Low power consumption battery power detection circuit and meter

Abstract

The application relates to the field of battery detection, in particular to a low-power-consumption battery power detection circuit and an instrument, which comprises a signal receiving module, an output end of the signal receiving module is connected to a signal collecting end, and the signal receiving module is used for sending a voltage value signal output by a battery to be detected to the signal collecting end; an operational amplifier module, an input end of the operational amplifier module is connected to the battery to be detected, an output end of the operational amplifier module is connected to an input end of the signal receiving module, and the operational amplifier module is used for collecting the voltage value signal output by the battery to be detected and transmitting the voltage value signal to the signal receiving module. When the application detects the battery to be detected, the battery to be detected does not need to discharge the operational amplifier module, voltage detection of the battery to be detected can be realized, and the loss of the battery to be detected can be reduced.

Description

Technical Field

[0001] This application relates to the field of battery detection, and in particular to a low-power battery power detection circuit and instrument. Background Technology

[0002] Industrial automation instruments typically have dedicated battery-powered circuits for components like RTCs and external clocks. To facilitate reading the remaining battery power, a dedicated battery power detection circuit is usually included. Common battery detection circuits include... Figure 1 As shown, the transistor is turned on by controlling the CON terminal so that the battery supplies power to the two resistors. The voltage between the two resistors is sampled by the ADC to calculate VBAT (the battery's output voltage), and then the remaining battery power is calculated.

[0003] However, in practical applications, CON samples the remaining battery power according to a preset sampling frequency. Especially when performing real-time sampling, the potential at the CON terminal needs to output a high level at a high frequency, causing VBAT to discharge frequently to the resistor, which shortens the battery's usable time and increases the battery replacement frequency. Utility Model Content

[0004] In a first aspect, this application provides a low-power battery power detection circuit, which adopts the following technical solution: A low-power battery power detection circuit includes: The signal receiving module has its output connected to the signal acquisition terminal, and it is used to send the voltage value signal output by the battery under test to the signal acquisition terminal. The operational amplifier module has its positive input connected to the battery under test, and its output connected to the input of the signal receiving module. The operational amplifier module is used to acquire the voltage value signal output by the battery under test and transmit the voltage value signal to the signal receiving module.

[0005] By adopting the above technical solution, the positive input terminal of the operational amplifier module is connected to the battery under test. The input impedance of the operational amplifier module is large, and the current flowing through the operational amplifier module is small. Therefore, when testing the battery under test, the voltage of the battery under test can be detected without discharging the operational amplifier module, thereby reducing the loss of the battery under test.

[0006] Preferably, the operational amplifier module includes a follower operational amplifier, the positive input terminal of which is connected to the battery under test, the negative input terminal of which is connected to the output terminal of which, and the follower operational amplifier is connected in series with a preset power supply.

[0007] By adopting the above technical solution, the positive input terminal of the follower operational amplifier is connected to the battery under test. The follower operational amplifier has a specific circuit configuration. Based on the function of voltage gain of 1, no matter what voltage signal is input to the input terminal of the follower operational amplifier, the output voltage is always consistent with the input voltage. This enables the signal receiving module to output the voltage value signal of the battery under test in real time, so as to realize the real-time monitoring of the battery under test.

[0008] Preferably, the voltage applied to the follower operational amplifier by the preset power supply is greater than the output voltage of the battery under test.

[0009] Preferably, it also includes a battery blocking module, the input terminal of which is connected to the battery under test, and the output terminal of which is connected to the positive input terminal of the operational amplifier module. The battery blocking module is used to regulate the signal on / off state between the battery under test and the operational amplifier module.

[0010] By adopting the above technical solution, the battery blocking module controls the signal to be in the on state, and the signal receiving module sends the voltage value signal output by the battery under test to the signal acquisition terminal. Through the on / off control of the battery blocking module, the voltage value output by the battery under test can be monitored in real time.

[0011] Preferably, the battery blocking module includes a switching unit, which is an NMOS transistor. The drain of the switching unit is connected to the output terminal of the battery under test, the source of the switching unit is connected to the positive input terminal of the operational amplifier module, and the gate of the switching unit is connected to an external control signal source. The external control signal source outputs a square wave signal to switch the on / off state between the source and drain of the switching unit.

[0012] By adopting the above technical solution, the input current of the NMOS transistor is extremely small or almost zero. In addition, the input current of the operational amplifier module is very small. When the battery under test is tested for power detection, the battery under test does not need to discharge to the NMOS transistor and the operational amplifier module. The power consumption of the battery under test for discharge detection is very small, thereby saving battery power and extending battery life.

[0013] Preferably, the battery blocking module further includes a circuit protection unit, which is located between the switching unit and the battery under test. One end of the circuit protection unit is connected to the output terminal of the battery under test, and the other end is connected to one end of the switching unit. The circuit protection unit is used to control the direction of current flow from the battery under test to the switching unit.

[0014] Preferably, the circuit protection unit uses a diode, with the anode of the diode connected to the battery under test and the cathode of the diode connected to the drain of the switching unit.

[0015] By adopting the above technical solution, a diode is added between the battery under test and the switching unit. The anode of the diode is connected to the battery under test, and the cathode of the diode is connected to the drain of the switching unit. This ensures that the current always flows from the battery under test to the switching unit, preventing the output current of the operational amplifier module from flowing into the battery under test and reducing the loss of the battery under test.

[0016] Secondly, this application provides an industrial automation instrument, which adopts the following technical solution: An industrial automation instrument includes a low-power battery power detection circuit as described in the first aspect, comprising an instrument power-on module, which continuously inputs a high level to a battery blocking module to control the battery blocking module to adjust the connection between the battery under test and the operational amplifier module to be in a conducting state.

[0017] Preferably, it also includes a signal processing module, which is used to receive the voltage value signal output by the signal receiving module and generate the remaining power of the battery under test based on the voltage value signal.

[0018] In summary, this application includes the following beneficial technical effects: the positive input terminal of the operational amplifier module is connected to the battery under test, the input impedance of the operational amplifier module is large, and the current flowing through the operational amplifier module is small. Therefore, when testing the battery under test, the voltage of the battery under test can be detected without discharging the operational amplifier module, thereby reducing the loss of the battery under test. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of a commonly used battery detection circuit; Figure 2 These are schematic diagrams of the detection circuits disclosed in Embodiments 1 and 2 of this application; Figure 3 This is a schematic diagram of the detection circuit disclosed in Embodiment 3 of this application.

[0020] Explanation of reference numerals in the attached diagram: 10, signal receiving module; 20, operational amplifier module; 21, follower operational amplifier; 30, battery blocking module; 31, switching unit; 32, circuit protection unit. Detailed Implementation

[0021] The present application will be further described in detail below with reference to the accompanying drawings.

[0022] In a first aspect, embodiments of this application disclose a low-power battery power detection circuit.

[0023] Example 1: As Figure 2As shown, the low-power battery power detection circuit includes a signal receiving module 10 and an operational amplifier module 20. The output terminal of the signal receiving module 10 is connected to the signal acquisition terminal, and the signal receiving module 10 is used to send the voltage value signal output by the battery under test to the signal acquisition terminal. The input terminal of the operational amplifier module 20 is connected to the battery under test, and the output terminal of the operational amplifier module 20 is connected to the input terminal of the signal receiving module 10. The operational amplifier module 20 is used to acquire the voltage value signal output by the battery under test and transmit the voltage value signal to the signal receiving module 10.

[0024] The signal receiving module 10 is connected to the signal processing module of the industrial automation instrument. The signal processing module has a signal acquisition terminal MCU_BATCAL. The main function of the signal receiving module 10 is to filter the received voltage signal, so that the signal processing module can perform analog-to-digital conversion and data calculation on the filtered voltage signal to calculate the voltage value output by the battery under test (VBAT) and the remaining power of the battery under test.

[0025] In this embodiment, the signal processing module includes an MCU, which is a single-chip microcomputer in the industrial instrument hardware circuit. The input terminal of the signal acquisition module 10 is connected to the signal acquisition terminal MCU_BATCAL of the MCU.

[0026] Specifically, the signal receiving module 10 also includes resistors R3 and R4 and capacitor C2. One end of resistor R3 is connected to the output of the follower operational amplifier, and the other end of resistor R3 is connected to the signal acquisition terminal MCU_BATCAL. Resistor R4 and capacitor C2 are connected in parallel, with one end of the parallel connection connected to the connection point between resistor R3 and the signal acquisition terminal MCU_BATCAL, and the other end grounded.

[0027] The input terminal of the operational amplifier module 20 is connected to the battery under test, and the output terminal of the operational amplifier module 20 is connected to the signal receiving module 10. The operational amplifier module 20 is used to receive the voltage value signal of the battery under test and transmit the voltage value signal to the signal receiving module 10.

[0028] Specifically, the operational amplifier module 20 includes a follower operational amplifier 21. The positive input terminal of the follower operational amplifier 21 is connected to the battery under test, and the negative input terminal of the follower operational amplifier 21 is connected to its output terminal. The follower operational amplifier 21 is connected in series with a preset power supply. The voltage applied to the follower operational amplifier 21 by the preset power supply is greater than the output voltage of the battery under test.

[0029] The preset power supply refers to the power supply provided by the instrument power-on module to the follower operational amplifier 21. The power supply voltage can be set according to the output voltage of the battery under test, as long as the voltage applied by the instrument power-on module to the follower operational amplifier 21 is greater than the output voltage of the battery under test.

[0030] Specifically, the operational amplifier module 20 also includes a resistor R2 and a capacitor C1. The positive input terminal of the follower operational amplifier is connected to one end of the resistor R2, and the other end of the resistor R2 is connected to the battery under test. The negative input terminal of the follower operational amplifier is connected to the output terminal of the follower operational amplifier. The follower operational amplifier can transmit the voltage of the received resistor under test to the signal receiving module 10. One end of the capacitor C1 is connected to the connection point of the series circuit between the follower operational amplifier and the preset power supply, and the other end of the capacitor C1 is grounded. In this embodiment, the output voltage of the battery under test is at most 3V. Therefore, the preset power supply is 3.3V, which ensures that the power supply of the follower operational amplifier can cover the output voltage of the battery under test.

[0031] It should be noted that both capacitors and resistors utilize their conventional circuit characteristics, and there are no restrictions on their values. Therefore, we will not elaborate further on this point.

[0032] The implementation principle is as follows: The positive input terminal of the follower operational amplifier 21 is connected to the battery under test, and the negative input terminal is connected to the output terminal of the follower operational amplifier 21. The follower operational amplifier 21 can transmit the voltage of the received resistor under test to the signal receiving module 10. The follower operational amplifier 21 has a specific circuit configuration. Based on the function of voltage gain of 1, the output voltage is always consistent with the input voltage, regardless of the voltage signal input to the input terminal of the follower operational amplifier 21. This enables the signal receiving module 10 to output the voltage value signal of the battery under test in real time, so as to realize the real-time monitoring of the battery under test.

[0033] Example 2: As Figure 2 and Figure 3 As shown, unlike Embodiment 1, the low-power battery power detection circuit also includes a battery blocking module 30. The input terminal of the battery blocking module 30 is connected to the battery under test, and the output terminal of the battery blocking module 30 is connected to the positive input terminal of the operational amplifier module 20. The battery blocking module 30 is used to regulate the signal on / off state between the battery under test and the operational amplifier module 20. When the battery blocking module 30 controls the battery under test to be in a conducting state with the operational amplifier module 20, the signal receiving module can receive the voltage value signal transmitted by the operational amplifier module 20.

[0034] The signal continuity status includes a conducting state and a disconnected state. A conducting state indicates that a circuit is formed between the battery under test (VBAT) and the operational amplifier module 20, meaning the signal receiving module 10 can receive the voltage signal. A disconnected state indicates that there is no circuit between the battery under test (VBAT) and the operational amplifier module 20, and the signal receiving module 10 cannot receive the voltage signal.

[0035] The battery blocking module 30 includes a switching unit 31, which is an NMOS transistor. The drain of the switching unit 31 is connected to the output terminal of the battery under test, and the source of the switching unit 31 is connected to the positive input terminal of the operational amplifier module 20. The gate of the switching unit 31 is connected to an external control signal source, which outputs a square wave signal to switch the on / off state between the source and drain of the NMOS transistor Q.

[0036] The external control signal source includes a high-level signal. When the switching unit 31 continuously receives a high-level signal, it controls the on / off state between its source and drain, thereby ensuring that the battery under test (VBAT) and the operational amplifier module 20 are in a conductive state. The high-level signal refers to the signal continuously input to the switching unit 31 after the automatic instrument is powered on. Under the control of the high-level signal, the switching unit 31 can adjust the battery under test and the operational amplifier module 20 to be in a conductive state, thus enabling a circuit between the battery under test (VBAT) and the operational amplifier module 20.

[0037] Specifically, the switching unit 31 uses an NMOS transistor Q. This application uses an N-channel field-effect transistor. During wiring, for the N-channel type, the drain of the NMOS transistor Q is connected to the output terminal of the battery under test, and the source of the switching unit 31 is connected to the positive input terminal of the follower operational amplifier 21. A resistor R2 is connected in series between the source of the switching unit 31 and the positive input terminal of the follower operational amplifier 21. The gate terminal (G) of the NMOS transistor Q is connected in series with a resistor R1 and then connected to the instrument power supply, which provides a 5V voltage.

[0038] For an N-channel MOSFET, the source (S) and drain (D) are connected to an N-type semiconductor. This structure allows the output current of the MOSFET to be effectively controlled by the input voltage. Notably, the input current of this device is extremely small or almost zero, and the source of the NMOS transistor is connected to the positive input of the follower operational amplifier 21. The current flowing through the NMOS transistor Q and the follower operational amplifier 21 is very small. The battery under test does not need to supply power to the NMOS transistor Q or the follower operational amplifier 21, allowing the follower operational amplifier 21 to transmit the entire output voltage of the battery under test to the signal receiving module 10. This conserves battery power and extends battery life.

[0039] It should be noted that no matter how large the resistor R2 connected in series between the NMOS transistor Q and the follower operational amplifier 21 is, the current flowing through the resistor R2 is extremely small. Therefore, the resistance value of the resistor R2 is not specifically limited.

[0040] Furthermore, when the automated instrument is not powered on, no voltage is applied to the gate (G) and source (S) of the NMOS transistor Q, i.e., VGS=0. Because the N+ type region between the drain and source is separated by the P-type substrate, two back-to-back PN junctions are formed. The resistance between these two PN junctions is as high as 10¹² Ω, preventing the formation of a conductive channel between D and S. Therefore, regardless of the polarity of the voltage applied between the drain and source, no drain current ID is generated.

[0041] When the automated instrument is powered on, a positive voltage is applied between the gate (G) and the source (S), i.e., VGS > 0. This generates an electric field between the gate and the substrate, pointing from the gate to the substrate. In the MOSFET Q, when the gate voltage VGS exceeds a certain threshold, it will conduct. This ensures that after the automated instrument is powered on, the instrument's power supply circuit continuously inputs a high level to the NMOS transistor Q to enable its conduction.

[0042] The implementation principle is as follows: When the automated instrument is powered on, the instrument's power supply circuit continuously inputs a high-level signal to the NMOS transistor Q. The NMOS transistor Q is in the on state based on the on / off state of the control signal based on the high-level signal. The source of the NMOS transistor is connected to the positive input terminal of the follower operational amplifier 21. The current flowing through the NMOS transistor Q and the follower operational amplifier 21 is very small. The battery under test does not need to supply power to the NMOS transistor Q and the follower operational amplifier 21. The follower operational amplifier 21 can then transmit all the output voltage of the battery under test to the signal receiving module 10, thereby saving battery power and extending battery life.

[0043] Example 3: Reference Figure 2 and Figure 3 Unlike embodiment 2, the battery blocking module 30 also includes a circuit protection unit 32. The circuit protection unit 32 is located between the switching unit 31 and the battery under test. One end of the circuit protection unit 32 is connected to the output terminal of the battery under test, and the other end is connected to the drain of the switching unit 31. The circuit protection unit 32 is used to control the direction of current flow from the battery under test to the switching unit 31.

[0044] Specifically, the circuit protection unit 32 is configured as a diode, with the anode of the diode connected to the battery under test and the cathode of the diode connected to the drain of the switching unit 31. This effectively prevents the current output from the switching unit 31 from flowing in reverse to the battery under test when the NMOS is turned off, thereby avoiding damage to the battery under test due to current.

[0045] The implementation principle is as follows: When the automated instrument is powered off, the current from the reverse output of the follower amplifier connects to the body diode in the NMOS transistor through the subsequent load circuit, causing the body diode to conduct. At this time, the source voltage is approximately 0.7V, the voltage required for the body diode to conduct. Simultaneously, the gate (G) is also connected to the instrument's power-on module, making Vgs = Vcc - 0.7V. This value is greater than the threshold voltage Vgsth of the NMOS transistor, so the current in the NMOS transistor flows from the source to the drain, causing some loss in the battery under test VBAT under current loading. Therefore, a diode D is added between VBAT and the NMOS transistor to ensure that the current direction always flows from the battery under test VBAT to the switching unit 31.

[0046] Secondly, embodiments of this application also disclose an industrial automation instrument.

[0047] Combination Figure 2 and Figure 3 The industrial automation instrument includes a low-power battery power detection circuit, comprising an instrument power-on module and a signal processing module. The instrument power-on module inputs a high-level signal to the battery blocking module 30 to control the battery blocking module 30 to adjust its signal acquisition state to the on state. The signal processing module receives the voltage value signal output by the signal receiving module 10 and generates the remaining power of the battery under test based on the voltage value signal.

[0048] The implementation principle is as follows: The instrument's power supply circuit continuously inputs a high-level signal to the NMOS transistor Q. Based on the high-level signal, the NMOS transistor Q is in the on state, which enables the signal processing module to receive the voltage value signal output by the signal receiving module 10 at the signal acquisition terminal. The processing chip then determines the remaining charge corresponding to the battery VBAT under test based on the voltage value signal.

[0049] The above are all preferred embodiments of this application, and are not intended to limit the scope of protection of this application. Therefore, all equivalent changes made in accordance with the structure, shape and principle of this application should be covered within the scope of protection of this application.

Claims

1. A low-power battery power detection circuit, characterized in that, include: The signal receiving module (10) has an output terminal connected to a signal acquisition terminal, and the signal receiving module (10) is used to send the voltage value signal output by the battery under test to the signal acquisition terminal. Operational amplifier module (20), the input terminal of the operational amplifier module (20) is connected to the battery under test, the output terminal of the operational amplifier module (20) is connected to the input terminal of the signal receiving module (10), the operational amplifier module (20) is used to collect the voltage value signal output by the battery under test and transmit the voltage value signal to the signal receiving module (10).

2. The low-power battery power detection circuit according to claim 1, characterized in that, The operational amplifier module (20) includes a follower operational amplifier (21), the positive input terminal of which is connected to the battery under test, the negative input terminal of which is connected to the output terminal of which is connected, and the follower operational amplifier (21) is connected in series with a preset power supply.

3. The low-power battery power detection circuit according to claim 1, characterized in that, It also includes a battery blocking module (30), the input terminal of which is connected to the battery under test, and the output terminal of which is connected to the positive input terminal of the operational amplifier module (20). The battery blocking module (30) is used to regulate the signal on / off state between the battery under test and the operational amplifier module (20).

4. The low-power battery power detection circuit according to claim 3, characterized in that, The battery blocking module (30) includes a switching unit (31), which is an NMOS transistor. The drain of the switching unit (31) is connected to the output terminal of the battery under test, and the source of the switching unit (31) is connected to the positive input terminal of the operational amplifier module (20). The gate of the switching unit (31) is connected to an external control signal source, which outputs a square wave signal to switch the on / off state between the source and drain of the switching unit (31).

5. The low-power battery charge detection circuit according to claim 4, characterized in that, The battery blocking module (30) further includes a circuit protection unit (32), which is located between the switch unit (31) and the battery under test. One end of the circuit protection unit (32) is connected to the output terminal of the battery under test, and the other end is connected to one end of the switch unit (31). The circuit protection unit (32) is used to control the direction of current flow from the battery under test to the switch unit (31).

6. The low-power battery power detection circuit according to claim 5, characterized in that, The circuit protection unit (32) uses a diode, and the anode of the diode is connected to the battery under test, while the cathode of the diode is connected to the drain of the switching unit (31).

7. The low-power battery power detection circuit according to claim 2, characterized in that, The voltage applied by the preset power supply to the follower operational amplifier (21) is greater than the output voltage of the battery under test.

8. An industrial automation instrument, characterized in that, The low-power battery power detection circuit according to any one of claims 1-7 further includes an instrument power-on module, which is used to continuously input a high level to the battery blocking module (30) to control the battery blocking module (30) to adjust the battery under test and the operational amplifier module (20) to be in a conducting state.

9. The industrial automation instrument according to claim 8, characterized in that, It also includes a signal processing module, which is used to receive the voltage value signal output by the signal receiving module (10) and generate the remaining power of the battery under test based on the voltage value signal.

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