US Patent No. 10,172,191

DRIVER CIRCUIT WITH LLC START-UP CONTROL


Patent No. 10,172,191
Issue Date January 01, 2019
Title Driver Circuit With Llc Start-up Control
Inventorship Christian Nesensohn, Gotzis (AT)
Manuel Egle, Hohenems (AT)
Assignee

Claim of US Patent No. 10,172,191

1. A driver circuit for at least one lighting means comprising one or more LEDs, the driver circuit comprising:an LLC circuit with a clocked inverter comprising a high potential switch and a low potential switch connected in series, wherein the high potential switch is connected to a DC voltage source and the low potential switch is connected to ground and a midpoint between the high potential switch and the low potential switch is configured to supply a resonant circuit, wherein the resonant circuit is coupled to a primary winding of a transformer for transforming electrical energy from the primary winding to a secondary winding, and the at least one lighting means are supplied with rectified current starting from the secondary winding, and
a control unit configured to control the high potential switch and the low potential switch of the clocked inverter by alternating cycles of the high and low potential switches after an activation of the driver circuit during a start phase, and wherein during the start phase after a single or after multiple alternating cycles of the high potential switch and the low potential switch, cycling of the high potential switch and the low potential switch is suspended for a duration of at least one alternating cycle of the high potential switch and the low potential switch until a criterion for ending the start phase is satisfied, said criterion being one of a number of switch cycles, a specific period of time after the activation, and a value of a feedback variable fed back to the control unit;
wherein after ending the start phase the control unit is configured to control the high potential switch and the low potential switch of the clocked inverter in normal operation mode to continuously cycle the high potential switch and the low potential switch, and a frequency of the alternating cycles of the high potential switch and the low potential switch of the clocked inverter is a manipulated variable in the normal operation mode, and frequency control is deactivated during the start phase.