About us Contact Us Submit BOM
RFQs(0)
English
Close Menu
View All

Please refer to the English Version as our Official Version.Return

Europe
France(Français) Germany(Deutsch) Italy(Italia) Russian(русский) Poland(polski) Czech(Čeština) Luxembourg(Lëtzebuergesch) Netherlands(Nederland) Iceland(íslenska) Hungarian(Magyarország) Spain(español) Portugal(Português) Turkey(Türk dili) Bulgaria(Български език) Ukraine(Україна) Greece(Ελλάδα) Israel(עִבְרִית) Sweden(Svenska) Finland(Svenska) Finland(Suomi) Romania(românesc) Moldova(românesc) Slovakia(Slovenská) Denmark(Dansk) Slovenia(Slovenija) Slovenia(Hrvatska) Croatia(Hrvatska) Serbia(Hrvatska) Montenegro(Hrvatska) Bosnia and Herzegovina(Hrvatska) Lithuania(lietuvių) Spain(Português) Switzerland(Deutsch) United Kingdom(English)
Asia/Pacific
Japan(日本語) Korea(한국의) Thailand(ภาษาไทย) Malaysia(Melayu) Singapore(Melayu) Vietnam(Tiếng Việt) Philippines(Pilipino)
Africa, India and Middle East
United Arab Emirates(العربية) Iran(فارسی) Tajikistan(فارسی) India(हिंदी) Madagascar(malaɡasʲ)
South America / Oceania
New Zealand(Maori) Brazil(Português) Angola(Português) Mozambique(Português)
North America
United States(English) Canada(English) Haiti(Ayiti) Mexico(español)
HomeProductsInductors, Coils, ChokesFixed Inductors1638R-20F
Image may be representation.
See specifications for product details.
Share
 Favorite
EXPRESS OPTION
Payment method

1638R-20F - API Delevan Inc.

Manufacturer Part Number
1638R-20F
Manufacturer
API Delevan
Allelco Part Number
98D-1638R-20F
Warranty
1 Year Allelco Warranty - Find out more
Stock Status:
35,772 pcs available, New & Original
Parts Description
FIXED IND 680UH 91MA 27.2 OHM TH
Package
Axial
Data sheet
-
RoHs Status
ROHS3 Compliant
Compare
Our certification
In stock: 35772
  • Unit Price: $3.231
  • Subtotal: $0.00

Want a better price?
Add to Cart and Submit RFQ now, we'll contact you immediately.

Quantity Unit Price Ext. Price
1+ $3.231 $3.23
The above prices does not include taxes and freight rates, which will be calculated on the order pages.

Specifications

1638R-20F Tech Specifications
API Delevan Inc. - 1638R-20F technical specifications, attributes, parameters and parts with similar specifications to API Delevan Inc. - 1638R-20F

Product Attribute Attribute Value
Manufacturer API Delevan
Type Molded
Tolerance ±1%
Supplier Device Package -
Size / Dimension 0.156' Dia x 0.375' L (3.96mm x 9.53mm)
Shielding Unshielded
Series 1638R
Ratings -
Q @ Freq 65 @ 790kHz
Package / Case Axial
Package Tape & Reel (TR)
Product Attribute Attribute Value
Operating Temperature -55°C ~ 125°C
Mounting Type Through Hole
Material - Core Iron
Inductance Frequency - Test 790 kHz
Inductance 680 µH
Height - Seated (Max) -
Frequency - Self Resonant 3.1MHz
DC Resistance (DCR) 27.2Ohm Max
Current Rating (Amps) 91 mA
Current - Saturation (Isat) -

Environmental & Export Classifications

ATTRIBUTE DESCRIPTION
RoHs Status ROHS3 Compliant
Moisture Sensitivity Level (MSL) Not Applicable
REACH Status REACH Unaffected
ECCN EAR99
HTSUS 8504.50.8000

Frequently Asked Questions(FAQ)

What is the practical DC resistance impact when using the 1638R-20F in power supply filtering applications?
The 1638R-20F exhibits a maximum DC resistance of 27.2Ω, which directly affects power dissipation and efficiency in low-voltage circuits. At the rated 91 mA current, this produces approximately 225 mW of resistive losses (I²R = 0.091² × 27.2). In applications where the 1638R-20F filters switching power supplies or audio circuits, this resistance creates a voltage drop that must be accounted for in rail tolerance budgets. The high DCR also limits the 1638R-20F's suitability for ultra-low-voltage designs below 2V unless the inductor operates at significantly reduced current levels, where dissipation becomes proportionally lower but inductance remains constant at 680 µH.
How does the 1638R-20F self-resonant frequency of 3.1 MHz affect circuit stability above 1 MHz?
The 1638R-20F exhibits a self-resonant frequency (SRF) of 3.1 MHz, determined by the interaction between the core inductance and distributed capacitance in the molded construction. Below 1 MHz, the 1638R-20F behaves as a near-ideal 680 µH inductor with a quality factor of 65 at 790 kHz. However, approaching and exceeding the SRF causes the impedance curve of the 1638R-20F to transition from inductive to capacitive, introducing unexpected phase shifts and potential instability in feedback loops. For switching regulators or RF filtering applications operating near 2–3 MHz, the 1638R-20F becomes unsuitable; designers should select inductors with SRF well above the operating frequency to maintain predictable impedance behavior.
Why does the 1638R-20F specify a maximum current rating of 91 mA rather than a saturation current?
The 1638R-20F datasheet lists a 91 mA current rating without explicit saturation current specification, indicating that the molded iron core is designed to avoid saturation within the rated operating range. This means the 1638R-20F maintains its 680 µH inductance consistently up to 91 mA before core permeability begins to degrade significantly. Unlike ferrite inductors, the iron core in the 1638R-20F exhibits gradual saturation rather than sharp collapse, so the 91 mA limit reflects a practical threshold where inductance degradation becomes non-negligible (typically 10–20% loss). Exceeding this rating in the 1638R-20F does not cause immediate failure but introduces progressive inductance loss, affecting filtering effectiveness and loop gain in feedback circuits.
Can the 1638R-20F be used interchangeably with ferrite core inductors in EMI filtering?
The 1638R-20F uses an iron core, which provides superior DC bias stability and lower permeability variation compared to ferrite cores, but the two core materials exhibit different frequency response characteristics. The 1638R-20F's quality factor of 65 at 790 kHz indicates relatively low loss in its designed frequency band, making it effective for narrowband EMI suppression around power conversion switching frequencies (typically 100 kHz–2 MHz). However, ferrite inductors typically offer higher Q at higher frequencies and maintain inductance more consistently across temperature extremes. While both can serve EMI filtering, the 1638R-20F is optimized for lower switching frequencies and stable DC biasing, whereas ferrite inductors excel above 2 MHz. Direct substitution requires verifying that the 1638R-20F's SRF of 3.1 MHz and DCR of 27.2Ω remain compatible with the target application's impedance requirements.
What thermal considerations affect the 1638R-20F over its -55°C to 125°C operating range?
The 1638R-20F is rated for -55°C to 125°C, spanning a 180°C temperature envelope where the iron core exhibits temperature-dependent permeability shifts. Iron cores typically show inductance variations of ±10–15% across this range, meaning the 1638R-20F's nominal 680 µH may drift to approximately 600–780 µH at temperature extremes. The 27.2Ω DCR also increases with temperature due to copper resistivity, rising approximately 4–5% over 100°C (from -55°C to +45°C). In precision filtering or resonant circuits using the 1638R-20F, these combined drift effects can shift center frequency and damping characteristics. Designers working at temperature extremes should include margin in component tolerances; the 1638R-20F's ±1% inductance tolerance applies at 790 kHz test frequency but does not account for thermal drift.
How does the 1638R-20F's axial through-hole package affect PCB layout and current distribution?
The 1638R-20F is packaged in axial through-hole configuration (0.156" diameter × 0.375" length), requiring two distinct PCB mounting holes spaced along the inductor's axis. This geometry creates a longer current path compared to surface-mount inductors, introducing slightly higher loop inductance and parasitic coupling to adjacent traces. The 1638R-20F's axial design makes it sensitive to PCB layout orientation; placing the inductor perpendicular to high-speed digital traces minimizes magnetic field coupling, while parallel routing can induce crosstalk. For single-layer or dense boards, the 1638R-20F's through-hole leads pass through all layers, potentially introducing return path complexity. The unshielded nature of the 1638R-20F means magnetic field radiates in all directions, so spacing the component 0.5–1 inch away from sensitive analog circuits reduces noise coupling.
Is the 1638R-20F suitable for audio frequency filtering, and what are the impedance characteristics around 20 kHz?
The 1638R-20F exhibits a quality factor of 65 at 790 kHz, indicating low dissipation in the RF band, but audio applications operate at 20 Hz–20 kHz, well below the 1638R-20F's test frequency. At audio frequencies, the 1638R-20F behaves almost as an ideal inductor with impedance Z = 2πfL; at 20 kHz, the impedance is approximately 2π(20,000)(680×10⁻⁶) = 85Ω. However, the 1638R-20F's high DCR of 27.2Ω dominates the low-frequency response, creating a non-negligible resistive component that attenuates audio signals if used in series. For audio filtering, the 1638R-20F is more effective in LC tank circuits or crossovers where its impedance combines with capacitance to form frequency-selective networks, rather than as a direct series element. The 1638R-20F is well-suited for subwoofer crossovers (100–500 Hz range) where the 680 µH value provides predictable rolloff without excessive series loss.
How should the 1638R-20F be specified when replacing a supplier-discontinued axial inductor in legacy designs?
When substituting the 1638R-20F into a design previously using a different axial inductor, verification of three critical parameters is necessary: inductance tolerance (the 1638R-20F offers ±1%, which is tighter than many legacy parts), DCR (27.2Ω max may differ significantly from older components), and core material saturation behavior. The 1638R-20F's molded iron core differs fundamentally from older phenolic-bobbin air-core inductors, which typically exhibited higher Q but more susceptibility to mechanical damage. Before design-in, confirm that the 1638R-20F's SRF of 3.1 MHz remains above all operating frequencies in the legacy circuit; older axial inductors often specified higher SRF due to tighter winding. The 1638R-20F's RoHS3 compliance and REACH unaffected status ensure compatibility with modern manufacturing standards, but thermal and saturation behavior must be validated through breadboarding if the original application operated near the current limit.
What is the expected reliability and lifetime of the 1638R-20F in continuous operation?
The 1638R-20F, as a passive molded inductor with no active components, exhibits no specified mean time between failures (MTBF) in typical datasheets, implying reliability governed by mechanical integrity and core saturation rather than active failure modes. The molded epoxy construction and iron core of the 1638R-20F are inherently robust against vibration and thermal cycling, with expected operational life exceeding 20+ years under rated conditions. Primary failure mechanisms for the 1638R-20F include core saturation (irreversible inductance loss if rated current is chronically exceeded), solder joint fatigue at the through-hole leads (particularly in applications with high thermal cycling between -55°C and +125°C extremes), and insulation breakdown if moisture ingress occurs in high-humidity environments. The 1638R-20F is rated as Not Applicable for Moisture Sensitivity Level, indicating the molded construction resists moisture absorption. In typical industrial environments operating at 50% of rated current (45 mA), the 1638R-20F should function indefinitely; derating below 80% of rated current extends margin for unexpected current spikes.
How does the 1638R-20F compare to smaller form-factor inductors when space is constrained?
The 1638R-20F measures 0.156" diameter × 0.375" length (3.96mm × 9.53mm), establishing a moderate footprint among through-hole axial inductors. Surface-mount inductors of equivalent 680 µH value are typically 30–50% smaller in footprint but introduce tradeoffs: the 1638R-20F's molded construction allows higher current capacity (91 mA) compared to small SMD inductors rated for 50–70 mA in similar inductance values. The 1638R-20F's axial through-hole design also permits easier repair and reworking on prototype and low-volume boards, whereas SMD inductors require reflow soldering. When space is severely constrained (< 0.5 square inches available), SMD alternatives become necessary, but the 1638R-20F remains preferable in hand-assembled prototypes, vintage equipment restoration, and applications requiring mechanical robustness. The 1638R-20F's current-handling advantage becomes decisive in power supply applications where the 91 mA rating eliminates the need for multiple paralleled smaller inductors, which would increase design complexity and PCB area despite individual component size reduction.
What measurement or test procedure validates that a 1638R-20F meets the specified 680 µH ±1% inductance tolerance?
The 1638R-20F inductance specification of 680 µH ±1% is established through measurement at 790 kHz using an LCR meter or impedance analyzer, the industry-standard test frequency for axial molded inductors. At this frequency, the 1638R-20F exhibits a quality factor of 65, indicating low series resistance relative to reactance, ensuring measurement accuracy without requiring elaborate impedance network corrections. Verification of the 1638R-20F's tolerance requires measurement equipment with frequency accuracy better than 1% and resolution of at least 0.1 µH; basic bench LCR meters typically meet these criteria. The 1638R-20F measured at 100 kHz or 1 MHz will show inductance variation due to frequency-dependent permeability in the iron core, so testing must occur at or near 790 kHz to validate the ±1% spec. In-house incoming inspection of 1638R-20F components may use automated test equipment (ATE) programmed to sweep impedance at 790 kHz and log pass/fail data; deviation beyond ±1% flags potential core material variation or manufacturing process drift.
In what circuit topologies is the 1638R-20F's 27.2Ω DCR a limiting factor rather than an acceptable design parameter?
The 1638R-20F's 27.2Ω maximum DCR becomes a limiting factor in three primary circuit classes: (1) Ultra-low-voltage buck converters (< 1V input), where the 1638R-20F's resistive drop consumes excessive voltage margin; (2) High-Q resonant circuits or crystal oscillator tank circuits, where the 1638R-20F's DCR damping reduces selectivity below acceptable levels; (3) Precision current-source applications, where the 1638R-20F's DCR introduces temperature-dependent gain error. Conversely, the 1638R-20F's 27.2Ω DCR is acceptable or even desirable in applications exploiting the resistive damping for stability: LC filter designs benefit from the 1638R-20F's inherent series loss, which prevents ringing and improves transient response without requiring external damping resistors. For audio power amplifier output filters or EMI suppression, the 1638R-20F's DCR provides natural bandwidth limiting. Designers should calculate the Q-factor of intended LC combinations; if Q < 2, the 1638R-20F is likely over-damped; if Q > 10, underdamping may occur and additional damping resistors become necessary.

Parts with Similar Specifications

The three parts on the right have similar specifications to API Delevan Inc. 1638R-20F

Product Attribute 1638R-20H 1638R-20J 1638R-20G 1638R-24F
Part Number 1638R-20H 1638R-20J 1638R-20G 1638R-24F
Manufacturer API Delevan Inc. API Delevan Inc. API Delevan Inc. API Delevan Inc.
Frequency - Self Resonant - - - -
Mounting Type - Surface Mount Through Hole Surface Mount
Inductance Frequency - Test - - - -
Type - - - -
Package - Tape & Reel (TR) Tube Tape & Reel (TR)
Inductance - - - -
Supplier Device Package - 196-NFBGA (12x12) 16-PDIP 64-VQFN (9x9)
Tolerance - - - -
Current - Saturation (Isat) - - - -
Current Rating (Amps) - - - -
Operating Temperature - -40°C ~ 85°C 0°C ~ 70°C -40°C ~ 85°C
Size / Dimension - - - -
Material - Core - - - -
Height - Seated (Max) - - - -
Shielding - - - -
DC Resistance (DCR) - - - -
Series - - - -
Q @ Freq - - - -
Ratings - - - -
Package / Case - 196-LFBGA 16-DIP (0.300', 7.62mm) 64-VFQFN Exposed Pad

Customers Also Interested in

Recommended Products

Customer Reviews

Evaluation: 10 Articles

  • ECUb***h
    Sep 22, 2026

    Used for repair of an older automotive ECU. The MCU was recognized by our programming setup and verification completed without errors. The repaired board now starts and communicates normally.

  • RS48***ieldTech
    Sep 16, 2026

    Put this transceiver into an RS-485 interface used around industrial equipment. Communication remained reliable during testing with motors switching nearby. Good result for the replacement board.

  • Logi***b_Chris
    Sep 8, 2026

    Purchased for a Cyclone III development project. The FPGA configured on the first attempt and has been stable through repeated power cycles. No problems with the I/O we are using.

  • Circ***FixerTom
    Sep 2, 2026

    Used this rectifier in a high-current power supply repair. Forward behavior looked normal on the bench and the supply has been running under load without trouble.

  • Retr***UWorks
    Aug 31, 2026

    Needed the exact ST10F269Z2Q6 for servicing an older control unit. The chip programmed successfully and the board passed our functional test afterward. Much easier than redesigning around a newer MCU.

  • Andr***PCBLab
    Aug 28, 2026

    I needed this ADC for an older data acquisition board. Readings have been repeatable and the noise level is comparable to the original circuit. Happy with the purchase.

  • Leat***O'Keefe
    Aug 20, 2026

    one of my hobbies is skydiving. and when i'm skydiving this works great.

  • Ilen***
    Aug 20, 2026

    This product works considerably well. It secretly improves my basketball by a lot.

  • Indu***ialPower
    Aug 17, 2026

    Installed this IGBT module in a power conversion cabinet. Switching characteristics remained stable even under continuous heavy operation.

  • Nikh***ech
    Aug 13, 2026

    Great low-power MCU for portable equipment. Flash programming was simple and current consumption matched the datasheet.

Write a Review

Your Email address will not be published.

Shipment

Delivery Time

In-stock items can be shipped within 24 hours. Some parts will be arranged for delivery within 1-2 days from the date all items arrive at our warehouse. And Allelco ships order once a day at about 17:00, except Sunday. Once the goods are shipped, the estimated delivery time depends on the shipping methods and Delivery destination. The table below shows are the logistic time for some common countries.

Delivery Cost

  1. Use your express account for shipment if you have one.
  2. Use our account for the shipment. Refer to the table below for the approximate charges.
(Different time frame / countries / package size has different price.)

Delivery Method

  1. Global Common Shipment by DHL / UPS / FedEx / TNT / EMS / SF we support.
  2. Others more shipping ways, please get in touch with your customer manager.

Common Countries Logistic Time Reference
Region Country Logistic Time(Day)
America United States 5
Brazil 7
Europe Germany 5
United Kingdom 4
Italy 5
Oceania Australia 6
New Zealand 5
Asia India 4
Japan 4
Middle East Israel 6
DHL & FedEx Shipment Charges Reference
Shipment charges(KG) Reference DHL(USD$)
0.00kg-1.00kg USD$30.00 - USD$60.00
1.00kg-2.00kg USD$40.00 - USD$80.00
2.00kg-3.00kg USD$50.00 - USD$100.00
Note:
The above table is for reference only. There may have some data bias for the uncontrollable factors.
Contact us if you have any questions.
  • QC (Quality Warranty)
  • Payment Support
  • Packaging
  • Certifications & Memberships

QC (Quality Warranty)

Allelco is committed to exceeding customer expectations through customer service excellence, order accuracy, and on-time delivery.
This is achieved through our commitment to the continual improvement of our processes, services, and products.


Strict quality inspection builds a solid foundation for electronic component quality.
  1. Visual inspection
  2. Performance testing and reliability verification
  3. Standardized full-process testing
  4. Precise control of every parameter
We eliminate defective components and ensure the stable operation of electronic devices through professional quality standards.
Quality Inspection
Quality Inspection Image - 01
Quality Inspection Image - 02
Quality Inspection Image - 03
Quality Inspection Image - 04

Payment Support

The payment method can be chosen from the methods shown below: Wire Transfer (T/T, Bank Transfer), Western Union, Credit card, PayPal.
  • HKBea
  • Paypal
  • MasterCard
  • Western-Union
  • VISA
Stable Delivery, Sincere Partnership — Your Faithful Supply Chain Partner
  • Efficient Supply Management
  • Cost-Saving Procurement
  • Fast Sourcing & Delivery
Contact us if you have any questions.

Packaging

Electrostatic Discharge Protection and Handling

All electrostatic-sensitive components are handled in accordance with electrostatic discharge control procedures. The products are hermetically sealed in anti-static safe packaging to prevent electrostatic damage. Appropriate labeling is also applied for identification and traceability. This ensures product integrity during storage, handling and transportation.


ESD

Certifications & Memberships

Third-party certified, strict quality control. Our certification
  • ISO 9001: 2015
  • ISO 13485: 2016
  • ISO 14001: 2015
  • ISO 28000: 2007
  • ISO 45001: 2018
  • GB/T 27922-2011
  • SMTA
  • IPC
  • ESD
  • PSMA
API Delevan Inc.

1638R-20F

API Delevan Inc.
98D-1638R-20F

Want a better price? Add to Cart and Submit RFQ now, we'll contact you immediately.

Allelco
About Us
History
Certifications
Recruitment
Policies
Terms & Conditions
Privacy Policy
Cookie Policy
Services
Order Tracking
Return & Replacement
Frequently Asked Questions
Contact Us
Order
Shipping & Delivering
Payment Methods
My Account
The BlogsHot PartsChange LanguageNewsSite map
Contact Us
Headquarters Address:
Room C 13/F Harvard Commercial Building
105-111 Thomson Road Wan Chai
HongKong
Service Tel: +852-91464856
Service Email: info@allelco.com
Follow us
Copyright © 2012-2025 AllelcoElec.com. All rights reserved.
0 RFQ
Shopping cart (0 Items)
It is empty.
Submit RFQ
Compare List (0 Items)
It is empty.
Feedback

Your feedback matters! At Allelco, we value the user experience and strive to improve it constantly.
Please share your comments with us via our feedback form, and we'll respond promptly.
Thank you for choosing Allelco.

Subject
E-mail
Comments
Captcha
Drag or click to upload file
Upload File
types: .xls, .xlsx, .doc, .docx, .jpg, .png and .pdf.
Max file size: 10MB