The Knowles Syfer 1808JA250271JGRU2X is a Class X1/Y1 safety-rated ceramic capacitor designed for high-voltage AC line filtering and safety-critical applications. This component delivers 270pF capacitance with ±5% tolerance at 250VAC, utilizing C0G (NP0) dielectric technology in a surface-mount 1808 (4520 metric) package format.
The C0G/NP0 dielectric composition provides exceptional stability characteristics with zero temperature coefficient across the -55°C to 125°C operating range, making this capacitor suitable for circuits requiring predictable performance under varying thermal conditions. Unlike higher-K dielectrics that exhibit significant capacitance drift with temperature and voltage, the C0G formulation maintains stable electrical properties, which proves advantageous in precision timing circuits, EMI suppression networks, and safety-barrier designs where capacitance consistency directly impacts regulatory compliance.
This safety capacitor meets DC Annex H and Humidity 3B Annex I qualification standards, indicating robust performance under continuous DC voltage stress and extended high-humidity exposure. These certifications address common failure mechanisms in AC line applications where moisture ingress and sustained voltage bias can degrade insulation resistance and dielectric strength over time. The 250VAC rating positions this component for direct connection across mains supplies in industrial equipment, medical devices, and consumer appliances requiring IEC 60384-14 compliance.
The 1808 footprint (4.50mm × 2.00mm) offers a practical balance between capacitance density and PCB space utilization for multilayer ceramic capacitor construction. Surface-mount configuration enables automated assembly processes while maintaining adequate creepage and clearance distances for safety-critical isolation barriers. The tape and reel packaging facilitates high-volume manufacturing with MSL-1 classification, requiring no special handling or baking procedures before reflow soldering.
As an active production component with current inventory availability, the 1808JA250271JGRU2X serves applications in switched-mode power supplies, motor drives, medical isolation circuits, and household appliance input filters where regulatory safety agencies mandate certified X1 or Y1 capacitors between line-to-line or line-to-ground connections. The RoHS3 compliant and REACH unaffected status ensures procurement compatibility with current environmental directives across global markets.
Replacement Challenges for Knowles Syfer 1808JA250271JGRU2X Safety MLCCs
Replacing the Knowles Syfer 1808JA250271JGRU2X is not only a matter of matching “270 pF” and “1808 package.” This part is a safety-oriented high-voltage multilayer ceramic capacitor with C0G/NP0 dielectric behavior, 250 VAC rating, ±5% tolerance, surface-mount construction, and environmental robustness features such as DC Annex H and Humidity 3B Annex I. A suitable replacement must be checked against electrical rating, dielectric stability, safety approval context, PCB land pattern, termination style, soldering process, and availability.
Common equivalent or alternative part numbers to review include:
- Knowles Syfer 1808JA250271JGRU2X
- KEMET CAS21C271JARAC7800
- Murata KCA43C0G2E271J100AA
- Vishay VJ1808Y271JXCAT5Z
- Johanson Dielectrics 502R29N271JV4E
Some alternatives are closer safety-capacitor replacements, while others may only be suitable in non-safety high-voltage RF, filtering, or coupling positions. Before approving any substitute, the replacement part should be checked against the original schematic function, applicable safety standard, creepage/clearance requirement, and production qualification process.
What the Knowles Syfer 1808JA250271JGRU2X Defines in the Original Design
The Knowles Syfer 1808JA250271JGRU2X is a 270 pF ±5% ceramic capacitor rated for 250 VAC, using C0G/NP0 dielectric material in an 1808 package, also known as 4520 metric. Its physical size is approximately 4.50 mm x 2.00 mm, and it is supplied in Tape & Reel packaging for automated surface-mount assembly.
| Specification | Knowles Syfer 1808JA250271JGRU2X Engineering Relevance |
|---|---|
| Manufacturer | Knowles Syfer |
| Capacitance | 270 pF; affects filtering corner frequency, coupling impedance, EMI behavior, and resonant response |
| Tolerance | ±5%; suitable where capacitance accuracy affects signal or noise suppression performance |
| Voltage Rating | 250 VAC; replacement must be evaluated using AC rating, not only DC voltage rating |
| Dielectric | C0G, NP0; provides low temperature drift, low loss, and stable capacitance under voltage and temperature |
| Operating Temperature | -55°C to +125°C; replacement should support the same environmental range if used in industrial, power, or safety-related circuits |
| Package | 1808 / 4520 metric; influences PCB pad compatibility, creepage spacing, and mechanical fit |
| Mounting Type | Surface Mount MLCC |
| Features | DC Annex H, Humidity 3B Annex I, high-voltage construction |
| Application Category | Safety |
| Compliance | RoHS3 compliant, REACH unaffected, MSL 1 |
The C0G/NP0 dielectric is a key selection factor. Unlike X7R or other Class II ceramics, C0G/NP0 offers minimal capacitance variation with temperature, voltage bias, and aging. This makes the Knowles Syfer 1808JA250271JGRU2X suitable for positions where predictable impedance is needed, such as EMI suppression, safety-related coupling, high-voltage filtering, and stable low-capacitance AC line interface circuits.
The 250 VAC rating also affects replacement strategy. A capacitor with a higher DC voltage rating may not automatically replace a safety-rated AC capacitor. If the original part is used across a mains-related barrier or in a certified safety function, the replacement should have matching safety certification and documentation. If the part is used only in a non-certified high-voltage signal path, a high-quality C0G high-voltage MLCC may be acceptable after validation.
Candidate Alternatives to Knowles Syfer 1808JA250271JGRU2X for 270 pF 250 VAC C0G Applications
The following table compares practical replacement candidates for the Knowles Syfer 1808JA250271JGRU2X. The suitability of each part depends on whether the circuit requires certified safety performance, exact 1808 footprint compatibility, C0G/NP0 stability, or simply a high-voltage 270 pF ceramic capacitor.
| Manufacturer | Part Number | Key Specifications | Product Features | Typical Applications | Why It Can Replace the Original Part | Main Differences or Limitations | Recommended Usage |
|---|---|---|---|---|---|---|---|
| Knowles Syfer | 1808JA250271JGRU2X | 270 pF, ±5%, 250 VAC, C0G/NP0, 1808 SMD, -55°C to +125°C | Safety-oriented MLCC, high-voltage construction, DC Annex H, Humidity 3B Annex I, Tape & Reel | Safety filtering, EMI suppression, AC line-related coupling, high-stability high-voltage circuits | Original reference device; maintains electrical, mechanical, and qualification baseline | Availability and lead time may drive substitution review | Preferred choice where BOM continuity and qualification status must remain unchanged |
| KEMET | CAS21C271JARAC7800 | 270 pF, ±5%, safety-certified SMD MLCC family, C0G/NP0 class option, high AC safety application range | Designed for surface-mount safety capacitor use; suitable for compact AC-line filtering designs | Line-to-ground filtering, isolation-related capacitive coupling, power supply EMI reduction | Similar capacitance, tolerance class, safety-capacitor positioning, and SMD assembly format | Exact safety class, agency approvals, dimensions, and derating must be checked against the KEMET datasheet and certification files | Strong candidate when a safety-certified replacement is required and footprint review confirms compatibility |
| Murata | KCA43C0G2E271J100AA | 270 pF, ±5%, C0G dielectric, safety-certified ceramic capacitor family, SMD construction | Stable Class I dielectric, low loss, safety-standard-oriented design | AC adapter input filtering, isolated converter EMI control, equipment requiring safety-approved capacitors | Matches the original capacitance target and C0G stability while offering a safety-capacitor alternative | Package size and safety rating may not be identical to 1808; PCB pad and clearance review required | Suitable when Murata safety capacitor sourcing is preferred and mechanical validation is possible |
| Vishay | VJ1808Y271JXCAT5Z | 270 pF, ±5%, 1808 SMD ceramic capacitor, high-voltage/safety-oriented MLCC family depending on exact series configuration | 1808 package availability, stable ceramic option, Tape & Reel assembly support | High-voltage filtering, EMI suppression, coupling in compact SMD layouts | Similar capacitance and package class can simplify layout compatibility | Verify exact voltage, dielectric, and safety approval status before use in mains-related positions | Practical option for designs prioritizing 1808 footprint continuity and multi-source availability |
| Johanson Dielectrics | 502R29N271JV4E | 270 pF, ±5%, C0G/NP0, high-voltage ceramic capacitor, typically DC-rated rather than AC safety-rated | Low-loss Class I dielectric, high-voltage MLCC construction | RF coupling, high-voltage signal filtering, snubbers, instrumentation circuits | Electrical capacitance and dielectric behavior are close for non-safety high-voltage circuits | Not a direct replacement for certified safety capacitor positions unless approvals match the application requirement | Use only where the original capacitor is not serving a safety-certified AC mains function |
KEMET CAS21C271JARAC7800 and Murata KCA43C0G2E271J100AA are generally the most relevant alternatives when the replacement must remain within a safety capacitor category. Vishay VJ1808Y271JXCAT5Z may be attractive where 1808 footprint continuity is a priority, but approval details should be confirmed. Johanson Dielectrics 502R29N271JV4E can be useful in high-voltage non-safety circuits, especially where C0G stability and RF behavior matter more than AC safety certification.
Engineering Comparison of Knowles Syfer 1808JA250271JGRU2X Replacement Options
A replacement decision should consider how each candidate behaves in the actual circuit rather than relying only on nominal capacitance. The table below compares the alternatives from a practical engineering perspective.
| Comparison Factor | Knowles Syfer 1808JA250271JGRU2X | KEMET CAS21C271JARAC7800 | Murata KCA43C0G2E271J100AA | Vishay VJ1808Y271JXCAT5Z | Johanson Dielectrics 502R29N271JV4E |
|---|---|---|---|---|---|
| Electrical Compatibility | Baseline 270 pF ±5%, 250 VAC, C0G/NP0 | Close match if AC safety rating and C0G option are confirmed | Close capacitance and dielectric match; voltage and approval details need review | Good nominal capacitance match; voltage and safety class must be verified | Good capacitance and C0G behavior, but usually not equivalent for AC safety use |
| Mechanical Compatibility | 1808 / 4520 metric footprint | May be close, but confirm exact case dimensions | May require pad or spacing review depending on KCA package | 1808 package can support easier layout substitution | Package may differ by series configuration; footprint check required |
| Safety-Certified Replacement Potential | Original safety-oriented device | Strong candidate if certification matches the original application | Strong candidate for certified safety capacitor designs | Depends on exact Vishay series approval | Limited unless certification matches the circuit requirement |
| Dielectric Stability | C0G/NP0, low drift, low loss | Comparable if C0G version is used | Comparable C0G behavior | Comparable if C0G/NP0 construction is selected | Comparable C0G/NP0 stability |
| Performance Differences | Known reference performance | May differ in insulation resistance, impulse rating, and agency file coverage | May offer different safety class or package geometry | May differ in ESR/ESL and voltage qualification | Suitable for stable high-voltage capacitance, less suitable for safety barriers |
| Reliability Considerations | Qualified original with humidity and high-voltage features | Review manufacturer qualification data and safety approvals | Review Murata safety documentation and mounting stress recommendations | Review soldering profile, flex robustness, and rating details | Review DC derating, cracking risk, and application voltage waveform |
| Package Availability | Tape & Reel, active part status | Tape & Reel availability commonly supports production | Production-friendly SMD format | Tape & Reel option supports assembly continuity | Availability depends on distributor stock and voltage/package option |
| Cost Considerations | Baseline cost may be affected by availability | May reduce sourcing risk through alternate manufacturer | May vary depending on safety certification and supply channel | Often considered when footprint-compatible sourcing is needed | May be cost-effective for non-safety designs |
| Best Fit Scenario | Existing qualified BOM and safety-related designs | Safety replacement where documentation alignment is achievable | Designs needing a Murata safety MLCC alternative | Layout-constrained designs needing an 1808 substitute | Non-safety high-voltage signal or RF filtering applications |
| Main Limitation | Supply availability or lead time | Requires confirmation of exact approval equivalence | Possible mechanical or certification mismatch | Datasheet confirmation needed before safety use | Not a drop-in safety-certified AC replacement in many designs |
For a certified AC-line or isolation-related position, KEMET CAS21C271JARAC7800 and Murata KCA43C0G2E271J100AA should be evaluated first because they are closer in application intent to the Knowles Syfer 1808JA250271JGRU2X. Vishay VJ1808Y271JXCAT5Z is useful when keeping the 1808 footprint is a major constraint, provided its safety and voltage ratings match the design requirement. Johanson Dielectrics 502R29N271JV4E should be treated as a functional electrical alternative for non-safety high-voltage C0G applications rather than a universal safety capacitor substitute.
For replacement part pricing, lead time checks, and sourcing support, obtain quotations through IC-Components.com or contact Info@IC-Components.com.
