Abstract: A method is described for calibrating a CDCCD circuit (100) comprising: first and second voltage input terminals (101, 102); first and second switching bridges, each comprising two controllable switches connected in series between said first and second input terminals; a series arrangement of a first inductor (131), load output terminals (191, 192), and a second inductor (132) coupled between bridge output nodes (113, 123); a current sensor (150) associated with said first inductor (131); a reference signal generator (160); a switch controller (170) receiving a measuring signal (S 1) from the current sensor and a reference signal (SR) from the reference signal generator; the method comprising the steps of: generating an AC current having a zero DC level; measuring a voltage at an output terminal; adjusting the current reference signal in such a way that the measured voltage is symmetrical with respect to the input voltage levels.

Abstract: A control unit for a lamp driver for controlling a lamp during various operation modes. Current through the lamp is increased, preferably linearly, during ignition mode from a first start value to a maximum value. The lamp starts up smoothly and warms up already in ignition mode. Leads to higher lamp voltage and improved switching behavior. May be further improved by changing the duty cycle of a down-converter in order to obtain commutation. May be even further improved by maintaining an alternator running at high frequency (>I 00 kHz) during run-up mode.