BLM18AG102SN1D Murata: Latest Datasheet & Key Specs

22 December 2025 0

BLM18AG102SN1D provides 1,000 Ω impedance ±25% at 100 MHz, 450 mA rated current and 0.5 Ω max DC resistance — making it a common 0603 ferrite bead choice for EMI suppression in compact designs. This part matters to PCB designers because it balances high-frequency attenuation with modest series loss, useful for power-rail noise control in consumer and industrial electronics.

The following synthesizes the latest datasheet highlights, practical layout and thermal guidance, verification steps and substitution rules so engineers can decide quickly whether the Murata bead fits their design constraints.

#1 — Quick background: What is BLM18AG102SN1D and where it fits

BLM18AG102SN1D Murata: Latest Datasheet & Key Specs

Core identity & key use cases

Point: BLM18AG102SN1D is a Murata BLM-series SMD ferrite bead in an 0603 (1608 metric) package used for targeted EMI suppression. Evidence: Datasheet nominal values show 1 kΩ impedance at 100 MHz and a 450 mA rated current. Explanation: That combination makes this bead ideal for single-line power filtering near ICs, choke function on sensitive signal traces, and decoupling chains where PCB real estate is limited. Refer to the Murata datasheet for official mechanical and electrical dimensions.

How this part compares inside Murata’s BLM family

Point: Within the BLM family, variants trade impedance, DC resistance and current handling. Evidence: Compared to lower-impedance 0603 beads, the 1 kΩ class raises high-frequency attenuation but increases series loss and thermal stress at high DC. Explanation: Choose this 1 kΩ@100 MHz bead when conducted noise sits in the 10–500 MHz band and available margin for series resistance is acceptable; choose lower-impedance BLMs for higher-current rails or where voltage drop must be minimized.

#2 — Datasheet highlights: Absolute electrical specs & performance

Electrical ratings (must include exact figures)

Point: Key absolute values determine allowable in-system use. Evidence: Impedance = 1,000 Ω ±25% @ 100 MHz; rated current = 450 mA (at upper operating conditions); DC resistance (max) = 0.5 Ω; single circuit. Explanation: These figures imply designers should derate working current for sustained thermal loading and verify insertion loss on populated boards rather than rely solely on free-air datasheet numbers.

ParameterValue
Impedance (100 MHz)1,000 Ω ±25%
Rated current450 mA
DC resistance (max)0.5 Ω
Package0603 (1608 metric)

Frequency response and EMI suppression behavior

Point: Ferrite beads show frequency-dependent impedance rather than a simple inductive response. Evidence: The datasheet impedance-vs-frequency curve peaks in the 10s–100s of MHz, delivering resistive damping where EMI energy concentrates. Explanation: For designers this means the BLM18AG102SN1D attenuates high-frequency noise effectively; however, impedance drops outside its optimal band and it should not be used where broadband low-frequency filtering is required.

#3 — Thermal, reliability & assembly guidance (practical design rules)

Thermal limits and rated current practice

Point: Operating temperature and current interact to change bead behavior. Evidence: Typical operating ranges span low-to-high ambient conditions and rated current is specified for acceptable deformation of characteristics. Explanation: Engineers should margin the 450 mA rating by accounting for PCB copper heat-sinking, ambient temperature, and duty cycle. Use temperature-rise measurements on a populated board to validate steady-state loss and avoid long-term impedance drift.

Soldering, footprint, and packaging notes

Point: Correct land pattern and reflow profile preserve performance and assembly yield. Evidence: Murata mechanical drawings list land pads for 0603 beads and recommend standard SnAgCu reflow thermal profiles. Explanation: Use manufacturer-recommended footprint to avoid tombstoning or lift; order in reel quantities for pick-and-place; treat as passive parts with typical handling and ESD precautions. Check the datasheet for exact pad dimensions before final PCB CAM.

#4 — Design examples & real-world application patterns

Typical circuit placements and layout best practices

Point: Placement determines effectiveness. Evidence: Practical layouts put the bead either at source (to block upstream noise) or at load (to protect sensitive ICs), often paired with a decoupling capacitor to form an RC notch. Explanation: Keep traces short on both sides, minimize parallel loops, place bead close to the pin being protected, and avoid adding series inductance that could form unwanted resonances with local capacitance.

Real-world use cases and measured results

Point: Measured attenuation and S-parameter tests validate choices. Evidence: Bench tests commonly show several dB to tens of dB reduction in conducted noise within the bead’s effective band. Explanation: Measure insertion loss and S21 on the populated board; use time-domain probing to verify ripple reduction on power rails. Remember the bead also adds small series resistance that can affect low-voltage rails under heavy load.

#5 — Sourcing, equivalents, and verification checklist (actionable next steps)

Where to get the official datasheet and how to verify part authenticity

Point: Always download the official PDF before release. Evidence: The manufacturer’s product information module and authorized distributors carry the latest revision. Explanation: Verify package code, ordering suffixes (e.g., reel or cut-tape variants), RoHS/REACH declarations and reel size. Cross-check markings and batch codes on samples against the manufacturer specification to ensure authenticity.

Cross-references and equivalent parts

Point: Substitutes require matching multiple parameters. Evidence: Equivalents must be compared on impedance at 100 MHz, rated current, DCR and package. Explanation: When swapping parts search for “ferrite bead 0603 1kΩ 450mA” and perform A/B tests on a pilot run to confirm thermal and EMI performance before wide substitution.

Summary

  • BLM18AG102SN1D is a compact 0603 Murata ferrite bead delivering ~1 kΩ impedance at 100 MHz with a 450 mA rating and 0.5 Ω max DCR, suitable for targeted EMI suppression near ICs and on power rails.
  • Designers should validate current derating and temperature rise on the populated PCB, pair the bead with nearby decoupling capacitors, and follow Murata land-pattern recommendations from the datasheet.
  • Before substituting alternatives, match impedance curve shape, DCR and thermal behavior, and run insertion-loss measurements on a prototype to verify real-world suppression.

Frequently Asked Questions

How should I validate BLM18AG102SN1D performance on my PCB?

Measure insertion loss (S21) on the populated board across the target frequency band and perform time-domain probing of the supply rail under representative loads. Compare measured impedance and temperature rise against expected datasheet behavior and adjust placement or add decoupling as needed.

What footprint and reflow considerations apply to this ferrite bead?

Use the Murata-recommended 0603 land pattern to minimize solder-attach issues; follow standard SnAgCu reflow profiles and control ramp rates to prevent tombstoning or excessive thermal stress. Handle reels with normal passive-component precautions and verify pad solderability on the PCB stack-up.

Which parameters are most critical when selecting an equivalent part?

Prioritize matching impedance at 100 MHz, rated DC current and maximum DC resistance, then verify the impedance-vs-frequency curve shape and thermal derating. Always pilot-test substitutes on a small production run to confirm EMI and power-integrity outcomes.