VARIABLE SENSOR INTERFACE FOR A CONTROL UNIT

Abstract

The invention relates to a variable sensor interface for a control unit, this variable sensor interface including a circuit board which is provided with components. In a sensor interface which can easily be used for the use of different sensor types, the circuit board has a predefined conductive track layout having a plurality of predefined mounting locations, the mounting locations being provided with components in a sensor-specific manner.

Claims

1. A variable sensor-interface for a control device, comprising a circuit board for connecting at least one external sensor, which is equipped with components, the circuit board includes a conductive track layout with a plurality of predetermined mounting locations for the components, allowing the mounting locations to be equipped with sensor-specific components.

2. A sensor-interface according to claim 1, wherein the components include a predetermined number of at least one of resistors or capacitors (C.sub.F) that are sensor-specifically connected to various mounting locations.

3. The sensor-interface according to claim 1, wherein the components include at least one protective circuit for at least one of transient interferences or ESD is connectable to the mounting locations.

4. The sensor-interface according to claim 1, wherein the components include at least one overcurrent protection circuit that is connectable to the mounting locations.

5. The sensor-interface according to claim 4, wherein the overcurrent protection circuit is arranged on one of the mounting locations, which is located in one or more current paths of the conductive track layout, providing a supply voltage or ground for the external sensor.

6. A control device for a motor vehicle which is connected to at least one sensor, which is connected to a sensor-interface, and the sensor-interface is embodied according to claim 1.

7. The control device according to claim 6, wherein at least one of an input or output of the sensor-interface is switched with a protection circuit for at least one of transient interferences or ESD.

8. The control device according to claim 6, wherein each input or output of the sensor-interface is switched with a protection circuit for at least one of transient interferences or ESD.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0012] The invention allows numerous embodiments. Two of them shall be explained in greater detail based on the figures shown in the drawing.

[0013] Shown are:

[0014] FIG. 1: a first exemplary embodiment of the control device according to the invention,

[0015] FIG. 2: a second exemplary embodiment of the control device according to the invention.

[0016] Identical features are marked with the same reference characters.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0017] FIG. 1 shows a first exemplary embodiment of a control device 1, as used for example in a motor vehicle. Here, the control device 1 has two outputs 2, 3 for the energy supply of external sensors, which are not shown in greater detail. The output 2 is switched with a first protective circuit 4 for transient interferences and ESD, which are switched serially with a first overcurrent protection circuit 5. This overcurrent protective circuit 5 is connected via a first resistor R1 to a first voltage source 6 of the control device 1. In case of short circuitry, the overcurrent protection circuit 5 limits the current of the supply voltage 6 at the output 2 and this way prevents any damage of the control device 1.

[0018] The second output 3 of the control device 1 is also connected via a second protection circuit 7 for transient interferences and ESD, which leads to a second overcurrent protection circuit 8. This second overcurrent protection circuit 8 is connected via the resistor R2 to a second voltage source 9 of the control device 1. A third resistor R3 is arranged between the first overcurrent protection circuit 5 and the first resistor R1 as well as the second overcurrent protective circuit 8 and the second resistor R2. By the assembly options of the resistors R1, R2, and R3 the two supply voltages 6, 9 of the control device 1 can be combined arbitrarily for the two outputs 2, 3. This is shown in greater detail in table 1.

TABLE-US-00001 TABLE 1 First output 2 Second output 3 R1 R2 R3 Voltage source 6 Voltage source 6 0 Ohm Not 0 Ohm equipped Voltage source 6 Voltage source 9 0 Ohm 0 Ohm Not equipped Voltage source 9 Voltage source 9 Not 0 Ohm 0 Ohm equipped

[0019] Here, the identification not equipped shall indicate an interruption in the conductive track layout 17. If the resistance amounts to 0 Ohm, a resistor bridge is provided in the conductive track layout 17.

[0020] FIG. 2 shows a second exemplary embodiment of a control device 10, which in addition to the output 2 for an external sensor provides two inputs 11, 12 for the external sensor. The output 2 is connected to the voltage source 6 via the first protection circuit 4 for transient interferences and ESD and via the first overcurrent protection circuit 5. The inputs 11 and 12 are each connected to a second and/or a third protective circuit 13, 14 for transient interferences and ESD. The second protective circuit 13 for transient interferences leads via a resistor R5 and a filter resistor R.sub.Filter to an internal input 15 of the control device 10, at which either an analog/digital converter, now shown in greater detail, can be connected or a digital PWM-input. The filter resistor R.sub.Filter is connected via a capacitor C.sub.Filter to the ground. The second protective circuit 13 for transient interferences and ESD is connected via a resistor R6 and the third protection circuit 14 for transient interferences and ESD via a resistor R7 to an overcurrent protection circuit 16, which in turn leads to the ground.

[0021] In the case to be discussed further the protective circuits 4, 13, 14 for transient interferences and ESD as well as the filter resistor R.sub.Filter and the filter capacitor C.sub.Filter are mandatory. The filter resistor R.sub.Filter and the filter capacitor C.sub.Filter are required according to EMC-specifications (EMC-electromagnetic compatibility). However, applications are also possible in which the filter resistor R.sub.Filter and the filter capacitor C.sub.Filter can be waived. The resistors R4 to R7 represent assembly options. Depending on the application, the value of the filter resistance R.sub.Filter and/or the filter capacitor C.sub.Filter must be adjusted, which occurs depending on the speed the sensor signals change. In table 2 the potential interface types shall be shown, which are realized with the resistors R4 to R7 by the various assembly options.

TABLE-US-00002 TABLE 2 Interface type R4 R5 R6 R7 Resistance/ Equipped 0 Ohm Not 0 Ohm temperature with 1% R equipped sensor (NTC, PCT, . . . ) 2-pin current Not equipped 0 Ohm Equipped Not interface equipped 3-pin PWM Equipped 0 Ohm Not 0 Ohm interface (open equipped collector) Passive inductive Equipped Equipped Equipped 0 Ohm speed sensor Analog voltage Not equipped 0 Ohm Not 0 Ohm equipped Analog current Not 0 Ohm Equipped 0 Ohm equipped

[0022] When using resistance and/or temperature sensors the inputs of the external sensor are switched to the inputs 11 and 12. The output 2 remains open. R4 represents a reference resistor, here.

[0023] In case of a 2-pin current interference the connection of the external sensor occurs to the output 2 and to the input 11. The input 12 remains open. R6 is here a current/voltage converter resistor.

[0024] If a 3-pin PWM-interface is used, the connection of the voltage supply occurs from the external sensor to the output 2 and the input 12. The input 11 is used as the input for the sensor signal and R4 is embodied as a pull-up resistor.

[0025] If the external sensor is embodied as a passive inductive speed sensor, the connections of the external sensor occur to the inputs 11 and 12. The output 2 remains open, while the resistors R4 and R5 serve to provide the signal with an offset, in order to allow feeding an analog-digital converter at the inner input 15. This way it is ensured that the sensor signal is always in the positive voltage range.

[0026] If the external sensor applied at the control device shows an analog voltage the voltage supply of the external sensor occurs by the output 2 and the input 12. The input 11 is the input for the sensor signal.

[0027] If the external sensor provides an analog current, the connection of the voltage supply of the external sensor occurs at the output 2 and at the input 12. The input 11 is the input of the sensor signal and the resistor R6 is a current/voltage converter resistor.

[0028] The variable interface explained is suitable for any type of control device, in which the connection of various sensors is provided. The particular advantage comprises that the circuit can be adjusted to the respective external sensor without any change of the conductive track layout of the circuit board being necessary, but only the assembly of the resistors needs to be adjusted.

LIST OF REFERENCE CHARACTERS

[0029] 1 control device

[0030] 2 output

[0031] 3 output

[0032] 4 protection circuit for transient interferences and ESD

[0033] 5 overcurrent protection circuit

[0034] 6 voltage source

[0035] 7 protection circuit for transient interferences and ESD

[0036] 8 overcurrent protection circuit

[0037] 9 voltage source

[0038] 10 control device

[0039] 11 input

[0040] 12 inlet

[0041] 13 protection circuit for transient interferences and ESD

[0042] 14 protection circuit for transient interferences and ESD

[0043] 15 internal input

[0044] 16 overcurrent protection circuit

[0045] 17 conductive track layout

[0046] R1 resistor

[0047] R2 resistor

[0048] R3 resistor

[0049] R4 resistor

[0050] R5 resistor

[0051] R6 resistor

[0052] R7 resistor

[0053] R.sub.Filter resistor

[0054] C.sub.Filter capacitor