Mermaid:Mechanic L1 Pro Failure Sequence

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

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