Semiconductor devices and physical quantity sensor devices

Abstract

To reduce the time required when selecting an optimum resistance value from series resistors connected to a thermistor, and acquire the data to be measured on the basis of the selected resistance value to improve the accuracy of measurement.SOLUTION: A series resistor selection circuit 1b includes a series resistor group Rg which is connected in series to an NTC thermistor and selects a series resistor from the series resistor group Rg on the basis of a selection signal sel. An A / D converter 1c converts from analog to digital a divided voltage V1 that is derived by dividing an internal supply voltage V0 by the NTC thermistor Rt and the series resistor selected by the series resistor selection circuit 1b and outputs divided voltage data V1d. A control circuit 1d selects a series resistor by actuating the A / D converter 1c in a low-bit-count mode in a period in which a series resistor is selected from within the series resistor group Rg, and actuates the A / D converter 1c in a high-bit-count mode after selecting an optimum series resistor whose divided voltage data V1d falls within a prescribed voltage range.SELECTED DRAWING: Figure 1

Claims

1. A thermistor for temperature detection, A series resistor selection circuit includes a group of series resistors connected in series with the thermistor, and selects a series resistor from the group of series resistors based on a selection signal. An analog-to-digital converter that converts the divided voltage obtained by dividing the internal power supply voltage by the thermistor and the series resistor into analog-to-digital data and outputs divided voltage data, During the series resistance selection period, the analog / digital converter is operated in low-bit mode to select the optimal series resistance within which the divided voltage data falls within a predetermined voltage range. After the selection of the optimal series resistance, the control circuit operates the analog / digital converter in high-bit mode. Semiconductor device.

2. The semiconductor device according to claim 1, wherein the predetermined voltage range is a voltage range corresponding to a non-saturated region within the temperature range of the object to be measured where the temperature dependence of the divided voltage is not saturated.

3. The semiconductor device according to claim 1, wherein the series resistance selection circuit comprises the series resistance group and the switch group that selects the series resistance from the series resistance group based on the selection signal.

4. The semiconductor device according to claim 3, wherein the series resistor group includes a plurality of series resistors having weighted resistance values ​​obtained by multiplying the resistance value of a unit series resistor by 2 squared, and the series resistor selection circuit selects the combined resistance of the series resistors by a combination of the switch group based on the selection signal.

5. The semiconductor device according to claim 1, further comprising an output unit that converts the divided voltage data output from the analog / digital converter, which operates in the high-bit mode after the selection of the optimal series resistance, into a format according to a communication standard and outputs it.

6. The semiconductor device according to claim 5, wherein the communication standard is one of SENT (Single Edge Nibble Transmission), PSI5 (Peripheral Sensor Interface 5), or DSI (Distributed System Interface).

7. The semiconductor device according to claim 1, wherein the analog-to-digital converter has a successive approximation type or delta-sigma type analog-to-digital conversion function.

8. The semiconductor device according to claim 1, wherein the control circuit narrows the range of the first operating voltage when the analog-to-digital converter is operated in the high-bit mode compared to the range of the second operating voltage when it is operated in the low-bit mode.

9. The aforementioned control circuit is As the first operating voltage range, the upper and lower limits of the predetermined voltage range are input to the analog / digital converter. As the second operating voltage range, a voltage higher than the upper limit voltage and a voltage lower than the lower limit voltage are input to the analog / digital converter. The semiconductor device according to claim 8.

10. A thermistor for temperature detection, A physical quantity sensor that detects a physical quantity and outputs a physical quantity detection signal, A series resistor selection circuit includes a group of series resistors connected in series with the thermistor, and selects a series resistor from the group of series resistors based on a selection signal. A multiplexer that switches between outputting a divided voltage obtained by dividing the internal power supply voltage between the thermistor and the series resistor, and the physical quantity detection signal based on a switching signal, An analog-to-digital converter that converts the voltage divider voltage and the physical quantity detection signal output from the multiplexer into analog and digital signals, respectively. The switching signal causes the multiplexer to output the physical quantity detection signal, the analog-to-digital converter to operate in high-bit mode, and the physical quantity detection signal is converted from analog to digital in high-bit mode to acquire the first physical quantity detection data. During the series resistor selection period, the switching signal causes the multiplexer to output the divided voltage, the analog-to-digital converter to operate in low-bit mode, and the optimal series resistor is selected so that the first temperature data obtained by converting the divided voltage in analog-to-digital mode falls within a predetermined voltage range. After selecting the optimal series resistance, the analog-to-digital converter is operated in the high-bit mode to convert the divided voltage from analog to digital in the high-bit mode and acquire the second temperature data. A control circuit that generates second physical quantity detection data by performing calculations on the first physical quantity detection data based on the second temperature data and a correction coefficient, A physical quantity sensor device having the following features.

11. The physical quantity sensor device according to claim 10, wherein the predetermined voltage range is a voltage range corresponding to a non-saturated region within the temperature range of the object to be measured where the temperature dependence of the divided voltage is not saturated.

12. The physical quantity sensor device according to claim 10, wherein the physical quantity sensor detects pressure as the physical quantity having a temperature dependence.

13. The physical quantity sensor device according to claim 10, wherein the series resistance selection circuit comprises the series resistance group and the switch group that selects the series resistance from the series resistance group based on the selection signal.

14. The physical quantity sensor device according to claim 13, wherein the series resistor group includes a plurality of series resistors having weighted resistance values ​​obtained by multiplying the resistance value of a unit series resistor by 2 squared, and the series resistor selection circuit selects the combined resistance of the series resistors by a combination of the switch group based on the selection signal.

15. The physical quantity sensor device according to claim 10, further comprising an output unit that converts the second physical quantity detection data into a format according to a communication standard and outputs it.

16. The physical quantity sensor device according to claim 15, wherein the communication standard is one of SENT (Single Edge Nibble Transmission), PSI5 (Peripheral Sensor Interface 5), or DSI (Distributed System Interface).

17. The physical quantity sensor device according to claim 10, wherein the analog / digital converter has a successive approximation type or delta-sigma type analog / digital conversion function.

18. The physical quantity sensor device according to claim 10, wherein the control circuit narrows the range of the first operating voltage when the analog / digital converter is operated in the high-bit mode compared to the range of the second operating voltage when it is operated in the low-bit mode.

19. The aforementioned control circuit is As the first operating voltage range, the upper and lower limits of the predetermined voltage range are input to the analog / digital converter. As the second operating voltage range, a voltage higher than the upper limit voltage and a voltage lower than the lower limit voltage are input to the analog / digital converter. The physical quantity sensor device according to claim 18.

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