If an output signal of the integrator is moving erratically, then the pumping can overcome the leaking, thereby increasing a voltage at a drive terminal of the transistor as well as the detect signal. A CCFL tube contains a gas, which is ionized to generate the desired light for the application. Note that some components illustrated in various figures have been described as having exemplary resistances or capacitances. For instance, consider a 6W application running at 10V battery voltage. The voltage at the secondary side of the transformer T increases correspondingly. This frequency should vary inversely with the value of capacitor The current flowing through resistors and can be sensed at node and then converted from AC to DC using a rectifier e.

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The circuit of cccl 13wherein the means for determining the second output voltage includes: This timer monitors a maximum time for a start up period of the CCFL. The transformer can include a primary coil having a center tap, thereby forming first and second primary windings, as well as a single secondary coil. Error amplifier provides its output signal to the gate of NMOS transistor In one embodiment, the primary to secondary turns ratio is approximately and the primary inductance is approximately uH.

Symmetrical drive to the power transformer gives a very dynamic choice of selecting transformers. The CCFL as claimed in claim 5, wherein the circuit, wherein said buffer circuit includes first and second diode, a capacitor and a resistor, a first diode input connected to the first primary winding One end of the input terminal of the second diode is connected to one end of the second primary winding, and the outputs of the first and second diodes connected to the node, said resistor and said capacitor connected in ccf, at the node and the between said battery.

This high Q circuit generally includes additional capacitors and inductors, which undesirably increase the number of components in the system. Circuit arrangement for operating electric lamps, and an operating method for electronic lamps. The method according to claim 30, wherein said first end includes a first and second windings of the first phase output, said second end including a second with winding and fourth winding, with the first phase and a second phase output with the phase of the output phase are out of phase.


The apparent brightness of the CCFL is controlled by the duty cycle of this switching operation. Additionally, the performs the lamp dimming function with an analog voltage or low frequency Pulse Width Modulation PWM control. This current is then mirrored using PMOS transistors and onto a capacitor Field of the Invention. During a fast transition, the voltage at the emitter of pnp transistor will eventually increase to cctl point where it will trip the OVP threshold of the chip, thereby shutting down CFFL circuit FIG.

Cfcl technique allows for fast edge transitions, yet minimizes overall power dissipation.

A method of physically implementing a transformer, the transformer having a core segment with a middle area, a first end area, and a second end area, the method comprising: A dashed box indicates that the components therein can be fabricated on one chip. In contrast, a high signal BRPOL indicates reverse operation, thereby providing a signal opposite to that of the variable duty factor signal to be transferred to fault logic circuit As the duty cycle changes with battery voltage, the overall resonant frequency might also change.

DC-AC Converter, Cold Cathode Fluorescent Lighting (CCFL) Power Supply

In normal operation, the voltage at nodes and should look like alternating, positive half sinusoids, as shown in FIG. Due to the leakage inductances of the transformer, voltages at the drains of the first and second NMOS transistors can potentially ring to values substantially higher than the ideal value e.

As the current ramps up in the primary winding, energy is transferred to the secondary winding and stored in the leakage inductance L leak and any parasitic capacitance on the secondary winding.

In this configuration, if CCFL tube is not properly seated using connectors and being the low voltage connector to CCFL tubethen a high voltage charge on connector will choose to jump across a gap to PCB tracethereby increasing the voltage on the OVP pin. The system of claim 26 CCFL and its coupling a first, second, third and fourth of the CCFL, characterized in that, further comprising a current sensing network.


However, the current decreases very quickly at first then ramps down to zero at a rate that is slower than the current ramped up.

The secondary terminals that are not connected to the CCFLs are connected to each other. APMOS transistor. In one embodiment, if the input voltage is equal to or less than the predetermined intermediate voltage and the CCFL current is equal to or greater than the predetermined value, the switching frequency of the CCFL will decrease towards its resonant frequency.

Additionally, most of the techniques herein described could also be applied to pmmos half bridge driving topology in which case a standard transformer could be used without the center tapped primary.

W hen transistor Q1 turns off, the current flowing in the inductor causes pin 6 to go high. The resonant frequency vcfl determined by the parasitic inductances and capacitances associated with transformer as well as some parasitic capacitances associated with CCFL Protecting a cold cathode fluorescent lamp from a large transient current when voltage supply transitions from a low to a high voltage. The clamping circuit also shuts off the CCFL once every dimming cycle by reducing the switching duty cycle to zero.

DC-AC Converter, Cold Cathode Fluorescent Lighting (CCFL) Power Supply – YouSpice

A CCFL tube contains a gas, which is ionized to generate the desired light for the application. This power is stored in the leakage inductance L leak. However, in other cases, the user would prefer that the brightness of the CCFL decrease as the user-supplied voltage increased.