US Patent No. 10,172,195

LED DRIVER


Patent No. 10,172,195
Issue Date January 01, 2019
Title Led Driver
Inventorship Andre Mitterbacher, Dornbirn (AT)
Paul Dalby, Cleveland (GB)
Deepak Makwana, Tyne and Wear (GB)
Wayne Bell, Durham (GB)
Assignee

Claim of US Patent No. 10,172,195

1. An operating device (1) for operating LED lighting means, comprising:a potential-isolated clocked converter (3), having a transformer (T), which has a primary winding (N1) and a secondary winding (N2), and having a controllable switch (M1) arranged on the primary side, wherein the converter (3) is supplied with a supply voltage on the primary side and the lighting means is supplied on the secondary side by means of an output voltage (Vout) of the converter (3),
means (4) for directly or indirectly detecting the output voltage (Vout), and
a control unit (ST) for controlling the switch (M1),
wherein while the switch (M1) is turned off, the secondary current (I2) through the secondary winding (N2) drops linearly, starting from a positive value,
wherein the control unit (ST) is configured to detect adaptively a discharge duration (Tdischarge) between turning off the switch (M1) and a subsequent drop of the secondary current (I2) to zero, and
wherein the discharge duration (Tdischarge) is determined by taking into account a value representing the detected output voltage (Vout) during a steady state that results from turning off the switch (M1), and detecting when the detected output voltage (Vout) drops below said value.