High-Side Motor Driver Charge Pump Timing for Lower Switching Loss
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Solution Overview
Problem
Existing motor driver circuits suffer from high power consumption due to continuous switching of the charge pump circuit during the on-period of the high-side transistor, leading to inefficiencies.
Innovation Solution
Implementing a voltage monitoring circuit and timer circuit to control the operation of the charge pump circuit, allowing it to operate only during predetermined times, and integrating the circuit on a semiconductor substrate to reduce switching loss and power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the charge pump circuit operates continuously during the on-period of the high-side transistor, then the gate voltage is maintained, but power consumption increases
Solution Approach 1:
The charge pump circuit operates periodically rather than continuously. A control circuit monitors the gate voltage and activates the charge pump only when the voltage drops below a threshold, creating intermittent operation cycles that reduce overall power consumption while maintaining reliable gate voltage levels when needed
Solution Approach 2:
The system uses its own gate voltage as the control signal for the charge pump operation. When the gate voltage naturally drops, this same voltage level triggers the charge pump to recharge it, creating a self-regulating mechanism that eliminates the need for continuous external control and reduces power consumption
2Reliability
If the charge pump circuit switches frequently, then the gate voltage is maintained, but switching loss increases
Solution Approach 1:
By implementing periodic operation with controlled duty cycle, the charge pump switches less frequently while still maintaining adequate gate voltage. The extended off-periods between charging cycles reduce the number of switching events and associated losses, while the on-periods are sufficient to recharge the gate capacitance
Solution Approach 2:
The system changes the operating parameters of the charge pump, specifically the duty cycle and frequency of operation. By optimizing these parameters, the circuit achieves effective gate voltage maintenance with reduced switching frequency, thereby minimizing switching losses while maintaining reliability
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The proposed solution reduces switching loss and power consumption by limiting the charge pump circuit's operation to specific times, enhancing the efficiency of the motor driver circuit.
Implementation Method 1
a charge pump circuit, configured to be active when the timer circuit measures the predetermined time, generate a boosted voltage in response to a clock signal, and supply the boosted voltage to a gate of the high-side transistor
Implementation Method 2
a voltage monitoring circuit, configured to compare a detection voltage with a threshold value, wherein the detection voltage is a gate voltage or a gate-source voltage of the high-side transistor
Implementation Method 3
a timer circuit, configured to start measuring a predetermined time in response to the control signal changing to an on state that the high-side transistor is instructed to turn on
Data Source
AI summary
The present disclosure provides a motor driver circuit. The motor driver circuit includes a high-side driver that drives a high-side transistor according to a control signal. The high-side driver includes a voltage monitoring circuit, a timer circuit and a charge pump circuit. The voltage monitoring circuit asserts a detection signal when a detection voltage of the high-side transistor becomes lower than a threshold value. The timer circuit starts measuring a predetermined time in response to the control signal changing to an on state that the high side transistor is instructed to turn on, or in response to an assertion of the detection signal when the control signal is in the on state. The charge pump circuit is active while the timer circuit measures the predetermined time, generates a boosted voltage in response to a clock signal and supplies the boosted voltage to a gate of the high-side transistor.