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Bourns 6721 250µH Toroidal Inductor Equivalent & Substitute Parts
Part Overview
The Bourns 6721 is a 250µH shielded toroidal inductor rated for 8A continuous current with 41mOhm maximum DC resistance. This through-hole component features iron powder core construction and operates across the -55°C to 105°C temperature range. The part is classified as obsolete, making equivalent substitutes necessary for ongoing production and maintenance applications requiring 250µH inductance in toroidal form factor.
Substiute Parts
Key Parameters
| Parameter | Value |
|---|---|
| Inductance | 250 µH |
| Inductance Tolerance | ±15% |
| Current Rating | 8 A |
| DC Resistance (Max) | 41 mOhm |
| Core Material | Iron Powder |
| Shielding | Shielded |
| Mounting Type | Through Hole |
| Package Type | Radial, Vertical, 4 Leads (Open) |
| Operating Temperature Range | -55°C to 105°C |
| Test Frequency | 1 kHz |
Substitute Part Grouping Explanation
Substitution eligibility for the Bourns 6721 is determined by the following critical parameters:
- Inductance Value: Must be 250µH ±15% tolerance
- Core Type: Iron powder construction required for equivalent magnetic characteristics
- Shielding: Shielded configuration mandatory
- Mounting: Through-hole radial/vertical orientation
- Current Capacity: Minimum 8A rating required
- DC Resistance: Maximum 41mOhm preferred; higher values acceptable if circuit design permits
- Test Frequency: 1 kHz measurement standard
The API Delevan PT250-1800 meets all substitution criteria with enhanced current rating (9.1A) and comparable DC resistance (55mOhm max), making it a direct functional equivalent despite the obsolete status of the original part.
Parameter Comparison
| Parameter | Bourns 6721 | API Delevan PT250-1800 | Compatibility |
|---|---|---|---|
| Inductance | 250 µH | 250 µH | Match |
| Inductance Tolerance | ±15% | ±15% | Match |
| Current Rating (Amps) | 8 A | 9.1 A | Substitute exceeds requirement |
| DC Resistance (Max) | 41 mOhm | 55 mOhm | Substitute within acceptable range |
| Core Material | Iron Powder | Iron Powder | Match |
| Shielding | Shielded | Shielded | Match |
| Mounting Type | Through Hole | Through Hole | Match |
| Package Configuration | Radial, Vertical, 4 Leads (Open) | Radial, Vertical (Open) | Compatible |
| Test Frequency | 1 kHz | 1 kHz | Match |
| RoHS Status | Non-compliant | Non-compliant | Match |
| REACH Status | Unaffected | Unaffected | Match |
| ECCN Classification | EAR99 | EAR99 | Match |
Engineering Selection Recommendations
The API Delevan PT250-1800 is the qualified substitute for the obsolete Bourns 6721. Selection is based on:
- Product Status: The PT250-1800 maintains active production status, ensuring supply chain continuity and availability
- Electrical Equivalence: Identical inductance value and tolerance with superior current rating margin (9.1A vs. 8A requirement)
- Regulatory Alignment: Both parts share identical RoHS non-compliant, REACH unaffected, and EAR99 ECCN classifications, maintaining compliance posture across applications
- Physical Compatibility: Through-hole radial/vertical configuration with open lead design supports direct PCB layout substitution
- Thermal Performance: Operating temperature specifications are compatible for standard industrial applications
The 14mOhm increase in maximum DC resistance (55mOhm vs. 41mOhm) is within acceptable engineering tolerance for most power distribution and filtering applications. Circuit thermal analysis is recommended for high-current or thermally constrained designs.
Frequently Asked Questions (FAQ)
Q: Can the PT250-1800 be used as a direct drop-in replacement for the Bourns 6721?
A: Yes. Both parts share identical inductance (250µH ±15%), core material (iron powder), shielding, and through-hole mounting configuration. The PT250-1800 provides higher current capacity (9.1A vs. 8A) and is actively manufactured.
Q: What is the impact of the 14mOhm higher DC resistance in the PT250-1800?
A: The PT250-1800 exhibits 55mOhm maximum DC resistance compared to 41mOhm in the Bourns 6721. This results in approximately 34% higher resistive losses at rated current. For 8A operation, this translates to additional power dissipation of approximately 0.896W. Verify thermal performance in your specific application.
Q: Are there dimensional differences between these parts?
A: Yes. The Bourns 6721 measures 2.125" L × 1.100" W × 2.250" H (53.97mm × 27.94mm × 57.15mm). The PT250-1800 is 1.800" diameter × 0.770" W (45.72mm × 19.56mm). Verify PCB layout clearance and mounting hole spacing before substitution.
Q: Do both parts meet the same regulatory requirements?
A: Both parts are RoHS non-compliant, REACH unaffected, and classified as EAR99 for export control purposes. Regulatory posture remains unchanged with substitution.
Q: What is the inductance test frequency for both parts?
A: Both the Bourns 6721 and API Delevan PT250-1800 are tested and specified at 1 kHz, ensuring measurement consistency across datasheets.
Q: Is the PT250-1800 available in the same packaging as the Bourns 6721?
A: The PT250-1800 is supplied in bulk packaging, whereas the Bourns 6721 original packaging is not specified in available data. Verify packaging requirements for your procurement and assembly processes.
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