Bidirectional Bipolar Switch Layout for Low-Drop Daisy Chain Power
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Solution Overview
Problem
Existing bidirectional switches in daisy chain power control systems experience significant voltage drops and fail to adequately supply power to control devices without defining input and output, limiting their effectiveness.
Innovation Solution
A bidirectional bipolar transistor switch arrangement using PNP transistors and low drop voltage diodes, calibrated with a resistor, allows for low voltage drop and independent power supply to control devices, enabling control with a single signal and minimizing current leakage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If existing bidirectional switch methods are used, then power control in daisy chain is achieved, but significant voltage drop occurs across the switching device
Solution Approach 1:
The switch is segmented into two separate bipolar transistors (first and second bipolar transistors) connected in parallel between the input and output terminals. Each transistor handles one polarity of current flow independently, allowing optimal design for low voltage drop in each direction without compromise from bidirectional requirements.
Solution Approach 2:
The invention changes the operating parameters by using bipolar transistors instead of unipolar transistors or other switching devices. Bipolar transistors provide lower on-state voltage drop due to their current-controlled nature and lower saturation voltage, directly addressing the voltage drop issue while maintaining reliable power control.
2Reliability
If existing bidirectional switch methods are used, then switching function is achieved, but power supply to control device is not adequately addressed
Solution Approach 1:
The parallel connection of the two bipolar transistors serves multiple functions simultaneously: it provides bidirectional switching capability, enables low voltage drop in both directions, and creates a natural path for powering the control device through the emitter-collector junction of the inactive transistor, eliminating the need for separate power supply arrangements.
Solution Approach 2:
The switch arrangement itself provides power to the control device through the inherent electrical path created by the parallel transistor configuration. The inactive transistor's emitter-collector path automatically supplies power without requiring external power supply circuitry, making the system self-sufficient.
3Adaptability or versatility
If bidirectional switch is implemented without defining input and output, then versatility is improved, but voltage drop and power supply control become problematic
Solution Approach 1:
While the overall switch is bidirectional and symmetric in function, each individual transistor is asymmetric in its operation - one transistor optimizes for forward current with low voltage drop, while the other optimizes for reverse current. This asymmetric design within a symmetric framework achieves both versatility and low loss.
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
The solution achieves a very low voltage drop across the switching device while providing power to control devices, allowing efficient control of power supply in daisy chain systems without defining input and output, enhancing system reliability and efficiency.
Implementation Method 1
two bipolar PNP transistors (Q1, Q2) connected in parallel between a first terminal and a second terminal
Implementation Method 2
two diodes (D1, D2) with low forward voltage drop
Data Source
Figure 1
Figure 2
AI summary
The invention relates to a bidirectional bipolar transistor switch arrangement, comprising: a first bipolar transistor (Q1) and a second bipolar transistor (Q2) connected in anti-parallel between a first terminal and a second terminal, a resistor (R1) connected to the base of the first bipolar transistor (Q1) and the second bipolar transistor and to a control terminal, a first diode (D1) connected with anode to the first terminal, a second diode (D2) connected with anode to the second terminal, the first diode and the second diode being connected via respective cathodes to a supply terminal. The bidirectional bipolar transistor switch arrangement is able to control the power supply within a daisy chain with low drop voltage.