# Power-rail sequencer

Canonical URL: https://eloragrid.ai/symbols/power-rail-sequencer
Publisher: Elora Grid
Updated: 2026-10-27
Lookup label: SEQ
Drawing use: Schematic
Reference families: Manufacturer

A power sequencer controls the order in which selected supply rails are enabled or disabled.

## In plain English

### What does Power-rail sequencer mean?

A power sequencer controls the order in which selected supply rails are enabled or disabled.

### A simple example

A controller board can bring its supplies up in the order required by its devices.

### What the drawings help you do

Show each rail-enable output and any feedback used to decide the next step. An ordered command is different from proof that a supply reached its intended condition. The drawing should therefore distinguish the requested sequence, actual rail voltages and the status inputs used by the controller.

### Before using this reference

- Identify each controlled rail and enable output.
- Show feedback used to advance or stop the sequence.
- Reference startup, shutdown and fault sequencing.

### Does enabling rail two prove rail one is ready?

Only if the selected sequence actually checks the required condition. A timed command alone and a feedback-qualified sequence provide different information, so show the implemented control method.

### Terms

- Rail: A named supply connection or voltage domain.
- Sequence: The defined order and conditions of the controlled actions.

Concept diagram: Start and supply-status inputs → Rail sequencing control → Ordered rail-enable outputs
Original functional explanation. Arrows show information or energy roles; two-headed arrows identify two-way interfaces. This is not a pinout, certified standards graphic or complete circuit.

- [Power supply sequencing](https://www.ti.com/product-category/power-management/sequencers/overview.html)


## What it represents

A power sequencer controls the order in which selected supply rails are enabled or disabled.
A controller board can bring its supplies up in the order required by its devices.
Show each rail-enable output and any feedback used to decide the next step. An ordered command is different from proof that a supply reached its intended condition. The drawing should therefore distinguish the requested sequence, actual rail voltages and the status inputs used by the controller. This is original functional artwork, not a certified standard graphic or device pinout.

## How to read it

- Identify each controlled rail and enable output.
- Show feedback used to advance or stop the sequence.
- Reference startup, shutdown and fault sequencing.
- An ordered enable signal does not itself prove that a rail reached its intended voltage.

## Information to show or reference

- Identify each controlled rail and enable output.
- Show feedback used to advance or stop the sequence.
- Reference startup, shutdown and fault sequencing.

## Important distinction

An ordered enable signal does not itself prove that a rail reached its intended voltage.

## Facts

- Representation type: Original functional block; not a certified IEC or IEEE graphic
- Concept input: Start and supply-status inputs
- Concept output: Ordered rail-enable outputs

## Public references

- [Power supply sequencing](https://www.ti.com/product-category/power-management/sequencers/overview.html) — Texas Instruments. Power supply sequencing: public technical context for the named function. Product and compliance details remain with the publisher.

## Graphic scope

Independent original educational concept illustration by Elora Grid. Not a certified standards graphic or manufacturer footprint. Unitless; not to scale. Original artwork licence: https://creativecommons.org/licenses/by/4.0/. Publisher material is linked only.