Digital controller for an electronic ballast
OwnerJohn Lam, Praveen Jaininventors
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Abstract
Provided are circuits and methods for a digital controller for an electronic ballast for a fluorescent lamp, comprising a feed-forward loop that provides information about a voltage firing angle, and a pulse width modulator that controls a duty ratio of at least one power switch of the electronic ballast according to the information. The digital controller may include a duty ratio controller implemented in the pulse width modulator. The digital controller may include one or more functions such as dimming, maintaining high power factor throughout the dimming range, low lamp power detection, lamp soft-start, and DC-link capacitor over-voltage detection for end of life protection or lamp failure protection. In one embodiment the ballast is a single stage, single switch ballast.
Claims9
A method for controlling an electronic ballast for a fluorescent lamp, comprising:
- using a feed-forward loop to provide information about a voltage firing angle;
- and
- using a digital pulse width modulator to control a duty ratio of at least one power switch of the electronic ballast according to the information;
- implementing a duty ratio controller in the digital pulse width modulator;
- wherein control of the electronic ballast is provided;
- wherein the ballast is a single stage, single switch ballast;
- and,
- wherein the duty ratio controller in said pulse width modulator comprises a reset upcounter and a pair of comparators.
Dependencies are inferred from the claim text.