Driver circuitry for commutated inductive loads
First Claim
1. A transconductance amplifier loop used as a pull-down driver circuit for commutating inductive loads comprising:
- an input voltage;
an operational amplifier coupled to said input voltage;
a driving transistor coupled to said operational amplifier for controlling a constant current;
a resistor coupled to said driving transistor;
a variable gain amplifier coupled to said resistor and to said operational amplifier.
1 Assignment
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Accused Products
Abstract
The present invention provides driver circuitry for commutated inductive loads, and in particular, inductive loads employed in multi-pole DC brushless motors. The preferred embodiment of the present invention typically implements three pull-up and three pull-down drivers for motor control. The pull-down driver circuit described in the present invention can be configured to be adjusted by an external component of the integrated circuit implementation in order for controlling turn-off transients. Voltage transients due to changes in load current in the control loop of the pull-down driver circuit can be minimized or deterministically controlled by controlling the rate of change of the input voltage. For the case of when the load current is to be completely switched from one inductor to another inductor, an additional unity gain buffer coupled to the input voltage is inserted into the control loop of the pull-down driver circuit for reducing the voltage transients that can result. The output voltage rise and fall times of the pull-up driver circuit of the present invention can be controlled by means of an accurate clock rate, a capacitance ratio value, an arbitrary voltage supply or by any combination of the above means. The present invention also provides circuitry for controlling the pull-up driver circuit and the pull-down driver circuits as required to assert the floating operation and as well dynamic breaking operation. The present invention is able to assert these operations by operating from either the power supply or from an energy storage capacitor that is charged to a value closely approximating the power supply voltage should the power supply be removed.
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Citations
17 Claims
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1. A transconductance amplifier loop used as a pull-down driver circuit for commutating inductive loads comprising:
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an input voltage; an operational amplifier coupled to said input voltage; a driving transistor coupled to said operational amplifier for controlling a constant current; a resistor coupled to said driving transistor; a variable gain amplifier coupled to said resistor and to said operational amplifier. - View Dependent Claims (2, 3, 4, 5)
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6. A pull-down driver circuit that reduces voltage transients that result when switching a load current from a first inductor to a second inductor comprising:
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an input voltage coupled to a first gain buffer; said first gain buffer coupled to an operational amplifier; a first current source coupled to said operational amplifier and to a first capacitor; a driving transistor coupled to an output of said operational amplifier as well as to said first capacitor as well as coupled to a first resistor. - View Dependent Claims (7, 8, 9)
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10. A method for controlling the output voltage rise and fall times of a pull-up driver circuit used in commutating of inductive loads comprising the steps of:
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providing an accurate clock rate for controlling said pull-up driver circuit; providing a capacitance ratio between a first and second capacitance of said pull-up driver circuit; controlling a voltage supply coupled to said pull-up driver circuit.
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11. A circuit coupled to pull-down and pull-up drivers circuits used for commutating inductive loads where said circuit disables and activates said pull-up and pull-down drivers circuits for asserting the desired operation, said circuit comprising:
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an inverter; a NAND logic gate coupled to said inverter; a NOR logic gate coupled to said inverter and to said NAND logic gate; said NOR gate coupled to said pull-down drivers circuits; said NAND gate coupled to said pull-down and said pull-up drivers circuits. - View Dependent Claims (12, 13, 14)
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15. A circuit that reduces voltage transients that result when switching a load current comprising:
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an operational amplifier receiving an input voltage; a current source coupled to an output of said operational amplifier; a driving transistor also coupled to said output of said operational amplifier, said driving transistor having an intrinsic gate-to-drain capacitance; an inductor coupled to an output of said driving transistor. - View Dependent Claims (16, 17)
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Specification