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This new start up period is shown by the voltages at pins FCOMP which restarts at zero, thereby ensuring a maximum frequency in the VCO, and then steadily increases and SSV which resets the duty cycle, which is described below in further detail. This new start up period, which lasts until time t2, satisfies the ccfl pmos that the voltage at pin OVPL is not greater than 2. In one embodiment resonant frequency is the set minimum frequency. Thus, time t2 begins post-strike period Unfortunately, users typically want to go immediately into duty cycle dimming.

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Duty cycle dimming, as used herein, refers to turning the CCFL on and off at a frequency ccfl pmos is faster than the human eye can discern but much slower than the switching frequency of the CCFL e. The apparent brightness of the CCFL is controlled by the duty cycle of this switching operation. To prevent an erroneous shut down, the CCFL can be kept at maximum brightness for 2 dimming cycles immediately after the first strike is detected. This provides a period of time for hard to start tubes to warm up before being turned off again for duty cycle dimming. Note that because standard dimming cycles are on the order of 6 mS, it is probable that 12 mS of maximum brightness as the CCFL turns on will be acceptable.

Referring to FIG.


Brightness cycles are determined by the voltage ramps generated at pin CT 1wherein ccfl pmos voltage varies from 0 to a high voltage e. To ensure two full-scale brightness cycles, fault logic circuit FIG.


In this embodiment, a user-supplied voltage can set the brightness of the CCFL by determining the duty cycle of the dimming period. In this configuration, current flows through both portions A and B of primary winding When the ccfl pmos at one secondary output is high e.

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Potentiometer digital Variable capacitor Varicap. Capacitor types Ceramic resonator Crystal oscillator Inductor Parametron Relay reed relay mercury switch. Hidden categories: Ccfl pmos with short description Articles needing additional references from May All articles needing additional references All articles with unsourced statements Articles with unsourced statements from September Articles containing potentially dated statements from All articles containing potentially dated statements Wikipedia articles needing clarification from August All Wikipedia articles needing clarification Wikipedia articles needing clarification from October Articles with unsourced statements from November Articles with specifically marked weasel-worded phrases from August Switched 3. Total downloads K Last month's downloads 2K. Rate it! Alternative apps.

The sources of the first and second NMOS transistors can be connected to a voltage source VSS, Of importance, the first primary winding is tightly coupled to the second primary winding. A method of improving a start up operation of a direct drive CCFL circuit, the method comprising: Note that the feedback loop need only be coupled ccfl pmos CCFL tube because, as previously noted, the current in CCFL tube should be substantially identical to the current in the regulated tube, i.

Typically, current through CCFL tubes and is lost due to coupling with the ground ccfl pmos via parasitic capacitive paths and Thus, for the current at sensing resistor to be 6 mA an exemplary valuethe current at the other end of CCFL tube i. Ccfl pmos importance, if parasitic capacitive paths and were different, then the overall tube current in CCFL tubes and would be different.


Over time and under such conditions, CCFL tubes and might age differently. Specifically, their light outputs could be noticeably different or one tube might even be driven to premature failure due to over currents. Advantageously, in accordance with one embodiment of the invention, the parasitic capacitive current can be matched by placing both CCFL tubes and on the same ground plane in the same manner. Note ccfl pmos some components illustrated in various figures have been described as having exemplary resistances or capacitances.

However, those skilled in the art will recognize that in other embodiments such components can have other values to modify performance outputs. Ccfl pmos, the present invention is not limited to the values of the disclosed embodiments.To efficiently and cost-effectively produce a light source, a CCFL circuit can include a PMOS transistor, first and second NMOS transistors, and a high turns ratio.

voltage across the CCFL ccfl pmos held at a higher than normal voltage to allow older tubes (or . Note that the. CCFL circuit can work with PMOS transistor Q2 on con .

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