Current sensing circuit for switching power converters

摘要

A current sensing circuit for a switched mode power converter employs a passive current sensing network coupled in parallel with the switched inductor. The passive current sensing network is impedance matched to the inductance its inherent resistance, and provides a current sensing node for single wire current sensing by a current sensing circuit. The passive current sensing network can be employed in each of a plurality of phased switching circuits that each contribute to an output of the power converter.

主权项

1. A current sensing circuit for a power converter, comprising:
a first current sense resistance and a second current sense resistance coupled in series at a current sense node to form a series current sense resistance; the series current sense resistance coupled in parallel with an inductor having an inductance and an inherent resistance, and a first end connected to a switching network; the first current sense resistance coupled to the first end of the inductor, and the second current sense resistance coupled to a second end of the inductor, wherein the first end of the inductor is coupled to a first end of a switching transistor, the switching transistor having a second end coupled to an input power source, the current sensing circuit further comprises:
a field effect transistor having a first end coupled to the current sense node; andan amplifier circuit having a first input coupled to a second end of the field effect transistor and a second input coupled to an offset voltage reference;wherein the switching transistor has a control terminal, andthe field effect transistor has a control terminal coupled to the control terminal of the switching transistor; and
a capacitance coupled in parallel with the first current sense resistance.