| 摘要 |
A hot restrike protection circuit (112) provides complete shut down protection for a self-oscillating high intensity discharge lamp ballast (10) of the type comprising a pair of complementary switching devices (22, 24) in a bridge configuration with a gate drive inductor (46) in series with a second induct or (48), i.e., a control inductor, at the junction between the switching devices. The hot restrike protection circuit effectively comprises a three-terminal device for couplin g across the control inductor. In particular, the HRP circuit comprises a sensing network (160) for sensing voltage across the control inductor, a breakdown network (170) for providing a breakdown path upon reaching a predetermined restrike voltage threshold across the control inductor, and a shutdown network (180) for shutting down operation o f the ballast until the lamp is sufficiently cool for restarting, thereby protecti ng ballast components during hot restrike, or re-ignition, of the lamp.
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