Switching Power Supply Input Voltage Detection Using Bipolar Transistor Breakdown
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Solution Overview
Problem
Conventional switching power supply units face issues with current consumption and resistance value variation when using resistor-voltage dividing circuits for input voltage detection, leading to increased complexity and size of the starting element.
Innovation Solution
The implementation of a semiconductor device with a field effect transistor and a bipolar transistor, where the bipolar transistor is connected in series between the input terminal and the drain of the field effect transistor, allowing for input voltage detection without a resistor-voltage dividing circuit, thereby reducing current consumption and simplifying the circuit.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If resistor-voltage dividing circuit is used for input voltage detection, then input voltage detection function is achieved, but current consumption increases and resistance value variation occurs
Solution Approach 1:
The patent extracts the voltage detection function from the resistor-voltage dividing circuit and implements it using a bipolar transistor's breakdown voltage characteristic. The bipolar transistor is connected in series between the input terminal and the drain of the field effect transistor, and its breakdown voltage is utilized to detect the input voltage level, thereby eliminating the need for continuous current flow through resistors.
Solution Approach 2:
The patent changes the detection parameter from voltage division ratio (resistor-based) to breakdown voltage threshold (transistor-based). By utilizing the breakdown voltage characteristic of the bipolar transistor, the system achieves voltage level detection without requiring continuous current flow, thus reducing power consumption while maintaining detection functionality.
2Measurement precision
If resistor-voltage dividing circuit is used for input voltage detection, then input voltage detection function is achieved, but circuit complexity increases
Solution Approach 1:
The patent merges the voltage detection function with the existing bipolar transistor in the starting circuit. By utilizing the breakdown voltage characteristic of the bipolar transistor that is already present in the circuit, the patent eliminates the need for separate resistor-voltage dividing circuitry, thereby reducing overall circuit complexity while maintaining detection capability.
Solution Approach 2:
The bipolar transistor serves multiple functions: it acts as part of the starting circuit and simultaneously provides input voltage detection through its breakdown voltage characteristic. This multi-functionality eliminates the need for dedicated detection circuitry, simplifying the overall system.
3Measurement precision
If resistor-voltage dividing circuit is used for input voltage detection, then input voltage detection function is achieved, but starting element area increases
Solution Approach 1:
The patent extracts the detection function from external or separate resistor-based circuits and integrates it into the bipolar transistor structure itself. By utilizing the inherent breakdown voltage characteristic of the bipolar transistor, the patent eliminates the need for additional resistor elements and their associated layout space, thereby reducing the overall starting element area.
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 effective input voltage detection without resistor-voltage dividing circuits, reducing power loss and eliminating resistance value variations, while simplifying the circuit constitution and minimizing the parts count, thus enhancing efficiency and miniaturization.
Implementation Method 1
the bipolar transistor makes the field effect transistor operate by conducting when primary side voltage applied to a drain terminal of the field effect transistor is greater than prescribed voltage
Data Source
AI summary
Aspects of the invention can include a semiconductor device, control IC for switching power supply and switching power supply unit, which allow input voltage detecting function to be realized without resistor-voltage dividing circuit. An npn-type element consisting of p-type region, collector region and emitter region is included inside of drain region of starting element. On a first interlayer insulating film, aspects of the invention can provide collector electrode wiring of npn-type element, emitter-drain electrode wiring serving as both emitter electrode wiring of npn-type electrode and drain electrode wiring of starting element, source electrode wiring of starting element, and gate electrode wiring of starting element. A first metal wiring can serve both as input terminal of starting element and input terminal of npn-type element is connected to collector electrode wiring. The npn-type element can function as input voltage detecting means for detecting input voltage drop applied to the first wiring.