The iW7040 integrates 64 open-drain current sinks, two LDOs and digital control for eight external DC/DC converters (step-up or step-down) to provide a complete solution for LED backlighting in applications such as LCD TVs. Using iWatt's innovative BroadLED™ technology, the iW7040 maintains channel-to-channel current matching of better than 2% and integrates iWatt's proprietary adaptive switch technology, significantly reducing power loss in LED backlighting applications. Each channel can operate from a supply up to 40V at a maximum average current of 75mA, with a peak current of 120mA when in adaptive switch mode. The iW7040 provides direct control of eight external DC/DC converters which, through dynamic voltage control, provide the lowest possible voltage on their outputs to maintain the minimum programmed current through the LED strings without wasting any additional energy. This feature, along with the adaptive switch technology, which utilizes a proprietary pulse-width modulation (PWM) scheme to individually regulate the current in each string of LEDs to minimize power loss while maintaining channel-to-channel current matching, enables LCD TVs using the iW7040 as its backlighting controller to meet stringent Energy Star^®standards established for HDTVs. The iW7040 protects each LED string from various fault conditions such as LED open/short on a cycle-by-cycle basis to maximize reliability. The IC itself is protected from faults like over voltage, over temperature and under-voltage lockout to ensure proper start-up and shutdown. The iW7040 also integrates a syncronization function so that multiple iW7040's can be synchronized to the same external clock and drive all the LEDs for very large panels while operating at the same frequency and matching the current between all channels.

Direct LED Driver Application in LCD Panel

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