A switchable current source, comprising: - an input current path with a controllable current source to feed a changeable current (Itrim) to the input current path, the input current path being configured to provide a reference voltage (VREF) being dependent on the changeable current (Itrim), - an output terminal (LDR_PIN) to provide an output current (ILDR), - an output current path to provide an output current (ILDR), the output current path being connected to the output terminal (LDR_PIN) and being configured to convert the output current (ILDR) into a sensing voltage (VSENS), - a regulator circuit having a first input terminal (E1_RC) to apply a first input signal (VPOS) and a second input terminal (E2_RC) to apply a second input signal (VNEG) and an output terminal (O_RC) to provide an output signal (VOUT2), wherein the regulator circuit is arranged to provide the output signal (VOUT2) in dependence on a comparison of the first and second input signals, - a controllable output driver being controlled in dependence on the output signal (VOUT2), wherein the controllable output driver is arranged to change the output current (ILDR) in dependence on the output signal (VOUT2), and - a feedback path coupled between the output current path and the first input terminal (E1_RC), characterised in that it further comprises, - a switching circuit configured to connect, in a first state, the first input terminal (E1_RC) and the second input termial (E2_RC) of the regulator circuit to the input current path and to connect, in a second state, the first input terminal (E1_RC) of the regulator circuit to the feedback path and the second input termial (E2_RC) of the regulator circuit to the input current path. - an input current path with a controllable current source to feed a changeable current (Itrim) to the input current path, the input current path being configured to provide a reference voltage (VREF) being dependent on the changeable current (Itrim), - an output terminal (LDR_PIN) to provide an output current (ILDR), - an output current path to provide an output current (ILDR), the output current path being connected to the output terminal (LDR_PIN) and being configured to convert the output current (ILDR) into a sensing voltage (VSENS), - a regulator circuit having a first input terminal (E1_RC) to apply a first input signal (VPOS) and a second input terminal (E2_RC) to apply a second input signal (VNEG) and an output terminal (O_RC) to provide an output signal (VOUT2), wherein the regulator circuit is arranged to provide the output signal (VOUT2) in dependence on a comparison of the first and second input signals, - a controllable output driver being controlled in dependence on the output signal (VOUT2), wherein the controllable output driver is arranged to change the output current (ILDR) in dependence on the output signal (VOUT2), and - a feedback path coupled between the output current path and the first input terminal (E1_RC), characterised in that it further comprises, - a switching circuit configured to connect, in a first state, the first input terminal (E1_RC) and the second input termial (E2_RC) of the regulator circuit to the input current path and to connect, in a second state, the first input terminal (E1_RC) of the regulator circuit to the feedback path and the second input termial (E2_RC) of the regulator circuit to the input current path.