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1. (WO1998051132) ELECTRONIC BALLAST WITH INVERTER PROTECTION CIRCUIT

Pub. No.:    WO/1998/051132    International Application No.:    PCT/US1998/000570
Publication Date: Fri Nov 13 00:59:59 CET 1998 International Filing Date: Wed Jan 14 00:59:59 CET 1998
IPC: H05B 41/285
Applicants: MOTOROLA INC.
Inventors: SODHI, Sameer
Title: ELECTRONIC BALLAST WITH INVERTER PROTECTION CIRCUIT
Abstract:
An electronic ballast (10) for powering at least one gas discharge lamp (20) comprising an AC-to-DC converter (100), an inverter (200), an output circuit (300), and an inverter protection circuit (400). Inverter protection circuit (400) includes a high voltage detection circuit (500), a no-load detection circuit (600), and a latch circuit (700), and is operable to turn off the inverter (200) in response to removal or failure of the gas discharge lamps. Inverter protection circuit (400) is well-suited for use in ballasts that power multiple, parallel-connected lamps and maintains operation of inverter (200) under a partially-loaded condition in which at least one operational lamp is present and each of the failed lamps has at least one open filament.