Current Sampling Circuit for Multi-Mode Buck-Boost Converters
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Solution Overview
Problem
Traditional current sampling circuits for multi-mode circuits dissipate energy and increase costs due to external resistance and require additional pins, making them inefficient and costly.
Innovation Solution
A novel current sampling circuit and associated control method that uses a multi-mode circuit with switches and an inductance to generate sampling currents, processing these currents to reduce power loss and pin count, allowing the circuit to operate in buck, boost, or buck-boost modes with reduced energy dissipation and pin requirements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If an external sampling resistance is used to sample current, then current sampling can be achieved, but energy is dissipated and lost and two extra pins are needed
Solution Approach 1:
The patent utilizes the existing switch body diodes and parasitic capacitances within the multi-mode circuit to perform current sampling, eliminating the need for external sampling resistance. The circuit's inherent components serve the dual purpose of their original function plus current sensing, thereby avoiding additional energy dissipation from external resistors.
Solution Approach 2:
The existing switches and their intrinsic components (body diodes, parasitic capacitances) are made to serve multiple functions: power switching and current sampling. This multi-functionality eliminates the need for dedicated external sampling components, reducing both energy loss and pin count.
2Measurement precision
If an external sampling resistance is used to sample current, then current sampling can be achieved, but two extra pins are needed increasing cost
Solution Approach 1:
The existing switches and their intrinsic components (body diodes, parasitic capacitances) are made to serve multiple functions: power switching and current sampling. This multi-functionality eliminates the need for dedicated external sampling components, reducing both energy loss and pin count.
Solution Approach 2:
The patent extracts the current sampling function from the external component domain and relocates it to the internal circuit domain by utilizing existing switch body diodes and parasitic capacitances. This extraction eliminates the need for external sampling resistance and associated pins.
3Measurement precision
If traditional current sampling method is used, then current can be sampled, but power loss increases
Solution Approach 1:
The patent utilizes the existing switch body diodes and parasitic capacitances within the multi-mode circuit to perform current sampling, eliminating the need for external sampling resistance. The circuit's inherent components serve the dual purpose of their original function plus current sensing, thereby avoiding additional energy dissipation from external resistors.
Data Source
AI summary
A multi-mode circuit has a first switch, a second switch, a third switch and a fourth switch. A current sampling circuit applied to the buck-boost has a first sampling circuit, a second sampling circuit and a current processing circuit. The first sampling circuit generates a first sampling current by sampling the current flowing through the first switch, the second sampling circuit generates a second sampling current by sampling the current flowing through the second switch, and the current processing circuit generates a third sampling current based on the first sampling current and the second sampling current. An average value of the third sampling current of one cycle represents the output current of the multi-mode circuit.