SAIC Motor has been granted a patent for a bidirectional isolated communication circuit and method for a differential signal. The circuit includes detection circuits for converting differential pairs into level signals and inhibiting common-mode interference, an isolation adjustment circuit for communication isolation, and a watchdog circuit for switching the circuit between different working modes based on the input signals. GlobalData’s report on SAIC Motor gives a 360-degree view of the company including its patenting strategy. Buy the report here.
According to GlobalData’s company profile on SAIC Motor, battery management systems was a key innovation area identified from patents. SAIC Motor's grant share as of June 2023 was 1%. Grant share is based on the ratio of number of grants to total number of patents.
Bidirectional isolated communication circuit for suppressing common-mode interference
A recently granted patent (Publication Number: US11677591B2) describes a circuit for bidirectional isolated communication of differential signals. The circuit includes a first detection circuit that receives a first differential pair from one direction and converts it into a first level signal, while also performing common-mode interference suppression. Similarly, a second detection circuit receives a second differential pair from the opposite direction and converts it into a second level signal, also performing common-mode interference suppression. An isolation adjustment circuit is placed between the two detection circuits to isolate the second level signal from the first level signal.
Additionally, the circuit includes a watchdog circuit that can be activated by either the first or second differential pair. When activated, the watchdog circuit switches the circuit for bidirectional isolated communication from a first mode to a second mode. The first mode operates with a lower current compared to the second mode.
The isolation adjustment circuit consists of a first drive circuit that drives the first detection circuit based on an input signal from the second direction, and a second drive circuit that drives the second detection circuit based on an input signal from the first direction. The circuit also includes adjustment circuits connected to the detection circuits and drive circuits, which convert the level signals into high-frequency signals. Isolation devices are placed between the adjustment circuits to ensure proper isolation.
Furthermore, the circuit includes a wake-up circuit that powers the watchdog circuit in the first mode. The wake-up circuit is activated by a third isolation device, which detects the presence of the first or second differential pair.
The circuit is designed to be powered by a power supply device, which provides a first power supply in the second mode when the watchdog circuit is active, and a second power supply in the first mode when the watchdog circuit is not active. The second power supply has a lower voltage compared to the first power supply.
The power supply device includes a universal-input linear voltage regulator for the first power supply and a low-power-consumption linear voltage regulator for the second power supply. Additionally, a secondary side circuit module is included to supply power to another bidirectional isolated communication circuit adjacent to the described circuit.
The method for bidirectional isolated communication of differential signals involves receiving the first and second differential pairs, converting them into level signals, and performing common-mode interference suppression. The circuit is then woken up by either differential pair, causing it to switch from the first mode to the second mode, isolating the second level signal from the first level signal. The first mode operates with a lower current compared to the second mode.
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