Power Supply Device Load-Based Mode Switching
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Solution Overview
Problem
Conventional low-power consumption switching regulators face challenges in reducing power consumption, particularly at light loads due to internal consumption currents, and existing methods to reduce input current through feedback of output voltage are hindered by startup and abnormal operation issues.
Innovation Solution
A power supply device incorporating an output transistor, feedback voltage generation, error amplifier, oscillator, slope voltage generation, comparator, PWM pulse generation, and on-time fixed pulse generation, along with a selector and driver to control the output transistor based on load conditions, allowing for efficient power management and reduced internal consumption currents.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If a switching regulator is used to reduce power consumption, then power efficiency is improved, but internal consumption current increases power consumption at light loads
Solution Approach 1:
The patent implements dynamic switching between two operating modes (PWM mode and PFM mode) based on load conditions. The control circuit automatically selects PWM mode for heavy loads and PFM mode for light loads, making the power consumption characteristics adaptive to varying load requirements. This dynamic operation resolves the contradiction by optimizing the balance between power efficiency and internal consumption current across different operating conditions.
Solution Approach 2:
The patent changes the operating parameters of the switching regulator by switching between different control modes. In PWM mode, the duty cycle is continuously adjustable for heavy loads, while in PFM mode, the switching frequency is reduced for light loads. This parameter change allows the system to minimize internal consumption current at light loads while maintaining power efficiency across the full load range.
2Use of energy by moving object
If output voltage is fed back to drive the control circuit to reduce input current, then power consumption is reduced, but startup and abnormal operation become problematic
Solution Approach 1:
The patent introduces an intermediary power supply circuit that temporarily provides power to the control circuit during startup and abnormal conditions. This intermediary power source acts as a bridge, allowing the control circuit to operate reliably during critical periods when output voltage feedback is insufficient. Once the output voltage stabilizes, the system transitions to using output feedback for power supply, achieving both low power consumption and reliable operation.
Solution Approach 2:
The patent performs preliminary action by pre-charging the control circuit using the input voltage through a separate power supply path before relying on output voltage feedback. This preliminary power supply ensures that the control circuit is already operational and can properly monitor and control the system when output voltage becomes available, preventing startup failures and ensuring reliable abnormal operation response.
Data Source
AI summary
A power supply device includes: a comparator that compares an error voltage and a slope voltage to generate a comparison signal; a PWM pulse generation portion that generates a PWM pulse based on a clock signal and the comparison signal; an on-time fixed pulse generation portion that uses the comparison signal as a trigger to generate an on-time fixed pulse where an on-time and an on-time number are constant; a selector that selects any one of the PWM pulse and the on-time fixed pulse; and a selector control portion that generates a selector control signal such that any one of the PWM pulse and the on-time fixed pulse is selected according to whether or not the comparison signal is kept at the same logic level over a predetermined mask period.