Low Power / UPF · All levels

Supply Sets & Power States

Power Intent Fundamentals: UPF supply sets define electrical rails and legal state combinations; power states encode which domains may be ON, OFF, or RETAINED.

What this topic teaches

Supply Sets & Power States translates low-power intent into release-grade evidence. UPF supply sets define electrical rails and legal state combinations; power states encode which domains may be ON, OFF, or RETAINED. The practical challenge is proving policy correctness under real transitions and ensuring each owner closes their layer without semantic drift.

The senior-engineer question

When power-state coverage, illegal-state count, and mode transition pass rate regresses, can you identify the failing transition, policy owner, implementation evidence, and minimum regression that proves closure?

diagram

POWER INTENT FLOW — Supply Sets & Power States

architecture intent
      |
      v
UPF objects (domain/supply/state/strategy)
      |
      v
RTL + synthesis + PD interpretation
      |
      v
verification + signoff evidence
      |
      v
release decision

Primary metric: power-state coverage, illegal-state count, and mode transition pass rate

Picture the low-power flow

Start with domain/state diagrams before diving into logs. These are the models to sketch in design and interview reviews.

Supply set to power state table

diagram

SUPPLY / STATE TABLE

state         VDD_CORE   VDD_AON   meaning
-----------   --------   -------   -----------------------
RUN           ON         ON        full functionality
RETENTION     OFF        ON        context retained
DEEP_SLEEP    OFF        ON        minimum leakage mode

PST must match PMU legal transitions.

Domain map

diagram

POWER DOMAIN MAP — Supply Sets & Power States

  +------------------- always_on -------------------+
  | PMU / control / retention rail                  |
  +---------+----------------------------+----------+
            |                            |
   +--------v---------+         +--------v---------+
   | domain_A         |         | domain_B         |
   | switchable       |<------->| switchable       |
   | iso/ret controls | crossings require policy   |
   +------------------+         +------------------+

Domain boundaries are policy boundaries, not drawing boundaries.

State transition path

diagram

STATE TRANSITIONS — Supply Sets & Power States

ON  --save-->  RETENTION  --off-->  OFF
 ^               |                    |
 |               +----restore<--------+
 +--------------------power_up--------+

Guard checks:
  - isolation asserted before OFF
  - restore before functional traffic
  - reset policy consistent with retained state

Ownership layers

diagram

LP OWNERSHIP LAYERS — Supply Sets & Power States

layer                owns                          typical failure
------------------   ---------------------------   --------------------------
architecture         domain strategy               infeasible power states
UPF intent           policy objects + bindings     wrong/missing policy
implementation       LP cell insertion/routing     illegal physical behavior
verification         transition scenarios          uncovered LP bug
signoff governance   waiver + release decisions    late escape to silicon

Evidence to collect

Primary metric: power-state coverage, illegal-state count, and mode transition pass rate.
Primary artifact: UPF supply-set block, PST table, and simulator power-state report.
Owners to bring into review: low-power architect, UPF owner, verification owner.
One failing transition timeline with state markers and control signals.
One report snippet proving policy intent versus implementation behavior.

Ownership map

diagram

OWNERSHIP MAP — Supply Sets & Power States

artifact              owner
----------------      -----------------
intent policy       low-power architect
implementation      UPF owner
verification        verification owner

Escapes happen when ownership is implicit.

Subpages in this topic

Each topic is taught across mechanism, inputs/outputs, reports, debug, worked example, pitfalls, interview, checklist, theory, design space, expanded case study, walkthrough, comparison matrix, software view, and silicon impact.

Key takeaways

Always name the transition context for every low-power metric.
Bind each policy decision to a specific owner and artifact.
Re-run LP simulation, formal, and implementation checks after changes.

Common pitfalls

Treating static pass reports as transition closure.
Fixing symptoms without checking policy binding and sequence order.
Shipping with ambiguous ownership on open LP violations.

Low-power deep dive

Power intent must be explicit, reviewable, and tool-consistent from day one.

Concept diagram

diagram

POWER INTENT FLOW

architecture -> UPF objects -> tool binding -> verification evidence

Metric graph

diagram

INTENT QUALITY

bound policies      ████████████ high
stale references    ███          medium risk
missing states      ██           high risk

Reports and artifacts

PST report
domain map
UPF lint
policy binding summary

Mini case study

One missing PST entry blocked legal retention mode and caused false debug loops.

Debug branches

Check legal state table first
Audit policy binding IDs
Freeze UPF revision tags

Senior review question

Ask: what transition evidence proves this topic is closed, and which owner signs it?

Key takeaways

State transition context must accompany every low-power metric claim.
Intent changes require simulation, formal, and implementation re-validation.

Common pitfalls

Comparing results from mismatched UPF revisions.
Assuming static checks replace transition validation.
Shipping with aged waivers and unclear ownership.

Execution drill pack 1

Use this pack to rehearse low-power closure on low-power/power-intent-fundamentals/supply-sets-and-states: transition framing, policy ownership, implementation evidence, and release confidence.

Transition checklist

State transition explicitly named with legal source/target states.
Crossing and domain ownership are mapped and agreed.
Policy controls are traced to always-on source logic.
Waveform bookmarks align controls with state timestamps.

Review prompts

Which policy object is first to deviate from intent?
Which owner can apply the smallest reversible fix?
What regression matrix proves no collateral damage?
Which waiver conditions would still block release?

Evidence capsule

diagram

LP EVIDENCE CAPSULE 1

PATH: low-power/power-intent-fundamentals/supply-sets-and-states
STATE WINDOW: <from -> to>
POLICY OBJECT: <isolation / retention / shifter / switch>
OWNER: <name>
PRIMARY ARTIFACT: <report/waveform/formal result>
RELEASE DECISION: <close / bounded waiver / escalate>

Execution drill pack 2

Use this pack to rehearse low-power closure on low-power/power-intent-fundamentals/supply-sets-and-states: transition framing, policy ownership, implementation evidence, and release confidence.

Transition checklist

State transition explicitly named with legal source/target states.
Crossing and domain ownership are mapped and agreed.
Policy controls are traced to always-on source logic.
Waveform bookmarks align controls with state timestamps.

Review prompts

Which policy object is first to deviate from intent?
Which owner can apply the smallest reversible fix?
What regression matrix proves no collateral damage?
Which waiver conditions would still block release?

Evidence capsule

diagram

LP EVIDENCE CAPSULE 2

PATH: low-power/power-intent-fundamentals/supply-sets-and-states
STATE WINDOW: <from -> to>
POLICY OBJECT: <isolation / retention / shifter / switch>
OWNER: <name>
PRIMARY ARTIFACT: <report/waveform/formal result>
RELEASE DECISION: <close / bounded waiver / escalate>

Execution drill pack 3

Use this pack to rehearse low-power closure on low-power/power-intent-fundamentals/supply-sets-and-states: transition framing, policy ownership, implementation evidence, and release confidence.

Transition checklist

State transition explicitly named with legal source/target states.
Crossing and domain ownership are mapped and agreed.
Policy controls are traced to always-on source logic.
Waveform bookmarks align controls with state timestamps.

Review prompts

Which policy object is first to deviate from intent?
Which owner can apply the smallest reversible fix?
What regression matrix proves no collateral damage?
Which waiver conditions would still block release?

Evidence capsule

diagram

LP EVIDENCE CAPSULE 3

PATH: low-power/power-intent-fundamentals/supply-sets-and-states
STATE WINDOW: <from -> to>
POLICY OBJECT: <isolation / retention / shifter / switch>
OWNER: <name>
PRIMARY ARTIFACT: <report/waveform/formal result>
RELEASE DECISION: <close / bounded waiver / escalate>

Execution drill pack 4

Use this pack to rehearse low-power closure on low-power/power-intent-fundamentals/supply-sets-and-states: transition framing, policy ownership, implementation evidence, and release confidence.

Transition checklist

State transition explicitly named with legal source/target states.
Crossing and domain ownership are mapped and agreed.
Policy controls are traced to always-on source logic.
Waveform bookmarks align controls with state timestamps.

Review prompts

Which policy object is first to deviate from intent?
Which owner can apply the smallest reversible fix?
What regression matrix proves no collateral damage?
Which waiver conditions would still block release?

Evidence capsule

diagram

LP EVIDENCE CAPSULE 4

PATH: low-power/power-intent-fundamentals/supply-sets-and-states
STATE WINDOW: <from -> to>
POLICY OBJECT: <isolation / retention / shifter / switch>
OWNER: <name>
PRIMARY ARTIFACT: <report/waveform/formal result>
RELEASE DECISION: <close / bounded waiver / escalate>

Execution drill pack 5

Use this pack to rehearse low-power closure on low-power/power-intent-fundamentals/supply-sets-and-states: transition framing, policy ownership, implementation evidence, and release confidence.

Transition checklist

State transition explicitly named with legal source/target states.
Crossing and domain ownership are mapped and agreed.
Policy controls are traced to always-on source logic.
Waveform bookmarks align controls with state timestamps.

Review prompts

Which policy object is first to deviate from intent?
Which owner can apply the smallest reversible fix?
What regression matrix proves no collateral damage?
Which waiver conditions would still block release?

Evidence capsule

diagram

LP EVIDENCE CAPSULE 5

PATH: low-power/power-intent-fundamentals/supply-sets-and-states
STATE WINDOW: <from -> to>
POLICY OBJECT: <isolation / retention / shifter / switch>
OWNER: <name>
PRIMARY ARTIFACT: <report/waveform/formal result>
RELEASE DECISION: <close / bounded waiver / escalate>

Execution drill pack 6

Use this pack to rehearse low-power closure on low-power/power-intent-fundamentals/supply-sets-and-states: transition framing, policy ownership, implementation evidence, and release confidence.

Transition checklist

State transition explicitly named with legal source/target states.
Crossing and domain ownership are mapped and agreed.
Policy controls are traced to always-on source logic.
Waveform bookmarks align controls with state timestamps.

Review prompts

Which policy object is first to deviate from intent?
Which owner can apply the smallest reversible fix?
What regression matrix proves no collateral damage?
Which waiver conditions would still block release?

Evidence capsule

diagram

LP EVIDENCE CAPSULE 6

PATH: low-power/power-intent-fundamentals/supply-sets-and-states
STATE WINDOW: <from -> to>
POLICY OBJECT: <isolation / retention / shifter / switch>
OWNER: <name>
PRIMARY ARTIFACT: <report/waveform/formal result>
RELEASE DECISION: <close / bounded waiver / escalate>

Execution drill pack 7

Use this pack to rehearse low-power closure on low-power/power-intent-fundamentals/supply-sets-and-states: transition framing, policy ownership, implementation evidence, and release confidence.

Transition checklist

State transition explicitly named with legal source/target states.
Crossing and domain ownership are mapped and agreed.
Policy controls are traced to always-on source logic.
Waveform bookmarks align controls with state timestamps.

Review prompts

Which policy object is first to deviate from intent?
Which owner can apply the smallest reversible fix?
What regression matrix proves no collateral damage?
Which waiver conditions would still block release?

Evidence capsule

diagram

LP EVIDENCE CAPSULE 7

PATH: low-power/power-intent-fundamentals/supply-sets-and-states
STATE WINDOW: <from -> to>
POLICY OBJECT: <isolation / retention / shifter / switch>
OWNER: <name>
PRIMARY ARTIFACT: <report/waveform/formal result>
RELEASE DECISION: <close / bounded waiver / escalate>

Practice this lesson