Mermaid:Mechanic L1 Pro Failure Sequence - Revision history

Polymorphic7: resized

2026-09-09T22:01:41Z

resized

← Older revision		Revision as of 22:01, 9 September 2026
Line 1:		Line 1:
			%%{init: {'theme':'default', 'sequence': {'width': 50, 'height': 30, 'actorMargin': 20, 'boxMargin': 5, 'messageFontSize': 10, 'noteFontSize': 10}}}%%
	sequenceDiagram		sequenceDiagram
	participant User		participant User

Polymorphic7 at 22:00, 9 September 2026

2026-09-09T22:00:36Z

← Older revision		Revision as of 22:00, 9 September 2026
Line 7:		Line 7:

	User->>PowerButton: Turns lamp ON directly		User->>PowerButton: Turns lamp ON directly
	Note over PowerButton,QX9920: Timer bypassed - no auto cutoff scheduled		Note over PowerButton,QX9920: Timer bypassed -<br/>no auto cutoff<br/>scheduled
	PowerButton->>QX9920: VIN applied, EN held high continuously		PowerButton->>QX9920: VIN applied, EN held<br/>high continuously
	QX9920->>Q1: DRV switches gate at full duty~~, cycle after cycle~~		QX9920->>Q1: DRV switches gate<br/>at full duty
	Q1->>LED: Sustained drive current, no rest ~~period~~		Q1->>LED: Sustained drive<br/>current, no rest

	loop Extended runtime ~~with~~ no shutoff		loop Extended runtime,<br/>no shutoff
	Q1->>Q1: Conduction + switching losses generate heat		Q1->>Q1: Conduction + switching<br/>losses generate heat
	Note over Q1: Heat dissipation can't keep pace ~~with duration~~		Note over Q1: Heat dissipation<br/>can't keep pace
	end		end

	Note over Q1: Junction ~~temperature~~ exceeds rated max		Note over Q1: Junction temp exceeds<br/>rated max
	Q1-->>Q1: Thermal failure (commonly fails shorted D-S)		Q1-->>Q1: Thermal failure -<br/>commonly fails shorted D-S
	Q1->>LED: Uncontrolled current - CS feedback ~~loop~~ no longer limits it		Q1->>LED: Uncontrolled current -<br/>CS feedback no longer limits
	Note over LED: LED experiences overcurrent stress ~~from failed Q1~~		Note over LED: LED experiences<br/>overcurrent stress

Polymorphic7: initial commit

2026-09-09T21:47:51Z

initial commit

New page

sequenceDiagram
participant User
participant PowerButton
participant QX9920
participant Q1
participant LED

User->>PowerButton: Turns lamp ON directly
Note over PowerButton,QX9920: Timer bypassed - no auto cutoff scheduled
PowerButton->>QX9920: VIN applied, EN held high continuously
QX9920->>Q1: DRV switches gate at full duty, cycle after cycle
Q1->>LED: Sustained drive current, no rest period

loop Extended runtime with no shutoff
Q1->>Q1: Conduction + switching losses generate heat
Note over Q1: Heat dissipation can't keep pace with duration
end

Note over Q1: Junction temperature exceeds rated max
Q1-->>Q1: Thermal failure (commonly fails shorted D-S)
Q1->>LED: Uncontrolled current - CS feedback loop no longer limits it
Note over LED: LED experiences overcurrent stress from failed Q1