I’m repairing a laptop but I don’t know what value inductor to use/get. The schematic has values, I just don’t know how to interpret other than it’s a 2mm inductor. It’s labeled 5A_Z120_25M_0805_2P on a 1.35V line.
Electronic – Help Identifying Inductor From a Schematic
component-valuesidentificationinductorschematics
Related Solutions
Another school of thought is to forget the inductor and split ground plane. Instead use a solid plane, but use careful placement and routing to ensure the digital/analogue signals stay in their respective portions of the PCB.
According to the figure below, you can see (for high speed signals) most of the return current flows very close to the trace (x is distance from centre of trace, h is trace height above plane):
No time to go into more detail right now (will try and add more later) but here are a couple of excellent links on the subject:
Henry Ott - Mixed Signal Layout
TI - High speed Layout Guidelines
You're right in your assumption that those 'inductors' are simply ferrite beads. Some engineer has been lazy and didn't use a distinctive label/reference designator, although the ohms and amps do give it away somewhat.
Ferrite beads are characterized by their DC current rating and characteristic impedance at 100MHz, which is the ohms-value you read there. Their actual DC resistance is much lower, much less than 1 ohm typically.
Related Topic
- Help with basic inductor
- Electronic – Help me identify a component from EAGLE schematic
- Electronic – Identify an inductor on a PCB
- Electronic – TBD resistor & capacitor(TBD means “To Be Discussed”)
- Electronic – How to identify these capacitor values
- Electronic – Identify SMD capacitor value
- Electronic – Air gap for inductor core
Best Answer
Looks like something with 120 Ohms Impedance (z120) at 25MHz (25M) that can take 5 Amps (5A) in a 0805 Case (0805)
Close but not quite would be a Würth 742792025.