Load detection circuit and method
AssigneeSemiconductor Components Industries, LLC
InventorsSam VERMEIR, Leo AICHRIEDLER
Life of this patent
Estimating the term…
Abstract
In one embodiment, a load detection circuit may include a first circuit configured to control a first transistor to form a load current to a load in a first operating mode of the load detection circuit, a second circuit configured to be coupled to form at least a portion of the load current in a second operating mode of the load detection circuit, and a detection circuit configured to detect the control electrode of the first transistor having a value that is less than a threshold value of the first transistor.
Claims20
A load detection circuit comprising:
- a driver circuit configured to form a drive signal to drive a control electrode of a drive transistor with a first control signal to form a voltage between a first current carrying electrode of the drive transistor and a second current carrying electrode of the drive transistor;
- a first switch coupled to selectively couple a first signal to the driver circuit responsively to a first state of a mode signal and to selective couple a second signal to the driver circuit responsively to a second state of the mode signal wherein the driver circuit is configured to form the voltage to have a first value responsively to receiving the first signal and to form the voltage to have a second value responsively to receiving the second signal;
- a diagnostic transistor configured to be coupled in parallel with the drive transistor, the diagnostic transistor having a control electrode configured to receive a second control signal, the second control signal having a third value responsively to the first state of the mode signal and having a fourth value responsively to the second state of the mode signal, wherein the third value substantially disables the diagnostic transistor;
- and
- a comparator configured to detect the control electrode of the drive transistor having a fifth value that is less than a threshold voltage of the drive transistor in response to the second state of the mode signal.
A method of forming a load detection circuit comprising:
- providing a current source;
- configuring the load detection circuit to operate in a first mode and selectively disable the current source and selectively apply a first control signal having a first value to a first transistor to control the first transistor to form a load current to a load;
- configuring the load detection circuit to operate in a second mode and selectively enable the current source to form at least a portion of the load current to the load and to selectively apply a second control signal having a second value to the first transistor to control the first transistor and form a first voltage across the first transistor wherein the first voltage is no less than the second value;
- and
- configuring a detect circuit to detect the second control signal having the second value that is substantially less than a threshold voltage of the first transistor.
A load detection circuit comprising:
- a first circuit configured to control a first transistor to form a load current to a load in a first operating mode of the load detection circuit;
- a second circuit configured to selectively form a portion of the load current in response to a second operating mode of the load detection circuit but not in the first operating mode;
- the first circuit configured to control the first transistor in a closed loop configuration to form a voltage drop across the first transistor in the second operating mode;
- and
- a detection circuit configured to detect the load current is less than a threshold value of the load current.
Dependencies are inferred from the claim text.