Circuit configuration for the voltage supply of a two-wire sensor

• US 6,717,416 B2
• Filed: 11/15/2001
• Issued: 04/06/2004
• Est. Priority Date: 09/14/2001
• Status: Active Grant

• Current Assignee: VEGA Grieshaber KG (Grieshaber Verwaltungsgesellschaft mbH)
• Original Assignee: VEGA Grieshaber KG (Grieshaber Verwaltungsgesellschaft mbH)
• Inventors: Wöhrle, Albert, Motzer, Juergen, Koernle, Ralf
• Primary Examiner(s): Zarneke, David A.
• Assistant Examiner(s): Hollington, Jermele M.
• Application Number:
  US09/987,742
• Publication Number:
  US 20030052705A1
• Time in Patent Office: 873 Days
• Field of Search: 324/133, 324/537, 324/538, 324/555, 361/86, 361/87, 361/91.1, 361/179, 361/181, 323/324, 323/326, 323/385
• US Class Current: 324/537
• CPC Class Codes: G01D 5/14 influencing the magnitude of a current or voltage

Abstract

A two-wire sensor (S) is connected to a pole via a first connection line (V1) in which a voltage longitudinal controller (SR) and a current-limiting resistor (R1) are positioned, and via a second connection line (V2) to which the other pole of a power supply source is connected. The output of the voltage longitudinal controller (SR) is connected to the second connection line (V2) via a first limiting diode (D1) and a second limiting diode (D2) which preferably is installed opposite the first connected diode. The joint node of the two limiting diodes (D1, D2) is connected to the control input of the voltage longitudinal controller (SR).

Claims

1. Circuit configuration for voltage supply of a two-wire sensor (S) which is connected to a supply voltage source (U) via a first connection line (V1) in which a voltage longitudinal controller (SR) is positioned, and a second connection line (V2),

wherein a controller output is connected to the second connection line (V2) via at least one limiting diode (D1), and wherein a current-limiting resistor (R1) is positioned in one of the two connection lines (V1) between the two-wire sensor (S) and the limiting diode (D1), characterized in that:

the controller output is connected to the second connection line (V2) via a series circuit comprising two limiting diodes (D1, D2), and that a joint node of the two limiting diodes (D1, D2) is connected to a control input of the voltage longitudinal controller (SR).

2. Circuit configuration as defined in claim 1, characterized in that a HART®

resistor is positioned in one of the two connection lines (V1, V2).

3. Circuit configuration as defined in claim 1, characterized in that:

voltage longitudinal controller (SR) comprises a field effect transistor (T1), a transistor (T2), and resistors (R2, R3, R4) wherein;

a terminal of the supply voltage source (U) is connected to an input of two-wire sensor (S) via a HART®

resistor (RH), a drain source path of the field effect transistor (T1), and the current-limiting resistor (R1) connected serially, the other input of the two-wire sensor is connected to an other terminal of the supply voltage source (U) via the second connection line (V2),

the HART®

resistor (RH), the drain source path of the field effect transistor (T1) and the current-limiting resistor (R1) are positioned in the first connection line (V1),

the source electrode of the field effect transistor (T1) is connected to the second connection line (V2) via a series circuit comprising a first and second limiting diode (D1, D2),

a first resistor (R4) is connected in parallel to the second limiting diode (D2),

one joint node of the second limiting diode (D2) and the first resistor (R4) is connected to a base of the transistor (T2), a collector of the transistor (T2) is connected to a gate electrode of the field effect transistor (T1) via a second resistor (R3), and an emitter of the transistor (T2) connected to the second connection line (V2), and

the gate electrode of the field effect transistor (T1) is connected to the source electrode thereof via a third resistor (R2).

4. Circuit configuration as defined in claim 3, characterized in that at least one additional limiting diode each (D3, D4, D5, D6) is connected parallel to each limiting diode (D1, D2).

5. Circuit configuration as defined in claim 4, characterized in that the series connected limiting diodes (D1 through D6) are oppositely polarized.