Electronic ballast and method for operating at least one discharge lamp

Abstract

In various embodiments, ballast for a discharge lamp includes input and output connections; inverter with bridge circuit with electronic switches and control device for controlling electronic switches, wherein switches are connected in series between input connections, wherein one electronic switch is coupled to first input connection and second electronic switch to second input connection, wherein a bridge midpoint is between electronic switches; including a current measuring device for measuring second electronic switch current; lamp choke series-connected between bridge midpoint and first output connection; capacitor parallel-connected with one of electronic switches; and coupling capacitor; wherein control device is coupled to current measuring device and renders an electronic switch conducting, if negative threshold value is exceeded when electronic switch is rendered nonconducting; or if negative threshold value of current through electronic switch is not exceeded after another electronic switch is rendered nonconducting, wherein control device increases first frequency in second case.