Ballast control card

Description

Priority is claimed under 35 U.S.C. §119: Convention Date Dec. 3, 2001 for U.S. Provisional Appln. No. 60/334,608.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a ballast control card, and more particularly, to a ballast control circuit provided on a through-slot wave solderable daughter card that is vertically mountable on a mother board.

2. Description of the Related Art

Electronic ballasts for controlling fluorescent or high-intensity discharge (HID) lamps usually require electronics necessary for preheating the lamp filaments, striking the lamp, driving the lamp to a given power, detecting lamp fault conditions, and safely deactivating the circuit.

Electronic ballasts for gas discharge circuits have come into widespread use because of the availability of power MOSFET switching devices and insulated gate bipolar transistors (IGBTs) that can replace previously used power bipolar switching devices. A number of integrated circuits (ICs) have been devised for driving gates of power MOSFETs or IGBTs in electronic ballasts. Examples include the IR2155, IR2157, and IR21571 products sold by International Rectifier Corporation and described in U.S. Pat. Nos. 5,545,955 and 6,211,623, the disclosures of which are incorporated herein by reference in their entireties.

SUMMARY OF THE INVENTION

The invention provides a fully integrated, fully protected 600V ballast control card designed to drive all types of fluorescent lamps. The ballast control card includes boost-type power factor correction (PFC) control and half-bridge ballast control for controlling a complete active power factor electronic ballast. The ballast control card of the present invention incorporates the ballast control IC with power factor correction disclosed in U.S. patent application Ser. No. 09/981,753 filed Oct. 19, 2001, the entire disclosure of which is incorporated herein by reference, and includes, together with the IC, the two power FETs, the PFC FET and related passive components.

In accordance with the present invention, ballast control circuitry, including the control IC and FETs, is provided on a through-slot wave solderable daughter card. The daughter card mounts vertically onto a mother board. Pads surrounding a slot formed through the mother board are soldered to pads on the vertical daughter card in a wave solder bath during production.

The ballast control card of the present invention greatly simplifies ballast design and drastically reduces ballast component count. Externally programmable features such as DC bus voltage level, preheat time and frequency, ignition ramp characteristics, and running mode operating frequency provide a high degree of flexibility for the ballast design engineer.

Comprehensive protection features such as protection from failure of a lamp to strike, filament failures, asymmetrical lamp voltage (end-of-life), low AC line condition, thermal overload, and lamp failure during normal operation, as well as an automatic restart function, have been included in the design.

The ballast control card of the present invention has the following features:

• Fully Integrated Ballast Control Card.
• Critical-Conduction Mode Boost Type PFC
• Half-Bridge Ballast Output
• Charge Pump Supply Input
• Programmable Preheat Time & Frequency
• Programmable Ignition Ramp
• Programmable Over-Current
• Internal Fault Counter
• Assymetrical Lamp Voltage Protection
• Lamp Filament Sensing & Protection
• Capacitive Mode Protection
• Brown-Out Protection
• Dynamic Restart
• Automatic Restart for Lamp Exchange
• Thermal Overload Protection
• Internal 15.6V Zener Clamp Diode on VCC
• Through-slot Wave-solderable Card Package

Other features and advantages of the present invention will become apparent from the following description of the invention which refers to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a typical application diagram for the ballast control card of the present invention.

FIG. 2 illustrates a top trace layer of the ballast control card of FIG. 1.

FIG. 3 shows a top solder mask for the ballast control card of FIG. 1.

FIG. 4 shows the top silk layer of the ballast control card of FIG. 1.

FIG. 5 shows a bottom trace layer of the ballast control card of FIG. 1.

FIG. 6 illustrates a bottom solder mask for the ballast control card of FIG. 1.

FIG. 7 illustrates bond wires of the ballast control card of FIG. 1.

FIG. 8 shows a bottom copper layer for a ballast motherboard according to the present invention.

FIG. 9 shows a top silk screen layer for a ballast motherboard according to the present invention.

FIG. 10 illustrates a bottom silk screen layer of a ballast motherboard according to the present invention.

FIG. 11 shows a bottom solder mask for a ballast motherboard according to the present invention.

FIG. 12 is a schematic diagram of a ballast control card circuit according to the present invention.

DETAILED DESCRIPTION OF EMBODIMENTS OF THE INVENTION

Referring to FIG. 1, a typical connection diagram for the ballast control card 2 of the present invention is shown schematically. The ballast drives a fluorescent lamp 4. A cover 6 is provided over internal ballast control circuit components (described further below) mounted on circuit board 8. The card typically is 37.05 mm by 14.5 mm. The thickness of the card is about 25 mils.

Programmable features of the ballast control, such as DC bus voltage level, preheat time and frequency, ignition ramp characteristics, and running mode operating frequency, are established by connecting external components to connecting pads provided on the edge of the ballast control card, as follows:

Typical external components are shown schematically in FIG. 1. The external components preferably are mounted on a mother board, which receives the ballast control daughter board, as described further below.

The ballast control receives power from a positive rectified AC line input which is applied, via transformer 10, to both the PFC circuitry and the main control circuitry. Resistor 12 allows external programming of a DC bus voltage level. An over-current threshold is established using resistor 14. Resistor 16 establishes a running mode frequency. Preheat timing is programmed by way of resistor 18 and capacitor 20. Capacitor 22 programs an ignition ramp.

Referring to FIGS. 2-7, the mechanical layout of the ballast control card is shown. FIG. 2 illustrates top layer traces, and FIG. 3 shows a top solder mask. A top silk screen layer is shown in FIG. 4. Bottom trace layer is shown in FIG. 5. FIG. 6 illustrates a bottom solder mask. Bond wires are shown in FIG. 7.

FIGS. 8-11 are mechanical drawings of the mother ballast board 40 according to the present invention. Mother board 40 includes a through-slot 42 which receives the connecting edge of ballast card 2. FIG. 8 illustrates a bottom copper layer on motherboard 40. FIG. 9 shows a top silk screen layer indicating a component layout, while FIG. 10 shows a bottom silk screen layer. FIG. 11 is a bottom solder mask for motherboard 40.

Referring to FIG. 12, a schematic diagram of internal and external circuitry for the ballast control card of the present invention is shown. Component labels correspond to those in other drawings, particularly FIGS. 4 and 7 showing daughter card component layout. Note that the resistors labeled RVBUS 1-3 in FIG. 12 corresponds to resistors RBUS 1-3 in FIG. 4. Also, CCOMP 1 and 2 in FIG. 4 are equivalent to CCOMP in FIG. 12. Similarly, whereas FIG. 12 shows two bootstrap capacitors CVCC 1 and 2, FIG. 4 includes an additional capacitor CVCC3. Capacitor CBOOT and resistor R7 as labeled in FIG. 12 correspond to capacitor CBS and resistor RLIM1, respectively, in the FIG. 4 layout.

The ballast control is built around IC 50, illustratively a product of assignee, International Rectifier Corporation, identified as the IR2167 IC. Further implementation details are provided in the IR2167 data sheet, available from International Rectifier Corporation and in pending U.S. patent application Ser. No. 09/981,753, filed Oct. 19, 2001, both of which are incorporated herein by reference in their entirety.

The ballast control card incorporates both the high and low side drive MOSFETS 52 and 54 and the power factor correction MOSFET (MPFC) on a single board.

Although the present invention has been described in relation to particular embodiments thereof, many other variations and modifications and other uses will become apparent to those skilled in the art. It is preferred, therefore, that the present invention be limited not by the specific disclosure herein, but only by the appended claims.