PSS6-5-5

FAQFrequently Asked Questions

• Can the PSS6-5-5 operate reliably when powered from a 5V USB source with voltage ripple and transient spikes? The PSS6-5-5 has a 4.5V minimum input specification, which places it near the lower boundary of typical 5V supply noise margins. USB sources commonly exhibit 200–500 mV peak ripple and transient undershoots during load changes. While the PSS6-5-5 will not latch up or fail catastrophically at momentary dips to 4.5V, sustained operation below 4.7V or repeated transients below 4.5V can cause output regulation loss and potential shutdown cycling. For reliable 5V USB input applications, use input filtering (ceramic capacitors rated ≥10 µF) and verify the source can deliver 1.2 A under worst-case load to maintain adequate margin. If the USB hub or port is marginal, consider a pre-regulation stage or a converter model with higher input minimums.
• What is the typical output impedance and transient response of the PSS6-5-5 when switching from no load to full 1A output? The PSS6-5-5 datasheet does not explicitly specify output impedance or transient overshoot magnitude. Typical isolated DC-DC modules in the PSS series exhibit output impedance in the range of 0.1–0.5 Ω at DC and transient overshoots of 5–10% (0.25–0.5V) during step-load changes, with settling times of 10–100 µs depending on feedback loop design. The remote on/off feature and OCP (over-current protection) indicate a control loop exists, but output capacitance and loop compensation are not published. For noise-sensitive applications (precision ADC front ends, RF subsystems), add a 10–47 µF low-ESR output filter capacitor close to the load, and perform bench characterization to confirm acceptable transient margins. If transient performance is critical, contact TDK-Lambda for detailed dynamic load models or select a rated module with published transient data.
• Is the PSS6-5-5 suitable as a backup or secondary 5V rail for a system that uses the main supply for load shedding? The PSS6-5-5 is rated for ITE (Information Technology Equipment) commercial applications and is designed for continuous-duty powering of embedded systems and peripherals. The remote on/off feature allows software-controlled enable/disable, making it suitable for load shedding or power-gating scenarios. However, the converter is not specifically rated for hot-swap, glitch-free switchover, or priority load sequencing. If the application requires seamless transition between primary and secondary 5V sources without momentary dropout, the PSS6-5-5 alone will not guarantee this—you will need external prioritization logic and hold-up capacitance on the output bus. The 5W power limit also means this converter cannot function as a replacement for the primary supply in systems requiring >5W at 5V; it is better suited for auxiliary rails, fan controllers, or sensor subsystems.
• Can the PSS6-5-5 be used in a 3.3V system as a regulated 5V intermediate supply for isolated I/O circuits or voltage-sensitive components? Yes, the PSS6-5-5 can accept 4.5–9V input, and many embedded systems with primary 5V rails or dual-rail supplies (5V + 3.3V) use a derived or auxiliary 5V bus as an intermediate. However, the PSS6-5-5 cannot be powered directly from a 3.3V source, as this falls below the 4.5V minimum input. If your system has 5V available, the PSS6-5-5 output (0–5V isolated) can supply isolated logic, gate drivers, or ADC reference voltage circuits. If only 3.3V is available as primary power, you would need a separate 3.3V to 5V boost converter upstream, or select a PSS model designed for lower input voltages. Verify isolated voltage ratings (input-to-output isolation typically 1–2 kV on PSS modules) against your system's EMC and safety requirements.
• What are the thermal and derating implications of operating the PSS6-5-5 at full 1A load in an enclosed chassis without forced airflow? The PSS6-5-5 is rated for -40°C to +85°C with derating, indicating that output current or power must be reduced above a specified internal junction temperature. At 84% efficiency and 5W output, approximately 0.95W of heat is generated internally. In a sealed or low-airflow enclosure, the module's case temperature will rise above ambient. TDK-Lambda does not publish a detailed derating curve in the brief spec, but similar 6W PSS modules typically require 50% derating above 70°C ambient or derate linearly above 50°C. For safe continuous operation at full 1A in an enclosed chassis, confirm ambient temperature will not exceed 60°C, or mount the module on a thermally conductive PCB with copper planes and verify case temperature during thermal characterization. If the chassis may reach 70°C or higher, reduce expected output current or add a small heatsink; alternatively, specify a larger PSS model or forced-air cooling.
• How does the PSS6-5-5 compare to the CC6-0505SF-E as a direct replacement, and what design changes would be needed? The CC6-0505SF-E is listed as a substitute in the datasheet. Both are 6-pin DIP isolated converters rated for 5V/1A output from a 4.5–9V input. The primary differences lie in packaging physical dimensions, internal compensation, and possibly isolation voltage. The PSS6-5-5 measures 1.12" × 0.80" × 0.31" (28.4 × 20.3 × 8.0 mm), while the CC6-0505SF-E may have a slightly different footprint; verify dimensions and pinout alignment before substitution. If replacing an existing PSS6-5-5 design with a CC6-0505SF-E, ensure PCB landing pads, mechanical clearance, and adjacent component spacing accommodate the alternate part. Both converters feature remote on/off and OCP; however, transient response, efficiency, and thermal characteristics may differ slightly, so bench-test the substitute under your full load and temperature range before production release. For mission-critical applications, cross-reference both datasheets and perform design verification rather than assuming full interchangeability.
• What is the isolation voltage rating between input and output on the PSS6-5-5, and is it suitable for safety-critical or high-voltage-adjacent applications? The PSS6-5-5 datasheet summary does not explicitly state the input-to-output isolation voltage rating. Typical PSS series isolated modules provide 1–2 kV isolation with reinforced insulation. Isolation voltage is essential in applications where input and output grounds are at different potentials (e.g., floating supply for gate drivers, multi-rail medical systems, or high-voltage measurement isolation). Before assuming the PSS6-5-5 meets isolation requirements for your application, obtain the full datasheet from TDK-Lambda or the distributor and verify: (1) the isolation voltage class and test method, (2) dielectric strength and breakdown characteristics, (3) any regulatory certifications (IEC 60950, UL, CSA). If the published isolation voltage is insufficient for your application, you may need a dedicated isolation barrier (optocoupler, isolated gate driver IC) or a different converter model. Do not assume isolation adequacy from the module form factor alone.
• Can the PSS6-5-5 be paralleled with other identical converters to increase output current beyond 1A? Paralleling multiple isolated DC-DC converters to increase total current is possible but requires careful design. The PSS6-5-5 is not explicitly rated for current-sharing or parallel operation. Without active current-sharing circuitry, mismatches in output voltage droop (a function of internal impedance and trim tolerance) will cause unequal current distribution—one module may source most current while others deliver minimal current, leading to unbalanced thermal load and potential converter damage. If higher output current is required, TDK-Lambda offers PSS models rated for 10W or higher (e.g., PSS10-5 series). Alternatively, passive current-sharing using small series resistors (0.1–0.5 Ω) and close output voltage monitoring can reduce imbalance, but this degrades regulation and adds complexity. For production designs requiring >5W at 5V, select a single higher-capacity converter rather than paralleling PSS6-5-5 units.
• What is the startup behavior of the PSS6-5-5 when the input voltage is ramped slowly from 0V to 9V? The PSS6-5-5 datasheet does not specify input ramp-rate tolerance or startup sequencing. Typical isolated converters begin switching operation once input voltage exceeds the minimum (4.5V) by a defined hysteresis margin, usually 0.3–0.5V. If input voltage rises slowly (ramp time >100 ms), the converter may oscillate in and out of a low-current mode during the ramp window. This behavior is generally non-destructive but can cause transient output glitches or false triggering of downstream logic. For controlled startup in systems with slow power-on sequences (e.g., hot-insertion or battery-powered startup), use the remote on/off control to hold the converter disabled until input voltage has stabilized above 5V. Verify startup timing and output ramp rate during prototype testing. If slow-ramp stability is critical, contact TDK-Lambda technical support for guidance or add input voltage-sensing circuitry to delay enable until supply is stable.
• Is the PSS6-5-5 suitable for automotive or vehicle applications with high transient input voltages (load-dump events)?? The PSS6-5-5 is rated for ITE (commercial information technology) applications with a 4.5–9V input range. Automotive systems, particularly 12V supplies, experience high-voltage transients during load-dump (generator disconnect) events that can exceed 40V for several milliseconds. The PSS6-5-5's 9V maximum input rating means it will not survive or regulate through such transients; the internal components (diodes, transformers) will be exposed to over-voltage stress and will likely fail. For automotive or industrial environments with harsh transients, select a converter specifically rated for automotive supplies (typically 7–32V with transient protection) or add input surge protection (varistor, TVS diode, ferrite choke) upstream. If retrofitting the PSS6-5-5 into an automotive design is unavoidable, implement input clamping (e.g., a 12V ideal-diode circuit or dual TVS diodes) to limit voltage to ≤9V. However, this adds cost and complexity; specifying an automotive-grade converter is the preferred approach.
• Does the PSS6-5-5 require a minimum load for stable output voltage regulation? The PSS6-5-5 datasheet does not specify a minimum load current or no-load stability. Many isolated DC-DC converters require 5–10% minimum load (50–100 mA for a 1A converter) to maintain stable output regulation due to feedback loop compensation and switching frequency constraints. No-load or very-light-load operation can cause output voltage to overshoot, drift, or oscillate. If your application includes periods of zero or very-light load (e.g., intermittent sensor reading, sleep states), verify that the PSS6-5-5 output remains within ±5% of nominal (4.75–5.25V) during these conditions. If output overshoot or drift occurs, add a small dummy load (10–50 mA resistor divider) to the output, or use a separate linear regulator (low-drop 5V LDO) downstream to clamp output voltage. Bench characterization under light-load conditions is recommended before production deployment.
• What filtering and decoupling is recommended on the PSS6-5-5 input and output to minimize conducted EMI and comply with industrial EMC standards? The PSS6-5-5 operates as an isolated switching-mode converter and generates high-frequency switching noise. Input filtering should include a 10–47 µF ceramic capacitor (≥16V rating) placed within 10 mm of the input pins to reduce input voltage ripple and suppress switching transients reflected back to the source. Output filtering should include a 10–47 µF ceramic capacitor (low ESR, ≥10V rating) at the output pins and a larger bulk electrolytic or ceramic capacitor (47–100 µF) nearby to handle transient load changes. For EMC compliance (EN 61000 industrial standards), add a common-mode choke (470 nH–2.2 µH) on the input and shield the converter module with Faraday shielding if high-frequency noise immunity is required. Trace layout should minimize loop area between input/output capacitors and module pins. The exact capacitor values and filtering topology depend on source impedance and load switching characteristics; refer to TDK-Lambda's application notes or perform conducted-emissions testing to verify compliance with your target standard (FCC Part 15, CE mark, etc.).
• Can the PSS6-5-5 be used in a redundant or N+1 supply configuration to improve system availability? The PSS6-5-5 is a single-output 5W converter and is not inherently designed for redundancy. In an N+1 configuration, two or more PSS6-5-5 units would supply the same 5V load, with automatic switchover if one converter fails. This requires additional external circuitry: ideal-diode OR-ing (e.g., LT4350 or equivalent), priority arbitration logic, and isolation between converter outputs if input supplies are separate. The remote on/off control simplifies disable logic during switchover. However, without published MTBF or failure-mode data, and given the 5W power limit per module, designing a robust redundant supply is complex and may not be cost-effective for non-critical systems. For mission-critical applications requiring redundancy, evaluate purpose-built redundant power modules (e.g., higher-capacity PSS or third-party solutions rated for N+1 operation) or specify dual independent supplies with manual or automatic transfer switch capability.
• What is the expected lifespan and reliability of the PSS6-5-5 in continuous industrial operation, and is there published MTBF data? The PSS6-5-5 datasheet does not provide published MTBF (Mean Time Between Failures), FIT (Failures in Time), or end-of-life projections. TDK-Lambda PSS series converters are industrial-grade modules with Moisture Sensitivity Level (MSL) 1 (unlimited humidity tolerance), suggesting robust component selection. Typical lifespans for quality isolated DC-DC converters under rated conditions (5V/1A, 25°C ambient) are 10–20+ years. Reliability in continuous operation depends on actual operating temperature, input voltage stability, and load cycling. At elevated temperatures (>50°C) or with frequent thermal cycling, electrolytic capacitors (if used internally) will degrade, potentially shortening lifespan. For industrial applications requiring quantified reliability, contact TDK-Lambda directly for MTBF, derating curves, and temperature-dependent failure-rate models. Implement preventive maintenance schedules (periodic testing, thermal monitoring) for mission-critical systems. The MSL 1 rating indicates the module can be stored indefinitely without moisture bake-out, a positive sign for supply-chain reliability.
• How should the PSS6-5-5 be protected against reverse-polarity input or accidental supply reversal during maintenance or field service? The PSS6-5-5 datasheet does not specify reverse-polarity protection or tolerance. Most isolated DC-DC converters lack internal reverse-polarity diodes and will suffer catastrophic failure (internal rectifier diodes short, transformer saturation, possible fire risk) if input polarity is reversed. To protect the PSS6-5-5 in field service environments, implement an external reverse-polarity protection circuit: a series Schottky diode (rated for input current and voltage) on the positive input line, or a P-channel MOSFET ideal-diode circuit with gate pull-down on negative input. Cost is minimal (1–2 USD for diode-based protection), and reliability improvement is substantial. Alternatively, use keyed connectors or polarized power input to prevent accidental reversal. For systems where the PSS6-5-5 may be field-replaceable or hot-swappable, adding reverse-polarity protection is strongly advised. Document protection diode forward-voltage drop (~0.3V for Schottky) in system power budget calculations.