Circuit assembly for a switchable line termination of a serial bus

Patent metadata

Field	Value
Publication number	US-2018367347-A1
Application number	US-201616061202-A
Country	US
Kind code	A1
Filing date	Dec 7, 2016
Priority date	Dec 14, 2015
Publication date	Dec 20, 2018
Grant date	—

Abstract

An electronic circuit arrangement, by which a line termination or terminating resistor of a serial bus, for example a CAN bus, is implemented in a switchable manner and can be electronically connected or disconnected by electronically operating switching elements and a microcontroller, or a computer port of the latter, which is present in an electronic control unit.

First claim

1 - 15 . (canceled)

16 . A circuit arrangement for a switchable line termination of a serial bus, comprising:
an electronic switching apparatus which is connected between signal lines of the serial bus and is configured, under the control of a control device of an electronic control unit, to connect a predetermined line termination to the serial bus or to disconnect the line termination from the serial bus.

17 . The circuit arrangement of claim 16 , wherein the electronic switching apparatus includes a first and a second electronic switching device, wherein the line termination includes a first and a second line termination element, wherein the first and second electronic switching devices are reverse-connected in series with one another, and wherein the first and second electronic switching devices are arranged to connect the first and second line termination elements to the first and second signal lines of the serial bus, respectively, or to disconnect them therefrom in a symmetrical and voltage-controlled manner.

18 . The circuit arrangement of claim 16 , wherein the first line termination element is a non-reactive resistor, the second line termination element is a non-reactive resistor, and the first and second line termination elements are connected in series and are configured to provide a termination device having a predetermined line terminating resistor for a physical end of the serial bus.

19 . The circuit arrangement of claim 16 , further comprising:
a blocking device having a blocking element; and a third electronic switching device to control the first electronic switching device and the second electronic switching device by supplying or withholding a control voltage; wherein the blocking element keeps the first electronic switching device and the second electronic switching device in a blocked state if the third electronic switching device withholds the control voltage from the first electronic switching device and the second electronic switching device.

20 . The circuit arrangement of claim 19 , wherein the blocking element is a non-reactive resistor which is connected to a common node of the first line termination element and of the second line termination element, and the third electronic switching device is an electronic switch, in particular a bipolar transistor or a MOSFET, which switches based on a control signal supplied by the external control device.

21 . The circuit arrangement of claim 16 , wherein the first electronic switching device and the second electronic switching device form a blocking device which is arranged to block a signal having an AC voltage characteristic on the serial bus.

22 . The circuit arrangement of claim 16 , wherein the first electronic switching device and the second electronic switching device are field effect transistors or MOSFETs.

23 . The circuit arrangement of claim 16 , wherein the serial bus is a differential bus, in particular a CAN bus, and the first electronic switching device and the second electronic switching device are configured to operate in a common mode range of the bus.

24 . The circuit arrangement of claim 16 , further comprising:
a voltage output device to output a medium bus voltage of the serial bus in a high-impedance manner.

25 . The circuit arrangement of claim 24 , further comprising:
a voltage source generation device to generate a low-impedance voltage source for providing the control voltage for the first and second electronic switching devices from the medium bus voltage which has been output, wherein the control voltage is generated so that a gate-source voltage which reliably turns on the first electronic switching device and the second electronic switching device is provided for the first electronic switching device and the second electronic switching device within a common mode range of the serial bus.

26 . The circuit arrangement of claim 25 , wherein the voltage source generation device is arranged to generate the control voltage for the first and second electronic switching devices within the common mode range of the serial bus on the basis of the medium bus voltage which has been output and, in the event of a shift in the medium bus voltage owing to operation, to track the control voltage and, in association with this, the switchability of the first electronic switching device and of the second electronic switching device at least within the limits of the common mode range of the serial bus.

27 . The circuit arrangement of claim 25 , further comprising:
a voltage regulating device to regulate the control voltage generated by the voltage regulators to a predetermined value.

28 . The circuit arrangement of claim 19 , further comprising:
an overvoltage limitation device for suppressing the interference of voltage spikes in the control voltage.

29 . The circuit arrangement of claim 25 , further comprising:
an overvoltage protection device for protecting the voltage source generation device from overvoltage.

30 . The circuit arrangement of claim 25 , further comprising:
a voltage output at which the output voltage of the voltage source generation device can be discharged to an external device for diagnostic purposes.

Assignees

• Knorr Bremse Systeme Fuer Nutzfahrzeuge Gmbh

Inventors

• Gscheidle Wolfgang

Classifications

• G06F13/4086

  Bus impedance matching, e.g. termination · CPC title

• H04L12/40032

  Details regarding a bus interface enhancer · CPC title

• H04L25/0298

  Arrangement for terminating transmission lines · CPC title

• H04L25/0278 Primary

  Arrangements for impedance matching · CPC title

• H04L2012/40215

  Controller Area Network CAN · CPC title