Automotive current sensor

An essentially temperature invarient current sensor suitable for use in an automobile to measure a current delivered from a source of electrical energy to a load and configured upon occurrence of internal failure to indicate a maximum current level, said sensor comprising:

• a shunt assembly connectable in line with said source and said load, said shunt assembly having at least one low-resistance shunt element constructed of a material having characteristically small resistance drift due to variations in ambient temperature;
• a difference mode amplifier having a first input electrically connected to a first terminal side of said shunt and a second input electrically connected to a second terminal side of said shunt element, said difference mode amplifier producing a difference signal representative of a voltage drop across said shunt element due to a flow of current;
• said difference mode amplifier further including means for producing upon disconnection of said first and second inputs from said shunt element a voltage difference sufficient to indicate said maximum current level;
• scaling circuitry electrically connected to receive said difference signal and operable to produce during normal operation of said difference mode amplifier a ratiometric current level signal;
• and
• said scaling circuitry further operable during failure of said difference mode amplifier to produce a signal indicating said maximum current level.