Active production, 47 µH wirewound for DC-DC filtering
The Murata LQH32DN470K53L is a drum-core wirewound inductor in the LQH32 series, rated 47 µH at 1 MHz test frequency with ±10% tolerance. The 170 mA continuous current rating and 170 mA saturation current are matched — the core saturates at the same level the winding can carry, so derating is straightforward: the inductor stays in its linear region up to the full rated current.
DC resistance and self-resonant frequency — the real filtering limits
Maximum DC resistance is 1.69 Ohm. At 170 mA, I²R loss is about 49 mW — negligible for most circuits, but in a dense layout near a regulator the temperature rise adds to the ambient. The ferrite core material keeps core losses low below 1 MHz. Self-resonant frequency is 15 MHz. Above that, the inductor's parasitic capacitance dominates and the impedance drops — the effective filtering band stops well below 15 MHz. For a buck converter switching at 500 kHz to 2 MHz, this inductor works; for a 10 MHz switcher, the margin is too thin. The unshielded construction means magnetic flux radiates — keep sensitive analog traces or other magnetics at least 5 mm away in layout.
Package and land pattern — 1210 (3225 metric)
Standard reflow profile for a ferrite-core wirewound — peak temperature 260°C, no moisture sensitivity level concern for this construction. The footprint is common across the LQH32 series; verify the pad geometry against the recommended land pattern in the product drawing.