SMPS Controller Circuit Input Voltage Compensation
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Solution Overview
Problem
Switching-mode power supplies (SMPS) experience overshoot and undershoot in voltage, current, or power delivery due to changes in input voltage, particularly when switching loads like LEDs, which can damage the load and cause undesirable flickering.
Innovation Solution
A controller circuit that generates first and second measured input voltages when the load is switched in and out, respectively, to drive a compensation voltage and adjust the SMPS operating mode, minimizing overshoot and undershoot by accounting for input voltage changes and optimizing digital dimming performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the SMPS switches the load on and off, then the voltage, current, or power supplied to the load is regulated, but overshoot and undershoot occur due to input voltage changes
Solution Approach 1:
The controller circuit measures the input voltage in advance before the load switching event occurs. Based on this preliminary measurement, the controller pre-adjusts the compensation voltage to compensate for the expected input voltage change, thereby preventing overshoot and undershoot before they occur.
Solution Approach 2:
The controller circuit continuously monitors the input voltage and uses this feedback information to dynamically adjust the compensation voltage. The feedback mechanism allows the system to respond to input voltage changes and maintain stable output by modifying the compensation voltage accordingly.
2Power
If the compensation voltage is increased to increase power supplied to the load, then the voltage, current, or power supplied to the load increases, but overshoot occurs when the load is switched in
Solution Approach 1:
Before the load is switched in, the controller circuit measures the input voltage and pre-adjusts the compensation voltage to an appropriate level. This preliminary adjustment ensures that when the load is switched in, the compensation voltage is already optimized to prevent overshoot while still providing sufficient power.
Solution Approach 2:
The compensation voltage is made dynamic rather than fixed. The controller circuit continuously adjusts the compensation voltage based on real-time input voltage measurements and load switching events, allowing the system to optimize power delivery while preventing overshoot under different operating conditions.
3Power
If the compensation voltage is decreased to decrease power supplied to the load, then the voltage, current, or power supplied to the load decreases, but undershoot occurs when the load is switched out
Solution Approach 1:
Before the load is switched out, the controller circuit measures the input voltage and pre-adjusts the compensation voltage to prevent undershoot. This advance preparation ensures that when the load is disconnected, the compensation voltage is already at a level that prevents negative voltage excursions.
Solution Approach 2:
The controller uses feedback from input voltage measurements to continuously optimize the compensation voltage level. This feedback mechanism allows the system to maintain stable operation during load transitions by adjusting the compensation voltage in response to detected input voltage changes.
Data Source
AI summary
A controller circuit for controlling a switching-mode power supply (SMPS) is configured to receive a load control signal indicating an on state when a load is to be coupled to the SMPS and an off state when the load is not to be coupled to the SMPS. In response to the load control signal transitioning from the on state to the off state, the controller circuit is configured to generate a first measured input voltage. In response to the load control signal transitioning from the off state to the on state, the controller circuit is configured to generate a second measured input voltage. The controller circuit is configured to drive a compensation voltage at a compensation element using the first measured input voltage and the second measured input voltage and selectively switch the SMPS using the compensation voltage after driving the compensation voltage.