Patent ID: 8502463

Claim:
An LED driver circuit comprising: a DC power source effective to provide a first DC voltage across positive and negative voltage rails; a DC/DC converter comprising a switching element having a drain terminal and a source terminal and a converter capacitor, the DC/DC converter effective by turning ON/OFF the switching element to provide a second DC voltage across the converter capacitor, the converter capacitor having first and second converter capacitor terminals defining first and second LED lighting device connection terminals, the first converter capacitor terminal coupled to the positive voltage rail; a switch current detection circuit coupled between the source terminal of the switching element and the negative voltage rail; a control circuit coupled to the DC/DC converter and effective upon receiving a drive power signal to control turning ON/OFF of the switching element wherein a constant current is maintained through an LED lighting device when it is coupled to the first and second connection terminals, the control circuit further effective to turn OFF the switching element based on a signal from the switch current detection circuit; a power supply circuit coupled between the second LED lighting device connection terminal and the negative voltage rail, the power supply circuit effective to detect a lighting condition at the second connection terminal and generate said drive power signal to the control circuit during said lighting condition, the power supply circuit further effective to detect an open circuit condition at the second connection terminal and disable said drive power signal during said open circuit condition.