Switching Converter Voltage Sampling Paths Without Extra Vbus Pin
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Solution Overview
Problem
In high power applications, the sampling circuit in conventional switching converters is unable to detect the voltage Vbus, preventing the integrated circuit control device from providing a switching control signal for the switching circuit, and adding a Vbus sampling pin increases cost and hinders miniaturization.
Innovation Solution
The integrated circuit control device includes a voltage sampling circuit with dual sampling paths and a discharge circuit, using a single pin to detect the AC input voltage and the first output voltage, allowing the switching control circuit to regulate the second output voltage without an additional pin for Vbus detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a Vbus sampling pin is added to detect the first output voltage, then the switching control circuit can regulate the second output voltage, but the number of pins increases and miniaturization is hindered
Solution Approach 1:
The first pin is designed to perform multiple functions: it can sample the AC input voltage through the first sampling path and sample the first output voltage through the second sampling path. This multi-functionality eliminates the need for an additional dedicated Vbus sampling pin, resolving the contradiction between detection capability and pin count.
Solution Approach 2:
The patent merges the function of detecting both the AC input voltage and the first output voltage (Vbus) into a single pin. By combining these detection functions in one pin rather than using separate pins, the device achieves voltage detection capability without increasing the pin count, thus enabling miniaturization.
2Reliability
If dual sampling paths are implemented in a single pin, then voltage detection capability is improved, but the circuit complexity increases
Solution Approach 1:
The circuit uses switching elements (such as MOSFETs or transistors) to dynamically connect different sampling paths to the first pin based on operational requirements. This dynamic switching allows the single pin to access different voltage sources (AC input or first output) at different times, achieving dual detection capability without permanently complex wiring.
Solution Approach 2:
The sampling circuit is segmented into multiple independent paths (first sampling path for AC input voltage, second sampling path for first output voltage), each with its own sampling capacitor and switching element. This segmentation allows each path to be independently controlled and managed, reducing the overall circuit complexity compared to a monolithic design.
Data Source
AI summary
An integrated circuit control device for a switching converter with a pre-stage circuit and a post-stage circuit is provided. The pre-stage circuit converts an AC input voltage to a first output voltage. The post-stage circuit converts the first output voltage to a second output voltage. The integrated circuit control device includes a first pin, a discharge circuit and a switching control circuit. The first pin receives a voltage sampling signal. The first pin is coupled to a first sampling path sampling a first voltage signal indicating the AC input voltage and coupled to a second sampling path sampling a second voltage signal indicating the first output voltage. The discharge circuit and the switching control circuit receive the voltage sampling signal through the first pin and control the switching converter based on the voltage sampling signal.