Method and apparatus for sensing a current in a circuit

摘要

Techniques are disclosed to sense a current in a circuit. For instance, current sense circuit according to the teachings of the present invention includes a current sense resistor coupled to an input of the current sense circuit. The current sense resistor is coupled to receive a current to be sensed from the input of the current sense circuit. The current to be sensed is converted to a current sense voltage. A first PN junction diode is coupled to the current sense resistor. A light emitting diode (LED) is coupled to the first PN junction diode to provide a current sense threshold substantially proportional to a difference between a forward voltage drop of the LED and a forward voltage drop of the first PN junction diode. The first PN junction diode is coupled to be biased from the forward voltage drop of the LED. The LED is coupled to the current sense resistor to generate an output when the current sense voltage from the current sense resistor reaches the current sense threshold.