Power Distribution Network Analysis
0:48
Accessing knowledge base.
Here’s a concise classification of the four PDN-droop levels, each defined by its local L–C interface:
Table
| Droop Level | Location | L–C Interface | Key Characteristics |
|---|---|---|---|
| Zeroth (On-Die) | Within the silicon | On-die interconnect inductance & embedded capacitance | • Decoupling caps embedded in the die (< nH L, < nF C) |
| • Fastest transient response (ps–ns) | |||
| First (Chip-Package) | Chip package pins and balls | Bond-wire or paddle inductance (~1–5 nH) + package decoupling (1–10 µF) | • Handles die-to-package switching currents |
| • Response in ns–tens of ns | |||
| Second (Package-Board) | PCB land pattern & package footprint | Lead-frame or ball inductance (5–20 nH) + board-side decoupling (10–100 µF) | • Bridges package to board planes |
| • Response in tens–ns to hundreds-ns | |||
| Third (Board-VRM) | VRM output to PCB planes | Bulk inductance of VRM-to-plane path (10–100 nH) + bulk capacitance (100–1000 µF) | • Governs slowest transients (µs–ms) |
| • Sets overall voltage droop under load steps |
- Each level “droops” (voltage sags) under fast load steps until the next-closest L–C stage can respond.
- Proper PDN design ensures enough capacitance at each level so that the switching current is first met by the fastest (lowest-L) stage, then handed off progressively to bulk stages.
- Tuning L–C values at each interface (e.g., package caps, board ceramic arrays, bulk electrolytics) controls both the magnitude of droop and the transient-recovery time at that hierarchy level.
Package decap selection
Board decap selection
Bulk cap options
PDN impedance analysis
Simulate droop response
282 days
To get started, talk to Flux or create a New Document.
![USB type-C PD DFP [ALT_1_ML1&2PP] [Net Pri Set] thumbnail](https://img-cdn.flux.ai/eyJidWNrZXQiOiJncmF2aXRvbi1lbGVjdHJpYy1zeW1ib2xzIiwia2V5IjoiZG9jdW1lbnRfYXNzZXRzL1VTQi10eXBlLUMtUEQtREZQLWltYWdlLWI3MmJlN2NhLTQ4YzktNDc2Zi04ZWFlLTIzMjVhMmQ3YjUyNi5wbmciLCJlZGl0cyI6eyJyZXNpemUiOnsid2lkdGgiOjEzNiwiaGVpZ2h0IjoxMzYsImZpdCI6ImNvbnRhaW4iLCJiYWNrZ3JvdW5kIjp7InIiOjAsImciOjAsImIiOjAsImFscGhhIjowfX19LCJvdXRwdXRGb3JtYXQiOiJ3ZWJwIn0=)
Welcome 👋
Flux helps you build PCBs faster with an AI teammate!
Create your account to collaborate, stay updated, fork your own version, and get instant answers from our AI agent.