Buck Converter Current Sensing via Peak Valley Sampling
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Solution Overview
Problem
Existing techniques for determining the average current of power converters are often inaccurate or require additional external components, particularly in integrated circuit implementations, which can be undesirable.
Innovation Solution
A circuit comprising a first and second current sampling unit and an output unit, configured to sample input current during non-overlapping phases and provide signals proportional to peak and valley currents to calculate the average output current, eliminating the need for additional pins and precise knowledge of component values.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional current sensing techniques are used to determine average current, then measurement capability is provided, but measurement precision is poor and additional external components are required
Solution Approach 1:
The patent combines multiple current sampling operations into a single integrated circuit. The first and second current sampling units are merged into one device, sharing common circuitry for sampling the input current during different phases. This integration eliminates the need for multiple separate external components while maintaining the capability to capture peak and valley currents for accurate average current calculation.
Solution Approach 2:
The integrated circuit performs multiple functions: it samples current during different phases, determines both peak and valley currents, calculates average current, and outputs the result. This multi-functional approach replaces what would traditionally require multiple separate components, reducing device complexity while improving measurement precision through coordinated operation of the sampling units.
2Measurement precision
If additional external components are used for current sensing, then measurement capability is improved, but device complexity increases
Solution Approach 1:
The patent merges the functionality of multiple current sampling circuits into a single integrated device. The first current sampling unit and second current sampling unit are combined within the same circuit, sharing common resources such as the input current connection and timing control logic. This consolidation maintains accurate current measurement capability while reducing the total component count and simplifying the overall circuit design.
3Measurement precision
If continuous current monitoring is implemented, then measurement accuracy is improved, but power consumption increases
Solution Approach 1:
The patent implements periodic current sampling instead of continuous monitoring. The first current sampling unit operates during a first phase of a switching period, and the second current sampling unit operates during a second phase of the same period. These phases are non-overlapping, meaning the sampling circuits are activated only during their designated time windows and remain inactive otherwise. This periodic operation maintains measurement accuracy by capturing relevant current information while significantly reducing power consumption compared to continuous monitoring.
Solution Approach 2:
The patent uses partial action by sampling the current only during specific phases rather than continuously. The first phase and second phase together cover the entire switching period, but at any given moment, only one sampling unit is active. This approach provides sufficient information for accurate average current calculation while minimizing the time that power-consuming sampling circuits are active, thereby reducing overall power consumption.
Data Source
AI summary
The disclosure describes techniques for measuring the average output current of a power converter circuit by determining peaks valleys in the output current. A current monitoring circuit may include an averaging unit, which may sample the output current during a current peak as well as during a current valley. During a hold phase the averaging unit may output a signal proportional to the average output current based on the sampled peak current and sampled valley current. In some examples, the averaging unit may include three functional units. A first unit may be configured to determine the output current, a second block may be configured to hold the previously determined peak current and a third block may be configured to hold the previously determined valley current. In this manner the averaging unit may continuously output a signal proportional to the average output current of the power converter.