Texas Instruments Corporation

Brian Jude Linehan

James Michael Walden

Kyoung Min Lee

Yang Zhang

In a transistor turnoff system, a transistor control circuit is configured to adjust a control voltage at a transistor control output responsive to a comparison signal at a control input. The control voltage has a slew rate. A comparator has a comparator output and first and second comparator inputs. The first comparator input is coupled to the transistor control output. The comparator is configured to: provide the comparison signal at the comparator output based on a reference voltage at the second comparator input; and deactivate the transistor control circuit by changing a state of the comparison signal responsive to the control voltage falling below the reference voltage. A slew-rate compensator is configured to increase the reference voltage by a compensation voltage that compensates for a time delay of the comparator or the transistor control circuit. The compensation voltage is proportional to the slew rate.

Slew-rate compensated transistor turnoff system

One example includes a circuit that includes a transistor control circuit having an input and an output adapted to be coupled to the output of the transistor control circuit and can provide a slew-rate compensation voltage proportional to a slew-rate of a control voltage of the transistor. A reference voltage source can be coupled to the slew-rate compensator to provide a reference voltage at the output of the reference voltage source, the slew-rate compensator configured to add the slew-rate compensation voltage to the reference voltage to provide an adjusted reference voltage at the output of the slew rate compensator. A reference comparator having a first input, a second input and an output is coupled to the input of the transistor control circuit. The first input can be coupled to the control terminal of the transistor, and the second input can be coupled to the output of the slew-rate compensator.

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Brian Jude Linehan