate power 2–3% per °C above 25°C ambient.
• Can the V28A5M175BG2 be paralleled with another identical module to achieve higher current (70A) at 5V output? Paralleling two V28A5M175BG2 modules for higher current is not recommended without active current sharing. Both converters regulate their output to nominally 5.0V, but line and load regulation tolerances cause output voltages to drift independently (typically ±2–3% regulation). If one module outputs 5.1V and the other 4.9V, the 5.1V unit will force current through the 4.9V unit's output diode, causing circulating current and unequal load sharing. One module will carry >35A while the other carries <30A, violating the maximum current rating and risking failure. To parallel safely, implement cross-wired current-sharing: connect a small sensing resistor (≤0.1Ω) in series with each output, and wire the sense signals to active load-share control logic that modulates the feedback of each converter to maintain equal current. Alternatively, specify a single high-current converter such as Vicor's 350W or 400W isolated module rather than paralleling two 175W units.
• What is the startup behavior and inrush current of the V28A5M175BG2 when powered up with the system at full load? The V28A5M175BG2 uses a soft-start internal circuit to limit inrush current during power-up. Typical inrush is ≤2–3× nominal input current, lasting 10–50ms, depending on input capacitance and load conditions. With a fully charged input filter capacitor and maximum output load applied at startup, inrush can reach ~150–200A peak into the input supply. If your 12V or 24V supply has weak current capability or high source impedance, this inrush will cause input voltage to sag below the UVLO threshold, preventing the V28A5M175BG2 from starting. Mitigation: place a 100µF low-ESR capacitor at the V28A5M175BG2 input to absorb inrush energy and maintain input voltage above UVLO. For systems with multiple load transients or frequent cycling, measure the actual inrush using a current probe; if inrush exceeds supply capability, add series input inductance (10–20µH ferrite-core inductor) to limit dI/dt.
• The V28A5M175BG2 has a Full Brick form factor—are there drop-in replacement modules with the same pinout from other vendors? The V28A5M175BG2 follows Vicor's proprietary Full Brick pinout, which is not a standardized industrial format like DIN or IEC. Other Vicor 175W or similar-power isolated modules in the Maxi series share pinouts, but cross-vendor replacements (e.g., Murata, RECOM, TDK) do not maintain pin compatibility. If you need to replace the V28A5M175BG2 with an alternative, you must re-design the PCB layout: verify input/output pin locations, signal polarity (remote on/off, enable), and sense connections. Before committing to an alternative, confirm that the replacement module accepts 9V–36V DC input, delivers 5V at 35A, and provides equivalent 3 kV isolation. Some alternatives may sacrifice efficiency, thermal performance, or operating temperature range; benchmark efficiency and thermal resistance at your duty cycle before switching. Staying with Vicor's modular ecosystem (V28A series) ensures pin compatibility and consistent software for power management interfaces.
• How do I configure the enable/disable control and remote sensing on the V28A5M175BG2, and what is the input impedance of the control lines? The V28A5M175BG2 provides enable/disable logic control via a dedicated pin. The exact pin function and input impedance depend on module configuration; consult the specific pinout diagram in the Vicor V28A5M175BG2 datasheet. Typically, enable pins are CMOS-compatible logic inputs with high impedance (≥1MΩ). To disable the converter, pull the enable pin to ground or supply a low logic level; ensure the control signal source can sink <1mA. For remote on/off, use an isolated GPIO from a microcontroller with a 10kΩ pull-up resistor to +5V or +3.3V rail (depending on module configuration). Remote sense (if available) allows voltage compensation for output cable drop; two sense wires connect to the 5V output at the load, allowing the converter to boost output voltage slightly to maintain 5V at the load terminals. If sense is not used, tie sense leads to the local output pins. Floating sense leads or open circuits may cause output voltage instability; verify all control and sense signals are properly terminated per datasheet.
• What is the mean time between failures (MTBF) for the V28A5M175BG2, and how does operating temperature affect reliability? Vicor publishes MTBF data for the V28A5M175BG2 series based on industry-standard models (MIL-HDBK-217 or Telcordia). Typical MTBF values are 100,000–300,000 hours at +25°C ambient, depending on operational stress. MTBF decreases significantly at higher temperatures; for every 10°C rise above 25°C, electrolytic capacitor lifetime halves. At +70°C ambient (common in enclosed equipment), MTBF may drop 30–50% due to accelerated capacitor aging. The V28A5M175BG2's operating range extends to +100°C, but continuous operation at or near this limit degrades capacitors within 2–3 years. For long-term reliability in industrial settings, operate the converter at ≤+60°C ambient. Calculate the internal junction temperature: if ambient is +50°C and power dissipation is 50W, junction ≈ +50°C + (50W × thermal resistance). Design for 15–20°C margin below +100°C to achieve 5–10 year MTBF targets. Implement conformal coating on the PCB to reduce moisture-induced failures in humid environments.
• Can the V28A5M175BG2 survive transient overvoltage events (e.g., 45V spikes on the input rail) without damage? The V28A5M175BG2 maximum input rating is 36V continuous. Input spikes above 36V will likely exceed the internal overvoltage protection threshold and trigger a shutdown; repeated spikes may degrade internal clamp circuitry. A single >45V transient lasting >10µs could cause latchup or permanent input stage failure. To protect the V28A5M175BG2, install a transient voltage suppressor (TVS) diode or varistor across the input, rated to clamp at 40–42V and handle the expected transient energy (e.g., 5W TVS or MOV). Choose a TVS with response time <1ns and energy rating ≥10J to survive automotive or industrial load-dump events. Alternatively, use a series input inductor (10–20µH) plus a shunt TVS; the inductor limits dV/dt, and the TVS clamps absolute voltage. Test the protection circuit with actual transient waveforms from your power supply to ensure adequate margin. Without input transient protection, the V28A5M175BG2 reliability in noisy industrial environments is at risk.
• What is the minimum hold-up time or holdup energy if input power is suddenly removed while the V28A5M175BG2 is running at full load? The V28A5M175BG2 does not specify a hold-up time; it will shut down immediately when input voltage falls below the UVLO threshold (typically ≈8V for a 9V–36V module). There is no internal energy storage or super-capacitor to sustain the 5V output after input loss. If your application requires continued 5V output during brief input power interruptions (e.g., during power supply switching or line transients), you must add external hold-up capacitance at the output. Calculate required capacitance: C = (I × Δt) / ΔV, where I is load current (35A), Δt is hold-up time needed (ms), and ΔV is acceptable voltage sag (e.g., 0.5V). For 10ms hold-up with 35A load and 0.5V sag: C ≈ (35A × 0.01s) / 0.5V ≈ 700µF. Use low-ESR ceramic or polymer capacitors to minimize voltage ripple during discharge. Place hold-up capacitors within 1 inch of the load to minimize inductive coupling effects.
• The V28A5M175BG2 is rated for -55°C to +100°C—how does efficiency and output regulation change at extreme temperatures? At -55°C, the V28A5M175BG2's switching frequency and control loop response may shift due to semiconductor parameter drift. Output voltage regulation typically widens to ±5–7% over the full temperature range versus ±3–4% at +25°C. Input-to-output voltage regulation may also degrade, meaning output droop under full-load transients increases at extreme cold. At -55°C, efficiency may drop 2–3% due to increased parasitic resistances and reduced transistor switching efficiency. Conversely, at +100°C, efficiency drops 3–5% as switching losses increase. For applications operating outdoors or in thermal chambers at -55°C, validate that the V28A5M175BG2's output voltage remains within ±5% of 5.0V under full load before committing design. If tighter regulation is required at extreme temperature, add a downstream LDO (Low Drop-Out) regulator to fine-tune the output to ±1–2%. Note that efficiency loss at extreme temperature means more heat dissipation; at -55°C, power loss may rise to 60W, requiring active cooling even in cold environments if full 175W output is sustained.
• Is the V28A5M175BG2 suitable for use in a redundant or N+1 hot-swap power architecture? The V28A5M175BG2 can be part of an N+1 redundant supply, but certain conditions must be met. For hot-swap (inserting a live converter while others are powered), implement diode ORing: place a Schottky diode (≥40A rating, low forward drop ≤0.3V) in series with each V28A5M175BG2 output. When one module is pulled for replacement, its diode blocks backfeed current from the OR bus to the removed module. The OR bus voltage will be set by the remaining modules' 5V output (a slight diode drop below nominal 5V). This topology works if all V28A5M175BG2 modules are identical and have synchronized outputs. If outputs drift due to component tolerances, the diode with lower forward drop will carry most current, leading to unequal loading. Use active current sharing with control feedback to all modules to maintain balanced current in N+1 architectures. Ensure that any external protection (circuit breaker or eFuse) can survive the inrush from a newly inserted module; otherwise, implement a soft-start ramp on insertion.
• How should I handle the V28A5M175BG2 return path and ground star point in a mixed-signal application with analog sensing and digital logic? The V28A5M175BG2's 3 kV isolation galvanically separates input and output grounds. In a mixed-signal system, maintain a single star point on the output side where analog return, digital return, and power return converge. Do not split the 5V return into separate analog and digital traces; instead, run all returns to a common ground plane beneath the V28A5M175BG2 output section, then bring a single return wire from that plane to any external sensors or analog signal conditioning. This prevents ground bounce and differential-mode noise between analog and digital circuits. The input side (primary ground) must remain isolated from the output star point. If your system requires a reference voltage tied to both input and output grounds, use an optoisolator or isolated ADC to bridge the 3 kV isolation barrier. Failure to maintain proper grounding star points will couple noise across the isolation barrier via parasitic capacitance, degrading ADC accuracy and potentially saturating input clamp diodes at extreme noise levels.
• Can I derate the V28A5M175BG2 for high-altitude operation, and what are the cooling implications above 10,000 feet? At high altitude (>10,000 feet), ambient air density decreases, reducing cooling effectiveness for convection-cooled devices. The V28A5M175BG2 Full Brick package relies on forced-air or free-convection cooling. At 20,000 feet, air density is approximately 40% of sea-level value, so natural convection cooling effectiveness drops proportionally. If the module is cooled by ambient air circulation, airflow velocity must increase 2–2.5× to maintain the same heat transfer at altitude. For systems operating above 10,000 feet, derate the V28A5M175BG2 power output 3–5% per 5,000 feet of altitude gain, or increase forced-air cooling intensity. Alternatively, use a liquid cooler or increase heatsink surface area. Additionally, verify that the V28A5M175BG2's MTBF calculation accounts for elevated operating temperature at altitude; if cooling fails due to reduced density, the converter may thermally throttle or shut down. For aerospace or high-altitude applications, specify the V28A5M175BG2 with derating curves provided by Vicor for your intended altitude.
• What EMI/RFI emissions can I expect from the V28A5M175BG2, and what filtering is needed to meet FCC Part 15B? The V28A5M175BG2, as an isolated DC-DC converter, generates high-frequency switching noise typically in the 100kHz–1MHz range and harmonics. Without proper filtering, conducted emissions (on power supply rails) and radiated emissions (from output cable harness) can exceed FCC Part 15B limits. To comply with FCC Part 15B Class B (commercial): (1) Install a 3-stage EMI filter on the V28A5M175BG2 input: a common-mode choke (10–100µH), a differential-mode inductor (2–5µH), and capacitors (high-frequency ceramic 10µF + electrolytic 100µF) to attenuate switching harmonics below 150kHz. (2) Shield the V28A5M175BG2 with a copper Faraday cage or aluminum enclosure. (3) Route the output cable as twisted pair or ribbon cable with shield grounded at both ends to the output star point. (4) Conduct emissions testing on a shielded test bench with spectrum analyzer to verify compliance below -20dBµV across 150kHz–30MHz. If conducted emissions exceed limits, add series output inductance (ferrite beads or choke) to further attenuate high-frequency switching currents. Many OEMs apply ferrite-core common-mode filters rated for 35A continuous to the output cable directly adjacent to the load connector.
• If I need to migrate from V28A5M175BG2 to a higher-power solution in the future, what are the modular options and pin compatibility considerations? Vicor offers higher-power isolated DC-DC modules in the Maxi (250W–500W) and larger form factors. The V48A5M250 (250W, 5V, 50A output) shares the same Full Brick pinout with the V28A5M175BG2, allowing a direct board-level upgrade if thermal and mechanical constraints permit. Input voltage range remains 9V–36V (or configurable variants), and isolation is standardized at 3 kV. However, the V48A5M250 is physically larger (requires PCB layout adjustment) and generates more heat (~75W at full power), demanding more aggressive cooling. If you anticipate future power growth >250W, consider board design that allocates extra heatsink area or integrates a modular fan connector from the outset. For a longer-term modular approach, design the input supply, output filtering, and load architecture to be converter-agnostic: use a standardized connector pattern and power distribution scheme that accepts any Vicor Full Brick or Maxi module. This future-proofs your platform against obsolescence and allows rapid technology insertion as Vicor releases new, higher-efficiency modules. Document the mechanical and electrical interfaces (pinout, power limits, control signals) to ease migration.