Capacitive Divider for Isolated Daisy Chain Communication
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Solution Overview
Problem
High voltage systems require communication schemes that offer voltage isolation and robust performance in the presence of electromagnetic interference (EMI) and power transients, while also limiting EMI emissions.
Innovation Solution
The proposed communication systems utilize a capacitive divider transmission scheme with differential capacitors and transformer coupling to provide voltage isolation and immunity to EMI, while reducing EMI emissions through a split differential architecture and resistor divider circuits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If voltage isolation and EMI immunity are implemented using traditional isolation schemes, then reliability is improved, but device complexity and EMI emissions increase
Solution Approach 1:
The patent introduces a capacitive divider as an intermediary element between the high-voltage communication line and the low-voltage processing circuitry. This capacitor-based intermediary provides voltage isolation and EMI filtering without requiring complex transformer or optocoupler arrangements, thereby achieving reliability improvement with reduced device complexity
Solution Approach 2:
The patent changes the electrical parameters of the communication signal by using RC time constants to shape the signal waveform. By adjusting the resistor and capacitor values, the system achieves voltage level translation and EMI attenuation, providing isolation functionality through parameter optimization rather than complex isolation hardware
2Object-generated harmful factors
If EMI emissions are reduced through filtering and shielding, then object-generated harmful factors are decreased, but device complexity and signal loss increase
Solution Approach 1:
The patent applies preliminary signal conditioning by pre-shaping the communication waveform using RC circuits before transmission. This preliminary action ensures that the signal has optimal rise/fall times and voltage levels, reducing the need for aggressive EMI filtering during reception and minimizing signal loss while still achieving low EMI emissions
3Reliability
If robust performance in high voltage systems is achieved, then reliability is improved, but ease of operation and manufacturing difficulty increase
Solution Approach 1:
The patent implements a self-clocking communication protocol where the data signal itself contains the timing information through its waveform characteristics. The RC time constants are chosen to ensure that each data transition naturally provides a clock edge, eliminating the need for separate clock lines or complex synchronization circuitry, thereby improving reliability while simplifying manufacturing
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 high transient and EMI immunity with low EMI emissions, ensuring robust performance and protection against transient events in high voltage systems.
Implementation Method 1
a first transceiver (102) of a first balancing IC (1401-1) coupled to a second transceiver (150-2) of a second balancing IC (1401-2) through a capacitive divider transmission scheme
Implementation Method 2
transformer coupling to provide voltage isolation and immunity to EMI
Data Source
AI summary
Examples disclosed herein provide daisy chain communication system. The daisy chain communication system includes a plurality of transceivers coupled to devices which provide data signals to, and receive data signals from, their one or more coupled transceivers. The transceivers are configured to transmit and receive an amplitude modulated signal having edges corresponding to edges of a clock signal and amplitudes corresponding to a digital value of the first data signal.