Electric lamp and discharge devices: systems – Periodic switch in the supply circuit – Impedance or current regulator in the supply circuit
Reexamination Certificate
1999-01-05
2001-04-03
Wong, Don (Department: 2821)
Electric lamp and discharge devices: systems
Periodic switch in the supply circuit
Impedance or current regulator in the supply circuit
C315S291000, C315S307000, C315S308000
Reexamination Certificate
active
06211623
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a gate driver circuit for MOS gated devices, and more specifically to a monolithic gate driver circuit for MOS gated devices, particularly those used in fluorescent lamp ballast circuits.
2. Description of the Related Art
Electronic ballasts for gas discharge circuits have recently come into widespread use because of the availability of power MOSFET switching devices and insulated gate bipolar transistors (“IGBTs”) to replace previously used power bipolar switching devices. Monolithic gate driver circuits, such as the IR2155 sold by International Rectifier Corporation and described in U.S. Pat. No. 5,545,955, the disclosure of which is incorporated herein by reference in its entirety, have been devised for driving the power MOSFETs or IGBTs in electronic ballasts. The IR2155 gate driver IC offers significant advantages over prior circuits in that it is packaged in a conventional DIP or SOIC package and contains internal level shifting circuitry, under voltage lockout circuitry, deadtime delay circuitry, and additional logic circuitry and inputs so that the driver can self-oscillate at a frequency determined by external resistors R
T
and capacitors C
T
.
Although the IR2155 offers a vast improvement over prior ballast control circuits, it lacks a number of desirable features such as: (i) a start-up procedure which ensures a flash-free start without an initial high voltage pulse across the lamp, (ii) non-zero voltage switching protection circuitry, (iii) over temperature shutdown circuitry, (iv) DC bus and AC on/off control circuitry, and (v) near or below resonance detection circuitry.
SUMMARY OF THE INVENTION
The present invention provides a novel monolithic electronic ballast controller IC which permits the driving of two MOS gated power semiconductors such as power MOSFETs or IGBTs, one designated as a “low side switch,” the other designated as a “high side switch,” the two switches being connected in a totem pole or half-bridge arrangement. Advantageously, the IC of the present invention executes a very specific set of instructions to control the fluorescent lamp and protect the ballast. Careful attention is paid to properly powering up and down the IC and the half-bridge, preheating and striking the lamp, running the lamp, sensing for numerous possible fault conditions, and recovering from these fault conditions based on the normal maintenance of a lamp.
The electronic ballast IC of the present invention (identified as the IR2157 by the assignee, International Rectifier Corporation) is designed to function in five basic modes of operation based upon the status of the various inputs to the IC. These 5 modes of operation include:
1) an under voltage lockout mode
2) a preheat mode
3) an ignition ramp mode
4) a run mode; and
5) a fault mode.
The circuitry is designed to switch between these modes in accordance with a “state diagram” and is additionally designed to ensure a flash-free start without an initial high voltage pulse across the lamp and to cleanly shutdown the IC upon the occurrence of non-zero voltage switching, an over temperature condition, a fault in the DC bus or AC line voltage, or in the event of a near or below resonance condition.
Other features and advantages of the present invention will become apparent from the following description of the invention which refers to the accompanying drawings.
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patent: 5049790 (1991-09-01), Herfurth et al.
patent: 5315214 (1994-05-01), Lessea
patent: 5373435 (1994-12-01), Jayaraman et al.
patent: 5550433 (1996-08-01), Tobler
patent: 5699238 (1997-12-01), Lee et al.
patent: 5705894 (1998-01-01), Krummel
patent: 5811941 (1998-09-01), Barton
patent: 5982110 (1999-11-01), Gradzki
patent: 0399613 (1990-11-01), None
patent: WO9325952 (1993-12-01), None
patent: WO9743878 (1997-11-01), None
patent: WO9846053 (1998-10-01), None
Houk Talbott M.
Ribarich Thomas J.
Wilhelm Dana S.
Alemu Ephrem
International Rectifier Corporation
Ostrolenk Faber Gerb & Soffen, LLP
Wong Don
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