A circuit, an adjusting method, and use of a control loop for adjusting a data retention voltage and/or a leakage current of a CMOS circuit for a sleep mode, wherein the CMOS circuit is operated to control in a measuring mode, whereby in the measuring mode a leakage current exclusively flows through the CMOS circuit, the control loop in the measuring mode adjusts the data retention voltage and/or the leakage current, and the adjustments of the control loop for the sleep mode are stored.