ABSOLUTE VALUE CURRENT-SENSING CIRCUIT FOR STEP-DOWN DC-TO-DC CONVERTERS WITH INTEGRATED POWER STAGE

摘要

It is proposed a system for measuring an output current ÎOUT of a DC-to-DC converter, the DC-to-DC converter comprising a transistor power stage. The system comprises:
a voltage measuring circuit, connected to the output of the power stage of the DC-to-DC converter, for measuring an average voltage drop VAVG′ on impedances RDS(P,N) of the transistors of the power stage;an impedance RComposite, connected to an output of the voltage measuring circuit providing a current IOUT′, the impedance RComposite reproducing the impedances RDS(P,N) of the transistors of the power stage and being traversed by the current IOUT′ such that ÎOUT=VAVG/(G·k·RComposite)=IOUT′/(G·k) wherein G·k is a scaling ratio.

主权项

1. A system for measuring an output current ÎOUT of a DC-to-DC converter, the DC-to-DC converter comprising a transistor power stage, the system comprising:
a voltage measuring circuit, connected to the output of the power stage of the DC-to-DC converter, for measuring an average voltage drop VAVG′ on impedances RDS(P,N) of the transistors of the power stage; and an impedance RComposite, connected to an output of the voltage measuring circuit providing a current IOUT′, the impedance RComposite reproducing the impedances RDS(P,N) of the transistors of the power stage and being traversed by the current IOUT′ such that ÎOUT=VAVG/(G·k·RComposite)=IOUT′/(G·k), wherein k is a scaling ratio and G is a voltage gain that amplifies the voltage VAVG′ to VAVG.