Charge Pump Frequency Switching for High-Side Driver EMI Control
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Solution Overview
Problem
Existing power converters face challenges in quickly driving high-side switches while minimizing electromagnetic interference (EMI), as the charge pump operates at a fixed frequency, either too low to drive switches quickly or too high to cause EMI.
Innovation Solution
A power converter with a charge pump frequency switching control mechanism, where the frequency of the clock signal generated by the clock generator circuit is adjusted based on the high-side control signal, allowing the charge pump to switch frequencies and supply power to the high-side driver circuit at either low or high frequencies as needed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the charge pump operates at a low fixed frequency, then the high-side driver circuit can charge the high-side switch, but the high-side driver circuit is unable to quickly drive the high-side switch for pulling up the voltage
Solution Approach 1:
The charge pump frequency is changed from fixed to dynamic. The control circuit dynamically adjusts the charge pump frequency based on the operating state of the high-side switch. When the high-side switch voltage is low, the charge pump operates at high frequency to quickly charge. When the voltage reaches the threshold, the frequency switches to low to maintain stability, thus resolving the contradiction between fast charging and stable operation
Solution Approach 2:
The charge pump frequency parameter is changed from a constant value to a variable value. The system transitions between high frequency and low frequency based on the voltage level of the high-side switch control terminal. This parameter change enables the system to achieve both fast voltage pulling (high frequency phase) and reduced EMI (low frequency phase)
2Speed
If the charge pump operates at a high fixed frequency, then the high-side driver circuit can quickly drive the high-side switch, but the high-side driver circuit switches the high-side switch at a high frequency for a long period of time, which causes electromagnetic interference (EMI)
Solution Approach 1:
The charge pump operates in periodic cycles, alternating between high frequency and low frequency modes. During each cycle, the high-side switch voltage is pulled up quickly at high frequency, then maintained at low frequency when the threshold is reached. This periodic frequency switching achieves fast voltage pulling while limiting the duration of high-frequency operation to reduce EMI
Solution Approach 2:
The system rushes through the voltage pulling phase at high frequency to quickly reach the target voltage level, then immediately transitions to low frequency operation. This approach minimizes the time spent at high frequency, thereby reducing electromagnetic interference while still achieving fast voltage establishment
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
This solution enables the power converter to quickly drive high-side switches by adjusting the charge pump frequency, thereby reducing the time to pull up the voltage of the high-side switch while minimizing EMI by reducing the high-frequency switching duration.
Implementation Method 1
The charge pump supplies power to a high-side driver circuit
Data Source
AI summary
A power converter having a charge pump frequency switching control mechanism is provided. In the power converter, frequencies of a plurality of pulse waves of a clock signal are determined, according to a level of a high-side control signal outputted to a control terminal of a high-side switch from a control circuit or a voltage of the control terminal (and a voltage of a second terminal) of the high-side switch. In the power converter, a charge pump supplies power to a high-side driver circuit at the frequencies of the clock signal, and the high-side driver circuit uses the power from the charge pump to drive the high-side switch and to pull up the voltage of the control terminal of the high-side switch.