Precision current sensing

摘要

Example current tracking circuits and systems as well as methods for tracking current are described herein. In one example, a current tracking circuit comprises a current mirror that receives a power supply input and a control signal as inputs, wherein the current mirror has a mirror ratio. The current tracking circuit also comprises a programmability sub-circuit coupled to the current mirror that trims a value of the mirror ratio. In another example, a method comprises performing current mirroring using a current mirror comprising a sense device, wherein a mirror ratio of the current mirror is based on a programmable sub-circuit. The method further comprises maintaining, by a voltage regulation loop, a collector potential of the sense device within a threshold difference level of a collector potential of a power device coupled to the sense device, wherein the sense device mirrors a current flowing in the power device.

主权项

1. A current tracking circuit comprising:
a current mirror that receives a power supply input and a control signal as inputs, wherein the current mirror has a mirror ratio; a programmable sub-circuit coupled to the current mirror that trims a value of the mirror ratio; wherein:
the programmable sub-circuit further comprises one or more Zener zap diodes configured to operate in one of an open state or a closed state, wherein the value of the mirror ratio depends on the state of the one or more Zener zap diodes,the one or more Zener zap diodes comprise a first Zener zap diode, a second Zener zap diode, and a third Zener zap diode,the first Zener zap diode and the second Zener zap diode are coupled to a terminal of a power transistor,the current mirror is a sense transistor coupled to the power transistor,the third Zener zap diode is coupled to a terminal of the sense transistor, andas compared to the mirror ratio when operating in the open state, the first Zener zap diode and the second Zener zap diode increases the mirror ratio when operating in the closed state and the third Zener zap diode decreases the mirror ratio when operating in the closed state.