CN112290947A - ADC reference voltage switching circuit and electronic equipment - Google Patents
ADC reference voltage switching circuit and electronic equipment Download PDFInfo
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- CN112290947A CN112290947A CN202010975684.2A CN202010975684A CN112290947A CN 112290947 A CN112290947 A CN 112290947A CN 202010975684 A CN202010975684 A CN 202010975684A CN 112290947 A CN112290947 A CN 112290947A
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- H03—ELECTRONIC CIRCUITRY
- H03M—CODING; DECODING; CODE CONVERSION IN GENERAL
- H03M1/00—Analogue/digital conversion; Digital/analogue conversion
- H03M1/12—Analogue/digital converters
- H03M1/124—Sampling or signal conditioning arrangements specially adapted for A/D converters
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Abstract
The application provides an ADC reference voltage switching circuit, which comprises a voltage comparison circuit, a voltage switching circuit and a main chip integrated with an ADC; the voltage comparison circuit compares the voltage of the analog input signal with one or more reference voltages respectively to obtain comparison results of high and low levels, and outputs the comparison results to the voltage switching circuit and the main chip respectively; the voltage switching circuit switches the output voltage to a corresponding reference voltage according to the comparison result and outputs the output voltage to a reference voltage input end of the main chip; and the main chip configures the reference voltage of the ADC into the voltage of the reference voltage input end according to the comparison result. According to the method and the device, the corresponding reference voltage can be provided for the ADC according to the magnitude of the voltage of the analog input signal, and meanwhile, the synchronism of the software configuration of the main chip to the reference voltage and the hardware switching of the voltage switching circuit to the reference voltage is also ensured. In addition, the application also provides an electronic device which comprises a main chip and the ADC reference voltage switching circuit.
Description
Technical Field
The application relates to the technical field of electronic systems, in particular to an ADC reference voltage switching circuit and electronic equipment.
Background
An Analog-to-Digital Converter (ADC) refers to a device that converts a continuously variable Analog input signal into a discrete Digital signal. In practice, an analog input signal, such as temperature, pressure, sound or image, needs to be converted into a digital form that is easier to store, process and transmit, and an analog/digital converter can perform this function.
At present, a plurality of wrist strap products all comprise ADCs and have the functions of temperature acquisition, voltage acquisition and the like, when a plurality of ADCs of the wrist strap products use one reference voltage together, because different ADCs need reference voltages with different sizes, and the difference between the reference voltage of the ADCs and the voltage of an analog input signal is large, the problem that the acquisition precision of the ADCs in the prior art is generally not high is caused.
Disclosure of Invention
In view of the foregoing problems, a primary object of the present invention is to provide an ADC reference level switching circuit and an electronic device, which are used to solve the existing technical problem that the acquisition accuracy of the ADC is not sufficient due to the mismatch between the reference voltage of the ADC and the voltage of the analog input signal.
The ADC reference voltage switching circuit comprises a voltage comparison circuit, a voltage switching circuit and a main chip integrated with an ADC;
the voltage comparison circuit compares the voltage of an analog input signal with one or more reference voltages respectively to obtain comparison results of high and low levels, and outputs the comparison results to the voltage switching circuit and the main chip respectively;
the voltage switching circuit switches the output voltage to the corresponding reference voltage according to the comparison result of the voltage comparison circuit and outputs the output voltage to the reference voltage input end of the main chip;
and the main chip starts corresponding configuration on the reference voltage of the ADC according to the comparison result of the voltage comparison circuit, and configures the reference voltage of the ADC into the voltage of the reference voltage input end.
According to still another aspect of the present application, there is provided an electronic device including a main chip integrated with one or more ADCs, each ADC independently configuring a reference voltage through the ADC reference voltage switching circuit, and the ADC reference voltage switching circuit described above.
The beneficial effect of this application lies in:
according to the ADC reference voltage switching circuit, the voltage of an analog input signal is compared with one or more reference voltages respectively through the voltage comparison circuit to obtain the comparison result of high and low levels, the voltage switching circuit switches the output voltage to the corresponding reference voltage according to the comparison result of the high and low levels and outputs the reference voltage to the reference voltage input end of the main chip, so that the appropriate reference voltage can be provided for the reference voltage input end of the main chip according to the magnitude of the analog input signal voltage, and the acquisition precision of the ADC is improved to the greatest extent; meanwhile, the main chip starts corresponding configuration on the reference voltage of the ADC according to the output result of the comparison circuit, and configures the reference voltage of the ADC as the voltage of the reference voltage input end, so that the synchronization of the software configuration of the main chip on the reference voltage and the hardware switching of the voltage switching circuit on the reference voltage is ensured, and the acquisition precision of the ADC is further ensured.
The foregoing description is only an overview of the technical solutions of the present application, and the present application can be implemented according to the content of the description in order to make the technical means of the present application more clearly understood, and the following detailed description of the present application is given in order to make the above and other objects, features, and advantages of the present application more clearly understandable.
Drawings
Various other advantages and benefits will become apparent to those of ordinary skill in the art upon reading the following detailed description of the preferred embodiments. The drawings are only for purposes of illustrating the preferred embodiments and are not to be construed as limiting the application. Also, like reference numerals are used to refer to like parts throughout the drawings. In the drawings:
FIG. 1 shows a schematic diagram of an ADC reference voltage switching circuit according to an embodiment of the present application;
FIG. 2 illustrates an ADC reference voltage switching circuit implementing two paths according to one embodiment of the present application;
FIG. 3 illustrates an ADC reference voltage switching circuit diagram implementing three-way according to one embodiment of the present application;
FIG. 4 is a software flow diagram illustrating the configuration of the ADC reference voltage by the main chip in the ADC reference voltage switching circuit shown in FIG. 3;
fig. 5 shows a schematic structural diagram of an electronic device according to an embodiment of the application.
Detailed Description
Exemplary embodiments of the present application will be described in more detail below with reference to the accompanying drawings. While exemplary embodiments of the present application are shown in the drawings, it should be understood that the present application may be embodied in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art.
The idea of the application is that: aiming at the current situation that the acquisition precision of the ADC is not high, the reference voltage switching circuit of the ADC is formed by the comparison circuit and the voltage switching circuit, so that the corresponding reference voltage can be provided for the ADC according to the voltage of the analog input signal, the reference voltage of the ADC is more matched with the voltage of the analog input signal, and the acquisition precision of the ADC is improved; meanwhile, the main chip can start corresponding configuration on the reference voltage of the ADC according to the output result of the comparison circuit, and configures the reference voltage of the ADC as the voltage of the reference voltage input end, so that the reference voltage configured by the software of the main chip and the hardware switching reference voltage of the voltage switching circuit are kept synchronous, and the problem that the configuration of the reference voltage of the ADC is not updated by the main chip due to the fact that only the hardware switches the reference voltage of the ADC is solved.
FIG. 1 shows a schematic diagram of an ADC reference voltage switching circuit according to an embodiment of the present application; the ADC reference voltage switching circuit comprises a voltage comparison circuit 1-1, a voltage switching circuit 1-2 and a main chip 1-3 integrated with an ADC; the voltage comparison circuit 1-1 is configured to compare a voltage of an analog input signal with one or more reference voltages to obtain comparison results of high and low levels, and output the comparison results to the voltage switching circuit 1-2 and the main chip 1-3, respectively.
The voltage switching circuit 1-2 has a function of switching two power supplies or switching multiple power supplies, and the voltage switching circuit 1-2 can switch the output voltage to a corresponding reference voltage according to the comparison result of the voltage comparing circuit 1-1 and output the output voltage to the reference voltage input end of the main chip 1-3.
The main chip 1-3 starts corresponding configuration for the reference voltage of the ADC according to the comparison result of the voltage comparison circuit 1-1, and configures the reference voltage of the ADC as the voltage of the reference voltage input end, so as to ensure the synchronism of the reference voltage configured by the main chip software and the reference voltage provided by the voltage switching circuit hardware.
As can be seen from FIG. 1, the ADC reference voltage switching circuit comprises a voltage comparison circuit 1-1, a voltage switching circuit 1-2 and a main chip 1-3 integrated with the ADC, wherein an analog input signal is input to the voltage comparison circuit 1-1, and meanwhile, the analog input signal is input to the main chip 1-3 of the ADC; the output end of the voltage comparison circuit 1-1 is respectively connected with the voltage switching circuit 1-2 and the main chip 1-3 integrated with the ADC; the output end of the voltage switching circuit 1-2 is also connected with the main chip 1-3 integrated with the ADC.
The analog signal refers to the measured temperature, pressure and the like, and is converted before being input into the voltage comparison circuit, so that a voltage value, namely the voltage of the analog input signal, is generated. The voltage comparison circuit 1-1 compares the voltage of the analog input signal with a preset reference voltage in the voltage comparison circuit 1-1, and if the voltage of the analog input signal is greater than the preset reference voltage in the voltage comparison circuit 1-1, the comparison result is a high level; if the voltage of the analog input signal is less than the preset reference voltage in the voltage comparison circuit 1-1, the comparison result is a low level. In practice, the comparison result can be represented by binary values, such as 0 for low level and 1 for high level, and the voltage comparison circuit 1-1 outputs the comparison result to the voltage switching circuit 1-2 and the main chip 1-3, respectively.
The following description will be made taking as an example a case where the comparison result of the voltage comparison circuit 1-1 is at a high level.
The voltage comparison circuit 1-1 outputs the comparison result of high level to the voltage switching circuit 1-2, the voltage switching circuit 1-2 switches to the corresponding reference voltage according to the comparison result of high level, for example, when the reference voltage has two selectable reference voltages, one is high level 220V and the other is low level 110V, and when the comparison result is high level, the voltage switching circuit 1-2 switches to high reference voltage, i.e. 220V. After the reference voltage is determined, the voltage switching circuit 1-2 outputs a 220V voltage to the reference voltage input terminal of the main chip 1-3 for use as a reference voltage of the ADC in the main chip 1-3. Meanwhile, the voltage switching circuit 1-2 outputs the comparison result of high level to the main chip 1-3, the main chip 1-3 starts corresponding configuration for the reference voltage of the ADC according to the comparison result of high voltage, and configures the reference voltage of the ADC as the voltage of the reference voltage input end, that is, 220V voltage, so that the main chip performs software configuration for the ADC reference voltage and the voltage switching circuit provides the reference voltage for the ADC on circuit hardware to achieve synchronization, thereby avoiding the problem that the reference voltage input to the main chip end is switched and the main chip does not modify the configuration of the reference voltage of the ADC.
As can be seen from the ADC reference voltage switching circuit in fig. 1, according to the magnitude of the analog input signal voltage, the present application can provide a suitable reference voltage for the reference voltage input end of the main chip, thereby greatly improving the acquisition accuracy of the ADC; meanwhile, the main chip starts corresponding configuration on the reference voltage of the ADC according to the output result of the comparison circuit, and configures the reference voltage of the ADC as the voltage of the reference voltage input end, so that the synchronism of the software configuration of the main chip on the reference voltage and the hardware switching reference voltage of the voltage switching circuit is ensured, and the acquisition precision of the ADC is further ensured.
In the ADC reference voltage switching circuit, the voltage comparison circuit 1-1 includes one or more voltage comparators, the voltage switching circuit 1-2 includes one or more single-pole double-throw analog switches, and the number of the voltage comparators is the same as that of the single-pole double-throw analog switches, and is set according to the number of the reference voltages selectable by the ADC.
For example, if the number of the reference voltages selectable by the ADC is three, two voltage comparators and two single-pole double-throw analog switches need to be provided, and if the ADC can select more reference voltages, the ADC can be implemented by adding the voltage comparators and the single-pole double-throw analog switches, where the number of the voltage comparators is the same as that of the single-pole double-throw analog switches, and both the numbers of the voltage comparators and the single-pole double-throw analog switches are one less than that of the reference voltages selectable by the ADC. Fig. 2 is a circuit diagram illustrating an ADC reference voltage switching circuit implementing two paths according to an embodiment of the present application, where the ADC reference voltage switching circuit shown in fig. 2 can implement two-path ADC reference voltage switching.
As can be seen from fig. 2, the ADC of this embodiment includes two selectable reference voltages, the voltage comparison circuit is implemented by a voltage comparator U1, and the voltage switching circuit is implemented by a single-pole double-throw analog switch U2.
For convenience of description, the lower of the two selectable reference voltages is denoted as a first reference voltage VDD1, and the higher of the two selectable reference voltages is denoted as a second reference voltage VDD 2; one voltage comparator included in the voltage comparison circuit is marked as a first comparator U1; the voltage switching circuit includes a single pole double throw analog switch denoted as a first single pole double throw analog switch U2.
The positive input end of the first comparator U1 is connected to the analog input signal ADC _ IN, the negative input end of the first comparator U1 is connected to the first reference voltage VDD1, and the output end of the first comparator U1 is connected to the enable end EN of the first single-pole double-throw analog switch and the first input/output end IO1 of the main chip U3, respectively.
A normally open contact NO of the first single-pole double-throw analog switch U2 is connected with a second reference voltage VDD2 with higher power voltage, a normally closed contact NC of the first single-pole double-throw analog switch U2 is connected with a first reference voltage VDD1 with higher power voltage, and an output end VDD _ REF of the first single-pole double-throw analog switch U2 is connected with a reference voltage input end VREF of the main chip U3; a pull-down resistor R1 is connected between the enable terminal EN of the first single-pole double-throw analog switch U1 and the ground terminal GND, and the pull-down resistor R1 is used to ensure that the output terminal VDD _ REF of the first single-pole double-throw analog switch U2 can maintain a stable level in a normal state where no analog input signal is input.
In this embodiment, there are two cases of the switching process of the ADC reference voltage, which are respectively described as follows:
IN one case, the voltage of the analog input signal ADC _ IN is less than the first reference voltage VDD 1.
In this case, the first comparator U1 outputs the comparison result as low level, and the first comparator U1 outputs the result to the enable terminal EN of the first spdt analog switch U2. At this time, the enable terminal EN of the first single-pole double-throw analog switch U2 is at a low level, the output terminal of the first single-pole double-throw analog switch U2 is connected to the normally closed contact NC thereof, and since the normally closed contact NC of the first single-pole double-throw analog switch U2 is connected to the first reference voltage VDD1 with a lower power supply voltage, the first single-pole double-throw analog switch U2 outputs the first reference voltage VDD1 to the reference voltage input terminal VREF of the main chip U3 to be used as the reference voltage of the ADC; meanwhile, the first comparator U1 outputs the comparison result of the low level to the first input/output terminal IO1 of the main chip U3, the main chip U3 starts corresponding configuration for the reference voltage of the ADC according to the low level of the first input/output terminal IO1, and configures the reference voltage of the ADC as the first reference voltage VDD1, so that the software configuration of the main chip for the reference voltage of the ADC is synchronized with the hardware switching of the voltage switching circuit for the reference voltage of the ADC.
IN another case, the voltage of the analog input signal ADC _ IN is equal to or greater than the first reference voltage VDD 1.
In this case, the first comparator U1 outputs the comparison result as high level, and the first comparator U1 outputs the result to the first single pole double throw analog switch U2. At this time, the enable terminal EN of the first single-pole double-throw analog switch U2 is at a high level, the output terminal of the first single-pole double-throw analog switch U2 is connected to the normally open contact NO, and since the normally open contact NC of the first single-pole double-throw analog switch U2 is connected to the second reference voltage VDD2 with a higher power supply voltage, the first single-pole double-throw analog switch U2 outputs the second reference voltage VDD2 to the reference voltage input terminal VREF of the main chip U3 to be used as the reference voltage of the ADC; meanwhile, the first comparator U1 outputs the comparison result of the high level to the first input/output terminal IO1 of the main chip U3, the main chip U3 starts corresponding configuration for the reference voltage of the ADC according to the high level of the first input/output terminal, and configures the reference voltage of the ADC to the second reference voltage VDD2, so that the software configuration for the reference voltage of the ADC by the main chip is synchronized with the hardware switching for the reference voltage of the ADC by the voltage switching circuit.
As can be seen from the ADC reference voltage switching circuit shown in fig. 2, the circuit can freely switch between two reference voltages according to the magnitude of the analog input signal voltage, provide a suitable reference voltage for the ADC, significantly improve the acquisition accuracy of the ADC, and the main chip can detect the level change on the IO and perform corresponding reference voltage configuration and modification on the ADC acquisition according to the level change, thereby avoiding the problem that the ADC reference voltage has been switched but the main chip does not update the ADC configuration.
Fig. 3 shows a circuit diagram of ADC reference voltage switching for implementing three-way according to an embodiment of the present application. The ADC reference voltage switching circuit shown in fig. 3 can implement switching of three ADC reference voltages.
As can be seen from fig. 3, the ADC includes three optional reference voltages, and for convenience of description, the lowest power supply voltage is referred to as a first reference voltage VDD1, the middle power supply voltage is referred to as a second reference voltage VDD2, and the highest power supply voltage is referred to as a third reference voltage VDD 3.
The voltage comparison circuit comprises two voltage comparators which are respectively marked as a first comparator U1-1 and a second comparator U1-2; the voltage switching circuit includes two single-pole double-throw analog switches, denoted as a first single-pole double-throw analog switch U2-1 and a second single-pole double-throw analog switch U2-2, respectively.
The positive input end of a first comparator U1-1 is connected with an analog input signal ADC _ IN, the negative input end of the first comparator U1-1 is connected with a first reference voltage VDD1, and the output end OUT1 of the first comparator VDD1 is respectively connected with the enable end EN1 of a first single-pole double-throw analog switch U2-1 and the first input/output end IO1 of a main chip U3; the positive input end of the second comparator U1-2 is connected with the analog input signal ADC _ IN, the negative input end of the second comparator U1-2 is connected with the second reference voltage VDD2, and the output end OUT2 of the second comparator U U U1-2 is respectively connected with the enable end EN2 of the second single-pole double-throw analog switch U2-2 and the second input/output end IO2 of the main chip U3.
A normally open contact NO1 of the first single-pole double-throw analog switch U2-1 is connected with a second reference voltage VDD2, a normally closed contact NC1 of the first single-pole double-throw analog switch U2-1 is connected with a first reference voltage VDD1, and an output end VDD _ REF12 of the first single-pole double-throw analog switch U2-1 is connected with a normally closed contact NC2 of the second single-pole double-throw analog switch U2-2; the normally open contact NO2 of the second single-pole double-throw analog switch U2-2 is connected with a third reference voltage VDD3, and the output end VDD _ REF of the second single-pole double-throw analog switch U2-2 is connected with the reference voltage input end VREF of the main chip U3.
In this embodiment, there are three cases of switching the ADC reference voltage, which are described as follows:
IN the first case, the voltage of the analog input signal ADC _ IN is less than the first reference voltage VDD 1.
In the first case, both the first comparator U1-1 and the second comparator U1-2 output a low level. At this time, the output terminal of the first single-pole double-throw analog switch U2-1 is connected to the normally closed contact NC1, and since the normally closed contact NC1 of the first single-pole double-throw analog switch U2-1 is connected to the first reference voltage VDD1 having a lower power supply voltage, the output terminal VDD _ REF12 of the first single-pole double-throw analog switch U2-1 outputs the first reference voltage VDD1 to the normally closed contact NC2 of the second single-pole double-throw analog switch U2-2. And the output terminal COM2 of the second single-pole double-throw analog switch U2-2 is connected to the normally closed contact NC2 when the second comparator U1-2 outputs a low level, so that the second single-pole double-throw analog switch U2-2 outputs the first reference voltage VDD1 to the reference voltage input terminal VREF of the main chip U3, and is used as the reference voltage of the ADC.
Meanwhile, the first comparator U1-1 outputs the comparison result of low level to the first input/output end IO1 of the main chip U3, the second comparator U1-2 also outputs the comparison result of low level to the second input/output end IO2 of the main chip U3, and the main chip U3 configures the reference voltage of the ADC as the first reference voltage VDD1 according to the low level of the first input/output end IO1 and the low level of the second input/output end IO2, so that the software configuration of the main chip to the reference voltage of the ADC is synchronous with the hardware switching of the voltage switching circuit to the reference voltage of the ADC.
IN the second case, the voltage of the analog input signal ADC _ IN is equal to or greater than the first reference voltage VDD1 and less than the second reference voltage VDD 2.
In the second case, the first comparator U1-1 outputs a high level and the second comparator U1-2 outputs a low level. The output end VDD _ REF12 of the first single-pole double-throw analog switch U2-1 is connected to a normally open contact NO1, and since the normally open contact NO1 of the first single-pole double-throw analog switch U2-1 is connected with the second reference voltage VDD2, the first single-pole double-throw analog switch U2-1 outputs the second reference voltage VDD2 to a normally closed contact NC2 of the second single-pole double-throw analog switch U2-2. And since the output terminal COM2 of the second single pole double throw analog switch U2-2 is connected to the normally closed contact NC2 when the output result of the second comparator U1-2 is low level, the second single pole double throw analog switch U2-2 outputs the second reference voltage VDD2 to the reference voltage input terminal VREF of the main chip U3 for use as the reference voltage of the ADC.
Meanwhile, the first comparator U1-1 outputs the comparison result of high level to the first input/output end IO1 of the main chip U3, the second comparator U1-2 outputs the comparison result of low level to the second input/output end IO2 of the main chip U3, and the main chip U3 configures the reference voltage of the ADC as the second reference voltage VDD2 according to the high level of the first input/output end IO1 and the low level of the second input/output end IO2, so that the software configuration of the ADC reference voltage by the main chip and the hardware switching of the ADC reference voltage by the voltage switching circuit are synchronous.
IN the third case, the voltage of the analog input signal ADC _ IN is equal to or higher than the second reference voltage VDD 2.
In the third case, the output of both the first comparator U1-1 and the second comparator U1-2 are high. The output terminal VDD _ REF12 of the first single-pole double-throw analog switch U2-1 is connected to the normally open contact NO1, and the second reference voltage VDD2 is output to the normally closed contact NC2 of the second single-pole double-throw analog switch U2-2. However, since the output terminal COM2 of the second single-pole double-throw analog switch U2-2 is connected to the normally-open contact NO2, the second single-pole double-throw analog switch U2-2 outputs the third reference voltage VDD3 to the reference voltage input terminal of the main chip U3, and is used as the reference voltage of the ADC.
Meanwhile, the first comparator U1-1 outputs the comparison result of high level to the first input/output end IO1 of the main chip U3, the second comparator U1-2 also outputs the comparison result of high level to the second input/output end IO2 of the main chip U3, and the main chip U3 configures the reference voltage of the ADC as a third reference voltage VDD3 according to the high level of the first input/output end IO1 and the high level of the second input/output end IO2, so that the software configuration of the main chip to the ADC reference voltage is synchronous with the hardware switching of the voltage switching circuit to the ADC reference voltage.
As can be seen from the ADC reference voltage switching circuit shown in fig. 3, the circuit can freely switch among three reference voltages according to the magnitude of the analog input signal voltage, provide a suitable reference voltage for the ADC, significantly improve the acquisition accuracy of the ADC, and the main chip can detect the level change on the IO and perform corresponding reference voltage configuration and modification on the ADC acquisition according to the level change, thereby avoiding the problem that the ADC reference voltage has been switched but the main chip does not update the ADC configuration.
In the above, mainly from the aspect of hardware, a voltage switching process of the ADC reference voltage switching circuit is described, and in the following, from the aspect of software, a process of configuring a reference voltage for an ADC by a main chip is described, and fig. 4 illustrates a schematic flow diagram of configuring a reference voltage for a main chip corresponding to an ADC reference voltage switching circuit for implementing three paths according to an embodiment of the present application.
It can be seen from fig. 4 that the main chip configures or modifies the reference voltage of the ADC by determining the level state of each input/output terminal thereof. In this embodiment, 0 indicates that the output result of the comparator is at a low level, and 1 indicates that the output result of the comparator is at a high level. The process of configuring the reference voltage by the master chip is specifically set out below.
The main chip firstly reads a second input/output result IO2, namely a comparison result of the higher voltage comparator, judges whether IO2 is 1, if IO2 is 1, configures the ADC reference voltage to be a third reference voltage VDD3 with the highest power voltage, and at this time, the ADC reference voltage switching circuit also outputs the third reference voltage VDD3 to the voltage input end of the main chip; if IO2 is not 1, determining whether IO1 is 1, if IO1 is 1, configuring the ADC reference voltage to a second reference voltage VDD2 with a medium power voltage, and then outputting the second reference voltage VDD2 to the voltage input terminal of the main chip by the ADC reference voltage switching circuit; if IO1 is not 1, the ADC reference voltage is configured to be the first reference voltage VDD1 with the lowest power supply voltage, and the ADC reference voltage switching circuit also outputs the first reference voltage VDD1 to the voltage input terminal of the main chip.
As can be seen from fig. 4, the software configuration process of the main chip for the reference voltage can be synchronized with the hardware switching process of the voltage switching circuit for the reference voltage, so that the acquisition function and the acquisition precision of the multiple ADCs can be ensured, and the problem of insufficient acquisition precision of part of ADCs when a plurality of ADCs share one reference voltage is solved. The ADC reference voltage switching circuit of the present application is not limited to performing two-way switching or three-way switching, and may be extended to more than three-way voltage switching according to the circuit diagrams of the embodiments shown in fig. 2 and fig. 3.
In some embodiments of the present application, the ADC includes N +1 selectable reference voltages, where N is a natural number greater than or equal to 3, and power supply voltages of the N +1 selectable reference voltages sequentially increase and are respectively denoted as a first reference voltage, a second reference voltage, …, an N-1 th reference voltage, an nth reference voltage, and an N +1 th reference voltage.
The voltage comparison circuit comprises N voltage comparators which are respectively marked as a first comparator, a second comparator, …, an N-1 th comparator and an Nth comparator; the voltage comparison circuit comprises N single-pole double-throw analog switches which are respectively marked as a first single-pole double-throw analog switch, a second single-pole double-throw analog switch, …, an N-2 single-pole double-throw analog switch, an N-1 single-pole double-throw analog switch and an N single-pole double-throw analog switch.
Taking the nth comparator as an example, a positive input terminal of the nth comparator is connected to the analog input signal, a negative input terminal of the nth comparator is connected to the nth reference voltage, and output terminals of the nth comparator are respectively connected to an enable terminal of the nth single-pole double-throw analog switch and an nth input/output terminal of the main chip.
Taking an N-1 single-pole double-throw analog switch and an N-single-pole double-throw analog switch as examples, a normally open contact of the N-1 single-pole double-throw analog switch is connected with an N reference voltage, a normally closed contact of the N-1 single-pole double-throw analog switch is connected with an output end of an N-2 single-pole double-throw analog switch, and an output end of the N-1 single-pole double-throw analog switch is connected with a normally closed contact of the N single-pole double-throw analog switch; the normally open contact of the Nth single-pole double-throw analog switch is connected with the (N + 1) th reference voltage, and the output end of the Nth single-pole double-throw analog switch is connected with the reference voltage input end of the main chip.
In this embodiment, the switching process of the reference voltage switching circuit of the ADC includes the following situations:
under the condition that the voltage of an analog input signal is smaller than a first reference voltage, N comparators output low levels, output ends of first to N-1 single-pole double-throw analog switches are connected to normally closed contacts, the first to N-1 single-pole double-throw analog switches correspondingly output the first reference voltage to normally closed contacts of second to N-1 single-pole double-throw analog switches respectively, the output end of the N-1 single-pole double-throw analog switch is connected to the normally closed contact, and the N-1 single-pole double-throw analog switch outputs the first reference voltage to a reference voltage input end of a main chip to be used as the reference voltage of an ADC. Meanwhile, the first comparator, the second comparator, the …, the N-1 th comparator and the Nth comparator all output a comparison result of low level to the main chip, and the main chip configures the reference voltage of the ADC as a first reference voltage according to the low level of the N input and output ends.
Under the second condition, when the voltage of the analog input signal is greater than or equal to the first reference voltage and less than the second reference voltage, the first comparator outputs a high level, the second comparator to the Nth comparator all output a low level, the output end of the first single-pole double-throw analog switch is connected to a normally open contact, the output ends of the second to the Nth single-pole double-throw analog switches are all connected to a normally closed contact, the first to the Nth single-pole double-throw analog switches respectively and correspondingly output the second reference voltage to the normally closed contacts of the second to the Nth single-pole double-throw analog switches, the output end of the Nth single-pole double-throw analog switch is connected to the normally closed contact, and the Nth single-pole double-throw analog switch outputs the second reference voltage to the reference voltage input end of the main chip. Meanwhile, the first comparator outputs the comparison result of high level to the main chip, the second comparator, …, the N-1 th comparator and the Nth comparator all output the comparison result of low level to the main chip, the main chip outputs high level according to the first comparator, and the second comparator to the Nth input and output ends are all low level, and the reference voltage of the ADC is configured to be the second reference voltage.
Analogizing in sequence until the N-1 th scene, under the condition that the voltage of the analog input signal is more than or equal to the N-1 th reference voltage and less than the N-1 th reference voltage, the first comparator to the N-1 th comparator output high level, the N-th comparator output low level, the output ends of the first single-pole double-throw analog switch to the N-1 th single-pole double-throw analog switch are connected to a normally open contact, the first single-pole double-throw analog switch outputs the second reference voltage to a normally closed contact of the second single-pole double-throw analog switch, the second single-pole double-throw analog switch outputs the third reference voltage to a normally closed contact of the third single-pole double-throw analog switch, and sequentially until the N-1 th single-pole double-throw analog switch outputs the N reference voltage to the normally closed contact of the N-pole double-throw analog switch, because the output end of the N-pole double-throw analog switch is connected to the normally closed contact, therefore, the Nth single-pole double-throw analog switch outputs the Nth reference voltage to the reference voltage input end of the main chip to be used as the reference voltage of the ADC. Meanwhile, the first comparator, the second comparator, the … and the N-1 th comparator output a comparison result of low level to the main chip, the N-1 th comparator outputs a comparison result of high level to the main chip, and the main chip configures the reference voltage of the ADC as an N-th reference voltage according to the high level from the first comparator to the N-1 th input/output end and the low level of the N-1 th input/output end.
Under the N-th condition, under the condition that the voltage of the analog input signal is greater than or equal to the N-th reference voltage, the N comparators output high levels, the output ends of the first single-pole double-throw analog switch and the N-th single-pole double-throw analog switch are connected to a normally open contact, and at the moment, the N-th single-pole double-throw analog switch outputs the (N + 1) -th reference voltage to the reference voltage input end of the main chip to be used as the reference voltage of the ADC. And meanwhile, the N comparators output the comparison result of the high level to the main chip, and the main chip configures the reference voltage of the ADC into the (N + 1) th reference voltage according to the condition that the N input and output ends are all high levels.
IN the N-way reference voltage switching circuit, the corresponding relationship between the analog input signal ADC _ IN and the comparator output signal and the output of the single-pole double-throw analog switch is shown IN the following table:
TABLE 1 correspondences between analog input signal ADC _ IN and comparator output signal and single pole double throw analog switch output
To sum up, the ADC reference voltage switching circuit of this application can realize the switching of two way or multichannel ADC reference voltage, and voltage switching circuit can be according to the size of analog input signal voltage, real-time adjustment ADC reference voltage, and main chip carries out corresponding configuration and modification to ADC's reference voltage in step from software, can guarantee multichannel ADC's collection function and collection precision like this to when avoiding a plurality of ADCs to share a reference voltage, the problem that the collection precision of partial ADC that exists is not enough.
In some embodiments of the present application, the main chip is integrated with a plurality of ADCs, each ADC independently configuring a reference voltage through an ADC reference voltage switching circuit.
A plurality of ADCs integrated in the main chip have temperature ADC, pressure ADC and the like, have different acquisition functions or types, reference voltage required by the ADCs of different types for acquiring signals is different, the acquisition precision of each ADC is ensured by respectively configuring the reference voltages for the ADCs, and the ADCs are independent from each other and do not influence each other.
In some embodiments of the present application, an electronic device 500 is further provided, please refer to fig. 5, and fig. 5 illustrates a schematic structural diagram of the electronic device, where the electronic device includes a main chip 510 and any one of the ADC reference voltage switching circuits 520, and the main chip 510 integrates one or more ADCs, each ADC independently configures a reference voltage through the ADC reference voltage switching circuit.
It should be noted that:
in the description provided herein, numerous specific details are set forth. However, it is understood that embodiments of the application may be practiced without these specific details. In some instances, well-known methods, structures and techniques have not been shown in detail in order not to obscure an understanding of this description.
Similarly, it should be appreciated that in the foregoing description of exemplary embodiments of the application, various features of the application are sometimes grouped together in a single embodiment, figure, or description thereof for the purpose of streamlining the application and aiding in the understanding of one or more of the various application aspects. However, the disclosed method should not be interpreted as reflecting an intention that: this application is intended to cover such departures from the present disclosure as come within known or customary practice in the art to which this invention pertains. Rather, as the following claims reflect, application is directed to less than all features of a single foregoing disclosed embodiment. Thus, the claims following the detailed description are hereby expressly incorporated into this detailed description, with each claim standing on its own as a separate embodiment of this application.
Furthermore, those skilled in the art will appreciate that while some embodiments described herein include some features included in other embodiments, rather than other features, combinations of features of different embodiments are meant to be within the scope of the application and form different embodiments. For example, in the following claims, any of the claimed embodiments may be used in any combination.
It should be noted that the above-mentioned embodiments illustrate rather than limit the application, and that those skilled in the art will be able to design alternative embodiments without departing from the scope of the appended claims. In the claims, any reference signs placed between parentheses shall not be construed as limiting the claim. The word "comprising" does not exclude the presence of elements or steps not listed in a claim. The word "a" or "an" preceding an element does not exclude the presence of a plurality of such elements. The application may be implemented by means of hardware comprising several distinct elements, and by means of a suitably programmed computer. In the unit claims enumerating several means, several of these means may be embodied by one and the same item of hardware. The usage of the words first, second and third, etcetera do not indicate any ordering. These words may be interpreted as names.
Claims (10)
1. An ADC reference voltage switching circuit is characterized by comprising a voltage comparison circuit, a voltage switching circuit and a main chip integrated with an ADC;
the voltage comparison circuit compares the voltage of an analog input signal with one or more reference voltages respectively to obtain comparison results of high and low levels, and outputs the comparison results to the voltage switching circuit and the main chip respectively;
the voltage switching circuit switches the output voltage to the corresponding reference voltage according to the comparison result of the voltage comparison circuit and outputs the output voltage to the reference voltage input end of the main chip;
and the main chip starts corresponding configuration on the reference voltage of the ADC according to the comparison result of the voltage comparison circuit, and configures the reference voltage of the ADC into the voltage of the reference voltage input end.
2. The ADC reference voltage switching circuit of claim 1 wherein the voltage comparison circuit comprises one or more voltage comparators, the voltage switching circuit comprises one or more single pole double throw analog switches, and the number of voltage comparators is the same as the number of single pole double throw analog switches, each set according to the number of reference voltages selectable by the ADC.
3. The ADC reference voltage switching circuit of claim 1 wherein the ADC comprises two selectable reference voltages, wherein the lower supply voltage is denoted as a first reference voltage and the higher supply voltage is denoted as a second reference voltage;
the voltage comparison circuit comprises a voltage comparator which is marked as a first comparator; the voltage comparison circuit comprises a single-pole double-throw analog switch which is marked as a first single-pole double-throw analog switch;
a positive input end of the first comparator is connected with the analog input signal, a negative input end of the first comparator is connected with the first reference voltage, and an output end of the first comparator is respectively connected with an enable end of the first single-pole double-throw analog switch and a first input/output end of the main chip;
the normally open contact of the first single-pole double-throw analog switch is connected with the second reference voltage, the normally closed contact of the first single-pole double-throw analog switch is connected with the first reference voltage, and the output end of the first single-pole double-throw analog switch is connected with the reference voltage input end of the main chip.
4. The ADC reference voltage switching circuit of claim 3,
under the condition that the voltage of the analog input signal is smaller than the first reference voltage, the first comparator outputs a low level, the output end of the first single-pole double-throw analog switch is connected to a normally closed contact, and the first single-pole double-throw analog switch outputs the first reference voltage to the reference voltage input end of the main chip; the main chip configures the reference voltage of the ADC as the first reference voltage according to the low level of the first input/output end;
when the voltage of the analog input signal is greater than or equal to the first reference voltage, the first comparator outputs a high level, the output end of the first single-pole double-throw analog switch is connected to a normally-open contact, and the first single-pole double-throw analog switch outputs the second reference voltage to the reference voltage input end of the main chip; and the main chip configures the reference voltage of the ADC as the second reference voltage according to the high level of the first input and output end.
5. The ADC reference voltage switching circuit of claim 1 wherein the ADC comprises three selectable reference voltages, wherein the lowest supply voltage is designated as a first reference voltage, the middle supply voltage is designated as a second reference voltage, and the highest supply voltage is designated as a third reference voltage;
the voltage comparison circuit comprises two voltage comparators which are respectively marked as a first comparator and a second comparator; the voltage comparison circuit comprises two single-pole double-throw analog switches which are respectively marked as a first single-pole double-throw analog switch and a second single-pole double-throw analog switch;
a positive input end of the first comparator is connected with the analog input signal, a negative input end of the first comparator is connected with the first reference voltage, and an output end of the first comparator is respectively connected with an enable end of the first single-pole double-throw analog switch and a first input/output end of the main chip;
a positive input end of the second comparator is connected with the analog input signal, a negative input end of the second comparator is connected with the second reference voltage, and an output end of the second comparator is respectively connected with an enable end of the second single-pole double-throw analog switch and a second input/output end of the main chip;
a normally open contact of the first single-pole double-throw analog switch is connected with the second reference voltage, a normally closed contact of the first single-pole double-throw analog switch is connected with the first reference voltage, and an output end of the first single-pole double-throw analog switch is connected with a normally closed contact of the two single-pole double-throw analog switches; and a normally open contact of the second single-pole double-throw analog switch is connected with the third reference voltage, and an output end of the second single-pole double-throw analog switch is connected with a reference voltage input end of the main chip.
6. The ADC reference voltage switching circuit of claim 5,
under the condition that the voltage of the analog input signal is smaller than the first reference voltage, the first comparator and the second comparator both output low levels, the output end of the first single-pole double-throw analog switch is connected to a normally closed contact, the first single-pole double-throw analog switch outputs the first reference voltage to the normally closed contact of the second single-pole double-throw analog switch, the output end of the second single-pole double-throw analog switch is connected to the normally closed contact, and the second single-pole double-throw analog switch outputs the first reference voltage to the reference voltage input end of the main chip; the main chip configures the reference voltage of the ADC as the first reference voltage according to the low level of the first input and output end and the low level of the second input and output end;
when the voltage of the analog input signal is greater than or equal to the first reference voltage and less than a second reference voltage, the first comparator outputs a high level, the second comparator outputs a low level, an output end of the first single-pole double-throw analog switch is connected to a normally open contact, the first single-pole double-throw analog switch outputs the second reference voltage to a normally closed contact of the second single-pole double-throw analog switch, an output end of the second single-pole double-throw analog switch is connected to a normally closed contact, and the second single-pole double-throw analog switch outputs the second reference voltage to a reference voltage input end of the main chip; the main chip configures the reference voltage of the ADC as the second reference voltage according to the high level of the first input and output end and the low level of the second input and output end;
when the voltage of the analog input signal is greater than or equal to the second reference voltage, the first comparator and the second comparator both output a high level, an output end of the first single-pole double-throw analog switch is connected to a normally open contact, the first single-pole double-throw analog switch outputs the second reference voltage to a normally closed contact of the second single-pole double-throw analog switch, an output end of the second single-pole double-throw analog switch is connected to the normally open contact, and the second single-pole double-throw analog switch outputs the third reference voltage to a reference voltage input end of the main chip; and the main chip configures the reference voltage of the ADC as the third reference voltage according to the high level of the first input and output end and the high level of the second input and output end.
7. The ADC reference voltage switching circuit according to claim 1, wherein the ADC comprises N +1 selectable reference voltages, N is a natural number greater than or equal to 3, and the power supply voltages of the N +1 selectable reference voltages are sequentially increased and respectively marked as a first reference voltage, a second reference voltage, …, an N-1 reference voltage, an Nth reference voltage and an N +1 reference voltage;
the voltage comparison circuit comprises N voltage comparators which are respectively marked as a first comparator, a second comparator, …, an N-1 th comparator and an Nth comparator; the voltage comparison circuit comprises N single-pole double-throw analog switches which are respectively marked as a first single-pole double-throw analog switch, a second single-pole double-throw analog switch, …, an N-2 single-pole double-throw analog switch, an N-1 single-pole double-throw analog switch and an N single-pole double-throw analog switch;
taking an nth comparator as an example, a positive input terminal of the nth comparator is connected to the analog input signal, a negative input terminal of the nth comparator is connected to the nth reference voltage, and an output terminal of the nth comparator is respectively connected to an enable terminal of the nth single-pole double-throw analog switch and an nth input/output terminal of the main chip;
taking an N-1 th single-pole double-throw analog switch and an N-th single-pole double-throw analog switch as examples, a normally open contact of the N-1 th single-pole double-throw analog switch is connected with the N-th reference voltage, a normally closed contact of the N-1 th single-pole double-throw analog switch is connected with an output end of the N-2 th single-pole double-throw analog switch, and an output end of the N-1 th single-pole double-throw analog switch is connected with a normally closed contact of the N-1 th single-pole double-throw analog switch; the normally open contact of the N single-pole double-throw analog switch is connected with the N +1 th reference voltage, and the output end of the N single-pole double-throw analog switch is connected with the reference voltage input end of the main chip.
8. The ADC reference voltage switching circuit of claim 7,
under the condition that the voltage of the analog input signal is smaller than the first reference voltage, the N comparators output low levels, the output ends of the first to the N-1 th single-pole double-throw analog switches are connected to normally closed contacts, the first to the N-1 th single-pole double-throw analog switches correspondingly output the first reference voltage to the normally closed contacts of the second to the N-1 th single-pole double-throw analog switches respectively, the output end of the N-1 th single-pole double-throw analog switch is connected to the normally closed contact, and the N-1 th single-pole double-throw analog switch outputs the first reference voltage to a reference voltage input end of the main chip; the main chip configures the reference voltage of the ADC as the first reference voltage according to the condition that the N input/output ends are all low level;
under the condition that the voltage of the analog input signal is greater than or equal to the first reference voltage and smaller than a second reference voltage, the first comparator outputs a high level, the second comparator to the Nth comparator all output a low level, the output end of the first single-pole double-throw analog switch is connected to a normally open contact, the output ends of the second to the Nth single-pole double-throw analog switches are all connected to a normally closed contact, the first to the Nth single-pole double-throw analog switches respectively and correspondingly output the second reference voltage to the normally closed contacts of the second to the Nth single-pole double-throw analog switches, the output end of the Nth single-pole double-throw analog switch is connected to the normally closed contact, and the Nth single-pole double-throw analog switch outputs the second reference voltage to the reference voltage input end of the main chip; the main chip outputs high level according to the first comparator, the second comparator to the Nth input/output end are all low level, and the reference voltage of the ADC is configured to be the second reference voltage;
……
when the voltage of the analog input signal is greater than or equal to the N-1 reference voltage and less than the N reference voltage, the first comparator to the N-1 comparator output high level, the N comparator output low level, the output ends of the first single-pole double-throw analog switch to the N-1 single-pole double-throw analog switch are all connected to a normally open contact, the first single-pole double-throw analog switch outputs the second reference voltage to the normally closed contact of the second single-pole double-throw analog switch, the second single-pole double-throw analog switch outputs the third reference voltage to the normally closed contact of the third single-pole double-throw analog switch, and sequentially until the N-1 single-pole double-throw analog switch outputs the N reference voltage to the normally closed contact of the N single-pole double-throw analog switch, the output end of the N single-pole double-throw analog switch is connected to the normally closed contact, the Nth single-pole double-throw analog switch outputs the Nth reference voltage to a reference voltage input end of the main chip; the main chip configures the reference voltage of the ADC as the Nth reference voltage according to the high level from the first comparator to the N-1 th input and output end and the low level from the Nth input and output end;
when the voltage of the analog input signal is greater than or equal to the Nth reference voltage, the N comparators output high levels, the output ends of the first to Nth single-pole double-throw analog switches are connected to normally-open contacts, and the Nth single-pole double-throw analog switch outputs the (N + 1) th reference voltage to the reference voltage input end of the main chip; and the main chip configures the reference voltage of the ADC into the N +1 th reference voltage according to the N input/output ends which are all high-level.
9. The ADC reference voltage switching circuit according to any one of claims 1 to 8, wherein a plurality of ADCs are integrated into the main chip, and each ADC is independently configured with a reference voltage by the ADC reference voltage switching circuit.
10. An electronic device comprising a main chip and the ADC reference voltage switching circuit of any one of claims 1 to 9, wherein the main chip is integrated with one or more ADCs, and each ADC is independently configured with a reference voltage by the ADC reference voltage switching circuit.
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| CN106501714A (en) * | 2016-12-09 | 2017-03-15 | 上海航空电器有限公司 | A kind of digitizing switch detection circuit and method with fault diagnosis functions |
| CN207399180U (en) * | 2017-11-01 | 2018-05-22 | 无锡华润矽科微电子有限公司 | Reference voltage adaptive circuit structure and related device |
| US10181857B1 (en) * | 2017-08-30 | 2019-01-15 | Texas Instruments Incorporated | Analog-to-digital converter error correction |
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| CN106501714A (en) * | 2016-12-09 | 2017-03-15 | 上海航空电器有限公司 | A kind of digitizing switch detection circuit and method with fault diagnosis functions |
| US10181857B1 (en) * | 2017-08-30 | 2019-01-15 | Texas Instruments Incorporated | Analog-to-digital converter error correction |
| CN207399180U (en) * | 2017-11-01 | 2018-05-22 | 无锡华润矽科微电子有限公司 | Reference voltage adaptive circuit structure and related device |
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