Systems and methods for regulating slew time of output voltage of DC motor drivers

A motor driver system comprising:

• a high-side transistor having a first terminal, a second terminal, and having a control terminal;
• a comparison circuit having a first input coupled to the second terminal of the high-side transistor, a second input coupled to an upper reference voltage, a third input coupled to a lower reference voltage and an output;
• a slew time detection circuit having a first input adapted to receive a pulse width modulated (PWM) signal and a second input coupled to the output of the comparison circuit and an output;
• a gate current control circuit having a first input coupled to receive a target slew voltage, a second input coupled to the output of the slew time detection circuit and an output;
• and
• a gate driver having a first input adapted to receive the PWM signal and a second input coupled to the output of the gate current control circuit, the gate driver having an output coupled to the control terminal.

A motor driver system, comprising:

• a low-side transistor having a first terminal, a second terminal coupled to a ground terminal, and having a control terminal;
• a comparison circuit having a first input, a second input adapted to be coupled to an upper reference voltage, a third input adapted to be coupled to a lower reference voltage and an output;
• a slew time detection circuit having a first input adapted to receive a pulse width modulated (PWM) signal and a second input coupled to the output of the comparison circuit and an output;
• a gate current control circuit having a first input coupled to receive a target slew time and a second input coupled to the output of the slew time detection circuit and an output;
• and
• a gate driver having a first input coupled to receive a low-side PWM signal and a second input coupled to the output of the gate current control circuit, the gate driver having an output coupled to the control terminal.

A method of regulating a slew time of an output voltage of a motor driver system, comprising:

• receiving a target slew time;
• comparing an output voltage of the driver system with an upper reference voltage and a lower reference voltage;
• providing a start signal and an end signal based on the comparison, wherein the start signal indicating when a transistor transitions to a linear region and the end signal indicating when the transistor transitions to a non-linear region;
• determining a slew time based on a duration between assertion of the start signal and assertion of the end signal;
• and
• increasing a gate current responsive to the slew time being greater than the target slew time and decreasing the gate current responsive to the slew time being less than the target slew time.