Measuring circuit

• US 20030222511A1
• Filed: 05/07/2003
• Published: 12/04/2003
• Est. Priority Date: 05/14/2002
• Status: Active Grant

• Current Assignee: Isabellenhütte Heusler GmbH
• Original Assignee: Isabellenhütte Heusler GmbH
• Inventors: Hetzler, Ullrich
• Granted Patent: US 6,946,845 B2
• Time in Patent Office: Days
• US Class Current: 307/151
• CPC Class Codes: G01R 19/18 using conversion of DC into AC, e.g. with choppers
• CPC Class Codes: H03F 2200/261 Amplifier which being suitable for instrumentation applications

Abstract

An ASIC for current, voltage and temperature measurements has signal inputs (RSHH, VBAT, ETS, ETR) for receiving input signals, several choppers, an amplifier, an analog/digital converter and a digital signal output for outputting the result of the measurement and for communicating with a higher-order control unit. The invention proposes that the measuring circuit contain several differential signal inputs (RSHH-RSHL, VBAT-RSHL, ETS-RSHL, ETR-RSHL and VBAT-ETS), wherein one respective chopper/multiplexer is arranged downstream of each signal input.

Claims

1. Measuring circuit for current and voltage measurements, with a signal input (RSHH, VBAT, ETS, ETR) for receiving an input signal, chopper means, an amplifier, a digital signal processor and a signal output for outputting an output signal, characterized by a plurality of signal inputs (RSHH, VBAT, ETS, ETR) for respectively receiving an input signal, all said input signals being measured in reference to a common reference potential (RSHL), wherein one respective chopper is arranged downstream of each signal input (RSHH, VBAT, ETS, ETR).

2. Measuring circuit according to claim 1, characterized by control means for automatically switching over said amplifier between two input channels so that two different signals to be measured can be applied to said amplifier.

3. Measuring circuit according to claim 2, characterized in that one of said different signals is a current signal and the other one is a voltage signal.

4. Measuring circuit according to claim 1, characterized by the fact that a temperature sensor is provided for measuring the temperature, wherein a chopper is arranged downstream of the temperature sensor.

5. Measuring circuit according to claim 1, characterized by the fact that the digital signal processing unit contains a digital demodulator, and an analog/digital converter is arranged between the amplifier and the demodulator.

6. Measuring circuit according to claim 5, characterized by the fact that the analog/digital converter includes a filter with a programmable order number.

7. Measuring circuit according to claim 1, characterized by the fact that each signal input has its own chopper which can be activated separately and can be connected to the amplifier or to the analog/digital converter by itself acting as a multiplexer or by separate multiplexer means.

8. Measuring circuit according to claim 1, characterized by the fact that several choppers are interconnected via a voltage bus.

9. Measuring circuit according to claim 1, characterized by a bipolar line system between the signal inputs (RSHH-RSHL, VBAT-RSHL, ETS-RSHL and ETR-RSHL, as well as VBAT-ETS) and the chopper and/or between the chopper and the amplifier and/or between the amplifier and the demodulator and/or between the demodulator and the signal output.

10. Measuring circuit according to claim 1, characterized by the fact that a sigma/delta modulator is arranged downstream of the amplifier.

11. Measuring circuit according to claim 1, characterized by a first controllable current source that can be connected to at least one of the signal inputs (RSHH, RSHL).

12. Measuring circuit according to claim 1 or 11, characterized by a second controllable current source that can be connected to at least one of the outputs (ETR, ETS and VBAT) in order to activate external sensors.

13. Measuring circuit according to claim 3, characterized by the fact that the gain of the amplifier is adjustable.

14. Measuring circuit according to claim 3, characterized by the fact that the chopper operates at a frequency of the order of 5-50 kHz.

15. Measuring circuit according to claim 14, characterized by the fact that the chopper operates at a frequency of 20 kHz.

16. Measuring circuit according to claim 1, characterized by a digital interface for adjusting at least one operating parameter of the measuring circuit.

17. Measuring circuit according to claim 16, characterized by the fact that the adjustable operating parameter is an absolute value and/or a temperature coefficient of a reference voltage.

18. Measuring circuit according to claim 1, characterized by an oscillator and/or a timer for internally generating clock signals.

19. Measuring circuit according to claim 1, characterized by the fact that the chopper, the amplifier, the digital signal processor, the multiplexer and/or the analog/digital converter can be switched off in order to reduce the current consumption.

20. Measuring circuit according to claim 1, characterized by an operating mode in which the measuring circuit carries out a measurement within predetermined time intervals, checks whether a predetermined threshold value has been exceeded, and, if so required, activates an external device.

21. Measuring circuit according to claim 1, characterized by comprising an integrated circuit.

22. Measuring circuit according to claim 1, including a measuring resistor (Rsh) connected to at least one of said signal inputs (RSHH), characterized in that said integrated circuit is mounted on said measuring resistor.