Inductor Current Sampling Circuit With Turn-Off Delay Compensation
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Solution Overview
Problem
Switching power supplies face sampling errors due to turn-off delay times in power switches, leading to inaccurate peak current measurements, especially when using external resistors for compensation, which is not suitable for integrated circuits and increases circuit complexity and cost.
Innovation Solution
A sampling circuit with an integrated control unit and energy storage element within the integrated circuit, which charges during the turn-off delay time to generate a compensation signal, allowing for accurate sampling without external large resistors, facilitating circuit integration and reducing costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If external resistors are used for compensation, then sampling accuracy can be improved, but device complexity and manufacturing cost increase
Solution Approach 1:
The patent combines the compensation function with the existing sampling circuit by integrating an energy storage element and control unit within the integrated circuit. This merging eliminates the need for external compensation resistors, thereby maintaining sampling accuracy while reducing device complexity and manufacturing cost.
Solution Approach 2:
The sampling circuit performs self-compensation through the integrated energy storage element that automatically charges during the power switch turn-off delay period. The control unit detects the delay period and controls the energy storage element to generate the compensation signal without requiring external components or additional manual adjustment.
2Measurement precision
If external resistors are used for compensation, then sampling accuracy can be improved, but manufacturing cost increases
Solution Approach 1:
The compensation function is merged into the integrated circuit itself through the energy storage element and control unit, eliminating the need for external compensation resistors. This integration reduces the bill of materials and assembly steps, thereby reducing manufacturing cost while maintaining sampling accuracy.
Solution Approach 2:
The patent uses a simple energy storage element (such as a capacitor) that can be easily manufactured and integrated, replacing expensive external compensation resistors. The energy storage element serves its purpose during the brief turn-off delay period and then resets, providing a cost-effective solution for compensation.
3Duration of action of moving object
If turn-off delay time is present in power switch, then switching power supply operation is enabled, but sampling accuracy deteriorates
Solution Approach 1:
The control unit detects the power switch turn-off delay period in advance and controls the energy storage element to charge during this delay period. By performing the compensation action preliminarily during the delay period, the circuit generates a compensation signal that accurately reflects the peak current despite the delay, thereby maintaining sampling accuracy.
Solution Approach 2:
The patent applies preliminary anti-action by generating a compensation signal that counteracts the sampling error caused by the turn-off delay. The energy storage element charges during the delay period and then discharges to produce a compensation signal that offsets the inaccurate sampling, thereby eliminating the harmful effect of the delay on measurement accuracy.
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 approach enables accurate sampling of peak currents by compensating for turn-off delay errors within the integrated circuit, reducing circuit complexity and cost while maintaining sampling accuracy, and is suitable for various packaging chips, including sealed chips.
Implementation Method 1
a sampling circuit 31 including a control unit and an energy storage element 312
Data Source
AI summary
A sampling circuit for a switching power supply, can include: a first sampling circuit configured to acquire a first sampling signal of a current flowing through an inductor in the switching power supply; and a second sampling circuit configured to obtain a compensation signal with a same rising slope as the first sampling signal within a turn-off delay time of a power switch in the switching power supply, and to superimpose the compensation signal on the first sampling signal to generate a second sampling signal.