Analog current sense circuit

摘要

Circuits and related methods for switched step-down and boost DC-to-DC converters have been achieved. Said DC-to-DC converters comprise an inductor (202) current sensing and limiting circuit to prevent the inductor current to exceed a defined limit. Said current sense circuit is using the voltage (VSD) on the on-state source-to-drain resistance (RDSon) of a power switch (204 or 409) to monitor the inductor current. Said voltage is amplified and serves as input of a regulator (207). Said regulator, being connected via one or more gate controllers to the gates of said power switches (409 or 204,205), controls the ON/OFF state of said power switches by pulse-width-modulation. Said power switches are switched ON/OFF if the current exceeds a defined limit. After a defined time period said power switches are switched on again. Gate controllers keep the power switch in an operating region having a stable source-to-drain resistance while said power switch is ON. The ON/OFF duty cycle of said power transistor switches is set in a way that the difference between charge/discharge energy is kept on a minimum. <IMAGE>