Overcurrent limiting for high side solenoid switch controls
First Claim
Patent Images
1. A high side solenoid switch overcurrent protection circuit comprising:
- a high side solenoid switch operable to connect a voltage source to a solenoid switch;
a sense resistor connecting said voltage source to a source node of said high side solenoid switch;
a bias circuit operable to provide a source to gate bias voltage to said high side solenoid switch; and
a secondary bias circuit operable to alter said source to gate bias voltage during an overcurrent validation; and
a comparator having first and second inputs, said first input connected to a first voltage divider and said second input connected to a second voltage divider;
said first voltage divider connected to an overcurrent transistor and operable to provide an overcurrent threshold current to said comparator; and
said second voltage divider directly connected to said voltage source.
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Abstract
An overcurrent protection circuit for a high side solenoid switch includes a primary bias circuit and a secondary bias circuit. The secondary bias circuit is operable to alter a source to gate bias voltage of the high side solenoid switch during an overcurrent.
13 Citations
14 Claims
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1. A high side solenoid switch overcurrent protection circuit comprising:
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a high side solenoid switch operable to connect a voltage source to a solenoid switch; a sense resistor connecting said voltage source to a source node of said high side solenoid switch; a bias circuit operable to provide a source to gate bias voltage to said high side solenoid switch; and a secondary bias circuit operable to alter said source to gate bias voltage during an overcurrent validation; and a comparator having first and second inputs, said first input connected to a first voltage divider and said second input connected to a second voltage divider; said first voltage divider connected to an overcurrent transistor and operable to provide an overcurrent threshold current to said comparator; and said second voltage divider directly connected to said voltage source. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. A method for limiting an overcurrent during an overcurrent validation period comprising the step of:
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altering a source to gate bias voltage of a high side solenoid switch, thereby limiting a current passing through said high side solenoid switch by altering a current path via activating a secondary bias circuit; and preventing current back-flow through said secondary bias circuit when no overcurrent is present. - View Dependent Claims (10, 11, 12, 13)
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14. A high side solenoid switch overcurrent protection circuit comprising:
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a circuit input operable to receive power from a voltage source; a sense resistor connecting said circuit input to a source node of a high side solenoid switch; a voltage divider having a voltage divider input connected to said circuit input and an output connected to a comparator; an overcurrent transistor having an emitter connected to said circuit input, a collector connected to a second voltage divider and an anode of a diode, and a base connected to an output of said sense resistor, such that a current passing through said sense resistor operates as a control current for said overcurrent transistor; said second voltage divider having an output connected to said comparator; said comparator having an output, and the output is a fault detection output; a cathode of said diode connected to a capacitor and a secondary bias resistor such that said capacitor and said secondary bias resistor are parallel; a first bias voltage resistor connected to said output of said sense resistor and to a second bias voltage resistor in series; said second bias voltage resistor connected to a gate node of said high side solenoid switch; each of said capacitor and said secondary bias resistor connected to a node connecting said first bias voltage resistor and said second bias voltage resistor; a bias current transistor having a collector connected to said node connecting said first bias voltage resistor and said second bias voltage resistor; a bias current resistor connected to an emitter of said bias current transistor and to ground; and a drain of said high side solenoid switch connected to an output, such that said drain of said high side solenoid switch can be connected to a solenoid.
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Specification