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Multiple-CCFL inverter all output shutdown circuit in any failure happened

IP.com Disclosure Number: IPCOM000013901D
Original Publication Date: 2001-Nov-15
Included in the Prior Art Database: 2003-Jun-19

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A multiple-CCFL (cold-cathode fluorescent lamp) inverter that had a complete safety protection was developed. When it happened any failure detected the inverter shut off all the high-voltage outputs. The protection circuit controlled all the STOP signals of each controller IC using a multiple-input NAND gate buffer. If it happened any failure with a CCFL, the controller IC shut off the high-voltage output of the failed CCFL only, however, the other CCFL were worked like as a normal condition. It was certainly abnormal condition and it cannot be judged whether it was completely safe or not. We thought it was not a perfect safety protection. It was connnected each IC reference-voltage-out (VREF_OUT) to each IC STOP signal input through a 6-input NAND gate buffer like a schematics. If it happened any failure with a CCFL, the error detected IC VREF_OUT went to inactive, the STOP signals of all IC went to active, then all the controller IC stopped working and all the high-voltage outputs were shut off. The inverter could not restart without reset signal input. It was a completely safety protection. 1