Weichanlaufschaltung für selbstschwingende Treiber

• Main Authors: PARRY, JOHN EDWARD, DERBY, GB, WOOD, PETER N., ROLLING HILLS ESTATES, CALIF., US
• Format: Patent
• Language: German
• Published: 31.07.1997
• Edition: 6
• Subjects: APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC,OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWERSUPPLY SYSTEMS; CONTROL OR REGULATION THEREOF; CONTROLLING; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUTPOWER; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER; ELECTRIC HEATING; ELECTRIC LIGHTING NOT OTHERWISE PROVIDED FOR; ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR; ELECTRICITY; GENERATION; PHYSICS; REGULATING; SYSTEMS FOR REGULATING ELECTRIC OR MAGNETIC VARIABLES

A half bridge driver chip for driving a resonant load, such as a ballast, has first and second pairs to which an oscillation frequency timing circuit, matched to the resonant frequency of the load. A constant voltage drop circuit is connected to these input pins to vary the voltage at the pins as a linear function of the input voltage Vcc. Consequently, when Vcc is increasing during the start-up of the circuit, the resonant frequency is initially high but decreases to its operation value as Vcc increases. This produces a soft start characteristic and a timed preheat cycle of the resonant load. In one embodiment, the constant voltage drop circuit is a zener diode; in another embodiment, it is strings of anti-parallel connected diodes.