BLM18AG601SN1 PCB Design Guide: Footprint, Pinout, and Alternatives
600 ohm at 100 MHz general-use 0603 ferrite bead rated for 500 mA at 125 C.
BLM18AG601SN1 is a Murata 0603 ferrite bead specified at 600 ohm +/-25% at 100 MHz, 0.38 ohm maximum initial DCR, and 500 mA at 125 C. Murata positions the BLM_A series for impedance from relatively low frequencies through the hundreds-of-megahertz noise range.
The pleasant story is that a ferrite bead is a one-part EMI fix. The mechanism is frequency-dependent impedance: resistance and reactance change with frequency, DC bias, and temperature. The 600 ohm headline is one point at 100 MHz, not a flat resistor value and not guaranteed attenuation in your circuit.
Use the base identity for electrical design and retain B, D, or J for procurement packaging. Then validate insertion loss and rail behavior on the actual board; the current rating does not prove the bead still has the impedance you need at the operating point.
What breaks boards
600 ohm is specified at one frequency
Ferrite-bead impedance is frequency-dependent and includes resistive and reactive components. Do not use the 600 ohm at 100 MHz value as a DC resistance or a flat broadband attenuation figure.
The current rating is thermal, not a filtering guarantee
500 mA is the rated current at 125 C. DC bias and temperature change impedance, while DCR creates rail drop and heat; validate the actual frequency and current operating point.
This is not a universal signal-line part
Murata classifies BLM18AG601SN1 as a general-use BLM_A bead. It can distort fast edges or create resonance with nearby capacitance, so use frequency data and damping analysis before putting it in a high-speed signal path.
Packaging suffixes are not electrical variants
The base identity ends before the B, D, or J packaging code. Keep the exact reel/bag suffix in procurement, but do not invent different electrical ratings for those packaging choices.
Validate the complete filter network
Murata's bead rating does not include your source impedance, load impedance, bypass capacitors, or layout parasitics. Measure the assembled rail or model the full network before treating the bead as an EMI fix.
Key specifications
| Parameter | Value | Source |
|---|---|---|
| Impedance | 600 ohm +/-25% at 100 MHz | Murata product page and JENF243A_0003AN-01 |
| Rated current | 500 mA at 125 C | Murata product page and JENF243A_0003AN-01 |
| DC resistance | 0.38 ohm maximum initial; 0.48 ohm after testing | JENF243A_0003AN-01 part table |
| Package | 1608 metric / 0603 inch; 1.6 x 0.8 x 0.8 mm nominal with +/-0.15 mm dimensions | Murata product page |
| Operating temperature | -55 C to +125 C | Murata product page |
| Application class | General-use BLM_A series; impedance generated from relatively low frequencies for 30 MHz to several hundred MHz noise suppression | Murata product page Features |
Verified against the manufacturer datasheet on 2026-07-14. Confirm the current revision before production use.
Alternatives
- BLM18AG471SN1: Same general-use 0603 family with 470 ohm at 100 MHz and 550 mA at 125 C; re-evaluate the frequency response.
- BLM18AG102SN1: Same family with 1000 ohm at 100 MHz and 450 mA at 125 C; higher nominal impedance is not automatically better.
Common questions
- Is BLM18AG601SN1 a 600 ohm resistor?
- No. It is a ferrite bead whose impedance magnitude is specified as 600 ohm +/-25% at 100 MHz; DC resistance is 0.38 ohm maximum initially.
- Can I run 500 mA through it?
- 500 mA is the Murata rating at 125 C, but you still must check DCR loss, temperature rise, DC-bias impedance, and the frequency response needed by the circuit.
Sources
- BLM18AG601SN1 product pageMurata Manufacturing Co., Ltd. · verified 2026-07-14 · manufacturer
- BLM18 reference specificationMurata Manufacturing Co., Ltd. · JENF243A_0003AN-01 · verified 2026-07-14 · manufacturer
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