초록 ▼

A dimming ballast circuit suitable for use with a phase dimmer has a switching network 70 consisting of a complimentary pair of switches 32, 34 which are driven by a low-power universally available controller IC 72. The controller IC 72 is configured with a floating ground arrangement 78. A current

A dimming ballast circuit suitable for use with a phase dimmer has a switching network 70 consisting of a complimentary pair of switches 32, 34 which are driven by a low-power universally available controller IC 72. The controller IC 72 is configured with a floating ground arrangement 78. A current sensor 112 assists in generating a positive feedback signal 110 which is provided to an inverting input of operational amplifier 152 of compensation network circuit 62. A level shifted phase dimmer signal is generated by a level shifting circuit 60 and the error difference between the positive feedback signal 110 and the level shifted signal is amplified by operational amplifier 152 to, in turn, control the output frequency of controller IC 72. The level shifting circuit 60 shifts the dimming signal 68 from a ground reference system to a floating ground design. A resonant feedback circuit 18 includes capacitors 42 and 56 that couple energy from a resonant load 14 back to the input dimming signal 68 for the purpose of providing a continuous load to the phase dimmer and damping for an input EMI filter 220.

대표청구항 ▼

1. A dimming ballast circuit designed to use a phase dimmer signal to control output of a fluorescent lamp, the dimming ballast circuit comprising:a controller integrated chip (IC) having an internal operational amplifier with a non-inverting input tied to a steady state voltage and with an invertin

1. A dimming ballast circuit designed to use a phase dimmer signal to control output of a fluorescent lamp, the dimming ballast circuit comprising:a controller integrated chip (IC) having an internal operational amplifier with a non-inverting input tied to a steady state voltage and with an inverting input tied to a floating ground, and a Class D output, the controller integrated chip configured in said floating ground arrangement, and configured to generate a drive signal from the phase dimmer signal; a switching network which receives a drive signal from the controller IC for operating the switching network, to control operation of the fluorescent lamp; a load circuit including the fluorescent lamp, connected to a series configured resonant inductor and resonant capacitor; a resonant feedback circuit including at least two capacitors, connected from said resonant inductor to said phase dimmer signal input; and a capacitor connected from a positive DC bus back to a node at a junction between first and second diodes.