A single-chip microcomputer power supply circuit suitable for battery management system

Abstract

The present invention discloses a single-chip power supply circuit suitable for a battery management system, comprising a first direct current source, a reference source, a signal conversion unit, a current mirror circuit unit and a reference source driving unit; the voltage output end of the first direct current source and the reference voltage output end of the reference source are respectively connected to the Vdda pin of the single-chip computer; the reference source driving unit comprises an output driver and a resistor string composed of a plurality of resistors connected in series, and the current output end of the output driver is connected to the power input end of the reference source. The signal conversion unit is used to convert a voltage signal into a current signal, and the current of the current mirror circuit unit flows through the resistor string in the reference source driving unit, and further provides a working power supply for the reference source after passing through the output driver, and at this time, the reference source can supply power to the ADC of the single-chip computer. The present invention can provide a traditional low-power LDO output power supply or a high-precision reference source for the single-chip computer ADC according to the accuracy and power consumption requirements, and can achieve low power consumption and low temperature drift.

Description

Technical Field

[0001] The invention relates to the technical field of direct current power supply, in particular to a single chip microcomputer power supply circuit suitable for a battery management system. Background Art

[0002] The power supply of the internal ADC of the microcontroller is provided by Vdda, an analog power supply. In application scenarios where the accuracy requirement is not high, the traditional low-power LDO (low-dropout linear regulator) can power the Vdda pin of the microcontroller. However, in applications where the accuracy requirement is very high, a high-precision, low-temperature drift reference source must be used as a separate ADC reference power supply, and the traditional LDO cannot meet the accuracy requirements.

[0003] However, since the reference sources are all low-voltage components and consume a lot of power, they will have a short standby time when used in the power-sensitive battery field. For example, in a battery management system, if the reference source is always used as the power supply for the microcontroller, it will cause power consumption problems. If this reference source is also used as a reference power supply to drive some thermistors, etc., the power consumption will increase. Summary of the invention

[0004] The purpose of the present invention is to provide a single-chip microcomputer power supply circuit suitable for a battery management system, which can provide a traditional LDO output power supply for the single-chip microcomputer ADC according to the accuracy and power consumption requirements, or be powered by a reference source, so as to achieve low power consumption and low temperature drift of the single-chip microcomputer power supply circuit.

[0005] The technical solution adopted by the present invention is: a single-chip microcomputer power supply circuit suitable for a battery management system, comprising a first DC source, a reference source, a signal conversion unit, a current mirror circuit unit and a reference source driving unit; the single-chip microcomputer comprises an analog circuit power supply pin Vdda and a driving output level pin;

[0006] The voltage output terminal of the first DC source and the reference voltage output terminal of the reference source are respectively connected to the Vdda pin of the single chip computer;

[0007] The signal conversion unit includes a first controllable switch Q1 and a loop resistor R1; a driving input end of the first controllable switch Q1 is connected to a driving output level pin of the single chip microcomputer, one end of the loop resistor R1 is grounded, and the other end is connected to a current mirror circuit via the first controllable switch Q1;

[0008] The current mirror circuit unit includes a second DC source, a second controllable switch Q2 and a third controllable switch Q3 whose driving input ends are interconnected, and mirror resistors R1 and R2; one end of each of the two mirror resistors is connected to the second DC source, and the other end is correspondingly connected to the current input ends of Q2 and Q3, respectively; the current output ends of Q2 and Q3 are respectively connected to the current input end of the first controllable switch Q1 and the reference source driving unit;

[0009] The reference source driving unit includes an output driver and a resistor string consisting of multiple resistors connected in series; one end of the resistor string is connected to the current output end of Q3, and the other end is grounded; the driving input end of the output driver is connected between the resistor string and the collector of Q3, and the current output end is connected to the power input end of the reference source.

[0010] In the present invention, the first DC source and the second DC source can adopt ordinary LDO DC power supplies, the signal conversion unit is used to convert the voltage signal into a current signal, the current of the current mirror circuit unit flows through the resistor string in the reference source driving unit, and further provides a working power supply for the reference source after passing through the output driver. At this time, the reference source can supply power to the ADC of the single-chip microcomputer, and the power output of the first DC source can be automatically stopped.

[0011] Furthermore, the reference source also includes an enable terminal, and the single-chip microcomputer also includes a reference source control output terminal, and the single-chip microcomputer transmits an enable control signal to the reference source through the reference source control output terminal. In this implementation, the reference source only starts to work in the enabled state, so that the single-chip microcomputer can independently select the LDO power supply or the reference source for power supply according to the accuracy requirements. When the reference source needs to be selected, the drive output level pin outputs the drive level and outputs the enable control signal at the same time.

[0012] Furthermore, the reference source driving unit also includes a voltage follower circuit, which includes a fifth controllable switch Q5 and a sixth resistor R6, the current input end of Q5 is connected to the second DC source, the current output end is connected to one end of R6, the driving input end is connected between the current output end of Q3 and R4, and the other end of R6 is grounded.

[0013] Optionally, the fifth controllable switch Q5 is an NPN transistor or an NMOS transistor. When a transistor is used, its collector is the current input section, the emitter is the current output terminal, and the base is the drive input terminal. When an NMOS transistor is used, its source is the current input section, the drain is the current output terminal, and the gate is the drive input terminal.

[0014] Optionally, Q1, Q4 and Q5 use NPN transistors, and Q2 and Q3 use PNP transistors.

[0015] Optionally, Q1 uses an NPN transistor, Q2 and Q3 use a PNP transistor, and Q4 and Q5 use an NMOS switch tube. Q4 and Q5 use MOS tubes instead of transistors to avoid the inability to provide sufficient driving current for the transistor base when the power consumption current is very small.

[0016] Optionally, Q1, Q4 and Q5 use N-channel MOS tubes, and Q2 and Q3 use P-channel MOS tubes, which can further reduce power consumption and improve driving capability.

[0017] Optionally, the output end of the first DC power supply is connected to the Vdda pin of the single-chip computer through a diode D1; the output voltage Vref of the reference source is greater than the voltage output value of the first DC source after the diode conduction voltage, and the first DC source will no longer provide current.

[0018] Optionally, the current output terminal of Q2 is connected to the current input terminal of Q1 and the control input terminal of Q2.

[0019] Since the voltage value output to the reference source is related to the drive level Vpow_EN output by the microcontroller, the resistance in the current mirror circuit unit and the resistance of the resistor string, by adjusting the resistance ratio of R1, R2, R3, and R5, a suitable voltage can be found to power the reference source. The voltage accuracy and temperature drift requirements of the power supply are not high, and it can be 200mV to 2V higher than the output of the reference source, which can avoid the reference source heating up and causing a large temperature rise.

[0020] Beneficial Effects

[0021] The present invention can provide the single-chip microcomputer ADC with a traditional low-power LDO output power supply or a high-precision reference source according to the accuracy and power consumption requirements: in the low-power state, the single-chip microcomputer is powered by a low-power high-voltage LDO through a diode D1; when used in a scene where power consumption is sensitive and accuracy requirements are high, such as a battery management system, a controllable power supply is generated to power the reference source, thereby starting the reference source, and the power output by the reference source replaces the traditional LDO power supply, so that the single-chip microcomputer can perform high-precision ADC conversion, and the low power consumption and low temperature drift of the single-chip microcomputer power supply circuit are realized as a whole, which can meet the high-precision requirements of the single-chip microcomputer ADC. At the same time, the present invention can achieve low temperature drift and low power consumption under the high-precision ADC conversion requirements by using MOS tubes as controllable switches. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 Shown is a circuit diagram of an embodiment of the present invention;

[0023] Figure 2 Shown is a circuit diagram of a second embodiment of the present invention;

[0024] Figure 3 FIG. 1 is a circuit diagram of a third embodiment of the present invention. DETAILED DESCRIPTION

[0025] The invention is further described below with reference to the accompanying drawings and specific embodiments.

[0026] The inventive concept of the present invention is to output a digital level drive through the pin of the single-chip microcomputer itself, and provide a working power supply for the reference source through a driving circuit, thereby controlling the operation of the reference source, so that the reference source provides a low-power and low-temperature drift power supply for the analog circuit power supply pin of the single-chip microcomputer to support the high-precision ADC conversion of the single-chip microcomputer. When high-precision ADC conversion is not required, the analog circuit power supply pin of the single-chip microcomputer can still be powered by a traditional LDO.

[0027] refer to Figures 1 to 3 , a single-chip microcomputer power supply circuit suitable for a battery management system, comprising a first DC source Vdd_MCU, a reference source Vref, a signal conversion unit, a current mirror circuit unit and a reference source driving unit; the single-chip microcomputer MCU comprises an analog circuit power supply pin Vdda and a driving output level pin Vpoe_EN;

[0028] The voltage output terminal of the first DC source and the reference voltage output terminal of the reference source are respectively connected to the Vdda pin of the single chip computer;

[0029] The signal conversion unit includes a first controllable switch Q1 and a loop resistor R1; a driving input end of the first controllable switch Q1 is connected to a driving output level pin of the single chip microcomputer, one end of the loop resistor R1 is grounded, and the other end is connected to a current mirror circuit via the first controllable switch Q1;

[0030] The current mirror circuit unit includes a second DC source, a second controllable switch Q2 and a third controllable switch Q3 whose driving input ends are interconnected, and mirror resistors R1 and R2; one end of each of the two mirror resistors is connected to the second DC source, and the other end is correspondingly connected to the current input ends of Q2 and Q3, respectively; the current output ends of Q2 and Q3 are respectively connected to the current input end of the first controllable switch Q1 and the reference source driving unit;

[0031] The reference source driving unit includes an output driver and a resistor string consisting of multiple resistors connected in series; one end of the resistor string is connected to the current output end of Q3, and the other end is grounded; the driving input end of the output driver is connected between the resistor string and the collector of Q3, and the current output end is connected to the power input end of the reference source.

[0032] In the present invention, the first DC source and the second DC source can adopt ordinary LDO DC power supplies, the signal conversion unit is used to convert the voltage signal into a current signal, the current of the current mirror circuit unit flows through the resistor string in the reference source driving unit, and further provides a working power supply for the reference source after passing through the output driver. At this time, the reference source can supply power to the ADC of the single-chip microcomputer, and the power output of the first DC source can be stopped at the same time.

[0033] Example 1

[0034] like Figure 1As shown, in this embodiment, the reference source also includes an enable terminal, and the single-chip microcomputer also includes a reference source control output terminal, and the single-chip microcomputer transmits an enable control signal EN to the reference source through the reference source control output terminal. In this implementation mode, the reference source starts working only when it is in the enabled state, so that the single-chip microcomputer can independently select the LDO power supply or the reference source for power supply according to the accuracy requirements. When the reference source needs to be selected, the drive output level pin outputs the drive level and outputs the enable control signal at the same time.

[0035] The reference source driving unit also includes a voltage follower circuit, which includes a fifth controllable switch Q5 and a sixth resistor R6, wherein the current input end of Q5 is connected to the second DC source, the current output end is connected to one end of R6, the driving input end is connected between the current output end of Q3 and R4, and the other end of R6 is grounded. The fifth controllable switch Q5 is an NPN transistor or a MOS transistor. When a transistor is used, its collector is the current input section, the emitter is the current output end, and the base is the driving input end.

[0036] In this embodiment, Q1, Q4 and Q5 are NPN transistors, and Q2 and Q3 are PNP transistors.

[0037] The output end of the first DC power supply is connected to the Vdda pin of the single chip microcomputer through a diode D1; the output voltage Vref of the reference source is greater than the voltage difference between the first DC source and the voltage across the diode. When the single chip microcomputer MCU has a separate Vref pin, the pin can also be connected to the output end of D1.

[0038] The current output terminal of Q2 is connected to the current input terminal of Q1 and the control input terminal of Q2.

[0039] Since the voltage value output to the reference source is related to the drive level Vpow_EN output by the microcontroller, the resistance in the current mirror circuit unit and the resistance of the resistor string, by adjusting the resistance ratio of R1, R2, R3, and R5, a suitable voltage can be found to power the reference source. The voltage accuracy and temperature drift requirements of the power supply are not high, and it can be 200mV to 2V higher than the output of the reference source, which can avoid the reference source heating up and causing a large temperature rise.

[0040] The working principle of the present invention is as follows.

[0041] In the signal conversion unit, Q1 and R1 form a current generating circuit, and the current I = (Vpow_EN-Vbe_Q1) / R1, Vbe_Q1 is the voltage drop on Q1, and the level of Vpow_EN is the level of the digital power supply of the microcontroller, generally Vdd_MCU. A current can be obtained by selecting the value of R1.

[0042] In the current mirror circuit, Q2, Q3, R2, and R3 form a current mirror, and the current Io=Iin* R3 / R2.

[0043] The output voltage of Q4 = Io*R5 = (Vpow_EN-Vbe_O1) / R1* R3 / R2* R5-Vbe_Q4, so by adjusting the resistance ratio of R1, R2, R3, and R5, you can find a suitable voltage to power the reference source. The voltage accuracy and temperature drift requirements of the power supply are not high, as long as it is 200mV to 2V higher than the output of the reference source. The current of Iin and Io can reach 10uA level. When selecting transistors, just ensure that the current amplification factor is greater than 10.

[0044] In addition, R6 and R7 provide a bias current to Q4 and Q5, which can be very small. More resistors can be connected in series on the output branch of Io to produce different voltage outputs.

[0045] The reference source startup mode is: the single-chip microcomputer outputs the Vpow_EN signal to make the current mirror circuit generate the current Io, Q4 is turned on, and the reference source module is connected to the power supply Vdd; at the same time, the single-chip microcomputer outputs the EN signal to control the reference source module, so that the reference source outputs the voltage, and Vdda is powered by the reference source. When low power consumption is required, the reference source is turned off with the EN signal, and the single-chip microcomputer pin Vdda is powered by the first power supply, but the current of the current mirror still exists. At this time, all circuits related to the reference source can be turned off by turning off the POW_EN signal, and the system power consumption is lower.

[0046] In application, the equivalent power consumption of the power supply and reference source can be controlled by controlling the duty cycle of Vpow_EN or EN. For example, the current of the entire circuit including the drive circuit and load behind Vref is IQ. When the enabling time is Ton and the closing time is Toff, the equivalent power consumption current of the entire power supply is Ieff=IQ*Ton / (Ton+Toff). For example, it is turned on for 10s and turned off for 30 minutes, which reduces the equivalent power consumption by 180 times.

[0047] Example 2

[0048] refer to Figure 2 As shown, different from the embodiment, in this embodiment, Q1 adopts NPN transistor, Q2 and Q3 adopt PNP transistor, Q4 and Q5 adopt NMOS switch tube, which can support the situation of very small current consumption.

[0049] Example 3

[0050] refer to Figure 3 As shown, the difference from Embodiment 1 and Embodiment 2 is that Q1, Q4 and Q5 use N-channel MOS tubes, and Q2 and Q3 use P-channel MOS tubes, which can further reduce power consumption and improve driving capability.

[0051] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the technical principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A single-chip microcomputer power supply circuit suitable for a battery management system, characterized in that: It includes a first direct current source, a reference source, a signal conversion unit, a current mirror circuit unit and a reference source driving unit; the single chip microcomputer includes an analog circuit power supply pin Vdda and a driving output level pin; The voltage output terminal of the first DC source and the reference voltage output terminal of the reference source are connected to the Vdda pin of the single chip computer; The signal conversion unit includes a first controllable switch Q1 and a loop resistor R1; the control input end of the first controllable switch Q1 is connected to the drive output level pin of the single chip microcomputer, one end of the loop resistor R1 is grounded, and the other end is connected to the current mirror circuit via the first controllable switch Q1; The current mirror circuit unit includes a second DC source, a second controllable switch Q2 and a third controllable switch Q3 whose driving input ends are interconnected, and mirror resistors R1 and R2; one end of each of the two mirror resistors is connected to the second DC source, and the other end is respectively connected to the current input ends of Q2 and Q3, the current output end of Q2 is connected to the current input end of the first controllable switch Q1, and the current output end of Q3 is connected to the reference source driving unit; The reference source driving unit includes an output driver and a resistor string consisting of resistors R4 and R5 connected in series; the resistor R4 is connected to the current output end of Q3, and the resistor R5 is grounded; The driving input terminal of the output driver is connected between the resistor R4 and the current output terminal of Q3, and the current output terminal of the output driver is connected to the power input terminal of the reference source.

2. The single-chip microcomputer power supply circuit suitable for a battery management system according to claim 1 is characterized in that: The reference source also includes an enable terminal, and the single-chip microcomputer also includes a reference source control output terminal. The single-chip microcomputer transmits an enable control signal to the reference source through the reference source control output terminal.

3. The single chip microcomputer power supply circuit suitable for a battery management system according to claim 1 or 2, characterized in that: The reference source driving unit also includes a voltage follower circuit, which includes a fifth controllable switch Q5 and a sixth resistor R6, wherein the current input end of Q5 is connected to the second DC source, the current output end is connected to one end of R6, the driving input end is connected between the current output end of Q3 and the resistor R4, and the other end of R6 is grounded.

4. The single chip microcomputer power supply circuit suitable for a battery management system according to claim 3, characterized in that: Q1, Q4 and Q5 use NPN transistors connected in emitter follower form, and Q2 and Q3 use PNP transistors.

5. The single chip microcomputer power supply circuit suitable for a battery management system according to claim 3, characterized in that: Q1 uses NPN transistor, Q2 and Q3 use PNP transistor, Q4 and Q5 use NMOS switch tube, and they are connected in a follower form.

6. The single chip microcomputer power supply circuit suitable for a battery management system according to claim 3, characterized in that: Q1, Q4 and Q5 use N-channel MOS tubes, and Q2 and Q3 use P-channel MOS tubes.

7. The single chip microcomputer power supply circuit suitable for a battery management system according to claim 1 or 2, characterized in that: The output end of the first DC power supply is connected to the Vdda pin of the single chip computer through a diode D1; the output voltage Vref of the reference source is greater than the voltage output value of the first DC source after the diode conduction voltage.

8. The single-chip microcomputer power supply circuit suitable for a battery management system according to claim 1 or 2, characterized in that: The current output terminal of Q2 is connected to the current input terminal of Q1 and the control input terminal of Q2.

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