An apparatus and method for determining an output voltage or output current in an SMPS circuit 10 are described. The SMPS circuit comprises a switching element 18 which in operation is switched according to consecutive switching cycles. An electrical value I<SUB>L</SUB> within the SMPS circuit 10 is compared to a reference value I<SUB>ref</SUB>. The electrical value I<SUB>L</SUB> varies within the switching cycle such that is equal to the reference value at least once during each cycle. The comparator signal comp is evaluated to determine timing information t of an instant of change in the signal. The timing information t is used for determining the output voltage V<SUB>out,Av</SUB> or output current I<SUB>out,Av.</SUB>
