Mermaid:Mechanic L1 Pro Failure Sequence: Difference between revisions
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%%{init: {'theme':'default', 'sequence': {'width': 50, 'height': 30, 'actorMargin': 20, 'boxMargin': 5, 'messageFontSize': 10, 'noteFontSize': 10}}}%% | |||
sequenceDiagram | sequenceDiagram | ||
participant User | participant User | ||
| Line 7: | Line 8: | ||
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 | QX9920->>Q1: DRV switches gate<br/>at full duty | ||
Q1->>LED: Sustained drive current, no rest | Q1->>LED: Sustained drive<br/>current, no rest | ||
loop Extended runtime | 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 | Note over Q1: Heat dissipation<br/>can't keep pace | ||
end | end | ||
Note over Q1: Junction | Note over Q1: Junction temp exceeds<br/>rated max | ||
Q1-->>Q1: Thermal failure | Q1-->>Q1: Thermal failure -<br/>commonly fails shorted D-S | ||
Q1->>LED: Uncontrolled current - CS feedback | Q1->>LED: Uncontrolled current -<br/>CS feedback no longer limits | ||
Note over LED: LED experiences overcurrent stress | Note over LED: LED experiences<br/>overcurrent stress | ||
Latest revision as of 22:01, 9 September 2026
%%{init: {'theme':'default', 'sequence': {'width': 50, 'height': 30, 'actorMargin': 20, 'boxMargin': 5, 'messageFontSize': 10, 'noteFontSize': 10}}}%%
sequenceDiagram
participant User
participant PowerButton
participant QX9920
participant Q1
participant LED
User->>PowerButton: Turns lamp ON directly
Note over PowerButton,QX9920: Timer bypassed -<br/>no auto cutoff<br/>scheduled
PowerButton->>QX9920: VIN applied, EN held<br/>high continuously
QX9920->>Q1: DRV switches gate<br/>at full duty
Q1->>LED: Sustained drive<br/>current, no rest
loop Extended runtime,<br/>no shutoff
Q1->>Q1: Conduction + switching<br/>losses generate heat
Note over Q1: Heat dissipation<br/>can't keep pace
end
Note over Q1: Junction temp exceeds<br/>rated max
Q1-->>Q1: Thermal failure -<br/>commonly fails shorted D-S
Q1->>LED: Uncontrolled current -<br/>CS feedback no longer limits
Note over LED: LED experiences<br/>overcurrent stress
%%{init: {'theme':'default', 'sequence': {'width': 50, 'height': 30, 'actorMargin': 20, 'boxMargin': 5, 'messageFontSize': 10, 'noteFontSize': 10}}}%%
sequenceDiagram
participant User
participant PowerButton
participant QX9920
participant Q1
participant LED
User->>PowerButton: Turns lamp ON directly
Note over PowerButton,QX9920: Timer bypassed -<br/>no auto cutoff<br/>scheduled
PowerButton->>QX9920: VIN applied, EN held<br/>high continuously
QX9920->>Q1: DRV switches gate<br/>at full duty
Q1->>LED: Sustained drive<br/>current, no rest
loop Extended runtime,<br/>no shutoff
Q1->>Q1: Conduction + switching<br/>losses generate heat
Note over Q1: Heat dissipation<br/>can't keep pace
end
Note over Q1: Junction temp exceeds<br/>rated max
Q1-->>Q1: Thermal failure -<br/>commonly fails shorted D-S
Q1->>LED: Uncontrolled current -<br/>CS feedback no longer limits
Note over LED: LED experiences<br/>overcurrent stress