70F476AI-RC Equivalent & Substitute Parts

Part Overview

The 70F476AI-RC is a 4.7 µH unshielded drum core wirewound inductor manufactured by Bourns Inc., rated for 661 mA continuous current with a maximum DC resistance of 457mOhm. This through-hole axial component operates across the temperature range of -55°C to 105°C and is designed for applications requiring fixed inductance in the microhenry range.

The 70F476AI-RC is classified as obsolete. Identifying equivalent substitute parts is necessary to maintain design continuity, ensure supply chain availability, and support ongoing production or repair requirements for systems utilizing this component.

Key Parameters

Parameter	Value
Inductance	4.7 µH
Inductance Tolerance	±10%
Current Rating	661 mA
DC Resistance (DCR)	457mOhm Max
Core Type	Drum Core, Wirewound
Shielding	Unshielded
Mounting Type	Through Hole
Package / Case	Axial
Operating Temperature Range	-55°C ~ 105°C
RoHS Status	ROHS3 Compliant

Substitute Part Grouping Explanation

Substitution eligibility for the 70F476AI-RC is determined by the following critical parameters:

Inductance value: 4.7 µH with ±10% tolerance
Core type: Drum core wirewound construction
Shielding configuration: Unshielded
Mounting: Through-hole axial package
Current rating: Minimum 661 mA
DC resistance: Maximum 457mOhm
Operating temperature: Minimum -55°C to 105°C coverage
Regulatory compliance: ROHS3 compliant

The substitute part B78108S1472K009 meets these substitution criteria. It maintains the same inductance value and tolerance, uses equivalent drum core wirewound construction, and operates within compatible electrical and thermal parameters. The substitute provides enhanced current handling (820 mA) and lower DC resistance (340mOhm), making it suitable for direct replacement in applications where the original part is no longer available.

Parameter Comparison

Parameter	70F476AI-RC (Bourns)	B78108S1472K009 (EPCOS - TDK)	Compatibility
Inductance	4.7 µH	4.7 µH	Matched
Inductance Tolerance	±10%	±10%	Matched
Current Rating (Amps)	661 mA	820 mA	Substitute exceeds requirement
DC Resistance (DCR)	457mOhm Max	340mOhm Max	Substitute exceeds requirement
Core Type	Drum Core, Wirewound	Drum Core, Wirewound	Matched
Material - Core	Iron	Ferrite	Different material, equivalent function
Shielding	Unshielded	Unshielded	Matched
Mounting Type	Through Hole	Through Hole	Matched
Package / Case	Axial	Axial	Matched
Operating Temperature Range	-55°C ~ 105°C	-55°C ~ 125°C	Substitute exceeds requirement
Q @ Freq	43 @ 7.9MHz	60 @ 7.96MHz	Substitute provides higher Q
Frequency - Self Resonant	53MHz	95MHz	Substitute provides higher SRF
RoHS Status	ROHS3 Compliant	ROHS3 Compliant	Matched
Size / Dimension	0.150" Dia x 0.250" L (3.81mm x 6.35mm)	0.157" Dia x 0.362" L (4.00mm x 9.20mm)	Slightly larger footprint

Engineering Selection Recommendations

The B78108S1472K009 is an active product from EPCOS - TDK Electronics and qualifies as a direct substitute for the obsolete 70F476AI-RC. Both components maintain ROHS3 compliance and are suitable for equivalent circuit applications.

Selection between these parts should account for the following factors:

The substitute part provides superior electrical performance with higher current rating (820 mA vs. 661 mA), lower DC resistance (340mOhm vs. 457mOhm), and extended operating temperature range (-55°C to 125°C vs. -55°C to 105°C). The substitute also exhibits higher quality factor and self-resonant frequency.

Physical dimensions differ slightly. The B78108S1472K009 measures 0.157" diameter by 0.362" length compared to the original 0.150" diameter by 0.250" length. PCB layout verification is required to confirm fit within existing mounting footprints.

Core material differs: the original uses iron core while the substitute uses ferrite core. Both configurations deliver the specified 4.7 µH inductance with ±10% tolerance and maintain unshielded drum core wirewound construction.

Frequently Asked Questions (FAQ)

Q: Can B78108S1472K009 directly replace 70F476AI-RC in all applications?

A: The B78108S1472K009 meets all critical electrical parameters for substitution: matching inductance (4.7 µH ±10%), equivalent core construction (drum core wirewound), identical shielding (unshielded), and compatible mounting (through-hole axial). Physical dimensions are slightly larger, requiring PCB layout verification. Both components are ROHS3 compliant.

Q: What is the difference between iron core and ferrite core in these inductors?

A: The 70F476AI-RC uses iron core material while the B78108S1472K009 uses ferrite core material. Both achieve the specified 4.7 µH inductance value. The ferrite-core substitute exhibits higher quality factor (60 vs. 43 @ 7.96MHz) and higher self-resonant frequency (95MHz vs. 53MHz), which may provide performance advantages in high-frequency applications.

Q: Are there physical space constraints with the substitute part?

A: The B78108S1472K009 has a larger footprint: 0.157" diameter by 0.362" length versus the original 0.150" diameter by 0.250" length. Verify that the PCB layout and component spacing accommodate the slightly larger dimensions before implementation.

Q: Does the higher current rating of the substitute affect circuit compatibility?

A: No. The substitute's higher current rating (820 mA vs. 661 mA) and lower DC resistance (340mOhm vs. 457mOhm) represent performance improvements. These characteristics do not create incompatibility; they provide additional design margin for the application.

Q: What is the product status difference between these parts?

A: The 70F476AI-RC is classified as obsolete, making it unavailable for new orders. The B78108S1472K009 is an active product with current manufacturing and supply availability, ensuring long-term component sourcing for production and maintenance requirements.

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