CURRENT CONTROLLED COMMUNICATION BUS SLAVE DEVICE POWER SUPPLY
A slave device power supply (PS) is disclosed for a two-wire current controlled communication bus (CB) with a variable bus voltage (Vbus). A slave device (SD) is arranged to draw a constant slave current (Islave) from the current controlled communication bus (CB) and provide slave device functions. The slave device (SD) comprises a slave device power supply (PS) comprising an energy storage (ES) arranged to power the slave device functions, and a charger (CH) for charging the energy storage (ES) from the constant slave current (Islave), thereby affecting a charge voltage (Vchrg). The charger (CH) comprises an overflow circuit (OC) arranged to draw excess charge current (Ivent) from the constant slave current (Islave). The overflow circuit (OC) is arranged to draw the excess charge current (Ivent) when a relationship between the charge voltage (Vchrg) and the variable bus voltage (Vbus) fulfils a predetermined overflow criterion.